Science.gov

Sample records for acetoacetate decarboxylase adc

  1. Purification of acetoacetate decarboxylase from Clostridium acetobutylicum ATCC 824 and cloning of the acetoacetate decarboxylase gene in Escherichia coli

    SciTech Connect

    Petersen, D.J.; Bennett, G.N. )

    1990-11-01

    In Clostridium acetobutylicum ATCC 824, acetoacetate decarboxylase (EC 4.1.1.4) is essential for solvent production, catalyzing the decarboxylation of acetoacetate to acetone. We report here the purification of the enzyme from C. acetobutylicum ATCC 824 and the cloning and expression of the gene encoding the acetoacetate decarboxylase enzyme in Escherichia coli. A bacteriophage lambda EMBL3 library of C. acetobutylicum DNA was screened by plaque hybridization, using oligodeoxynucleotide probes derived from the N-terminal amino acid sequence obtained from the purified protein. Phage DNA from positive plaques was analyzed by Southern hybridization. Restriction mapping and subsequent subcloning of DNA fragments hybridizing to the probes localized the gene within an {approximately}2.1-kb EcoRI/BglII fragment. A polypeptide with a molecular weight of {approximately}28,000 corresponding to that of the purified acetoacetate decarboxylase was observed in both Western blots (immunoblots) and maxicell analysis of whole-cell extracts of E. coli harboring the clostridial gene. Although the expression of the gene is tightly regulated in C. acetobutylicum, it was well expressed in E. coli, although from a promoter sequence of clostridial origin.

  2. Sbi00515, a Protein of Unknown Function from Streptomyces bingchenggensis, Highlights the Functional Versatility of the Acetoacetate Decarboxylase Scaffold.

    PubMed

    Mueller, Lisa S; Hoppe, Robert W; Ochsenwald, Jenna M; Berndt, Robert T; Severin, Geoffrey B; Schwabacher, Alan W; Silvaggi, Nicholas R

    2015-06-30

    The acetoacetate decarboxylase-like superfamily (ADCSF) is a group of ~4000 enzymes that, until recently, was thought to be homogeneous in terms of the reaction catalyzed. Bioinformatic analysis shows that the ADCSF consists of up to seven families that differ primarily in their active site architectures. The soil-dwelling bacterium Streptomyces bingchenggensis BCW-1 produces an ADCSF enzyme of unknown function that shares a low level of sequence identity (~20%) with known acetoacetate decarboxylases (ADCs). This enzyme, Sbi00515, belongs to the MppR-like family of the ADCSF because of its similarity to the mannopeptimycin biosynthetic protein MppR from Streptomyces hygroscopicus. Herein, we present steady state kinetic data that show Sbi00515 does not catalyze the decarboxylation of any α- or β-keto acid tested. Rather, we show that Sbi00515 catalyzes the condensation of pyruvate with a number of aldehydes, followed by dehydration of the presumed aldol intermediate. Thus, Sbi00515 is a pyruvate aldolase-dehydratase and not an acetoacetate decarboxylase. We have also determined the X-ray crystal structures of Sbi00515 in complexes with formate and pyruvate. The structures show that the overall fold of Sbi00515 is nearly identical to those of both ADC and MppR. The pyruvate complex is trapped as the Schiff base, providing evidence that the Schiff base chemistry that drives the acetoacetate decarboxylases has been co-opted to perform a new function, and that this core chemistry may be conserved across the superfamily. The structures also suggest possible catalytic roles for several active site residues. PMID:26039798

  3. Conversion of levulinic acid to 2-butanone by acetoacetate decarboxylase from Clostridium acetobutylicum.

    PubMed

    Min, Kyoungseon; Kim, Seil; Yum, Taewoo; Kim, Yunje; Sang, Byoung-In; Um, Youngsoon

    2013-06-01

    In this study, a novel system for synthesis of 2-butanone from levulinic acid (γ-keto-acid) via an enzymatic reaction was developed. Acetoacetate decarboxylase (AADC; E.C. 4.1.1.4) from Clostridium acetobutylicum was selected as a biocatalyst for decarboxylation of levulinic acid. The purified recombinant AADC from Escherichia coli successfully converted levulinic acid to 2-butanone with a conversion yield of 8.4-90.3 % depending on the amount of AADC under optimum conditions (30 °C and pH 5.0) despite that acetoacetate, a β-keto-acid, is a natural substrate of AADC. In order to improve the catalytic efficiency, an AADC-mediator system was tested using methyl viologen, methylene blue, azure B, zinc ion, and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) as mediators. Among them, methyl viologen showed the best performance, increasing the conversion yield up to 6.7-fold in comparison to that without methyl viologen. The results in this study are significant in the development of a renewable method for the synthesis of 2-butanone from biomass-derived chemical, levulinic acid, through enzymatic decarboxylation. PMID:23624707

  4. Characterization of arginine decarboxylase from Dianthus caryophyllus.

    PubMed

    Ha, Byung Hak; Cho, Ki Joon; Choi, Yu Jin; Park, Ky Young; Kim, Kyung Hyun

    2004-04-01

    Arginine decarboxylase (ADC, EC 4.1.1.9) is a key enzyme in the biosynthesis of polyamines in higher plants, whereas ornithine decarboxylase represents the sole pathway of polyamine biosynthesis in animals. Previously, we characterized a genomic clone from Dianthus caryophyllus, in which the deduced polypeptide of ADC was 725 amino acids with a molecular mass of 78 kDa. In the present study, the ADC gene was subcloned into the pGEX4T1 expression vector in combination with glutathione S-transferase (GST). The fusion protein GST-ADC was water-soluble and thus was purified by sequential GSTrap-arginine affinity chromatography. A thrombin-mediated on-column cleavage reaction was employed to release free ADC from GST. Hiload superdex gel filtration FPLC was then used to obtain a highly purified ADC. The identity of the ADC was confirmed by immunoblot analysis, and its specific activity with respect to (14)C-arginine decarboxylation reaction was determined to be 0.9 CO(2) pkat mg(-1) protein. K(m) and V(max) of the reaction between ADC and the substrate were 0.077 +/- 0.001 mM and 6.0 +/- 0.6 pkat mg(-1) protein, respectively. ADC activity was reduced by 70% in the presence of 0.1 mM Cu(2+) or CO(2+), but was only marginally affected by Mg(2+), or Ca(2+) at the same concentration. Moreover, spermine at 1 mM significantly reduced its activity by 30%. PMID:15120115

  5. Arginine decarboxylase as the source of putrescine for tobacco alkaloids

    NASA Technical Reports Server (NTRS)

    Tiburcio, A. F.; Galston, A. W.

    1986-01-01

    The putrescine which forms a part of nicotine and other pyrrolidine alkaloids is generally assumed to arise through the action of ornithine decarboxylase (ODC). However, we have previously noted that changes in the activity of arginine decarboxylase (ADC), an alternate source of putrescine, parallel changes in tissue alkaloids, while changes in ODC activity do not. This led us to undertake experiments to permit discrimination between ADC and ODC as enzymatic sources of putrescine destined for alkaloids. Two kinds of evidence presented here support a major role for ADC in the generation of putrescine going into alkaloids: (a) A specific 'suicide inhibitor' of ADC effectively inhibits the biosynthesis of nicotine and nornicotine in tobacco callus, while the analogous inhibitor of ODC is less effective, and (b) the flow of 14C from uniformly labelled arginine into nicotine is much more efficient than that from ornithine.

  6. Molecular and functional analyses of amino acid decarboxylases involved in cuticle tanning in Tribolium castaneum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspartate 1-decarboxylase (ADC) and dopa decarboxylase (DDC) provide b–alanine and dopamine used in insect cuticle tanning. Beta-alanine is conjugated with dopamine to yield N-b-alanyldopamine (NBAD), a substrate for the phenoloxidase laccase that catalyzes the synthesis of cuticle protein cross-li...

  7. Whole cells in enantioselective reduction of benzyl acetoacetate

    PubMed Central

    Ribeiro, Joyce Benzaquem; Ramos, Aline de Souza; Lopes, Raquel de Oliveira; da Silva, Gabriela Veloso Vieira; de Souza, Rodrigo Octavio Mendonça Alves

    2014-01-01

    The β-ketoester benzyl acetoacetate was enantioselectively reduced to benzyl (S)-3-hydroxybutanoate by seven microorganism species. The best result using free cells was obtained with the yeast Hansenula sp., which furnished 97% ee and 85% of conversion within 24 h. After immobilization in calcium alginate spheres, K.marxianus showed to be more stable after 2 cycles of reaction. PMID:25477927

  8. Lipase-catalyzed synthesis of partial acylglycerols of acetoacetate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A commercially available immobilized preparation of Rhizomucor miehei lipase (Lipozyme RMIM) has been employed in the synthesis of partial glycerides of acetoacetate. Due to the chemical reactivitity of the acetoacetyl group, these glycerides could have novel uses in e.g. polymer formation. Both 1...

  9. Deuterium Exchange in Ethyl Acetoacetate: An Undergraduate GC-MS [Gas Chromatography-Mass Spectroscopy] Experiment

    ERIC Educational Resources Information Center

    Heinson, C. D.; Williams, J. M.; Tinnerman, W. N.; Malloy, T. B.

    2005-01-01

    The role of ethanol O-d in nullifying the deuterolysis may be demonstrated by determining that transesterification of methyl acetoacetate of the ethyl ester occurs as well as deuterium exchange of the five acetoacetate hydrogens. The significant acidity of the methylene protons in the acetoacetate group, the efficacy of base catalysis, the role of…

  10. Simultaneous Silencing of Two Arginine Decarboxylase Genes Alters Development in Arabidopsis

    PubMed Central

    Sánchez-Rangel, Diana; Chávez-Martínez, Ana I.; Rodríguez-Hernández, Aída A.; Maruri-López, Israel; Urano, Kaoru; Shinozaki, Kazuo; Jiménez-Bremont, Juan F.

    2016-01-01

    Polyamines (PAs) are small aliphatic polycations that are found ubiquitously in all organisms. In plants, PAs are involved in diverse biological processes such as growth, development, and stress responses. In Arabidopsis thaliana, the arginine decarboxylase enzymes (ADC1 and 2) catalyze the first step of PA biosynthesis. For a better understanding of PA biological functions, mutants in PA biosynthesis have been generated; however, the double adc1/adc2 mutant is not viable in A. thaliana. In this study, we generated non-lethal A. thaliana lines through an artificial microRNA that simultaneously silenced the two ADC genes (amiR:ADC). The generated transgenic lines (amiR:ADC-L1 and -L2) showed reduced AtADC1 and AtADC2 transcript levels. For further analyses the amiR:ADC-L2 line was selected. We found that the amiR:ADC-L2 line showed a significant decrease of their PA levels. The co-silencing revealed a stunted growth in A. thaliana seedlings, plantlets and delay in its flowering rate; these phenotypes were reverted with PA treatment. In addition, amiR:ADC-L2 plants displayed two seed phenotypes, such as yellow and brownish seeds. The yellow mutant seeds were smaller than adc1, adc2 mutants and wild type seeds; however, the brownish were the smallest seeds with arrested embryos at the torpedo stage. These data reinforce the importance of PA homeostasis in the plant development processes. PMID:27014322

  11. Simultaneous Silencing of Two Arginine Decarboxylase Genes Alters Development in Arabidopsis.

    PubMed

    Sánchez-Rangel, Diana; Chávez-Martínez, Ana I; Rodríguez-Hernández, Aída A; Maruri-López, Israel; Urano, Kaoru; Shinozaki, Kazuo; Jiménez-Bremont, Juan F

    2016-01-01

    Polyamines (PAs) are small aliphatic polycations that are found ubiquitously in all organisms. In plants, PAs are involved in diverse biological processes such as growth, development, and stress responses. In Arabidopsis thaliana, the arginine decarboxylase enzymes (ADC1 and 2) catalyze the first step of PA biosynthesis. For a better understanding of PA biological functions, mutants in PA biosynthesis have been generated; however, the double adc1/adc2 mutant is not viable in A. thaliana. In this study, we generated non-lethal A. thaliana lines through an artificial microRNA that simultaneously silenced the two ADC genes (amiR:ADC). The generated transgenic lines (amiR:ADC-L1 and -L2) showed reduced AtADC1 and AtADC2 transcript levels. For further analyses the amiR:ADC-L2 line was selected. We found that the amiR:ADC-L2 line showed a significant decrease of their PA levels. The co-silencing revealed a stunted growth in A. thaliana seedlings, plantlets and delay in its flowering rate; these phenotypes were reverted with PA treatment. In addition, amiR:ADC-L2 plants displayed two seed phenotypes, such as yellow and brownish seeds. The yellow mutant seeds were smaller than adc1, adc2 mutants and wild type seeds; however, the brownish were the smallest seeds with arrested embryos at the torpedo stage. These data reinforce the importance of PA homeostasis in the plant development processes. PMID:27014322

  12. Acetoacetate Accelerates Muscle Regeneration and Ameliorates Muscular Dystrophy in Mice.

    PubMed

    Zou, Xiaoting; Meng, Jiao; Li, Li; Han, Wanhong; Li, Changyin; Zhong, Ran; Miao, Xuexia; Cai, Jun; Zhang, Yong; Zhu, Dahai

    2016-01-29

    Acetoacetate (AA) is a ketone body and acts as a fuel to supply energy for cellular activity of various tissues. Here, we uncovered a novel function of AA in promoting muscle cell proliferation. Notably, the functional role of AA in regulating muscle cell function is further evidenced by its capability to accelerate muscle regeneration in normal mice, and it ameliorates muscular dystrophy in mdx mice. Mechanistically, our data from multiparameter analyses consistently support the notion that AA plays a non-metabolic role in regulating muscle cell function. Finally, we show that AA exerts its function through activation of the MEK1-ERK1/2-cyclin D1 pathway, revealing a novel mechanism in which AA serves as a signaling metabolite in mediating muscle cell function. Our findings highlight the profound functions of a small metabolite as signaling molecule in mammalian cells. PMID:26645687

  13. Structures of Bacterial Biosynthetic Arginine Decarboxylases

    SciTech Connect

    F Forouhar; S Lew; J Seetharaman; R Xiao; T Acton; G Montelione; L Tong

    2011-12-31

    Biosynthetic arginine decarboxylase (ADC; also known as SpeA) plays an important role in the biosynthesis of polyamines from arginine in bacteria and plants. SpeA is a pyridoxal-5'-phosphate (PLP)-dependent enzyme and shares weak sequence homology with several other PLP-dependent decarboxylases. Here, the crystal structure of PLP-bound SpeA from Campylobacter jejuni is reported at 3.0 {angstrom} resolution and that of Escherichia coli SpeA in complex with a sulfate ion is reported at 3.1 {angstrom} resolution. The structure of the SpeA monomer contains two large domains, an N-terminal TIM-barrel domain followed by a {beta}-sandwich domain, as well as two smaller helical domains. The TIM-barrel and {beta}-sandwich domains share structural homology with several other PLP-dependent decarboxylases, even though the sequence conservation among these enzymes is less than 25%. A similar tetramer is observed for both C. jejuni and E. coli SpeA, composed of two dimers of tightly associated monomers. The active site of SpeA is located at the interface of this dimer and is formed by residues from the TIM-barrel domain of one monomer and a highly conserved loop in the {beta}-sandwich domain of the other monomer. The PLP cofactor is recognized by hydrogen-bonding, {pi}-stacking and van der Waals interactions.

  14. Enhanced and suppressed mineralization by acetoacetate and β-hydroxybutyrate in osteoblast cultures.

    PubMed

    Saito, Akihiro; Yoshimura, Kentaro; Miyamoto, Yoichi; Kaneko, Kotaro; Chikazu, Daichi; Yamamoto, Matsuo; Kamijo, Ryutaro

    2016-04-29

    It is known that diabetes aggravates alveolar bone loss associated with periodontitis. While insulin depletion increases the blood concentration of ketone bodies, i.e., acetoacetate and β-hydroxybutyrate, their roles in bone metabolism have not been much studied until today. We investigated the effects of acetoacetate and β-hydroxybutyrate on mineralization of extracellular matrix in cultures of mouse osteoblastic MC3T3-E1 cells and primary mouse osteoblasts in the presence and absence of bone morphogenetic protein-2. Acetoacetate potentiated alkaline phosphatase activity in MC3T3-E1 cells in a concentration-dependent manner, ranging from physiological to pathological concentrations (0.05-5 mmol/L). In contrast, β-hydroxybutyrate lowered it in the same experimental settings. Mineralization in cultures of these cells was also up-regulated by acetoacetate and down-regulated by β-hydroxybutyrate. Similar results were obtained in cultures of mouse primary osteoblasts. Neither alkaline phosphatase mRNA nor its protein expression in MC3T3-E1 cells was affected by acetoacetate or β-hydroxybutyrate, indicating that these ketone bodies control the enzyme activity of alkaline phosphatase in osteoblasts and hence their mineralization bi-directionally. Finally, either gene silencing of monocarboxylate transporter-1, a major transmembrate transporter for ketone bodies, nullified the effects of ketone bodies on alkaline phosphatase activity in MC3T3-E1 cells. Collectively, we found that ketone bodies bidirectionally modulates osteoblast functions, which suggests that ketone bodies are important endogenous factors that regulate bone metabolism in both physiological and pathological situations. PMID:27018251

  15. Automated Defect Classification (ADC)

    1998-01-01

    The ADC Software System is designed to provide semiconductor defect feature analysis and defect classification capabilities. Defect classification is an important software method used by semiconductor wafer manufacturers to automate the analysis of defect data collected by a wide range of microscopy techniques in semiconductor wafer manufacturing today. These microscopies (e.g., optical bright and dark field, scanning electron microscopy, atomic force microscopy, etc.) generate images of anomalies that are induced or otherwise appear on wafermore » surfaces as a result of errant manufacturing processes or simple atmospheric contamination (e.g., airborne particles). This software provides methods for analyzing these images, extracting statistical features from the anomalous regions, and applying supervised classifiers to label the anomalies into user-defined categories.« less

  16. Aspartate Decarboxylase is Required for a Normal Pupa Pigmentation Pattern in the Silkworm, Bombyx mori

    PubMed Central

    Dai, Fangyin; Qiao, Liang; Cao, Cun; Liu, Xiaofan; Tong, Xiaoling; He, Songzhen; Hu, Hai; Zhang, Li; Wu, Songyuan; Tan, Duan; Xiang, Zhonghuai; Lu, Cheng

    2015-01-01

    The pigmentation pattern of Lepidoptera varies greatly in different development stages. To date, the effects of key genes in the melanin metabolism pathway on larval and adult body color are distinct, yet the effects on pupal pigmentation remains unclear. In the silkworm, Bombyx mori, the black pupa (bp) mutant is only specifically melanized at the pupal stage. Using positional cloning, we found that a mutation in the Aspartate decarboxylase gene (BmADC) is causative in the bp mutant. In the bp mutant, a SINE-like transposon with a length of 493 bp was detected ~2.2 kb upstream of the transcriptional start site of BmADC. This insertion causes a sharp reduction in BmADC transcript levels in bp mutants, leading to deficiency of β-alanine and N-β-alanyl dopamine (NBAD), but accumulation of dopamine. Following injection of β-alanine into bp mutants, the color pattern was reverted that of the wild-type silkworms. Additionally, melanic pupae resulting from knock-down of BmADC in the wild-type strain were obtained. These findings show that BmADC plays a crucial role in melanin metabolism and in the pigmentation pattern of the silkworm pupal stage. Finally, this study contributes to a better understanding of pupa pigmentation patterns in Lepidoptera. PMID:26077025

  17. Aspartate Decarboxylase is Required for a Normal Pupa Pigmentation Pattern in the Silkworm, Bombyx mori.

    PubMed

    Dai, Fangyin; Qiao, Liang; Cao, Cun; Liu, Xiaofan; Tong, Xiaoling; He, Songzhen; Hu, Hai; Zhang, Li; Wu, Songyuan; Tan, Duan; Xiang, Zhonghuai; Lu, Cheng

    2015-01-01

    The pigmentation pattern of Lepidoptera varies greatly in different development stages. To date, the effects of key genes in the melanin metabolism pathway on larval and adult body color are distinct, yet the effects on pupal pigmentation remains unclear. In the silkworm, Bombyx mori, the black pupa (bp) mutant is only specifically melanized at the pupal stage. Using positional cloning, we found that a mutation in the Aspartate decarboxylase gene (BmADC) is causative in the bp mutant. In the bp mutant, a SINE-like transposon with a length of 493 bp was detected ~2.2 kb upstream of the transcriptional start site of BmADC. This insertion causes a sharp reduction in BmADC transcript levels in bp mutants, leading to deficiency of β-alanine and N-β-alanyl dopamine (NBAD), but accumulation of dopamine. Following injection of β-alanine into bp mutants, the color pattern was reverted that of the wild-type silkworms. Additionally, melanic pupae resulting from knock-down of BmADC in the wild-type strain were obtained. These findings show that BmADC plays a crucial role in melanin metabolism and in the pigmentation pattern of the silkworm pupal stage. Finally, this study contributes to a better understanding of pupa pigmentation patterns in Lepidoptera. PMID:26077025

  18. Genetics Home Reference: aromatic l-amino acid decarboxylase deficiency

    MedlinePlus

    ... aromatic l-amino acid decarboxylase deficiency aromatic l-amino acid decarboxylase deficiency Enable Javascript to view the expand/ ... PDF Open All Close All Description Aromatic l-amino acid decarboxylase (AADC) deficiency is an inherited disorder that ...

  19. Effect of acetoacetate on glucose metabolism in the soleus and extensor digitorum longus muscles of the rat.

    PubMed Central

    Maizels, E Z; Ruderman, N B; Goodman, M N; Lau, D

    1977-01-01

    1. The effect of acetoacetate on glucose metabolism was compared in the soleus, a slow-twitch red muscle, and the extensor digitorum longus, a muscle composed of 50% fast-twitch red and 50% white fibres. 2. When incubated for 2h in a medium containing 5 mM-glucose and 0.1 unit of insulin/ml, rates of glucose uptake, lactate release and glucose oxidation in the soleus were 19.6, 18.6 and 1.47 micronmol/h per g respectively. Acetoacetate (1.7 mM) diminished all three rates by 25-50%; however, it increased glucose conversion into glycogen. In addition, it caused increases in tissue glucose, glucose 6-phosphate and fructose 6-phosphate, suggesting inhibition of phosphofructokinase. The concentrations of citrate, an inhibitor of phosphofructokinase, and of malate were also increased. 3. Rates of glucose uptake and lactate release in the extensor digitorum longus were 50-80% of those in the soleus. Acetoacetate caused moderate increases in tissue glucose 6-phosphate and possibly citrate, but it did not decrease glucose uptake or lactate release. 4. The rate of glycolysis in the soleus was approximately five times that previously observed in the perfused rat hindquarter, a muscle preparation in which acetoacetate inhibits glucose oxidation, but does not alter glucose uptake or glycolysis. A similar rate of glycolysis was observed when the soleus was incubated with a glucose-free medium. Under these conditions, tissue malate and the lactate/pyruvate ratio in the medium were decreased, and acetoacetate did not decrease lactate release or increase tissue citrate or glucose 6-phosphate. An intermediate rate of glycolysis, which was not decreased by acetoacetate, was observed when the soleus was incubated with glucose, but not insulin. 5. The data suggest that acetoacetate glucose inhibits uptake and glycolysis in red muscle under conditions that resemble mild to moderate exercise. They also suggest that the accumulation of citrate in these circumstances is linked to the rate

  20. An Archaeal Glutamate Decarboxylase Homolog Functions as an Aspartate Decarboxylase and Is Involved in β-Alanine and Coenzyme A Biosynthesis

    PubMed Central

    Tomita, Hiroya; Yokooji, Yuusuke; Ishibashi, Takuya; Imanaka, Tadayuki

    2014-01-01

    β-Alanine is a precursor for coenzyme A (CoA) biosynthesis and is a substrate for the bacterial/eukaryotic pantothenate synthetase and archaeal phosphopantothenate synthetase. β-Alanine is synthesized through various enzymes/pathways in bacteria and eukaryotes, including the direct decarboxylation of Asp by aspartate 1-decarboxylase (ADC), the degradation of pyrimidine, or the oxidation of polyamines. However, in most archaea, homologs of these enzymes are not present; thus, the mechanisms of β-alanine biosynthesis remain unclear. Here, we performed a biochemical and genetic study on a glutamate decarboxylase (GAD) homolog encoded by TK1814 from the hyperthermophilic archaeon Thermococcus kodakarensis. GADs are distributed in all three domains of life, generally catalyzing the decarboxylation of Glu to γ-aminobutyrate (GABA). The recombinant TK1814 protein displayed not only GAD activity but also ADC activity using pyridoxal 5′-phosphate as a cofactor. Kinetic studies revealed that the TK1814 protein prefers Asp as its substrate rather than Glu, with nearly a 20-fold difference in catalytic efficiency. Gene disruption of TK1814 resulted in a strain that could not grow in standard medium. Addition of β-alanine, 4′-phosphopantothenate, or CoA complemented the growth defect, whereas GABA could not. Our results provide genetic evidence that TK1814 functions as an ADC in T. kodakarensis, providing the β-alanine necessary for CoA biosynthesis. The results also suggest that the GAD activity of TK1814 is not necessary for growth, at least under the conditions applied in this study. TK1814 homologs are distributed in a wide range of archaea and may be responsible for β-alanine biosynthesis in these organisms. PMID:24415726

  1. Capacitor-Chain Successive-Approximation ADC

    NASA Technical Reports Server (NTRS)

    Cunningham, Thomas

    2003-01-01

    A proposed successive-approximation analog-to-digital converter (ADC) would contain a capacitively terminated chain of identical capacitor cells. Like a conventional successive-approximation ADC containing a bank of binary-scaled capacitors, the proposed ADC would store an input voltage on a sample-and-hold capacitor and would digitize the stored input voltage by finding the closest match between this voltage and a capacitively generated sum of binary fractions of a reference voltage (Vref). However, the proposed capacitor-chain ADC would offer two major advantages over a conventional binary-scaled-capacitor ADC: (1) In a conventional ADC that digitizes to n bits, the largest capacitor (representing the most significant bit) must have 2(exp n-1) times as much capacitance, and hence, approximately 2(exp n-1) times as much area as does the smallest capacitor (representing the least significant bit), so that the total capacitor area must be 2(exp n) times that of the smallest capacitor. In the proposed capacitor-chain ADC, there would be three capacitors per cell, each approximately equal to the smallest capacitor in the conventional ADC, and there would be one cell per bit. Therefore, the total capacitor area would be only about 3(exp n) times that of the smallest capacitor. The net result would be that the proposed ADC could be considerably smaller than the conventional ADC. (2) Because of edge effects, parasitic capacitances, and manufacturing tolerances, it is difficult to make capacitor banks in which the values of capacitance are scaled by powers of 2 to the required precision. In contrast, because all the capacitors in the proposed ADC would be identical, the problem of precise binary scaling would not arise.

  2. From Protease to Decarboxylase: THE MOLECULAR METAMORPHOSIS OF PHOSPHATIDYLSERINE DECARBOXYLASE.

    PubMed

    Choi, Jae-Yeon; Duraisingh, Manoj T; Marti, Matthias; Ben Mamoun, Choukri; Voelker, Dennis R

    2015-04-24

    Phosphatidylserine decarboxylase (PSDs) play a central role in the synthesis of phosphatidylethanolamine in numerous species of prokaryotes and eukaryotes. PSDs are unusual decarboxylase containing a pyruvoyl prosthetic group within the active site. The covalently attached pyruvoyl moiety is formed in a concerted reaction when the PSD proenzyme undergoes an endoproteolytic cleavage into a large β-subunit, and a smaller α-subunit, which harbors the prosthetic group at its N terminus. The mechanism of PSD proenzyme cleavage has long been unclear. Using a coupled in vitro transcription/translation system with the soluble Plasmodium knowlesi enzyme (PkPSD), we demonstrate that the post-translational processing is inhibited by the serine protease inhibitor, phenylmethylsulfonyl fluoride. Comparison of PSD sequences across multiple phyla reveals a uniquely conserved aspartic acid within an FFXRX6RX12PXD motif, two uniquely conserved histidine residues within a PXXYHXXHXP motif, and a uniquely conserved serine residue within a GS(S/T) motif, suggesting that PSDs belong to the D-H-S serine protease family. The function of the conserved D-H-S residues was probed using site-directed mutagenesis of PkPSD. The results from these mutagenesis experiments reveal that Asp-139, His-198, and Ser-308 are all essential for endoproteolytic processing of PkPSD, which occurs in cis. In addition, within the GS(S/T) motif found in all PSDs, the Gly-307 residue is also essential, but the Ser/Thr-309 is non-essential. These results define the mechanism whereby PSDs begin their biochemical existence as proteases that execute one autoendoproteolytic cleavage reaction to give rise to a mature PSD harboring a pyruvoyl prosthetic group. PMID:25724650

  3. TiCl4-promoted condensation of methyl acetoacetate, isobutyraldehyde, and indole: a theoretical and experimental study.

    PubMed

    Renzetti, Andrea; Marrone, Alessandro; Gérard, Stéphane; Sapi, Janos; Nakazawa, Hiroshi; Re, Nazzareno; Fontana, Antonella

    2015-04-14

    The mechanism of the TiCl4-promoted condensation of methyl acetoacetate, isobutyraldehyde, and indole was studied by a combination of theoretical and experimental techniques. The energy profile of plausible reaction paths was evaluated by DFT calculations, and various reaction intermediates were isolated or observed in solution by NMR spectroscopy. Theoretical and experimental results indicate that the reaction proceeds in three steps, all promoted by titanium: (1) formation of the enolate ion of methyl acetoacetate, (2) Knoevenagel condensation of the enolate ion and aldehyde, and (3) Michael addition of indole to the Knoevenagel adduct. The study sheds light on the role of titanium in the reaction, providing a mechanistic model for analogous reactions. PMID:25746215

  4. Conformational analysis, tautomerization, IR, Raman, and NMR studies of benzyl acetoacetate

    NASA Astrophysics Data System (ADS)

    Tayyari, Sayyed Faramarz; Naghavi, Farnaz; Pojhan, Sahar; McClurg, Ryan W.; Sammelson, Robert E.

    2011-02-01

    A complete conformational analysis of the keto and enol forms of benzyl acetoacetate (BAA), a β-dicarbonyl compound, was carried out by ab initio calculations, at the density functional theory (DFT) level. By inspection of all possible conformers and tautomers, 22 stable cis-enol, 28 stable trans-enol, and five keto conformers were obtained. Among all stable cis-enol forms only six of them are engaged in intramolecular hydrogen bond. The hydrogen bond strength of the most stable conformer of BAA is compared with that of acetylacetone (AA) and dimethyl oxaloacetate (DMOA). Harmonic vibrational frequencies of the most stable enol and keto forms and their deuterated analogues were also calculated and compared with the experimental data. According to the theoretical calculations, the hydrogen bond strength of the most stable enol conformer of BAA is 56.7 kJ/mol (calculated at the B3LYP/6-311++G ∗∗ level), about 10 kJ/mol less than that of AA. This weakening of hydrogen bond is consistent with the spectroscopic results. NMR studies indicate that BAA exists mainly as a keto tautomer in all considered solutions. The Gibbs energies for keto/enol tautomerization were calculated at the B3LYP level, with several basis sets, in both gas phase and CH 3CN solution (using PCM model), for the most stable enol and keto conformers.

  5. Mechanistic insight into alkylation of the ethyl acetoacetate anion with different ethyl halides

    NASA Astrophysics Data System (ADS)

    Marković, S.; Đurđević, J.; Vukosavljević, M.; Petrović, Z.

    2013-12-01

    The alkylation reactions of the ambident ethyl acetoacetate anion with C2H5X (X = F, Cl, Br, and I) in the O2, C3, and O4 positions of the anion were investigated at the B3LYP/6-311+G( d,p) level of theory. It was found that the ethylation reaction does not occur in the position O4, as well as with ethyl fluoride in any position of the anion, due to very high activation energies and thermodynamic instability of the hypothetic products. The activation energies for the reactions in the position O2 are lower in comparison to the position C3, but the products of the reactions in the C3 position are more stable than those in the position O4, implying that the C/O products ratio is controlled by both thermodynamic and kinetic factors, leading to the O2-product with the chloride, and C3-product with the iodide as leaving group.

  6. Condensation of anhydrides or dicarboxylic acids with compounds containing active methylene groups. Part 1: Condensation of phthalic anhydride with acetoacetic and malonic ester

    NASA Technical Reports Server (NTRS)

    Oshkaya, V. P.; Vanag, G. Y.

    1985-01-01

    Phthalic anhydride was condensed with acetoacetic ester in acetic anhydride and triethylamine solution, and when phthalyl chloride was reacted with sodium acetoacetic ester compounds were formed of the phthalide and indandione series: phthalylacetoacetic ester and a derivative of indan-1,3-dione which after boiling with hydrochloric acid yielded indan-1,3-dione. Phthalylmalonic ester was obtained from phthalic anhydride and malonic ester in the presence of triethylamine.

  7. Control unit implementation for a reconfigurable ADC

    NASA Astrophysics Data System (ADS)

    Stojcevski, Aleksandar; Vibhute, Vidya; Singh, Jugdutt; Zayegh, Aladin

    2004-03-01

    A control unit has been proposed, which is used to reconfigure a pipeline ADC for a mobile terminal receiver that can drastically reduce the power dissipation dependent on adjacent channel interference. The proposed design automatically scales the word length by monitoring the quantization noise along the in-band and out-of-bands powers in the UTRA-TDD spectrum. The new ADC performance was evaluated in a simulation UTRA-TDD environment because of the large near far problem caused by adjacent channel interference from adjacent mobiles and base stations. Results show that by using the control unit to reconfigure the ADC, up to 88% power dissipation could be saved, when compared to a fixed 16 bits ADC without the use of the control unit. This will prolong talk and standby time in a moble terminal.

  8. ALLYLISOPROPYLACETAMIDE INDUCES RAT HEPATIC ORNITHINE DECARBOXYLASE

    EPA Science Inventory

    In rat liver, allylisopropylacetamide (AIA) treatment strongly induced (25-fold) the activity of rat hepatic ornithine decarboxylase (ODC). y either the oral or the subcutaneous routes, AIA produced a long-lasting induction (30 to 4O hours) of hepatic ODC activity. hree analogs o...

  9. FcWRKY70, a WRKY protein of Fortunella crassifolia, functions in drought tolerance and modulates putrescine synthesis by regulating arginine decarboxylase gene.

    PubMed

    Gong, Xiaoqing; Zhang, Jingyan; Hu, Jianbing; Wang, Wei; Wu, Hao; Zhang, Qinghua; Liu, Ji-Hong

    2015-11-01

    WRKY comprises a large family of transcription factors in plants, but most WRKY members are still poorly understood. In this study, we report functional characterization of a Group III WRKY gene (FcWRKY70) from Fortunella crassifolia. FcWRKY70 was greatly induced by drought and abscisic acid, but slightly or negligibly by salt and cold. Overexpression of FcWRKY70 in tobacco (Nicotiana nudicaulis) and lemon (Citrus lemon) conferred enhanced tolerance to dehydration and drought stresses. Transgenic tobacco and lemon exhibited higher expression levels of ADC (arginine decarboxylase), and accumulated larger amount of putrescine in comparison with wild type (WT). Treatment with D-arginine, an inhibitor of ADC, caused transgenic tobacco plants more sensitive to dehydration. Knock-down of FcWRKY70 in kumquat down-regulated ADC abundance and decreased putrescine level, accompanied by compromised dehydration tolerance. The promoter region of FcADC contained two W-box elements, which were shown to be interacted with FcWRKY70. Taken together, our data demonstrated that FcWRKY70 functions in drought tolerance by, at least partly, promoting production of putrescine via regulating ADC expression. PMID:25808564

  10. AdcAII of Streptococcus pneumoniae Affects Pneumococcal Invasiveness

    PubMed Central

    Brown, Lindsey R.; Gunnell, Steven M.; Cassella, Adam N.; Keller, Lance E.; Scherkenbach, Lisa A.; Mann, Beth; Brown, Matthew W.; Hill, Rebecca; Fitzkee, Nicholas C.; Rosch, Jason W.; Tuomanen, Elaine I.; Thornton, Justin A.

    2016-01-01

    Across bacterial species, metal binding proteins can serve functions in pathogenesis in addition to regulating metal homeostasis. We have compared and contrasted the activities of zinc (Zn2+)-binding lipoproteins AdcA and AdcAII in the Streptococcus pneumoniae TIGR4 background. Exposure to Zn2+-limiting conditions resulted in delayed growth in a strain lacking AdcAII (ΔAdcAII) when compared to wild type bacteria or a mutant lacking AdcA (ΔAdcA). AdcAII failed to interact with the extracellular matrix protein laminin despite homology to laminin-binding proteins of related streptococci. Deletion of AdcA or AdcAII led to significantly increased invasion of A549 human lung epithelial cells and a trend toward increased invasion in vivo. Loss of AdcAII, but not AdcA, was shown to negatively impact early colonization of the nasopharynx. Our findings suggest that expression of AdcAII affects invasiveness of S. pneumoniae in response to available Zn2+ concentrations. PMID:26752283

  11. ICE1 of Poncirus trifoliata functions in cold tolerance by modulating polyamine levels through interacting with arginine decarboxylase

    PubMed Central

    Huang, Xiao-San; Zhang, Qinghua; Zhu, Dexin; Fu, Xingzheng; Wang, Min; Zhang, Qian; Moriguchi, Takaya; Liu, Ji-Hong

    2015-01-01

    ICE1 (Inducer of CBF Expression 1) encodes a MYC-like basic helix–loop–helix transcription factor that acts as a central regulator of cold response. In this study, we elucidated the function and underlying mechanisms of PtrICE1 from trifoliate orange [Poncirus trifoliata (L.) Raf.]. PtrICE1 was upregulated by cold, dehydration, and salt, with the greatest induction under cold conditions. PtrICE1 was localized in the nucleus and could bind to a MYC-recognizing sequence. Ectopic expression of PtrICE1 in tobacco and lemon conferred enhanced tolerance to cold stresses at either chilling or freezing temperatures. Yeast two-hybrid screening revealed that 21 proteins belonged to the PtrICE1 interactome, in which PtADC (arginine decarboxylase) was confirmed as a bona fide protein interacting with PtrICE1. Transcript levels of ADC genes in the transgenic lines were slightly elevated under normal growth condition but substantially increased under cold conditions, consistent with changes in free polyamine levels. By contrast, accumulation of the reactive oxygen species, H2O2 and O2 –, was appreciably alleviated in the transgenic lines under cold stress. Higher activities of antioxidant enzymes, such as superoxide dismutase and catalase, were detected in the transgenic lines under cold conditions. Taken together, these results demonstrated that PtrICE1 plays a positive role in cold tolerance, which may be due to modulation of polyamine levels through interacting with the ADC gene. PMID:25873670

  12. ICE1 of Poncirus trifoliata functions in cold tolerance by modulating polyamine levels through interacting with arginine decarboxylase.

    PubMed

    Huang, Xiao-San; Zhang, Qinghua; Zhu, Dexin; Fu, Xingzheng; Wang, Min; Zhang, Qian; Moriguchi, Takaya; Liu, Ji-Hong

    2015-06-01

    ICE1 (Inducer of CBF Expression 1) encodes a MYC-like basic helix-loop-helix transcription factor that acts as a central regulator of cold response. In this study, we elucidated the function and underlying mechanisms of PtrICE1 from trifoliate orange [Poncirus trifoliata (L.) Raf.]. PtrICE1 was upregulated by cold, dehydration, and salt, with the greatest induction under cold conditions. PtrICE1 was localized in the nucleus and could bind to a MYC-recognizing sequence. Ectopic expression of PtrICE1 in tobacco and lemon conferred enhanced tolerance to cold stresses at either chilling or freezing temperatures. Yeast two-hybrid screening revealed that 21 proteins belonged to the PtrICE1 interactome, in which PtADC (arginine decarboxylase) was confirmed as a bona fide protein interacting with PtrICE1. Transcript levels of ADC genes in the transgenic lines were slightly elevated under normal growth condition but substantially increased under cold conditions, consistent with changes in free polyamine levels. By contrast, accumulation of the reactive oxygen species, H2O2 and O2 (-), was appreciably alleviated in the transgenic lines under cold stress. Higher activities of antioxidant enzymes, such as superoxide dismutase and catalase, were detected in the transgenic lines under cold conditions. Taken together, these results demonstrated that PtrICE1 plays a positive role in cold tolerance, which may be due to modulation of polyamine levels through interacting with the ADC gene. PMID:25873670

  13. ADC and TDC implemented using FPGA

    SciTech Connect

    Wu, Jinyuan; Hansen, Sten; Shi, Zonghan; /Fermilab

    2007-11-01

    Several tests of FPGA devices programmed as analog waveform digitizers are discussed. The ADC uses the ramping-comparing scheme. A multi-channel ADC can be implemented with only a few resistors and capacitors as external components. A periodic logic levels are shaped by passive RC network to generate exponential ramps. The FPGA differential input buffers are used as comparators to compare the ramps with the input signals. The times at which these ramps cross the input signals are digitized by time-to-digital-converters (TDCs) implemented within the FPGA. The TDC portion of the logic alone has potentially a broad range of HEP/nuclear science applications. A 96-channel TDC card using FPGAs as TDCs being designed for the Fermilab MIPP electronics upgrade project is discussed. A deserializer circuit based on multisampling circuit used in the TDC, the 'Digital Phase Follower' (DPF) is also documented.

  14. New Interactive Data Browsing Features of the ADC Viewer

    NASA Astrophysics Data System (ADS)

    Thomas, B.; Shaya, E.; Blackwell, J.; Gass, J.; Oliversen, N.; Schneider, G.; Cheung, C.; White, R. A.

    1999-05-01

    The Astronomical Data Center (ADC, http://adc.gsfc.nasa.gov) has more than 700 catalogs and ~ 2000 journal tables of astronomical data that are easily accessed using the ADC Table Viewer (http://adc.gsfc.nasa.gov/viewer). This tool encompasses many data view and visualization capabilities such as the sorting, subsetting, and search of data. Additionally, its modular design allows it to leverage the abilities of the other ADC tools such as mission search and sky map plotting (IMPReSS) and the plotting/over-plotting of selected data (CatsEye). We report on the latest features of the ADC Viewer. This next generation software now empowers the user to upload their own tables, to perform non-trivial column arithmetic, to search regions of the sky using circular (in addition to square) regions and to download their tables in a variety of formats including FITS and tab or comma delimited ASCII text.

  15. Poly(vinyl alcohol) acetoacetate-based tissue adhesives are non-cytotoxic and non-inflammatory.

    PubMed

    Bhatia, Sujata K; Arthur, Samuel D

    2008-08-01

    Polymer-based tissue adhesives composed of poly(vinyl alcohol) acetoacetate (PVOH acac) and cross-linking amines were investigated for their effects on cell survival and inflammatory cell activation using in vitro mouse cell cultures. Cytotoxicity of tissue adhesives was evaluated by placing adhesives in direct contact with 3T3 fibroblast cells. Tissue adhesives formulated from PVOH acac and 3-aminopropyltrialkoxysilane (APS) were non-cytotoxic to fibroblasts; adhesives formulated from PVOH acac and aminated poly(vinyl alcohol) (PVOH amine) were also non-cytotoxic to fibroblasts. In contrast, a commercial adhesive composed of 2-octyl cyanoacrylate was highly cytotoxic to fibroblasts. The inflammatory potential of tissue adhesives was evaluated by exposing J774 macrophage cells to adhesives, and measuring TNF-alpha release from macrophages. PVOH acac-based tissue adhesives did not elicit inflammatory TNF-alpha release from macrophages. These results suggest that PVOH acac-based tissue adhesives are non-cytotoxic and non-inflammatory. Such tissue adhesives represent a promising technology for a variety of medical applications, including surgical wound closure and tissue engineering, and the results are also significant in the design of in vitro cell culture systems to study biomaterials. PMID:18414803

  16. Evolution of Substrate Specificity within a Diverse Family of [beta/alpha]-Barrel-fold Basic Amino Acid Decarboxylases X-ray Structure Determination of Enzymes with Specificity for L-Arginine and Carboxynorspermidine

    SciTech Connect

    Deng, Xiaoyi; Lee, Jeongmi; Michael, Anthony J.; Tomchick, Diana R.; Goldsmith, Elizabeth J.; Phillips, Margaret A.

    2010-08-26

    Pyridoxal 5{prime}-phosphate (PLP)-dependent basic amino acid decarboxylases from the {beta}/{alpha}-barrel-fold class (group IV) exist in most organisms and catalyze the decarboxylation of diverse substrates, essential for polyamine and lysine biosynthesis. Herein we describe the first x-ray structure determination of bacterial biosynthetic arginine decarboxylase (ADC) and carboxynorspermidine decarboxylase (CANSDC) to 2.3- and 2.0-{angstrom} resolution, solved as product complexes with agmatine and norspermidine. Despite low overall sequence identity, the monomeric and dimeric structures are similar to other enzymes in the family, with the active sites formed between the {beta}/{alpha}-barrel domain of one subunit and the {beta}-barrel of the other. ADC contains both a unique interdomain insertion (4-helical bundle) and a C-terminal extension (3-helical bundle) and it packs as a tetramer in the asymmetric unit with the insertions forming part of the dimer and tetramer interfaces. Analytical ultracentrifugation studies confirmed that the ADC solution structure is a tetramer. Specificity for different basic amino acids appears to arise primarily from changes in the position of, and amino acid replacements in, a helix in the {beta}-barrel domain we refer to as the 'specificity helix.' Additionally, in CANSDC a key acidic residue that interacts with the distal amino group of other substrates is replaced by Leu{sup 314}, which interacts with the aliphatic portion of norspermidine. Neither product, agmatine in ADC nor norspermidine in CANSDC, form a Schiff base to pyridoxal 5{prime}-phosphate, suggesting that the product complexes may promote product release by slowing the back reaction. These studies provide insight into the structural basis for the evolution of novel function within a common structural-fold.

  17. Dopa decarboxylase activity of the living human brain

    SciTech Connect

    Gjedde, A.; Reith, J.; Dyve, S.; Leger, G.; Guttman, M.; Diksic, M.; Evans, A.; Kuwabara, H. )

    1991-04-01

    Monoaminergic neurons use dopa decarboxylase to form dopamine from L-3,4-dihydroxyphenylalanine (L-dopa). We measured regional dopa decarboxylase activity in brains of six healthy volunteers with 6-({sup 18}F)fluoro-L-dopa and positron emission tomography. We calculated the enzyme activity, relative to its Km, with a kinetic model that yielded the relative rate of conversion of 6-({sup 18}F)fluoro-L-dopa to ({sup 18}F)fluorodopamine. Regional values of relative dopa decarboxylase activity ranged from nil in occipital cortex to 1.9 h-1 in caudate nucleus and putamen, in agreement with values obtained in vitro.

  18. Three Distinct Glutamate Decarboxylase Genes in Vertebrates

    PubMed Central

    Grone, Brian P.; Maruska, Karen P.

    2016-01-01

    Gamma-aminobutyric acid (GABA) is a widely conserved signaling molecule that in animals has been adapted as a neurotransmitter. GABA is synthesized from the amino acid glutamate by the action of glutamate decarboxylases (GADs). Two vertebrate genes, GAD1 and GAD2, encode distinct GAD proteins: GAD67 and GAD65, respectively. We have identified a third vertebrate GAD gene, GAD3. This gene is conserved in fishes as well as tetrapods. We analyzed protein sequence, gene structure, synteny, and phylogenetics to identify GAD3 as a homolog of GAD1 and GAD2. Interestingly, we found that GAD3 was lost in the hominid lineage. Because of the importance of GABA as a neurotransmitter, GAD3 may play important roles in vertebrate nervous systems. PMID:27461130

  19. A kinetic analysis of Drosophila melanogaster dopa decarboxylase.

    PubMed

    Black, B C; Smarrelli, J

    1986-03-01

    The kinetic mechanism of dopa decarboxylase (3,4-dihydroxy-L-phenylalanine carboxy-lyase, EC 4.1.1.28) was investigated in Drosophila melanogaster. Based on initial velocity and product inhibition studies, an ordered reaction is proposed for dopa decarboxylase. This kinetic mechanism is interpreted in the context of measured enzyme activities and the catecholamine pools in Drosophila. The 1(2)amd gene is immediately adjacent to the gene coding for dopa decarboxylase (Ddc) and determines hypersensitivity to alpha-methyldopa in Drosophila. Dopa decarboxylase does not decarboxylate alpha-methyldopa and hence does not generate a toxic product capable of inhibiting 1(2)amd gene function. We propose that the 1(2)amd gene is involved with an unknown catecholamine pathway involving dopa but not dopamine. PMID:3081033

  20. Keto-isovalerate decarboxylase enzymes and methods of use thereof

    DOEpatents

    McElvain, Jessica; O'Keefe, Daniel P.; Paul, Brian James; Payne, Mark S.; Rothman, Steven Cary; He, Hongxian

    2016-01-19

    Provided herein are polypeptides and polynucleotides encoding such polypeptides which have ketoisovalerate decarboxylase activity. Also provided are recombinant host cells comprising such polypeptides and polynucleotides and methods of use thereof.

  1. High-performance liquid chromatography method with radiochemical detection for measurement of nitric oxide synthase, arginase, and arginine decarboxylase activities.

    PubMed

    Volke, A; Wegener, G; Vasar, E; Volke, V

    2006-01-01

    Nitric oxide has been shown to be involved in numerous biological processes, and many studies have aimed to measure nitric oxide synthase (NOS) activity. Recently, it has been demonstrated that arginase and arginine decarboxylase (ADC), two enzymes that also employ arginine as a substrate, may regulate NOS activity. We aimed to develop a HPLC-based method to measure simultaneously the products of these three enzymes. Traditionally, the separation of amino acids and related compounds with HPLC has been carried out with precolumn derivatization and reverse phase chromatography. We describe here a simple and fast HPLC method with radiochemical detection to separate radiolabeled L-arginine, L-citrulline, L-ornithine, and agmatine. 3H-labeled L-arginine, L-citrulline, agmatine, and 14C-labeled L-citrulline were used as standards. These compounds were separated in the normal phase column (Allure Acidix 250 x 4.6 mm i.d.) under isocratic conditions in less than 20 min with good sensitivity. Using the current method, we have shown the formation of L-citrulline and L-ornithine in vitro using brain tissue homogenate of rats and that of agmatine by Escherichia coli ADC. PMID:16541190

  2. Analysis and correction of gradient nonlinearity bias in ADC measurements

    PubMed Central

    Malyarenko, Dariya I.; Ross, Brian D.; Chenevert, Thomas L.

    2013-01-01

    Purpose Gradient nonlinearity of MRI systems leads to spatially-dependent b-values and consequently high non-uniformity errors (10–20%) in ADC measurements over clinically relevant field-of-views. This work seeks practical correction procedure that effectively reduces observed ADC bias for media of arbitrary anisotropy in the fewest measurements. Methods All-inclusive bias analysis considers spatial and time-domain cross-terms for diffusion and imaging gradients. The proposed correction is based on rotation of the gradient nonlinearity tensor into the diffusion gradient frame where spatial bias of b-matrix can be approximated by its Euclidean norm. Correction efficiency of the proposed procedure is numerically evaluated for a range of model diffusion tensor anisotropies and orientations. Results Spatial dependence of nonlinearity correction terms accounts for the bulk (75–95%) of ADC bias for FA = 0.3–0.9. Residual ADC non-uniformity errors are amplified for anisotropic diffusion. This approximation obviates need for full diffusion tensor measurement and diagonalization to derive a corrected ADC. Practical scenarios are outlined for implementation of the correction on clinical MRI systems. Conclusions The proposed simplified correction algorithm appears sufficient to control ADC non-uniformity errors in clinical studies using three orthogonal diffusion measurements. The most efficient reduction of ADC bias for anisotropic medium is achieved with non-lab-based diffusion gradients. PMID:23794533

  3. Modeling of channel mismatch in time-interleaved SAR ADC

    NASA Astrophysics Data System (ADS)

    Dengquan, Li; Liang, Zhang; Zhangming, Zhu; Yintang, Yang

    2015-09-01

    In a time-interleaved analog-to-digital converter (TI ADC), several individual ADCs operate in parallel to achieve a higher sampling rate. Low power consumption as well as good linearity can be obtained by applying successive approximation register (SAR) converters as sub-channel ADCs. In spite of the advantages, this structure suffers from three mismatches, which are offset mismatch, gain mismatch, and time skew. This paper focuses on a TI SAR ADC with a number of channels. The mismatch effects in the frequency domain are analyzed and the derived close form formulas are verified based on Matlab. In addition, we clarify that the standard deviation of DNL and INL of an M-channel TI ADC is reduced by a factor of \\sqrt M compared to a single channel ADC. The formulas can be used to derive the corresponding requirements when designing a TI ADC. Our analysis process is able to inform the study of calibration algorithms. Project supported by the National Natural Science Foundation of China (Nos. 61234002, 61322405, 61306044, 61376033) and the National High-Tech Program of China (No. 2013AA014103).

  4. Photonic ADC: overcoming the bottleneck of electronic jitter.

    PubMed

    Khilo, Anatol; Spector, Steven J; Grein, Matthew E; Nejadmalayeri, Amir H; Holzwarth, Charles W; Sander, Michelle Y; Dahlem, Marcus S; Peng, Michael Y; Geis, Michael W; DiLello, Nicole A; Yoon, Jung U; Motamedi, Ali; Orcutt, Jason S; Wang, Jade P; Sorace-Agaskar, Cheryl M; Popović, Miloš A; Sun, Jie; Zhou, Gui-Rong; Byun, Hyunil; Chen, Jian; Hoyt, Judy L; Smith, Henry I; Ram, Rajeev J; Perrott, Michael; Lyszczarz, Theodore M; Ippen, Erich P; Kärtner, Franz X

    2012-02-13

    Accurate conversion of wideband multi-GHz analog signals into the digital domain has long been a target of analog-to-digital converter (ADC) developers, driven by applications in radar systems, software radio, medical imaging, and communication systems. Aperture jitter has been a major bottleneck on the way towards higher speeds and better accuracy. Photonic ADCs, which perform sampling using ultra-stable optical pulse trains generated by mode-locked lasers, have been investigated for many years as a promising approach to overcome the jitter problem and bring ADC performance to new levels. This work demonstrates that the photonic approach can deliver on its promise by digitizing a 41 GHz signal with 7.0 effective bits using a photonic ADC built from discrete components. This accuracy corresponds to a timing jitter of 15 fs - a 4-5 times improvement over the performance of the best electronic ADCs which exist today. On the way towards an integrated photonic ADC, a silicon photonic chip with core photonic components was fabricated and used to digitize a 10 GHz signal with 3.5 effective bits. In these experiments, two wavelength channels were implemented, providing the overall sampling rate of 2.1 GSa/s. To show that photonic ADCs with larger channel counts are possible, a dual 20-channel silicon filter bank has been demonstrated. PMID:22418205

  5. High performance 14-bit pipelined redundant signed digit ADC

    NASA Astrophysics Data System (ADS)

    Narula, Swina; Pandey, Sujata

    2016-03-01

    A novel architecture of a pipelined redundant-signed-digit analog to digital converter (RSD-ADC) is presented featuring a high signal to noise ratio (SNR), spurious free dynamic range (SFDR) and signal to noise plus distortion (SNDR) with efficient background correction logic. The proposed ADC architecture shows high accuracy with a high speed circuit and efficient utilization of the hardware. This paper demonstrates the functionality of the digital correction logic of 14-bit pipelined ADC at each 1.5 bit/stage. This prototype of ADC architecture accounts for capacitor mismatch, comparator offset and finite Op-Amp gain error in the MDAC (residue amplification circuit) stages. With the proposed architecture of ADC, SNDR obtained is 85.89 dB, SNR is 85.9 dB and SFDR obtained is 102.8 dB at the sample rate of 100 MHz. This novel architecture of digital correction logic is transparent to the overall system, which is demonstrated by using 14-bit pipelined ADC. After a latency of 14 clocks, digital output will be available at every clock pulse. To describe the circuit behavior of the ADC, VHDL and MATLAB programs are used. The proposed architecture is also capable of reducing the digital hardware. Silicon area is also the complexity of the design.

  6. Evaluation of oxalate decarboxylase and oxalate oxidase for industrial applications.

    PubMed

    Cassland, Pierre; Sjöde, Anders; Winestrand, Sandra; Jönsson, Leif J; Nilvebrant, Nils-Olof

    2010-05-01

    Increased recirculation of process water has given rise to problems with formation of calcium oxalate incrusts (scaling) in the pulp and paper industry and in forest biorefineries. The potential in using oxalate decarboxylase from Aspergillus niger for oxalic acid removal in industrial bleaching plant filtrates containing oxalic acid was examined and compared with barley oxalate oxidase. Ten different filtrates from chemical pulping were selected for the evaluation. Oxalate decarboxylase degraded oxalic acid faster than oxalate oxidase in eight of the filtrates, while oxalate oxidase performed better in one filtrate. One of the filtrates inhibited both enzymes. The potential inhibitory effect of selected compounds on the enzymatic activity was tested. Oxalate decarboxylase was more sensitive than oxalate oxidase to hydrogen peroxide. Oxalate decarboxylase was not as sensitive to chlorate and chlorite as oxalate oxidase. Up to 4 mM chlorate ions, the highest concentration tested, had no inhibitory effect on oxalate decarboxylase. Analysis of the filtrates suggests that high concentrations of chlorate present in some of the filtrates were responsible for the higher sensitivity of oxalate oxidase in these filtrates. Oxalate decarboxylase was thus a better choice than oxalate oxidase for treatment of filtrates from chlorine dioxide bleaching. PMID:19763895

  7. A low-power SAR ADC for IRFPA ROIC

    NASA Astrophysics Data System (ADS)

    Gao, Lei; Ding, Ruijun; Zhou, Jie; Wang, Pan; Chen, Guoqiang

    2012-12-01

    This paper presents a low power ADC for the 512*512 infrared focal plane arrays (IRFPA) readout integrated circuit(ROIC). The major structure, the working mode and the simulation result of the readout integrated circuit are shown in this paper. The power supply voltage of 0.35μm standard CMOS process is 3.3V in this design, and then the output range of the Direct Injection (DI) input circuit is reached 2V. Successive-approximation-register (SAR) ADC architecture is used in this readout integrated circuit. And each ADC is shared by one column of the IRFPA. This SAR ADC is made up of a 13-bit digital-analog converter (DAC), a high resolution comparator, and a digital control circuit. The most important part is the voltage-scaling and charge-scaling charge redistribution DAC. In this DAC, charge scaling with a capacitor ladder to determine the least significant bits is combined with voltage scaling with a resister ladder to determine the most significant bits. The comparator uses three-stage operational amplifier structure to get a 77dB differential gain. The Common-Mode input rang of the comparator is 1V to 3V, and minimum resolvable voltage difference is 0.3mV. This SAR ADC has some advantages, especially in low power and high speed. The simulation result shows that the resolution of the ADC is 12 bit and the conversion time of the ADC is 6.5μs, while the power of each ADC is as low as 300μW. Finally, this SAR ADC can satisfy the request of 512*512 IRFPAs ROIC with a 100Hz frame rate.

  8. Importance of Time Scale and Local Environment in Electron-Driven Proton Transfer. The Anion of Acetoacetic Acid.

    PubMed

    Keolopile, Zibo G; Gutowski, Maciej; Buonaugurio, Angela; Collins, Evan; Zhang, Xinxing; Erb, Jeremy; Lectka, Thomas; Bowen, Kit H; Allan, Michael

    2015-11-18

    Anion photoelectron spectroscopy (PES) and electron energy-loss spectroscopy (EELS) probe different regions of the anionic potential energy surface. These complementary techniques provided information about anionic states of acetoacetic acid (AA). Electronic structure calculations facilitated the identification of the most stable tautomers and conformers for both neutral and anionic AA and determined their relative stabilities and excess electron binding energies. The most stable conformers of the neutral keto and enol tautomers differ by less than 1 kcal/mol in terms of electronic energies corrected for zero-point vibrations. Thermal effects favor these conformers of the keto tautomer, which do not support an intramolecular hydrogen bond between the keto and the carboxylic groups. The valence anion displays a distinct minimum which results from proton transfer from the carboxylic to the keto group; thus, we name it an ol structure. The minimum is characterized by a short intramolecular hydrogen bond, a significant electron vertical detachment energy of 2.38 eV, but a modest adiabatic electron affinity of 0.33 eV. The valence anion was identified in the anion PES experiments, and the measured electron vertical detachment energy of 2.30 eV is in good agreement with our computational prediction. We conclude that binding an excess electron in a π* valence orbital changes the localization of a proton in the fully relaxed structure of the AA(-) anion. The results of EELS experiments do not provide evidence for an ultrarapid proton transfer in the lowest π* resonance of AA(-), which would be capable of competing with electron autodetachment. This observation is consistent with our computational results, indicating that major gas-phase conformers and tautomers of neutral AA do not support the intramolecular hydrogen bond that would facilitate ultrarapid proton transfer and formation of the ol valence anion. This is confirmed by our vibrational EELS spectrum. Anions

  9. A low power 12-bit ADC for nuclear instrumentation

    SciTech Connect

    Adachi, R.; Landis, D.; Madden, N. ); Silver, E.; LeGros, M. )

    1992-10-01

    A low power, successive approximation, analog-to-digital converter (ADC) for low rate, low cost, battery powered applications is described. The ADC is based on a commercial 50 mW successive approximation CMOS device (CS5102). An on-chip self-calibration circuit reduces the inherent differential nonlinearity to 7%. A further reduction of the differential nonlinearity to 0.5% is attained with a four bit Gatti function. The Gatti function is distributed to minimize battery power consumption. All analog functions reside with the ADC while the noisy digital functions reside in the personal computer based histogramming memory. Fiber optic cables carry afl digital information between the ADC and the personal computer based histogramming memory.

  10. Identification and characterization of phenylpyruvate decarboxylase genes in Saccharomyces cerevisiae.

    PubMed

    Vuralhan, Zeynep; Morais, Marcos A; Tai, Siew-Leng; Piper, Matthew D W; Pronk, Jack T

    2003-08-01

    Catabolism of amino acids via the Ehrlich pathway involves transamination to the corresponding alpha-keto acids, followed by decarboxylation to an aldehyde and then reduction to an alcohol. Alternatively, the aldehyde may be oxidized to an acid. This pathway is functional in Saccharomyces cerevisiae, since during growth in glucose-limited chemostat cultures with phenylalanine as the sole nitrogen source, phenylethanol and phenylacetate were produced in quantities that accounted for all of the phenylalanine consumed. Our objective was to identify the structural gene(s) required for the decarboxylation of phenylpyruvate to phenylacetaldehyde, the first specific step in the Ehrlich pathway. S. cerevisiae possesses five candidate genes with sequence similarity to genes encoding thiamine diphosphate-dependent decarboxylases that could encode this activity: YDR380w/ARO10, YDL080C/THI3, PDC1, PDC5, and PDC6. Phenylpyruvate decarboxylase activity was present in cultures grown with phenylalanine as the sole nitrogen source but was absent from ammonia-grown cultures. Furthermore, the transcript level of one candidate gene (ARO10) increased 30-fold when phenylalanine replaced ammonia as the sole nitrogen source. Analyses of phenylalanine catabolite production and phenylpyruvate decarboxylase enzyme assays indicated that ARO10 was sufficient to encode phenylpyruvate decarboxylase activity in the absence of the four other candidate genes. There was also an alternative activity with a higher capacity but lower affinity for phenylpyruvate. The candidate gene THI3 did not itself encode an active phenylpyruvate decarboxylase but was required along with one or more pyruvate decarboxylase genes (PDC1, PDC5, and PDC6) for the alternative activity. The K(m) and V(max) values of the two activities differed, showing that Aro10p is the physiologically relevant phenylpyruvate decarboxylase in wild-type cells. Modifications to this gene could therefore be important for metabolic engineering

  11. On-focal-plane ADC: recent progress at JPL

    NASA Astrophysics Data System (ADS)

    Zhou, Zhimin; Pain, Bedabrata; Panicacci, Roger; Mansoorian, Barmak; Nakamura, Junichi; Fossum, Eric R.

    1996-06-01

    Two 8 bit successive approximation analog-to-digital converters (ADC), an 8 bit single slope ADC and a 12 bit current mode incremental sigma delta ((Sigma) -(Delta) ) ADC have been designed, fabricated, and tested. The 20.4 micrometers and 40 micrometers pitch successive approximation test chip designs are compatible with active pixel sensors (APS) column parallel architectures. A 64 X 64 photogate APS with this ADC integrated on-chip was fabricated in a 1.2 micrometers N-well CMOS process and achieves 8 bit accuracy. A 1 K X 1 K APS with 11 micrometers pixels and a single slope ADC in each column was fabricated in a 0.55 micrometers N-well CMOS process and also achieves 8 bit accuracy. The successive approximation designs consume as little as 49 (mu) W at a 500 KHz conversion rate meeting the low power requirements inherent in column parallel architectures. The current mode (Sigma) -(Delta) ADC test chip is designed to be multiplexed among 8 columns in a semi-column parallel current mode APS architecture. It consumes 800 (mu) W at a 5 KHz conversion rate.

  12. On-chip ADC for infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Gao, Lei; Chen, Guo-qiang; Wang, Pan; Ding, Rui-jun

    2013-09-01

    This paper presents a low power and small area analog-digital converter (ADC) for infrared focal plane arrays (IRFPA) readout integrated circuit (ROIC). Successive approximation register (SAR) ADC architecture is used in this IRFPA readout integrated circuit. Each column of the IRFPA shares one SAR ADC. The most important part is the three-level DAC. Compared to the previous design, this three-level DAC needs smaller area, has lower power, and more suitable for IRFPA ROIC. In this DAC, its most significant bit (MSB) sub-DAC uses charge scaling, while the least significant bit (LSB) sub-DAC uses voltage scaling. Where the MSB sub-DAC consists of a four-bit charge scaling DAC and a five-bit sub-charge scaling DAC. We need to put a scaling capacitor Cs between these two sub-DACs. Because of the small area, we have more design methods to make the ADC has a symmetrical structure and has higher accuracy. The ADC also needs a high resolution comparator. In this design the comparator uses three-stage operational amplifier structure to have a 77dB differential gain. As the IR focal plane readout circuit signal is stepped DC signal, the circuit design time without adding the sample and hold circuit, so we can use a DC signal instead of infrared focal plane readout circuit output analog signals to be simulated. The simulation result shows that the resolution of the ADC is 12 bit.

  13. Ornithine Decarboxylase, Polyamines, and Pyrrolizidine Alkaloids in Senecio and Crotalaria

    PubMed Central

    Birecka, Helena; Birecki, Mieczyslaw; Cohen, Eric J.; Bitonti, Alan J.; McCann, Peter P.

    1988-01-01

    When tested for ornithine and arginine decarboxylases, pyrrolizidine alkaloid-bearing Senecio riddellii, S. longilobus (Compositae), and Crotalaria retusa (Leguminosae) plants exhibited only ornithine decarboxylase activity. This contrasts with previous studies of four species of pyrrolizidine alkaloid-bearing Heliotropium (Boraginaceae) in which arginine decarboxylase activity was very high relative to that of ornithine decarboxylase. Unlike Heliotropium angiospermum and Heliotropium indicum, in which endogenous arginine was the only detectable precursor of putrescine channeled into pyrrolizidines, in the species studied here—using difluoromethylornithine and difluoromethylarginine as the enzyme inhibitors—endogenous ornithine was the main if not the only precursor of putrescine converted into the alkaloid aminoalcohol moiety. In S. riddellii and C. retusa at flowering, ornithine decarboxylase activity was present mainly in leaves, especially the young ones. However, other very young organs such as inflorescence and growing roots exhibited much lower or very low activities; the enzyme activity in stems was negligible. There was no correlation between the enzyme activity and polyamine or alkaloid content in either species. In both species only free polyamines were detected except for C. retusa roots and inflorescence—with relatively very high levels of these compounds—in which conjugated putrescine, spermidine, and spermine were also found; agmatine was not identified by HPLC in any plant organ except for C. retusa roots with rhizobial nodules. Organ- or age-dependent differences in the polyamine levels were small or insignificant. The highest alkaloid contents were found in young leaves and inflorescence. PMID:16665870

  14. Genetic analysis of the pyruvate decarboxylase reaction in yeast glycolysis.

    PubMed Central

    Schmitt, H D; Zimmermann, F K

    1982-01-01

    Six different pyruvate decarboxylase mutants of Saccharomyces cerevisiae were isolated. They belong to two unlinked complementation groups. Evidence is presented that one group is affected in a structural gene. The fact that five of the six mutants had residual pyruvate decarboxylase activity provided the opportunity for an intensive physiological characterization. It was shown that the loss of enzyme activity in vitro is reflected in a lower fermentation rate, an increased pyruvate secretion, and slower growth on a 2% glucose medium. The different effects of antimycin A on leaky mutants grown on ethanol versus the same mutants grown on glucose support the view that glucose induces some of the glycolytic enzymes, especially pyruvate decarboxylase. PMID:7050079

  15. Improvement of pipeline ADC resolution in sequential stages of conversion

    NASA Astrophysics Data System (ADS)

    Małkiewicz, Ł.

    2014-11-01

    Due to high discrepancy between possible combinations of rate and resolution of today's analog to digital converters (ADCs) and capabilities of the digital systems in favour of the latter, improvement of ADCs performance still is and will likely long be an actual issue. A perspective class of converters that allows further improvements of conversion quality, are adaptive pipeline ADCs (APADCs). APADCs on top of having all of the virtues of pipeline ADCs, such as an excellent compromise of relatively high speed due to pipelining of conversion iterations and high accuracy, as well as relatively low complexity, sizes and power consumption, thanks to computing of codes of input samples using digital signal processing (DSP) algorithms, allow full optimization of their functioning and achievement of better performance than of conventional pipeline ADCs. Optimization of APADC requires identification of factors critically influencing performance of APADC. This work focuses on one of them - the difference between resolution of estimates computed by a given stage of APADC and resolution of feedback DACs in following stages producing their analog equivalents, which creates a need for estimates resolution reduction in the course of conversion. The influence of the latter on work and performance of APADC is analyzed in the paper and a method to compensate this influence and improve resolution of APADC in sequential stages of conversion, is developed. Results of simulation experiments that prove effectiveness of the proposed solution and allow to estimate the benefits resulting from it, are presented.

  16. Utility of histogram analysis of ADC maps for differentiating orbital tumors

    PubMed Central

    Xu, Xiao-Quan; Hu, Hao; Su, Guo-Yi; Liu, Hu; Hong, Xun-Ning; Shi, Hai-Bin; Wu, Fei-Yun

    2016-01-01

    PURPOSE We aimed to evaluate the role of histogram analysis of apparent diffusion coefficient (ADC) maps for differentiating benign and malignant orbital tumors. METHODS Fifty-two patients with orbital tumors were enrolled from March 2013 to November 2014. Pretreatment diffusion-weighted imaging was performed on a 3T magnetic resonance scanner with b factors of 0 and 800 s/mm2, and the corresponding ADC maps were generated. Whole-tumor regions of interest were drawn on all slices of the ADC maps to obtain histogram parameters, including ADCmean, ADCmedian, standard deviation (SD), skewness, kurtosis, quartile, ADC10, ADC25, ADC75, and ADC90. Histogram parameter differences between benign and malignant orbital tumors were compared. The diagnostic value of each significant parameter in predicting malignant tumors was established. RESULTS Age, ADCmean, ADCmedian, quartile, kurtosis, ADC10, ADC25, ADC75, and ADC90 parameters were significantly different between benign and malignant orbital tumor groups, while gender, location, SD, and skewness were not significantly different. The best diagnostic performance in predicting malignant orbital tumors was achieved at the threshold of ADC10=0.990 (AUC, 0.997; sensitivity, 96.2%; specificity, 100%). CONCLUSION Histogram analysis of ADC maps holds promise for differentiating benign and malignant orbital tumors. ADC10 has the potential to be the most significant parameter for predicting malignant orbital tumors. PMID:26829400

  17. Parallel data analysis in a multichannel flash-ADC-system

    SciTech Connect

    Eckerlin, G.; Elsen, E.; Schmitt, H.V.D.; Wagner, A.; Walter, P.V.; Zimmer, M.

    1987-02-01

    Parallel analysis of drift chamber signals with M68000 processors has proven to be an efficient way to deal with the tremendous data flow generated by high speed (100 MHz) Flash-ADCs in real time. The authors report on the experience gained with a network of 34 processors, placed in 3 VME crates, to read out the 3072 Flash-ADC channels of the JADE Jet-Chamber at PETRA (1). The properties of such a system are compared to more conventional readout schemes for drift chambers.

  18. Histogram analysis of ADC in brain tumor patients

    NASA Astrophysics Data System (ADS)

    Banerjee, Debrup; Wang, Jihong; Li, Jiang

    2011-03-01

    At various stage of progression, most brain tumors are not homogenous. In this presentation, we retrospectively studied the distribution of ADC values inside tumor volume during the course of tumor treatment and progression for a selective group of patients who underwent an anti-VEGF trial. Complete MRI studies were obtained for this selected group of patients including pre- and multiple follow-up, post-treatment imaging studies. In each MRI imaging study, multiple scan series were obtained as a standard protocol which includes T1, T2, T1-post contrast, FLAIR and DTI derived images (ADC, FA etc.) for each visit. All scan series (T1, T2, FLAIR, post-contrast T1) were registered to the corresponding DTI scan at patient's first visit. Conventionally, hyper-intensity regions on T1-post contrast images are believed to represent the core tumor region while regions highlighted by FLAIR may overestimate tumor size. Thus we annotated tumor regions on the T1-post contrast scans and ADC intensity values for pixels were extracted inside tumor regions as defined on T1-post scans. We fit a mixture Gaussian (MG) model for the extracted pixels using the Expectation-Maximization (EM) algorithm, which produced a set of parameters (mean, various and mixture coefficients) for the MG model. This procedure was performed for each visits resulting in a series of GM parameters. We studied the parameters fitted for ADC and see if they can be used as indicators for tumor progression. Additionally, we studied the ADC characteristics in the peri-tumoral region as identified by hyper-intensity on FLAIR scans. The results show that ADC histogram analysis of the tumor region supports the two compartment model that suggests the low ADC value subregion corresponding to densely packed cancer cell while the higher ADC value region corresponding to a mixture of viable and necrotic cells with superimposed edema. Careful studies of the composition and relative volume of the two compartments in tumor

  19. Methods to Design and Synthesize Antibody-Drug Conjugates (ADCs)

    PubMed Central

    Yao, Houzong; Jiang, Feng; Lu, Aiping; Zhang, Ge

    2016-01-01

    Antibody-drug conjugates (ADCs) have become a promising targeted therapy strategy that combines the specificity, favorable pharmacokinetics and biodistributions of antibodies with the destructive potential of highly potent drugs. One of the biggest challenges in the development of ADCs is the application of suitable linkers for conjugating drugs to antibodies. Recently, the design and synthesis of linkers are making great progress. In this review, we present the methods that are currently used to synthesize antibody-drug conjugates by using thiols, amines, alcohols, aldehydes and azides. PMID:26848651

  20. Improve mask inspection capacity with Automatic Defect Classification (ADC)

    NASA Astrophysics Data System (ADS)

    Wang, Crystal; Ho, Steven; Guo, Eric; Wang, Kechang; Lakkapragada, Suresh; Yu, Jiao; Hu, Peter; Tolani, Vikram; Pang, Linyong

    2013-09-01

    As optical lithography continues to extend into low-k1 regime, resolution of mask patterns continues to diminish. The adoption of RET techniques like aggressive OPC, sub-resolution assist features combined with the requirements to detect even smaller defects on masks due to increasing MEEF, poses considerable challenges for mask inspection operators and engineers. Therefore a comprehensive approach is required in handling defects post-inspections by correctly identifying and classifying the real killer defects impacting the printability on wafer, and ignoring nuisance defect and false defects caused by inspection systems. This paper focuses on the results from the evaluation of Automatic Defect Classification (ADC) product at the SMIC mask shop for the 40nm technology node. Traditionally, each defect is manually examined and classified by the inspection operator based on a set of predefined rules and human judgment. At SMIC mask shop due to the significant total number of detected defects, manual classification is not cost-effective due to increased inspection cycle time, resulting in constrained mask inspection capacity, since the review has to be performed while the mask stays on the inspection system. Luminescent Technologies Automated Defect Classification (ADC) product offers a complete and systematic approach for defect disposition and classification offline, resulting in improved utilization of the current mask inspection capability. Based on results from implementation of ADC in SMIC mask production flow, there was around 20% improvement in the inspection capacity compared to the traditional flow. This approach of computationally reviewing defects post mask-inspection ensures no yield loss by qualifying reticles without the errors associated with operator mis-classification or human error. The ADC engine retrieves the high resolution inspection images and uses a decision-tree flow to classify a given defect. Some identification mechanisms adopted by ADC to

  1. MIREX INDUCES ORNITHINE DECARBOXYLASE ACTIVITY IN FEMALE RAT LIVER

    EPA Science Inventory

    Ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine synthesis, was significantly induced in female rat liver following oral administration of the pesticide, mirex. fter dual oral exposure (120 mg/kg; 21 and 4 hrs prior to sacrifice) induction of ODC activity in r...

  2. Antibody-Drug Conjugates (ADCs) Derived from Interchain Cysteine Cross-Linking Demonstrate Improved Homogeneity and Other Pharmacological Properties over Conventional Heterogeneous ADCs.

    PubMed

    Behrens, Christopher R; Ha, Edward H; Chinn, Lawrence L; Bowers, Simeon; Probst, Gary; Fitch-Bruhns, Maureen; Monteon, Jorge; Valdiosera, Amanda; Bermudez, Abel; Liao-Chan, Sindy; Wong, Tiffany; Melnick, Jonathan; Theunissen, Jan-Willem; Flory, Mark R; Houser, Derrick; Venstrom, Kristy; Levashova, Zoia; Sauer, Paul; Migone, Thi-Sau; van der Horst, Edward H; Halcomb, Randall L; Jackson, David Y

    2015-11-01

    Conventional antibody-drug conjugates (ADCs) are heterogeneous mixtures of chemically distinct molecules that vary in both drugs/antibody (DAR) and conjugation sites. Suboptimal properties of heterogeneous ADCs have led to new site-specific conjugation methods for improving ADC homogeneity. Most site-specific methods require extensive antibody engineering to identify optimal conjugation sites and introduce unique functional groups for conjugation with appropriately modified linkers. Alternative nonrecombinant methods have emerged in which bifunctional linkers are utilized to cross-link antibody interchain cysteines and afford ADCs containing four drugs/antibody. Although these methods have been shown to improve ADC homogeneity and stability in vitro, their effect on the pharmacological properties of ADCs in vivo is unknown. In order to determine the relative impact of interchain cysteine cross-linking on the therapeutic window and other properties of ADCs in vivo, we synthesized a derivative of the known ADC payload, MC-MMAF, that contains a bifunctional dibromomaleimide (DBM) linker instead of a conventional maleimide (MC) linker. The DBM-MMAF derivative was conjugated to trastuzumab and a novel anti-CD98 antibody to afford ADCs containing predominantly four drugs/antibody. The pharmacological properties of the resulting cross-linked ADCs were compared with analogous heterogeneous ADCs derived from conventional linkers. The results demonstrate that DBM linkers can be applied directly to native antibodies, without antibody engineering, to yield highly homogeneous ADCs via cysteine cross-linking. The resulting ADCs demonstrate improved pharmacokinetics, superior efficacy, and reduced toxicity in vivo compared to analogous conventional heterogeneous ADCs. PMID:26393951

  3. Histogram-Based Calibration Method for Pipeline ADCs.

    PubMed

    Son, Hyeonuk; Jang, Jaewon; Kim, Heetae; Kang, Sungho

    2015-01-01

    Measurement and calibration of an analog-to-digital converter (ADC) using a histogram-based method requires a large volume of data and a long test duration, especially for a high resolution ADC. A fast and accurate calibration method for pipelined ADCs is proposed in this research. The proposed calibration method composes histograms through the outputs of each stage and calculates error sources. The digitized outputs of a stage are influenced directly by the operation of the prior stage, so the results of the histogram provide the information of errors in the prior stage. The composed histograms reduce the required samples and thus calibration time being implemented by simple modules. For 14-bit resolution pipelined ADC, the measured maximum integral non-linearity (INL) is improved from 6.78 to 0.52 LSB, and the spurious-free dynamic range (SFDR) and signal-to-noise-and-distortion ratio (SNDR) are improved from 67.0 to 106.2dB and from 65.6 to 84.8dB, respectively. PMID:26070196

  4. The use of MRI apparent diffusion coefficient (ADC) in monitoring the development of brain infarction

    PubMed Central

    2011-01-01

    Background To study the rules that apparent diffusion coefficient (ADC) changes with time and space in cerebral infarction, and to provide the evidence in defining the infarction stages. Methods 117 work-ups in 98 patients with cerebral infarction (12 hyperacute, 43 acute, 29 subacute, 10 steady, and 23 chronic infarctions) were imaged with both conventional MRI and diffusion weighted imaging. The average ADC values, the relative ADC (rADC) values, and the ADC values or rADC values from the center to the periphery of the lesion were calculated. Results The average ADC values and the rADC values of hyperacute and acute infarction lesion depressed obviously. rADC values in hyperacute and acute stage was minimized, and increased progressively as time passed and appeared as "pseudonormal" values in approximately 8 to 14 days. Thereafter, rADC values became greater than normal in chronic stage. There was positive correlation between rADC values and time (P < 0.01). The ADC values and the rADC values in hyperacute and acute lesions had gradient signs that these lesions increased from the center to the periphery. The ADC values and the rADC values in subacute lesions had adverse gradient signs that these lesions decreased from the center to the periphery. Conclusion The ADC values of infarction lesions have evolution rules with time and space. The evolution rules with time and those in space can be helpful to decide the clinical stage, and to provide the evidence in guiding the treatment or judging the prognosis in infarction. PMID:21211049

  5. Putrescine accumulation confers drought tolerance in transgenic Arabidopsis plants over-expressing the homologous Arginine decarboxylase 2 gene.

    PubMed

    Alcázar, Rubén; Planas, Joan; Saxena, Triambak; Zarza, Xavier; Bortolotti, Cristina; Cuevas, Juan; Bitrián, Marta; Tiburcio, Antonio F; Altabella, Teresa

    2010-07-01

    In Arabidopsis, a model genus missing a functional ornithine decarboxylase pathway, most of the key genes involved in polyamine biosynthesis are duplicated. This gene redundancy has been related to the involvement of certain gene isoforms in the response to specific environmental stimuli. We have previously shown that drought stress induces Arginine decarboxlase 2 expression, while transcript levels for Arginine decarboxlase 1 remain constant. Accumulation of putrescine and increased arginine decarboxlase activity (EC 4.1.1.19) levels in response to different abiotic stresses have been reported in many different plant systems, but the biological meaning of this increase remains unclear. To get a new insight into these questions, we have studied the response to drought of transgenic Arabidopsis thaliana lines constitutively expressing the homologous Arginine decarboxlase 2 gene. These lines contain high levels of putrescine with no changes in spermidine and spermine content even under drought stress. Drought tolerance experiments indicate that the different degree of resistance to dehydration correlates with Put content. Although no significant differences were observed in the number of stomata between wild-type and transgenic plants, a reduction in transpiration rate and stomata conductance was observed in the ADC2 over-expressor lines. These results indicate that one of the mechanisms involved in the drought tolerance of transgenic plants over-producing Put is related to a reduction of water loss by transpiration. PMID:20206537

  6. Minimal Power Latch for Single-Slope ADCs

    NASA Technical Reports Server (NTRS)

    Hancock, Bruce R.

    2013-01-01

    Column-parallel analog-to-digital converters (ADCs) for imagers involve simultaneous operation of many ADCs. Single-slope ADCs are well adapted to this use because of their simplicity. Each ADC contains a comparator, comparing its input signal level to an increasing reference signal (ramp). When the ramp is equal to the input, the comparator triggers a latch that captures an encoded counter value (code). Knowing the captured code, the ramp value and hence the input signal are determined. In a column-parallel ADC, each column contains only the comparator and the latches; the ramp and code generation are shared. In conventional latch or flip-flop circuits, there is an input stage that tracks the input signal, and this stage consumes switching current every time the input changes. With many columns, many bits, and high code rates, this switching current can be substantial. It will also generate noise that may corrupt the analog signals. A latch was designed that does not track the input, and consumes power only at the instant of latching the data value. The circuit consists of two S-R (set-reset) latches, gated by the comparator. One is set by high data values and the other by low data values. The latches are cross-coupled so that the first one to set blocks the other. In order that the input data not need an inversion, which would consume power, the two latches are made in complementary polarity. This requires complementary gates from the comparator, instead of complementary data values, but the comparator only triggers once per conversion, and usually has complementary outputs to begin with. An efficient CMOS (complementary metal oxide semiconductor) implementation of this circuit is shown in the figure, where C is the comparator output, D is the data (code), and Q0 and Q1 are the outputs indicating the capture of a zero or one value. The latch for Q0 has a negative-true set signal and output, and is implemented using OR-AND-INVERT logic, while the latch for Q1 uses

  7. The crystal structure and mechanism of orotidine 5'-monophosphate decarboxylase.

    PubMed

    Appleby, T C; Kinsland, C; Begley, T P; Ealick, S E

    2000-02-29

    The crystal structure of Bacillus subtilis orotidine 5'-monophosphate (OMP) decarboxylase with bound uridine 5'-monophosphate has been determined by multiple wavelength anomalous diffraction phasing techniques and refined to an R-factor of 19.3% at 2.4 A resolution. OMP decarboxylase is a dimer of two identical subunits. Each monomer consists of a triosephosphate isomerase barrel and contains an active site that is located across one end of the barrel and near the dimer interface. For each active site, most of the residues are contributed by one monomer with a few residues contributed from the adjacent monomer. The most highly conserved residues are located in the active site and suggest a novel catalytic mechanism for decarboxylation that is different from any previously proposed OMP decarboxylase mechanism. The uridine 5'-monophosphate molecule is bound to the active site such that the phosphate group is most exposed and the C5-C6 edge of the pyrimidine base is most buried. In the proposed catalytic mechanism, the ground state of the substrate is destabilized by electrostatic repulsion between the carboxylate of the substrate and the carboxylate of Asp60. This repulsion is reduced in the transition state by shifting negative charge from the carboxylate to C6 of the pyrimidine, which is close to the protonated amine of Lys62. We propose that the decarboxylation of OMP proceeds by an electrophilic substitution mechanism in which decarboxylation and carbon-carbon bond protonation by Lys62 occur in a concerted reaction. PMID:10681442

  8. A cryogenic SAR ADC for infrared readout circuits

    NASA Astrophysics Data System (ADS)

    Hongliang, Zhao; Yiqiang, Zhao; Zhisheng, Zhang

    2011-11-01

    A cryogenic successive approximation register (SAR) analog to digital converter (ADC) is presented. It has been designed to operate in cryogenic infrared readout systems as they are cooled from room temperature to their final cryogenic operation temperature. In order to preserve the circuit's performance over this wide temperature range, a temperature-compensated time-based comparator architecture is used in the ADC, which provides a steady performance with ultra low power for extreme temperature (from room temperature down to 77 K) operation. The converter implemented in a standard 0.35 μm CMOS process exhibits 0.64 LSB maximum differential nonlinearity (DNL) and 0.59 LSB maximum integral nonlinearity (INL). It achieves 9.3 bit effective number of bits (ENOB) with 200 kS/s sampling rate at 77 K, dissipating 0.23 mW under 3.3 V supply voltage and occupies 0.8 × 0.3 mm2.

  9. A trimming technique for capacitive SAR ADC as sensor interface

    NASA Astrophysics Data System (ADS)

    Ke, Liu; Zhankun, Du; Li, Shao; Xiao, Ma

    2015-12-01

    This work presented a trimming technique and algorithm applied in a capacitive successive approximation register (SAR) analog to digital converter (ADC) for a sensor interface, which can be integrated with the preceding sensor and the following controlling circuit. Without spending a special calibration phase or adding complicated functions, this circuit keeps a 12-bit resolution by trimming the capacitor array. Its merits of low power and small area make it suitable to be embedded in a power and cost sensitive system such as a battery-supplied sensor network node. The prototype 12-bit ADC is implemented by 0.5 μm 2P3M CMOS technology, with the wide supply range of 2-5 V, its power consumption is only 300 μA at a sampling speed of 200 kHz. Project supported by the National Natural Science Foundation of China (No. 61204034).

  10. Effect Of Clock Mode On Radiation Hardness Of An ADC

    NASA Technical Reports Server (NTRS)

    Lee, Choon I.; Rax, Bernie G.; Johnston, Allan H.

    1995-01-01

    Report discusses techniques for testing and evaluating effects of total dosages of ionizing radiation on performances of high-resolution successive-approximation analog-to-digital converters (ADCs), without having to test each individual bit or transition. Reduces cost of testing by reducing tests to few critical parametric measurements, from which one determines approximate radiation failure levels providing good approximations of responses of converters for purpose of total-dose-radiation evaluations.

  11. HVM die yield improvement as a function of DRSEM ADC

    NASA Astrophysics Data System (ADS)

    Maheshwary, Sonu; Haas, Terry; McGarvey, Steve

    2010-03-01

    Given the current manufacturing technology roadmap and the competitiveness of the global semiconductor manufacturing environment in conjunction with the semiconductor manufacturing market dynamics, the market place continues to demand a reduced die manufacturing cost. This continuous pressure on lowering die cost in turn drives an aggressive yield learning curve, a key component of which is defect reduction of manufacturing induced anomalies. In order to meet and even exceed line and die yield targets there is a need to revamp defect classification strategies and place a greater emphasize on increasing the accuracy and purity of the Defect Review Scanning Electron Microscope (DRSEM) Automated Defect Classification (ADC) results while placing less emphasis on the ADC results of patterned/un-patterned wafer inspection systems. The increased emphasis on DRSEM ADC results allows for a high degree of automation and consistency in the classification data and eliminates variance induced by the manufacturing staff. This paper examines the use of SEM based Auto Defect Classification in a high volume manufacturing environment as a key driver in the reduction of defect limited yields.

  12. Retinoic acid modulation of ultraviolet light-induced epidermal ornithine decarboxylase activity

    SciTech Connect

    Lowe, N.J.; Breeding, J.

    1982-02-01

    Irradiation of skin with ultraviolet light of sunburn range (UVB) leads to a large and rapid induction of the polyamine biosynthetic enzyme ornithine decarboxylase in the epidermis. Induction of epidermal ornithine decarboxylase also occurs following application of the tumor promoting agent 12-0-tetradecanoylphorbol-13 acetate and topical retinoic acid is able to block both this ornithine decarboxylase induction and skin tumor promotion. In the studies described below, topical application of retinoic acid to hairless mouse skin leads to a significant inhibition of UVB-induced epidermal ornithine decarboxylase activity. The degree of this inhibition was dependent on the dose, timing, and frequency of the application of retinoic acid. To show significant inhibition of UVB-induced ornithine decarboxylase the retinoic acid had to be applied within 5 hr of UVB irradiation. If retinoic acid treatment was delayed beyond 7 hr following UVB, then no inhibition of UVB-induced ornithine decarboxylase was observed. The quantities of retinoic acid used (1.7 nmol and 3.4 nmol) have been shown effective at inhibiting 12-0-tetradecanoyl phorbol-13 acetate induced ornithine decarboxylase. The results show that these concentrations of topical retinoic acid applied either before or immediately following UVB irradiation reduces the UVB induction of epidermal ornithine decarboxylase. The effect of retinoic acid in these regimens on UVB-induced skin carcinogenesis is currently under study.

  13. Vector-mediated chromosomal integration of the glutamate decarboxylase gene in streptococcus thermophilus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The integrative vector pINTRS was used to transfer glutamate decarboxylase (GAD) activity to Streptococcus thermophilus ST128, thus allowing for the production of '-aminobutyric acid (GABA). In pINTRS, the gene encoding glutamate decarboxylase, gadB, was flanked by DNA fragments homologous to a S. ...

  14. Characterization of ornithine decarboxylase of tobacco cells and tomato ovaries.

    PubMed Central

    Heimer, Y M; Mizrahi, Y

    1982-01-01

    Some characteristics of L-ornithine decarboxylase of tomato ovaries and tobacco cells are described. The enzyme has a pH optimum of 8.0. It requires pyridoxal phosphate and thiol reagent (dithiothreitol) for activity. It is specific for L-ornithine and has an apparent Km of 1.4 X 10-4 M. It has an apparent molecular weight of 107000. Putrescine inhibited the activity in vitro. Spermidine and spermine also inhibit the enzyme, but less effectively. It is concluded that the enzyme is similar to that of mammalian origin and likewise fulfils a function related to cell proliferation. PMID:7082296

  15. Recent Advances in Site Specific Conjugations of Antibody Drug Conjugates (ADCs).

    PubMed

    Gao, Wenlong; Zhang, Jingxin; Xiang, Jun; Zhang, Lei; Wu, Chengbin; Dhal, Pradeep K; Chen, Bo

    2016-01-01

    Antibody-drug conjugates (ADCs) take the advantage of antigen specificity of monoclonal antibodies to deliver highly potent cytotoxic drugs selectively to antigen-expressing tumor cells. The recent approval of Adcetris™ and Kadcyla™ as well as emerging data from numerous ongoing clinical trials underscore the role of ADCs as a new therapeutic option for cancer patients. However, conventional conjugation methods generally result in a heterogeneous mixture of ADCs, which can result in significant therapeutic liabilities and can lead to complicated manufacturing processes. The increased understanding from the clinical investigation of current ADCs and site-specific bioconjugation technologies has enabled scientists to accelerate the discovery and development of the next generation ADCs with defined and homogeneous composition. The present manuscript reviews the recent advances and trends in the research and development of novel ADCs obtained by site-specific conjugation method. PMID:27174056

  16. A sub-microwatt asynchronous level-crossing ADC for biomedical applications.

    PubMed

    Li, Yongjia; Zhao, Duan; Serdijn, Wouter A

    2013-04-01

    A continuous-time level-crossing analog-to-digital converter (LC-ADC) for biomedical applications is presented. When compared to uniform-sampling (US) ADCs LC-ADCs generate fewer samples for various sparse biomedical signals. Lower power consumption and reduced design complexity with respect to conventional LC-ADCs are achieved due to: 1) replacing the n-bit digital-to-analog converter (DAC) with a 1-bit DAC; 2) splitting the level-crossing detections; and 3) fixing the comparison window. Designed and implemented in 0.18 μm CMOS technology, the proposed ADC uses a chip area of 220 × 203 μm(2). Operating from a supply voltage of 0.8 V, the ADC consumes 313-582 nW from 5 Hz to 5 kHz and achieves an ENOB up to 7.9 bits. PMID:23853297

  17. Minimal Power Latch for Single-Slope ADCs

    NASA Technical Reports Server (NTRS)

    Hancock, Bruce R. (Inventor)

    2015-01-01

    A latch circuit that uses two interoperating latches. The latch circuit has the beneficial feature that it switches only a single time during a measurement that uses a stair step or ramp function as an input signal in an analog to digital converter. This feature minimizes the amount of power that is consumed in the latch and also minimizes the amount of high frequency noise that is generated by the latch. An application using a plurality of such latch circuits in a parallel decoding ADC for use in an image sensor is given as an example.

  18. A fast integrating eight-bit bilinear ADC

    SciTech Connect

    Biery, K.A.; Ouimette, D.A.; Ritchie, J.L.

    1988-10-01

    A fast gated charge integrating ADC has been developed for measuring short photomultiplier pulses at very high event rates. The circuit is bilinar with 100 pC full scale and a least count of 150 fC. It features dc coupling, a minimum gate width of 20 ns, a minimum time between events of 200 ns plus gate width, a two event buffer, and front-end zero suppression with 100 ns read time per hit channel. Five hundred channels have been built and installed in the rare K/sub L//sup 0/ decay experiment E791 at Brookhaven National Laboratory. 3 refs., 6 figs., 1 tab.

  19. Crystal structure of pyruvate decarboxylase from Zymobacter palmae

    PubMed Central

    Buddrus, Lisa; Andrews, Emma S. V.; Leak, David J.; Danson, Michael J.; Arcus, Vickery L.; Crennell, Susan J.

    2016-01-01

    Pyruvate decarboxylase (PDC; EC 4.1.1.1) is a thiamine pyrophosphate- and Mg2+ ion-dependent enzyme that catalyses the non-oxidative decarboxylation of pyruvate to acetaldehyde and carbon dioxide. It is rare in bacteria, but is a key enzyme in homofermentative metabolism, where ethanol is the major product. Here, the previously unreported crystal structure of the bacterial pyruvate decarboxylase from Zymobacter palmae is presented. The crystals were shown to diffract to 2.15 Å resolution. They belonged to space group P21, with unit-cell parameters a = 204.56, b = 177.39, c = 244.55 Å and R r.i.m. = 0.175 (0.714 in the highest resolution bin). The structure was solved by molecular replacement using PDB entry 2vbi as a model and the final R values were R work = 0.186 (0.271 in the highest resolution bin) and R free = 0.220 (0.300 in the highest resolution bin). Each of the six tetramers is a dimer of dimers, with each monomer sharing its thiamine pyrophosphate across the dimer interface, and some contain ethylene glycol mimicking the substrate pyruvate in the active site. Comparison with other bacterial PDCs shows a correlation of higher thermostability with greater tetramer interface area and number of interactions. PMID:27599861

  20. Branched-chain 2-keto acid decarboxylases derived from Psychrobacter.

    PubMed

    Wei, Jiashi; Timler, Jacobe G; Knutson, Carolann M; Barney, Brett M

    2013-09-01

    The conversion of branched-chain amino acids to branched-chain acids or alcohols is an important aspect of flavor in the food industry and is dependent on the Ehrlich pathway found in certain lactic acid bacteria. A key enzyme in the pathway, the 2-keto acid decarboxylase (KDC), is also of interest in biotechnology applications to produce small branched-chain alcohols that might serve as improved biofuels or other commodity feedstocks. This enzyme has been extensively studied in the model bacterium Lactococcus lactis, but is also found in other bacteria and higher organisms. In this report, distinct homologs of the L. lactis KDC originally annotated as pyruvate decarboxylases from Psychrobacter cryohalolentis K5 and P. arcticus 273-4 were cloned and characterized, confirming a related activity toward specific branched-chain 2-keto acids derived from branched-chain amino acids. Further, KDC activity was confirmed in intact cells and cell-free extracts of P. cryohalolentis K5 grown on both rich and defined media, indicating that the Ehrlich pathway may also be utilized in some psychrotrophs and psychrophiles. A comparison of the similarities and differences in the P. cryohalolentis K5 and P. arcticus 273-4 KDC activities to other bacterial KDCs is presented. PMID:23826991

  1. Crystal structure of pyruvate decarboxylase from Zymobacter palmae.

    PubMed

    Buddrus, Lisa; Andrews, Emma S V; Leak, David J; Danson, Michael J; Arcus, Vickery L; Crennell, Susan J

    2016-09-01

    Pyruvate decarboxylase (PDC; EC 4.1.1.1) is a thiamine pyrophosphate- and Mg(2+) ion-dependent enzyme that catalyses the non-oxidative decarboxylation of pyruvate to acetaldehyde and carbon dioxide. It is rare in bacteria, but is a key enzyme in homofermentative metabolism, where ethanol is the major product. Here, the previously unreported crystal structure of the bacterial pyruvate decarboxylase from Zymobacter palmae is presented. The crystals were shown to diffract to 2.15 Å resolution. They belonged to space group P21, with unit-cell parameters a = 204.56, b = 177.39, c = 244.55 Å and Rr.i.m. = 0.175 (0.714 in the highest resolution bin). The structure was solved by molecular replacement using PDB entry 2vbi as a model and the final R values were Rwork = 0.186 (0.271 in the highest resolution bin) and Rfree = 0.220 (0.300 in the highest resolution bin). Each of the six tetramers is a dimer of dimers, with each monomer sharing its thiamine pyrophosphate across the dimer interface, and some contain ethylene glycol mimicking the substrate pyruvate in the active site. Comparison with other bacterial PDCs shows a correlation of higher thermostability with greater tetramer interface area and number of interactions. PMID:27599861

  2. Evolution of a novel lysine decarboxylase in siderophore biosynthesis.

    PubMed

    Burrell, Matthew; Hanfrey, Colin C; Kinch, Lisa N; Elliott, Katherine A; Michael, Anthony J

    2012-10-01

    Structural backbones of iron-scavenging siderophore molecules include polyamines 1,3-diaminopropane and 1,5-diaminopentane (cadaverine). For the cadaverine-based desferroxiamine E siderophore in Streptomyces coelicolor, the corresponding biosynthetic gene cluster contains an ORF encoded by desA that was suspected of producing the cadaverine (decarboxylated lysine) backbone. However, desA encodes an l-2,4-diaminobutyrate decarboxylase (DABA DC) homologue and not any known form of lysine decarboxylase (LDC). The only known function of DABA DC is, together with l-2,4-aminobutyrate aminotransferase (DABA AT), to synthesize 1,3-diaminopropane. We show here that S. coelicolor desA encodes a novel LDC and we hypothesized that DABA DC homologues present in siderophore biosynthetic clusters in the absence of DABA AT ORFs would be novel LDCs. We confirmed this by correctly predicting the LDC activity of a DABA DC homologue from a Yersinia pestis siderophore biosynthetic pathway. The corollary was confirmed for a DABA DC homologue, adjacent to a DABA AT ORF in a siderophore pathway in the cyanobacterium Anabaena variabilis, which was shown to be a bona fide DABA DC. These findings enable prediction of whether a siderophore pathway will utilize 1,3-diaminopropane or cadaverine, and suggest that the majority of bacteria use DABA AT and DABA DC for siderophore, rather than norspermidine/polyamine biosynthesis. PMID:22906379

  3. Evaluation of commercial ADC radiation tolerance for accelerator experiments

    NASA Astrophysics Data System (ADS)

    Chen, K.; Chen, H.; Kierstead, J.; Takai, H.; Rescia, S.; Hu, X.; Xu, H.; Mead, J.; Lanni, F.; Minelli, M.

    2015-08-01

    Electronic components used in high energy physics experiments are subjected to a radiation background composed of high energy hadrons, mesons and photons. These particles can induce permanent and transient effects that affect the normal device operation. Ionizing dose and displacement damage can cause chronic damage which disable the device permanently. Transient effects or single event effects are in general recoverable with time intervals that depend on the nature of the failure. The magnitude of these effects is technology dependent with feature size being one of the key parameters. Analog to digital converters are components that are frequently used in detector front end electronics, generally placed as close as possible to the sensing elements to maximize signal fidelity. We report on the development of a technique for testing analog to digital converters for radiation effects, in particular for single event effects. A total of seventeen commercial ADCs were evaluated for ionizing dose tolerance and extensive SEU measurements performed on a twelve and fourteen bit ADCs. Mitigation strategies for single event effects (SEE) are discussed for their use in the large hadron collider environment.

  4. Separation of effector cells mediating antibody-dependent cellular cytotoxicity (ADC) to erythrocyte targets from those mediating ADC to tumor targets.

    PubMed

    Pollack, S B; Nelson, K; Grausz, J D

    1976-04-01

    Murine spleen cells mediate antibody-dependent cellular cytotoxicity (ADC) both to erythrocyte targets in a 51Cr release assay and to syngeneic tumor targets in a microcytotoxicity assay. The effector cells active in the two ADC assays can be separated by passage of the spleen cells through columns of Sephadex G-10 at 37 degrees C. Cells mediating ADC to sarcoma cells did not adhere to the G-10 and were recovered in the column effluent. These nonadherent cells were not cytotoxic to antibody-coated chicken red blood cells. Spleen cells which mediated ADC in a 51Cr release assay to the red cell targets adhered to G-10. Adherent effector cells could subsequently be recovered from the columns by elution with 5 X 10(-4) M EDTA. PMID:815438

  5. Isolation and characterization of the dopa decarboxylase gene of Drosophila melanogaster.

    PubMed Central

    Hirsh, J; Davidson, N

    1981-01-01

    We have isolated chromosomal deoxyribonucleic acid clones containing the Drosophila dopa decarboxylase gene. We describe an isolation procedure which can be applied to other nonabundantly expressed Drosophila genes. The dopa decarboxylase gene lies within or very near polytene chromosome band 37C1-2. The gene is interrupted by at least one intron, and the primary mode of regulation is pretranslational. At least two additional sequences hybridized by in vivo ribonucleic acid-derived probes are found within a 35-kilobase region surrounding the gene. The developmental profile of ribonucleic acid transcribed from one of these regions differs from that of the dopa decarboxylase transcript. Images PMID:6086012

  6. Iterative Method and Dithering with Averaging used for Correction of ADC Error

    NASA Astrophysics Data System (ADS)

    Kamenský, M.; Kováč, K.

    2009-01-01

    Additive iterative method in combination with averaging of dithered samples is designed for self-correction of ADC linearity error in the paper. Iterative method is one of the automated error correction techniques. Dithering is a special tool for quantizer performance enhancement. Dither theory for Gaussian noise and averaging has been used for exhibition of method abilities in ADC characteristic improvement.

  7. An 18 bit 50 kHz ADC for low earth orbit

    NASA Technical Reports Server (NTRS)

    Thelen, Donald C.

    1992-01-01

    A fourth order incremental analog to digital converter (ADC) is proposed which performs 18 bit conversions at a 50 kHz rate on sampled and held data. A new self calibration scheme is presented which eases the matching requirements of capacitors, and the performance of the operational amplifiers in the ADC by changing coefficients in the digital postprocessing.

  8. An endosymbiont positively modulates ornithine decarboxylase in host trypanosomatids

    SciTech Connect

    Frossard, Mariana Lins; Seabra, Sergio Henrique; Matta, Renato Augusto da; Souza, Wanderley de; Garcia de Mello, Fernando; Motta, Maria Cristina Machado . E-mail: motta@biof.ufrj.br

    2006-05-05

    Summary: Some trypanosomatids, such as Crithidia deanei, are endosymbiont-containing species. Aposymbiotic strains are obtained after antibiotic treatment, revealing interesting aspects of this symbiotic association. Ornithine decarboxylase (ODC) promotes polyamine biosynthesis and contributes to cell proliferation. Here, we show that ODC activity is higher in endosymbiont-bearing trypanosomatids than in aposymbiotic cells, but isolated endosymbionts did not display this enzyme activity. Intriguingly, expressed levels of ODC were similar in both strains, suggesting that ODC is positively modulated in endosymbiont-bearing cells. When the aposymbiotic strain was grown in conditioned medium, obtained after cultivation of the endosymbiont-bearing strain, cellular proliferation as well as ODC activity and localization were similar to that observed in the endosymbiont-containing trypanosomatids. Furthermore, dialyzed-heated medium and trypsin treatment reduced ODC activity of the aposymbiont strain. Taken together, these data indicate that the endosymbiont can enhance the protozoan ODC activity by providing factors of protein nature, which increase the host polyamine metabolism.

  9. Altered subcellular localization of ornithine decarboxylase in Alzheimer's disease brain

    SciTech Connect

    Nilsson, Tatjana . E-mail: Tatjana.Nilsson@ki.se; Bogdanovic, Nenad; Volkman, Inga; Winblad, Bengt; Folkesson, Ronnie; Benedikz, Eirikur

    2006-06-02

    The amyloid precursor protein can through ligand-mimicking induce expression of ornithine decarboxylase (ODC), the initial and rate-limiting enzyme in polyamine biosynthesis. We report here the regional distribution and cellular localization of ODC immunoreactivity in Alzheimer's disease (AD) brains. In frontal cortex and hippocampus of control cases, the most pronounced ODC immunoreactivity was found in the nucleus. In possible and definite AD the immunoreactivity had shifted to the cytoplasm. In cerebellum of control cases, ODC staining was found in a small portion of Purkinje cells, mostly in the nucleus. In AD, both possible and definite, the number of stained Purkinje cells increased significantly and immunoreactivity was shifted to the cytoplasm, even though it was still prominent in the nucleus. In conclusion, our study reveals an early shift of the ODC immunoreactivity in AD from the nuclear compartment towards the cytoplasm.

  10. Autonomous Community Construction Technology to Achieve Service Assurance in ADCS

    NASA Astrophysics Data System (ADS)

    Mahmood, Khalid; Lu, Xiaodong; Mori, Kinji

    Autonomous Decentralized Community System (ADCS) makes its basis on offering customized and dynamic services to group of end-users having common preferences at specified time and location. Owing to extreme dynamism in the system caused by rapidly varying user's demands, and severe mobility of users, it is quite difficult to assure timely service provision to all community members. This paper presents autonomous decentralized community system construction by autonomous division and integration technologies to procure service assurance under dynamic situations, without involving significant communication overhead. By adopting the concept of size threshold, the proposed technique continuously maintains the appropriate size of community in constantly and rapidly changing operating environment, to deliver optimal quality of service in terms of response time. The effectiveness of proposed technology has been shown through simulation, which reveals remarkable improvement (up to 29%) in response time.

  11. A Liquid-Based Colorimetric Assay of Lysine Decarboxylase and Its Application to Enzymatic Assay.

    PubMed

    Kim, Yong Hyun; Sathiyanarayanan, Ganesan; Kim, Hyun Joong; Bhatia, Shashi Kant; Seo, Hyung-Min; Kim, Jung-Ho; Song, Hun-Seok; Kim, Yun-Gon; Park, Kyungmoon; Yang, Yung-Hun

    2015-12-28

    A liquid-based colorimetric assay using a pH indicator was introduced for high-throughput monitoring of lysine decarboxylase activity. The assay is based on the color change of bromocresol purple, measured at 595 nm in liquid reaction mixture, due to an increase of pH by the production of cadaverine. Bromocresol purple was selected as the indicator because it has higher sensitivity than bromothymol blue and pheonol red within a broad range and shows good linearity within the applied pH. We applied this for simple determination of lysine decarboxylase reusability using 96-well plates, and optimization of conditions for enzyme overexpression with different concentrations of IPTG on lysine decarboxylase. This assay is expected to be applied for monitoring and quantifying the liquid-based enzyme reaction in biotransformation of decarboxylase in a high-throughput way. PMID:26282689

  12. The Impact of Population Density on the Likelihood of Aid to Dependent Children (ADC) Clients Becoming Economically Self-Sufficient.

    ERIC Educational Resources Information Center

    Bendixen-Noe, Mary K.; And Others

    The impact of population density on the likelihood of Aid to Dependent Children (ADC) clients becoming economically self-sufficient was examined through a study of 2,647 ADC recipients referred to a total of 8 comprehensive vocational assessment centers (CVACs) for ADC clients that were established in Ohio in 1992. Of the CVACs, two were from each…

  13. Glutamic acid decarboxylase isoform distribution in transgenic mouse septum: an anti-GFP immunofluorescence study.

    PubMed

    Verimli, Ural; Sehirli, Umit S

    2016-09-01

    The septum is a basal forebrain region located between the lateral ventricles in rodents. It consists of lateral and medial divisions. Medial septal projections regulate hippocampal theta rhythm whereas lateral septal projections are involved in processes such as affective functions, memory formation, and behavioral responses. Gamma-aminobutyric acidergic neurons of the septal region possess the 65 and 67 isoforms of the enzyme glutamic acid decarboxylase. Although data on the glutamic acid decarboxylase isoform distribution in the septal region generally appears to indicate glutamic acid decarboxylase 67 dominance, different studies have given inconsistent results in this regard. The aim of this study was therefore to obtain information on the distributions of both of these glutamic acid decarboxylase isoforms in the septal region in transgenic mice. Two animal groups of glutamic acid decarboxylase-green fluorescent protein knock-in transgenic mice were utilized in the experiment. Brain sections from the region were taken for anti-green fluorescent protein immunohistochemistry in order to obtain estimated quantitative data on the number of gamma-aminobutyric acidergic neurons. Following the immunohistochemical procedures, the mean numbers of labeled cells in the lateral and medial septal nuclei were obtained for the two isoform groups. Statistical analysis yielded significant results which indicated that the 65 isoform of glutamic acid decarboxylase predominates in both lateral and medial septal nuclei (unpaired two-tailed t-test p < 0.0001 for LS, p < 0.01 for MS). This study is the first to reveal the dominance of glutamic acid decarboxylase isoform 65 in the septal region in glutamic acid decarboxylase-green fluorescent protein transgenic mice. PMID:26643381

  14. Simulation of continuously logical ADC (CL ADC) of photocurrents as a basic cell of image processor and multichannel optical sensor systems

    NASA Astrophysics Data System (ADS)

    Krasilenko, Vladimir G.; Nikolskyy, Aleksandr I.; Lazarev, Alexander A.; Krasilenko, Oksana V.; Krasilenko, Irina A.

    2013-05-01

    The paper considers results of design and modeling of continuously logical analog-to-digital converters (ADC) based on current mirrors for image processor and multichannel optical sensor systems with parallel inputs-outputs. For such multichannel serial-parallel analog-to-digital converters (SP ADC) it is needed base photoelectron cells, which are considered in paper. Its have a number of advantages: high speed and reliability, simplicity, small power consumption, high integration level for linear and matrix structures. We show design of the continuously logical ADC of photocurrents and its base digit cells (ABC) and its simulations. We consider CL ADC for Gray and binary codes. Each channel of the structure consists of several base digit cells (ABC) on 20-30 CMOS FETs and one photodiode. The supply voltage of the ABC is 1-3.3V, the range of an input photocurrent is 0.1 - 10μA, the transformation time is 30ns at 5-8 bit binary or Gray codes, power consumption is about 1mW. One channel of ADC with iteration is based on one ABC-3(G) and SHD, and it has only 40 CMOS transistors. The general power consumption of the ADC, in this case, is only 50-100μW, if the maximum input current is 1μA. The CL ADC opens new prospects for realization of linear and matrix image processor and photo-electronic structures with picture operands, which are necessary for neural networks, digital optoelectronic processors, neural-fuzzy controllers, and so forth.

  15. Structure and Function of 4-Hydroxyphenylacetate Decarboxylase and Its Cognate Activating Enzyme.

    PubMed

    Selvaraj, Brinda; Buckel, Wolfgang; Golding, Bernard T; Ullmann, G Matthias; Martins, Berta M

    2016-01-01

    4-Hydroxyphenylacetate decarboxylase (4Hpad) is the prototype of a new class of Fe-S cluster-dependent glycyl radical enzymes (Fe-S GREs) acting on aromatic compounds. The two-enzyme component system comprises a decarboxylase responsible for substrate conversion and a dedicated activating enzyme (4Hpad-AE). The decarboxylase uses a glycyl/thiyl radical dyad to convert 4-hydroxyphenylacetate into p-cresol (4-methylphenol) by a biologically unprecedented Kolbe-type decarboxylation. In addition to the radical dyad prosthetic group, the decarboxylase unit contains two [4Fe-4S] clusters coordinated by an extra small subunit of unknown function. 4Hpad-AE reductively cleaves S-adenosylmethionine (SAM or AdoMet) at a site-differentiated [4Fe-4S]2+/+ cluster (RS cluster) generating a transient 5'-deoxyadenosyl radical that produces a stable glycyl radical in the decarboxylase by the abstraction of a hydrogen atom. 4Hpad-AE binds up to two auxiliary [4Fe-4S] clusters coordinated by a ferredoxin-like insert that is C-terminal to the RS cluster-binding motif. The ferredoxin-like domain with its two auxiliary clusters is not vital for SAM-dependent glycyl radical formation in the decarboxylase, but facilitates a longer lifetime for the radical. This review describes the 4Hpad and cognate AE families and focuses on the recent advances and open questions concerning the structure, function and mechanism of this novel Fe-S-dependent class of GREs. PMID:26959876

  16. A 10-bit ratio-independent cyclic ADC with offset canceling for a CMOS image sensor

    NASA Astrophysics Data System (ADS)

    Kaiming, Nie; Suying, Yao; Jiangtao, Xu; Zhaorui, Jiang

    2014-03-01

    A 10-bit ratio-independent switch-capacitor (SC) cyclic analog-to-digital converter (ADC) with offset canceling for a CMOS image sensor is presented. The proposed ADC completes an N-bit conversion in 1.5N clock cycles with one operational amplifier. Combining ratio-independent and polarity swapping techniques, the conversion characteristic of the proposed cyclic ADC is inherently insensitive both to capacitor ratio and to amplifier offset voltage. Therefore, the circuit can be realized in a small die area and it is suitable to serve as the column-parallel ADC in CMOS image sensors. A prototype ADC is fabricated in 0.18-μm one-poly four-metal CMOS technology. The measured results indicate that the ADC has a signal-to-noise and distortion ratio (SNDR) of 53.6 dB and a DNL of +0:12/-0:14 LSB at a conversion rate of 600 kS/s. The standard deviation of the offset variation of the ADC is reduced from 2.5 LSB to 0.5 LSB. Its power dissipation is 250 μW with a 1.8 V supply, and its area is 0.03 × 0.8 mm2.

  17. A low-power small-area ADC array for IRFPA readout

    NASA Astrophysics Data System (ADS)

    Zhong, Shengyou; Yao, Libin

    2013-09-01

    The readout integrated circuit (ROIC) is a bridge between the infrared focal plane array (IRFPA) and image processing circuit in an infrared imaging system. The ROIC is the first part of signal processing circuit and connected to detectors directly, so its performance will greatly affect the detector or even the whole imaging system performance. With the development of CMOS technologies, it's possible to digitalize the signal inside the ROIC and develop the digital ROIC. Digital ROIC can reduce complexity of the whole system and improve the system reliability. More importantly, it can accommodate variety of digital signal processing techniques which the traditional analog ROIC cannot achieve. The analog to digital converter (ADC) is the most important building block in the digital ROIC. The requirements for ADCs inside the ROIC are low power, high dynamic range and small area. In this paper we propose an RC hybrid Successive Approximation Register (SAR) ADC as the column ADC for digital ROIC. In our proposed ADC structure, a resistor ladder is used to generate several voltages. The proposed RC hybrid structure not only reduces the area of capacitor array but also releases requirement for capacitor array matching. Theory analysis and simulation show RC hybrid SAR ADC is suitable for ADC array applications

  18. Zn2+ Uptake in Streptococcus pyogenes: Characterization of adcA and lmb Null Mutants

    PubMed Central

    Tedde, Vittorio; Rosini, Roberto; Galeotti, Cesira L.

    2016-01-01

    An effective regulation of metal ion homeostasis is essential for the growth of microorganisms in any environment and in pathogenic bacteria is strongly associated with their ability to invade and colonise their hosts. To gain a better insight into zinc acquisition in Group A Streptococcus (GAS) we characterized null deletion mutants of the adcA and lmb genes of Streptococcus pyogenes strain MGAS5005 encoding the orthologues of AdcA and AdcAII, the two surface lipoproteins with partly redundant roles in zinc homeostasis in Streptococcus pneumoniae. Null adcA and lmb mutants were analysed for their capability to grow in zinc-depleted conditions and were found to be more susceptible to zinc starvation, a phenotype that could be rescued by the addition of Zn2+ ions to the growth medium. Expression of AdcA, Lmb and HtpA, the polyhistidine triad protein encoded by the gene adjacent to lmb, during growth under conditions of limited zinc availability was examined by Western blot analysis in wild type and null mutant strains. In the wild type strain, AdcA was always present with little variation in expression levels between conditions of excess or limited zinc availability. In contrast, Lmb and HtpA were expressed at detectable levels only during growth in the presence of low zinc concentrations or in the null adcA mutant, when expression of lmb is required to compensate for the lack of adcA expression. In the latter case, Lmb and HtpA were overexpressed by several fold, thus indicating that also in GAS AdcA is a zinc-specific importer and, although it shares this function with Lmb, the two substrate-binding proteins do not show fully overlapping roles in zinc homeostasis. PMID:27031880

  19. ADCS Prevention Instrument Project: overview and initial results.

    PubMed

    Ferris, Steven H; Aisen, Paul S; Cummings, Jeffrey; Galasko, Douglas; Salmon, David P; Schneider, Lon; Sano, Mary; Whitehouse, Peter J; Edland, Steven; Thal, Leon J

    2006-01-01

    One objective of the Alzheimer's Disease Cooperative Study (ADCS) is to develop new or improved instruments and assessment methods for evaluating treatment efficacy in Alzheimer disease (AD) clinical trials. The ADCS Instrument Committee has previously helped to define the state of the art in assessment for AD and Mild Cognitive Impairment clinical trials. We are now entering an exciting era of primary prevention trials to evaluate promising treatments that may delay disease onset and there is a need to develop appropriate instruments for these trials. The ADCS instrument committee has undertaken a project to develop instruments for prevention studies that assess domains known to be important in AD. Prevention trials are long and require large numbers of subjects, making them costly and requiring a high burden of participation for subjects. The current study focused on developing instruments that can be completed at home and in the clinic. The instruments are being evaluated in a cohort of nondemented elderly participating in a 4-year longitudinal study that simulates the design of a primary prevention trial. This report describes the design, baseline characteristics, and some longitudinal outcomes of the study cohort through the completion of the first 2 years of follow-up. We also describe the assessment domains to be measured with our new experimental instruments. This study recruited 644 subjects, 75 years of age and older. Participation in a "book club" that provided free books of interest to elders was offered as a recruitment incentive. Approximately 23% had some mild cognitive symptoms consistent with a Clinical Dementia Rating of 0.5. All subjects received a standardized in-clinic evaluation at baseline, which is repeated annually for 4 years to identify cases suspected of developing dementia and to measure longitudinal change on established clinical assessments. Subjects completed a set of self-administered experimental instruments at home or in the

  20. ADCS controllers comparison for small satellitess in Low Earth Orbit

    NASA Astrophysics Data System (ADS)

    Calvo, Daniel; Laverón-Simavilla, Ana; Lapuerta, Victoria

    2016-07-01

    Fuzzy logic controllers are flexible and simple, suitable for small satellites Attitude Determination and Control Subsystems (ADCS). In a previous work, a tailored Fuzzy controller was designed for a nanosatellite. Its performance and efficiency were compared with a traditional Proportional Integrative Derivative (PID) controller within the same specific mission. The orbit height varied along the mission from injection at around 380 km down to 200 km height, and the mission required pointing accuracy over the whole time. Due to both, the requirements imposed by such a low orbit, and the limitations in the power available for the attitude control, an efficient ADCS is required. Both methodologies, fuzzy and PID, were fine-tuned using an automated procedure to grant maximum efficiency with fixed performances. The simulations showed that the Fuzzy controller is much more efficient (up to 65% less power required) in single manoeuvres, achieving similar, or even better, precision than the PID. The accuracy and efficiency improvement of the Fuzzy controller increase with orbit height because the environmental disturbances decrease, approaching the ideal scenario. However, the controllers are meant to be used in a vast range of situations and configurations which exceed those used in the calibration process carried out in the previous work. To assess the suitability and performance of both controllers in a wider framework, parametric and statistical methods have been applied using the Monte Carlo technique. Several parameters have been modified randomly at the beginning of each simulation: the moments of inertia of the whole satellite and of the momentum wheel, the residual magnetic dipole and the initial conditions of the test. These parameters have been chosen because they are the main source of uncertainty during the design phase. The variables used for the analysis are the error (critical for science) and the operation cost (which impacts the mission lifetime and

  1. Evaluation of commercial ADC radiation tolerance for accelerator experiments

    DOE PAGESBeta

    Chen, K.; Chen, H.; Kierstead, J.; Takai, H.; Rescia, S.; Hu, X.; Xu, H.; Mead, J.; Lanni, F.; Minelli, M.

    2015-08-17

    Electronic components used in high energy physics experiments are subjected to a radiation background composed of high energy hadrons, mesons and photons. These particles can induce permanent and transient effects that affect the normal device operation. Ionizing dose and displacement damage can cause chronic damage which disable the device permanently. Transient effects or single event effects are in general recoverable with time intervals that depend on the nature of the failure. The magnitude of these effects is technology dependent with feature size being one of the key parameters. Analog to digital converters are components that are frequently used in detectormore » front end electronics, generally placed as close as possible to the sensing elements to maximize signal fidelity. We report on radiation effects tests conducted on 17 commercially available analog to digital converters and extensive single event effect measurements on specific twelve and fourteen bit ADCs that presented high tolerance to ionizing dose. We discuss mitigation strategies for single event effects (SEE) for their use in the large hadron collider environment.« less

  2. Evaluation of commercial ADC radiation tolerance for accelerator experiments

    SciTech Connect

    Chen, K.; Chen, H.; Kierstead, J.; Takai, H.; Rescia, S.; Hu, X.; Xu, H.; Mead, J.; Lanni, F.; Minelli, M.

    2015-08-17

    Electronic components used in high energy physics experiments are subjected to a radiation background composed of high energy hadrons, mesons and photons. These particles can induce permanent and transient effects that affect the normal device operation. Ionizing dose and displacement damage can cause chronic damage which disable the device permanently. Transient effects or single event effects are in general recoverable with time intervals that depend on the nature of the failure. The magnitude of these effects is technology dependent with feature size being one of the key parameters. Analog to digital converters are components that are frequently used in detector front end electronics, generally placed as close as possible to the sensing elements to maximize signal fidelity. We report on radiation effects tests conducted on 17 commercially available analog to digital converters and extensive single event effect measurements on specific twelve and fourteen bit ADCs that presented high tolerance to ionizing dose. We discuss mitigation strategies for single event effects (SEE) for their use in the large hadron collider environment.

  3. Anti-glutamic acid decarboxylase antibody positive neurological syndromes.

    PubMed

    Tohid, Hassaan

    2016-07-01

    A rare kind of antibody, known as anti-glutamic acid decarboxylase (GAD) autoantibody, is found in some patients. The antibody works against the GAD enzyme, which is essential in the formation of gamma aminobutyric acid (GABA), an inhibitory neurotransmitter found in the brain. Patients found with this antibody present with motor and cognitive problems due to low levels or lack of GABA, because in the absence or low levels of GABA patients exhibit motor and cognitive symptoms. The anti-GAD antibody is found in some neurological syndromes, including stiff-person syndrome, paraneoplastic stiff-person syndrome, Miller Fisher syndrome (MFS), limbic encephalopathy, cerebellar ataxia, eye movement disorders, and epilepsy. Previously, excluding MFS, these conditions were calledhyperexcitability disorders. However, collectively, these syndromes should be known as "anti-GAD positive neurological syndromes." An important limitation of this study is that the literature is lacking on the subject, and why patients with the above mentioned neurological problems present with different symptoms has not been studied in detail. Therefore, it is recommended that more research is conducted on this subject to obtain a better and deeper understanding of these anti-GAD antibody induced neurological syndromes. PMID:27356651

  4. Multiple roles of the active site lysine of Dopa decarboxylase.

    PubMed

    Bertoldi, Mariarita; Voltattorni, Carla Borri

    2009-08-15

    The pyridoxal 5'-phosphate dependent-enzyme Dopa decarboxylase, responsible for the irreversible conversion of l-Dopa to dopamine, is an attractive drug target. The contribution of the pyridoxal-Lys303 to the catalytic mechanisms of decarboxylation and oxidative deamination is analyzed. The K303A variant binds the coenzyme with a 100-fold decreased apparent equilibrium binding affinity with respect to the wild-type enzyme. Unlike the wild-type, K303A in the presence of l-Dopa displays a parallel progress course of formation of both dopamine and 3,4-dihydroxyphenylacetaldehyde (plus ammonia) with a burst followed by a linear phase. Moreover, the finding that the catalytic efficiencies of decarboxylation and of oxidative deamination display a decrease of 1500- and 17-fold, respectively, with respect to the wild-type, is indicative of a different impact of Lys303 mutation on these reactions. Kinetic analyses reveal that Lys303 is involved in external aldimine formation and hydrolysis as well as in product release which affects the rate-determining step of decarboxylation. PMID:19580779

  5. Dimerization of Bacterial Diaminopimelate Decarboxylase Is Essential for Catalysis.

    PubMed

    Peverelli, Martin G; Soares da Costa, Tatiana P; Kirby, Nigel; Perugini, Matthew A

    2016-04-29

    Diaminopimelate decarboxylase (DAPDC) catalyzes the final step in the diaminopimelate biosynthesis pathway of bacteria. The product of the reaction is the essential amino acid l-lysine, which is an important precursor for the synthesis of the peptidoglycan cell wall, housekeeping proteins, and virulence factors of bacteria. Accordingly, the enzyme is a promising antibacterial target. Previous structural studies demonstrate that DAPDC exists as monomers, dimers, and tetramers in the crystal state. However, the active oligomeric form has not yet been determined. We show using analytical ultracentrifugation, small angle x-ray scattering, and enzyme kinetic analyses in solution that the active form of DAPDC from Bacillus anthracis, Escherichia coli, Mycobacterium tuberculosis, and Vibrio cholerae is a dimer. The importance of dimerization was probed further by generating dimerization interface mutants (N381A and R385A) of V. cholerae DAPDC. Our studies indicate that N381A and R385A are significantly attenuated in catalytic activity, thus confirming that dimerization of DAPDC is essential for function. These findings provide scope for the development of new antibacterial agents that prevent DAPDC dimerization. PMID:26921318

  6. Ornithine decarboxylase antizyme inhibitor 2 regulates intracellular vesicle trafficking

    SciTech Connect

    Kanerva, Kristiina; Maekitie, Laura T.; Baeck, Nils; Andersson, Leif C.

    2010-07-01

    Antizyme inhibitor 1 (AZIN1) and 2 (AZIN2) are proteins that activate ornithine decarboxylase (ODC), the key enzyme of polyamine biosynthesis. Both AZINs release ODC from its inactive complex with antizyme (AZ), leading to formation of the catalytically active ODC. The ubiquitously expressed AZIN1 is involved in cell proliferation and transformation whereas the role of the recently found AZIN2 in cellular functions is unknown. Here we report the intracellular localization of AZIN2 and present novel evidence indicating that it acts as a regulator of vesicle trafficking. We used immunostaining to demonstrate that both endogenous and FLAG-tagged AZIN2 localize to post-Golgi vesicles of the secretory pathway. Immuno-electron microscopy revealed that the vesicles associate mainly with the trans-Golgi network (TGN). RNAi-mediated knockdown of AZIN2 or depletion of cellular polyamines caused selective fragmentation of the TGN and retarded the exocytotic release of vesicular stomatitis virus glycoprotein. Exogenous addition of polyamines normalized the morphological changes and reversed the inhibition of protein secretion. Our findings demonstrate that AZIN2 regulates the transport of secretory vesicles by locally activating ODC and polyamine biosynthesis.

  7. Histidine Decarboxylase Deficiency Prevents Autoimmune Diabetes in NOD Mice.

    PubMed

    Alkan, Manal; Machavoine, François; Rignault, Rachel; Dam, Julie; Dy, Michel; Thieblemont, Nathalie

    2015-01-01

    Recent evidence has highlighted the role of histamine in inflammation. Since this monoamine has also been strongly implicated in the pathogenesis of type-1 diabetes, we assessed its effect in the nonobese diabetic (NOD) mouse model. To this end, we used mice (inactivated) knocked out for the gene encoding histidine decarboxylase, the unique histamine-forming enzyme, backcrossed on a NOD genetic background. We found that the lack of endogenous histamine in NOD HDC(-/-) mice decreased the incidence of diabetes in relation to their wild-type counterpart. Whereas the proportion of regulatory T and myeloid-derived suppressive cells was similar in both strains, histamine deficiency was associated with increased levels of immature macrophages, as compared with wild-type NOD mice. Concerning the cytokine pattern, we found a decrease in circulating IL-12 and IFN-γ in HDC(-/-) mice, while IL-6 or leptin remained unchanged, suggesting that histamine primarily modulates the inflammatory environment. Paradoxically, exogenous histamine given to NOD HDC(-/-) mice provided also protection against T1D. Our study supports the notion that histamine is involved in the pathogenesis of diabetes, thus providing additional evidence for its role in the regulation of the immune response. PMID:26090474

  8. Chloroform induction of ornithine decarboxylase activity in rats.

    PubMed Central

    Savage, R E; Westrich, C; Guion, C; Pereira, M A

    1982-01-01

    Chloroform is a drinking water contaminant that has been demonstrated to be carcinogenic to mice and rats resulting in an increased incidence of liver and kidney tumors, respectively. The mechanism of chloroform carcinogenicity might be by tumor initiation and/or promotion. Since induction of ornithine decarboxylase (ODC) activity has been proposed as a molecular marker for tumor promoters, we have investigated the effect of chloroform on ODC activity in rats. Chloroform induced a dose-dependent increase of hepatic ODC with an apparent threshold at 100 mg/kg body weight. Female rats were two to four times more susceptible to to chloroform. Upon daily dosing of chloroform for 7 days the liver became less susceptible, with the last dose of chloroform resulting in only 10% of the activity observed after a single dose. Nuclear RNA polymerase I activity was also induced by chloroform. Chloroform, rather than increasing the activity of renal ODC, resulted in a 35% reduction. The induction by chloroform of hepatic ODC activity might be associated with regenerative hyperplasia while the renal carcinogenicity of chloroform could not be demonstrated to be associated with ODC induction. PMID:7151757

  9. Cysteine-dependent inactivation of hepatic ornithine decarboxylase.

    PubMed Central

    Murakami, Y; Kameji, T; Hayashi, S

    1984-01-01

    When rat liver homogenate or its postmitochondrial supernatant was incubated with L-cysteine, but not D-cysteine, ornithine decarboxylase (ODC) lost more than half of its catalytic activity within 30 min and, at a slower rate, its immunoreactivity. The inactivation correlated with production of H2S during the incubation. These changes did not occur in liver homogenates from vitamin B6-deficient rats. A heat-stable inactivating factor was found in both dialysed cytosol and washed microsomes obtained from the postmitochondrial supernatant incubated with cysteine. The microsomal inactivating factor was solubilized into Tris/HCl buffer, pH 7.4, containing dithiothreitol. Its absorption spectrum in the visible region resembled that of Fe2+ X dithiothreitol in Tris/HCl buffer. On the other hand FeSO4 inactivated partially purified ODC in a similar manner to the present inactivating factor. During the incubation of postmitochondrial supernatant with cysteine, there was a marked increase in the contents of Fe2+ loosely bound to cytosolic and microsomal macromolecules. Furthermore, the content of such reactive iron in the inactivating factor preparations was enough to account for their inactivating activity. These data suggested that H2S produced from cysteine by some vitamin B6-dependent enzyme(s) converted cytosolic and microsomal iron into a reactive loosely bound form that inactivated ODC. PMID:6696745

  10. Accumulation of ornithine decarboxylase-antizyme complex in HMOA cells.

    PubMed Central

    Murakami, Y; Fujita, K; Kameji, T; Hayashi, S

    1985-01-01

    A new method was developed for the assay of ornithine decarboxylase (ODC)-antizyme complex, in which alpha-difluoromethylornithine (DFMO)-inactivated ODC was used to release active ODC competitively from the complex. ODC-antizyme complex was present in the extracts of hepatoma tissue-culture (HTC) cells and of ODC-stabilized variant HMOA cells, in much larger amounts in the latter. Cellular amounts of the complex fluctuated after a change of medium in a similar manner in HTC and HMOA cells, increasing during the period of ODC decay. After treatment with cycloheximide, the decay of ODC-antizyme complex in HMOA cells was more rapid than the decay of free ODC, but it was much slower than the decay of free ODC or complexed ODC in HTC cells. Administration of putrescine caused a rapid increase in the amount of ODC-antizyme complex in both HTC and HMOA cells, but nevertheless the decay of total ODC (free ODC plus ODC-antizyme complex) was more rapid with putrescine than with cycloheximide. These results suggested the possibility that ODC is degraded through complex-formation with antizyme. In contrast with complexed antizyme, free antizyme was not stabilized in HMOA cells. PMID:3919709

  11. Localization of histidine decarboxylase mRNA in rat brain.

    PubMed

    Bayliss, D A; Wang, Y M; Zahnow, C A; Joseph, D R; Millhorn, D E

    1990-08-01

    The recent cloning of a cDNA encoding fetal rat liver histidine decarboxylase (HDC), the synthesizing enzyme for histamine, allows the study of the central histaminergic system at the molecular level. To this end, Northern blot and in situ hybridization analyses were used to determine the regional and cellular distribution of neurons which express HDC mRNA in rat brain. Three hybridizing species which migrate as 1.6-, 2.6-, and 3.5-kb RNA were identified with Northern blots. The major (2.6 kb) and minor (3.5 kb) species, characteristic of HDC mRNA in fetal liver, were expressed at high levels in diencephalon and at just detectable levels in hippocampus, but not in other brain regions. In contrast, the 1.6-kb species was present in all brain regions examined except the olfactory bulb. Cells which contain HDC mRNA were found by in situ hybridization in the hypothalamus; HDC mRNA-containing cells were not detected in other areas, including the hippocampus. Hypothalamic neurons which express HDC mRNA were localized to all aspects of the tuberomammillary nucleus, a result consistent with previous immunohistochemical findings. PMID:19912749

  12. Processing and topology of the yeast mitochondrial phosphatidylserine decarboxylase 1.

    PubMed

    Horvath, Susanne E; Böttinger, Lena; Vögtle, F-Nora; Wiedemann, Nils; Meisinger, Chris; Becker, Thomas; Daum, Günther

    2012-10-26

    The inner mitochondrial membrane plays a crucial role in cellular lipid homeostasis through biosynthesis of the non-bilayer-forming lipids phosphatidylethanolamine and cardiolipin. In the yeast Saccharomyces cerevisiae, the majority of cellular phosphatidylethanolamine is synthesized by the mitochondrial phosphatidylserine decarboxylase 1 (Psd1). The biogenesis of Psd1 involves several processing steps. It was speculated that the Psd1 precursor is sorted into the inner membrane and is subsequently released into the intermembrane space by proteolytic removal of a hydrophobic sorting signal. However, components involved in the maturation of the Psd1 precursor have not been identified. We show that processing of Psd1 involves the action of the mitochondrial processing peptidase and Oct1 and an autocatalytic cleavage at a highly conserved LGST motif yielding the α- and β-subunit of the enzyme. The Psd1 β-subunit (Psd1β) forms the membrane anchor, which binds the intermembrane space-localized α-subunit (Psd1α). Deletion of a transmembrane segment in the β-subunit results in mislocalization of Psd1 and reduced enzymatic activity. Surprisingly, autocatalytic cleavage does not depend on proper localization to the inner mitochondrial membrane. In summary, membrane integration of Psd1 is crucial for its functionality and for maintenance of mitochondrial lipid homeostasis. PMID:22984266

  13. Processing and Topology of the Yeast Mitochondrial Phosphatidylserine Decarboxylase 1*

    PubMed Central

    Horvath, Susanne E.; Böttinger, Lena; Vögtle, F.-Nora; Wiedemann, Nils; Meisinger, Chris; Becker, Thomas; Daum, Günther

    2012-01-01

    The inner mitochondrial membrane plays a crucial role in cellular lipid homeostasis through biosynthesis of the non-bilayer-forming lipids phosphatidylethanolamine and cardiolipin. In the yeast Saccharomyces cerevisiae, the majority of cellular phosphatidylethanolamine is synthesized by the mitochondrial phosphatidylserine decarboxylase 1 (Psd1). The biogenesis of Psd1 involves several processing steps. It was speculated that the Psd1 precursor is sorted into the inner membrane and is subsequently released into the intermembrane space by proteolytic removal of a hydrophobic sorting signal. However, components involved in the maturation of the Psd1 precursor have not been identified. We show that processing of Psd1 involves the action of the mitochondrial processing peptidase and Oct1 and an autocatalytic cleavage at a highly conserved LGST motif yielding the α- and β-subunit of the enzyme. The Psd1 β-subunit (Psd1β) forms the membrane anchor, which binds the intermembrane space-localized α-subunit (Psd1α). Deletion of a transmembrane segment in the β-subunit results in mislocalization of Psd1 and reduced enzymatic activity. Surprisingly, autocatalytic cleavage does not depend on proper localization to the inner mitochondrial membrane. In summary, membrane integration of Psd1 is crucial for its functionality and for maintenance of mitochondrial lipid homeostasis. PMID:22984266

  14. Ethanolic fermentation in transgenic tobacco expressing Zymomonas mobilis pyruvate decarboxylase.

    PubMed Central

    Bucher, M; Brändle, R; Kuhlemeier, C

    1994-01-01

    During oxygen limitation in higher plants, energy metabolism switches from respiration to fermentation. As part of this anaerobic response the expression of genes encoding pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) is strongly induced. In addition there is ample evidence for post-translational regulation. In order to understand this multi-level regulation of the anaerobic response, we provided tobacco with the constitutive capacity of ethanolic fermentation by expressing a PDC gene derived from the obligate anaerobe Zymomonas mobilis. The protein accumulated to high levels and was active in an in vitro assay. During the first 2-4 h of anoxia, acetaldehyde accumulated to 10- to 35-fold and ethanol to 8- to 20-fold higher levels than in wild-type. Under normoxic conditions no accumulation of acetaldehyde and ethanol could be measured. Instead, the two products may be immediately re-metabolized in tobacco leaf tissue. We show that aerobic fermentation takes place when the respiratory system is inhibited. Although these conditions enhance ethanolic fermentation under normoxia, they fail to increase ADH transcript levels. These results indicate that anaerobic transcription is triggered not by the metabolic consequences of oxygen limitation, but directly through an oxygen-sensing system. Images PMID:8026460

  15. Gene therapy for aromatic L-amino acid decarboxylase deficiency.

    PubMed

    Hwu, Wuh-Liang; Muramatsu, Shin-ichi; Tseng, Sheng-Hong; Tzen, Kai-Yuan; Lee, Ni-Chung; Chien, Yin-Hsiu; Snyder, Richard O; Byrne, Barry J; Tai, Chun-Hwei; Wu, Ruey-Meei

    2012-05-16

    Aromatic L-amino acid decarboxylase (AADC) is required for the synthesis of the neurotransmitters dopamine and serotonin. Children with defects in the AADC gene show compromised development, particularly in motor function. Drug therapy has only marginal effects on some of the symptoms and does not change early childhood mortality. Here, we performed adeno-associated viral vector-mediated gene transfer of the human AADC gene bilaterally into the putamen of four patients 4 to 6 years of age. All of the patients showed improvements in motor performance: One patient was able to stand 16 months after gene transfer, and the other three patients achieved supported sitting 6 to 15 months after gene transfer. Choreic dyskinesia was observed in all patients, but this resolved after several months. Positron emission tomography revealed increased uptake by the putamen of 6-[(18)F]fluorodopa, a tracer for AADC. Cerebrospinal fluid analysis showed increased dopamine and serotonin levels after gene transfer. Thus, gene therapy targeting primary AADC deficiency is well tolerated and leads to improved motor function. PMID:22593174

  16. Arginase, Arginine Decarboxylase, Ornithine Decarboxylase, and Polyamines in Tomato Ovaries (Changes in Unpollinated Ovaries and Parthenocarpic Fruits Induced by Auxin or Gibberellin).

    PubMed Central

    Alabadi, D.; Aguero, M. S.; Perez-Amador, M. A.; Carbonell, J.

    1996-01-01

    Arginase (EC 3.5.3.1) activity has been found in the ovaries and Young fruits of tomato (Lycopersicon esculentum Mill. cv Rutgers).Changes in arginase, arginine decarboxylase (EC 4.1.1.19), and ornithine decarboxylase activity (EC 4.1.1.17) and levels of free and conjugated putrescine, spermidine, and spermine were determined in unpollinated ovaries and in parthenocarpic fruits during the early stages of development induced by 2,4-dichlorophenoxyacetic acid (2,4-D) or gibberellic acid (GA3). Levels of arginase, free spermine, and conjugates of the three polyamines were constant in unpollinated ovaries and characteristic of a presenescent step. A marked decrease in arginase activity, free spermine, and polyamine conjugates was associated with the initiation of fruit growth due to cell division, and when cell expansion was initiated, the absence of arginase indicated a redirection of nitrogen metabolism to the synthesis of arginine. A transient increase in arginine decarboxylase and ornithine decarboxylase was also observed in 2,4-D-induced fruits. In general, 2,4-D treatments produced faster changes than GA3, and without treatment, unpollinated ovaries developed only slightly and senescence was hardly visible. Sensitivity to 2,4-D and GA3 treatment remained for at least 2 weeks postanthesis. PMID:12226441

  17. Electrical design note for a 5000 ADC, 230 {mu}H power supply filter choke

    SciTech Connect

    Visser, A.T.

    1993-04-01

    This note describes the design of a 5000 ADC, 230 {mu}H choke made from standard transformer cores. Five of these chokes have been made for CDF and MTF. NOTE: Special magnets can also be made using standard cores.

  18. A FASTBUS flash ADC system for the Mark II vertex chamber

    SciTech Connect

    Barker, L.

    1988-10-01

    This is a description of a flash ADC system built for the Mark II experiment at the Stanford Linear Accelerator Center (SLAC). This system was designed for use in the experiment's vertex chamber where signals could occur over a relatively long time, approximately 10 microseconds. This long time, coupled with fast cable amplifiers, necessitated an alternate design approach than was used with a dE/dX FASTBUS flash ADC design. 1 ref., 6 figs.

  19. A 10-bit column-parallel cyclic ADC for high-speed CMOS image sensors

    NASA Astrophysics Data System (ADS)

    Ye, Han; Quanliang, Li; Cong, Shi; Nanjian, Wu

    2013-08-01

    This paper presents a high-speed column-parallel cyclic analog-to-digital converter (ADC) for a CMOS image sensor. A correlated double sampling (CDS) circuit is integrated in the ADC, which avoids a stand-alone CDS circuit block. An offset cancellation technique is also introduced, which reduces the column fixed-pattern noise (FPN) effectively. One single channel ADC with an area less than 0.02 mm2 was implemented in a 0.13 μm CMOS image sensor process. The resolution of the proposed ADC is 10-bit, and the conversion rate is 1.6 MS/s. The measured differential nonlinearity and integral nonlinearity are 0.89 LSB and 6.2 LSB together with CDS, respectively. The power consumption from 3.3 V supply is only 0.66 mW. An array of 48 10-bit column-parallel cyclic ADCs was integrated into an array of CMOS image sensor pixels. The measured results indicated that the ADC circuit is suitable for high-speed CMOS image sensors.

  20. SEMICONDUCTOR INTEGRATED CIRCUITS: Improved low-distortion sigma-delta ADC with DWA for WLAN standards

    NASA Astrophysics Data System (ADS)

    Di, Li; Yintang, Yang; Zhangming, Zhu; Lichun, Shi; Xiaofeng, Wu; Jiangan, Wang

    2010-02-01

    An improved low distortion sigma-delta ADC (analog-to-digital converter) for wireless local area network standards is presented. A feed-forward MASH 2-2 multi-bit cascaded sigma-delta ADC is adopted; however, this work shows a much better performance than the ADCs which have been presented to date by adding a feedback factor in the second stage to improve the performance of the in-band SNDR (signal to noise and distortion ratio), using 4-bit ADCs in both stages to minimize the quantization noise. Data weighted averaging technology is therefore used to decrease the mismatch noise induced by the 4-bit DACs, which improves the SFDR (spurious free dynamic range) of the ADC. The modulator has been implemented by a 0.18 μm CMOS process and operates at a single 1.8 V supply voltage. Experimental results show that for a 1.25 MHz @ -6 dBFS input signal at 160 MHz sampling frequency, the improved ADC with all non-idealities considered achieves a peak SNDR of 80.9 dB and an SFDR of 87 dB, and the effective number of bits is 13.15 bits.

  1. Design trade-offs in ADC architectures dedicated to uncooled focal plane arrays

    NASA Astrophysics Data System (ADS)

    Robert, P.; Dupont, B.; Pochic, D.

    2008-04-01

    This paper presents two different architectures for the design of Analog to Digital Converters specifically adapted to infrared bolometric image sensors. Indeed, the increasing demand for integrated functions in uncooled readout circuits leads to on-chip ADC design as an interface between the internal analog core and the digital processing electronics. However specifying an on-chip ADC dedicated to focal plane array raises many questions about its architecture and its performance requirements. We will show that two architecture approaches are needed to cover the different sensor features in terms of array size and frame speed. A monolithic 14 bits ADC with a pipeline architecture, and a column 13 bits ADC with an original dual-ramp architecture, will be described. Finally, we will show measurement results to confirm the monolithic ADC is suitable for small array, as 160 x 120 with low frame speed, while a column ADC is more compliant for higher array, as 640 x 480 with a 60 Hz frame speed or 1024 x 768 arrays.

  2. A new case of malonyl-CoA decarboxylase deficiency with mild clinical features.

    PubMed

    Liu, Huan; Tan, Dongqiong; Han, Lianshu; Ye, Jun; Qiu, Wenjuan; Gu, Xuefan; Zhang, Huiwen

    2016-05-01

    Malonyl-CoA decarboxylase deficiency is an extremely rare autosomal recessive inborn error of fatty acid metabolism. It usually follows a severe disease course and presents poor prognosis without treatment. Here, we report an affected female juvenile with a mild clinical and biochemical phenotype who mainly featured poor schooling without cardiomyopathy and metabolic acidosis. She was suspected of malonyl-CoA decarboxylase deficiency due to a 57-kb deletion in 16q23.3 encompassing the MLCYD gene revealed by chromosome microarray. Malonyl-CoA decarboxylase deficiency was then confirmed by acylcarnitine analysis and organic acid analysis. Real-time PCR analysis of the patient revealed the first three exon deletion of the MLYCD gene, which was maternally inherited. DNA sequencing of the MLYCD gene of the patient identified a novel heterozygous mutation (c.911G>A, p.G304E) in exon 4 that was paternally inherited. The patient urine malonic acid dissolved and had a better school record in 6 month after initiation of fat-limited diet. At 1 year post treatment, the blood malonylcarnitine level decreased remarkably. Our result expands the phenotype of malonyl-CoA decarboxylase deficiency and suggests attentions should be paid to the mild form of disorders, for example, malonyl-CoA decarboxylase deficiency, which usually present a severe disease course. © 2016 Wiley Periodicals, Inc. PMID:26858006

  3. Stimulation of Lysine Decarboxylase Production in Escherichia coli by Amino Acids and Peptides1

    PubMed Central

    Cascieri, T.; Mallette, M. F.

    1973-01-01

    A commercial hydrolysate of casein stimulated production of lysine decarboxylase (EC 4.1.1.18) by Escherichia coli B. Cellulose and gel chromatography of this hydrolysate yielded peptides which were variably effective in this stimulation. Replacement of individual, stimulatory peptides by equivalent amino acids duplicated the enzyme levels attained with those peptides. There was no indication of specific stimulation by any peptide. The peptides were probably taken up by the oligopeptide transport system of E. coli and hydrolyzed intracellularly by peptidases to their constituent amino acids for use in enzyme synthesis. Single omission of amino acids from mixtures was used to screen them for their relative lysine decarboxylase stimulating abilities. Over 100 different mixtures were evaluated in establishing the total amino acid requirements for maximal synthesis of lysine decarboxylase by E. coli B. A mixture containing all of the common amino acids except glutamic acid, aspartic acid, and alanine increased lysine decarboxylase threefold over an equivalent weight of casein hydrolysate. The nine most stimulatory amino acids were methionine, arginine, cystine, leucine, isoleucine, glutamine, threonine, tyrosine, and asparagine. Methionine and arginine quantitatively were the most important. A mixture of these nine was 87% as effective as the complete mixture. Several amino acids were inhibitory at moderate concentrations, and alanine (2.53 mM) was the most effective. Added pyridoxine increased lysine decarboxylase activity 30%, whereas other B vitamins and cyclic adenosine 5′-monophosphate had no effect. PMID:4588201

  4. 64-Channel, 5 GSPS ADC Module with Switched Capacitor Arrays

    NASA Astrophysics Data System (ADS)

    Bogdan, M.; Huan, H.; Wakely, S.

    2013-08-01

    We present a 5 GSPS ADC/Data processing module with up to 64 channels and 2048 cells per channel, designed for fast-sampling, front-end applications. This is a 6U VME board that incorporates 16 pieces DRS4 (http://drs.web.psi.ch, [1]) Switched Capacitor Array chips developed at Paul Scherrer Institut, Switzerland. The 16 DRS4 chips are grouped in four independent input blocks. A block, with a geometric size of 43×120 mm, has four pieces DRS4 chips, four pieces AD9222 converters, and one Altera Stratix III FPGA. Each DRS4 chip has eight channels and each channel has 1024 sampling cells, which can be daisy-chained for larger sampling depth. This feature allows for a great level of flexibility in choosing the number of channels relative to capacitor array size, for a particular application. The first prototype Printed Circuit Board (PCB) was designed for a sampling depth of 2048 cells and 16 channels in a 42 mm wide block, i.e. 64 channels for the 6U VME board. This compact form factor allows for these input blocks to be used as front-end electronics for the Cherenkov Telescope Array (CTA) cameras. In this VME board, the four blocks are fully independent and can run each in different modes without any conflict. A global FPGA, also a Stratix III device, provides control and interfacing. The module can run with a local oscillator or with input system clocks in the range of 20-550 MHz. The front panel is fitted with a 2.5 Gbps serial link transceiver.

  5. A New Triglycyl Peptide Linker for Antibody-Drug Conjugates (ADCs) with Improved Targeted Killing of Cancer Cells.

    PubMed

    Singh, Rajeeva; Setiady, Yulius Y; Ponte, Jose; Kovtun, Yelena V; Lai, Katharine C; Hong, E Erica; Fishkin, Nathan; Dong, Ling; Jones, Gregory E; Coccia, Jennifer A; Lanieri, Leanne; Veale, Karen; Costoplus, Juliet A; Skaletskaya, Anna; Gabriel, Rabih; Salomon, Paulin; Wu, Rui; Qiu, Qifeng; Erickson, Hans K; Lambert, John M; Chari, Ravi V J; Widdison, Wayne C

    2016-06-01

    A triglycyl peptide linker (CX) was designed for use in antibody -: drug conjugates (ADC), aiming to provide efficient release and lysosomal efflux of cytotoxic catabolites within targeted cancer cells. ADCs comprising anti-epithelial cell adhesion molecule (anti-EpCAM) and anti-EGFR antibodies with maytansinoid payloads were prepared using CX or a noncleavable SMCC linker (CX and SMCC ADCs). The in vitro cytotoxic activities of CX and SMCC ADCs were similar for several cancer cell lines; however, the CX ADC was more active (5-100-fold lower IC50) than the SMCC ADC in other cell lines, including a multidrug-resistant line. Both CX and SMCC ADCs showed comparable MTDs and pharmacokinetics in CD-1 mice. In Calu-3 tumor xenografts, antitumor efficacy was observed with the anti-EpCAM CX ADC at a 5-fold lower dose than the corresponding SMCC ADC in vivo Similarly, the anti-EGFR CX ADC showed improved antitumor activity over the respective SMCC conjugate in HSC-2 and H1975 tumor models; however, both exhibited similar activity against FaDu xenografts. Mechanistically, in contrast with the charged lysine-linked catabolite of SMCC ADC, a significant fraction of the carboxylic acid catabolite of CX ADC could be uncharged in the acidic lysosomes, and thus diffuse out readily into the cytosol. Upon release from tumor cells, CX catabolites are charged at extracellular pH and do not penetrate and kill neighboring cells, similar to the SMCC catabolite. Overall, these data suggest that CX represents a promising linker option for the development of ADCs with improved therapeutic properties. Mol Cancer Ther; 15(6); 1311-20. ©2016 AACR. PMID:27197308

  6. Purification and properties of diaminopimelate decarboxylase from Escherichia coli

    PubMed Central

    White, P. J.; Kelly, Bridget

    1965-01-01

    1. Diaminopimelate decarboxylase from a soluble extract of Escherichia coli A.T.C.C. 9637 was purified 200-fold by precipitation of nucleic acids, fractionation with acetone and then with ammonium sulphate, adsorption on calcium phosphate gel and chromatography on DEAE-cellulose or DEAE-Sephadex. 2. The purified enzyme showed only one component in the ultracentrifuge, with a sedimentation coefficient of 5·4s. One major peak and three much smaller peaks were observed on electrophoresis of the enzyme at pH8·9. 3. The mol.wt. of the enzyme was approx. 200000. The catalytic constant was 2000mol. of meso-diaminopimelic acid decomposed/min./mol. of enzyme, at 37°. The relative rates of decarboxylation at 25°, 37° and 45° were 0·17:1·0:1·6. At 37° the Michaelis constant was 1·7mm and the optimum pH was 6·7–6·8. 4. There was an excess of acidic amino acids over basic amino acids in the enzyme, which was bound only on basic cellulose derivatives at pH6·8. 5. The enzyme had an absolute requirement for pyridoxal phosphate as a cofactor; no other derivative of pyridoxine had activity. A thiol compound (of which 2,3-dimercaptopropan-1-ol was the most effective) was also needed as an activator. 6. In the presence of 2,3-dimercaptopropan-1-ol (1mm), heavy-metal ions (Cu2+, Hg2+) did not inhibit the enzyme, but there was inhibition by several amino acids with analogous structures to diaminopimelate, generally at high concentrations relative to the substrate. Penicillamine was inhibitory at relatively low concentrations; its action was prevented by pyridoxal phosphate. PMID:14343156

  7. Ultraviolet radiation induction of ornithine decarboxylase in rat keratinocytes

    SciTech Connect

    Rosen, C.F.; Gajic, D.; Drucker, D.J. )

    1990-05-01

    UV radiation plays an important role in the induction of cutaneous malignancy, including basal cell and squamous cell carcinomas and malignant melanoma. In addition to its effects on DNA damage and repair mechanisms, UV radiation has been shown to modulate the expression of specific genes, altering the levels of their mRNAs and the synthesis of their corresponding proteins. In order to gain further information about the molecular effects of UV radiation, we have studied the regulation of ornithine decarboxylase (ODC) gene expression in response to UVB radiation. ODC is the rate-limiting enzyme in polyamine biosynthesis, is involved in growth and differentiation, and has been implicated in carcinogenesis. Keratinocytes grown in culture were either sham-irradiated or exposed to increasing doses of UVB (1-5 mJ/cm2). Northern blot analysis of keratinocyte RNA under basal conditions demonstrated the presence of two ODC mRNA transcripts. Increasing exposure to UVB resulted in a dose-dependent increase in the levels of both ODC mRNA transcripts. The induction of ODC gene expression following UVB was noted 2 h after UVB exposure, and ODC mRNA levels continued to increase up to 24 h after UVB exposure. The UVB-induced increase in ODC gene expression was not serum dependent, despite the ability of serum alone to induce ODC gene expression. The mRNA transcripts for actin and hexosaminidase A were not induced after UVB exposure. These studies show that the UVB-induced increase in ODC activity is due, at least in part, to an increase in ODC gene expression and they provide a useful model for the analysis of the molecular effects of UVB radiation.

  8. Theoretical study of the reaction mechanism of phenolic acid decarboxylase.

    PubMed

    Sheng, Xiang; Lind, Maria E S; Himo, Fahmi

    2015-12-01

    The cofactor-free phenolic acid decarboxylases (PADs) catalyze the non-oxidative decarboxylation of phenolic acids to their corresponding p-vinyl derivatives. Phenolic acids are toxic to some organisms, and a number of them have evolved the ability to transform these compounds, including PAD-catalyzed reactions. Since the vinyl derivative products can be used as polymer precursors and are also of interest in the food-processing industry, PADs might have potential applications as biocatalysts. We have investigated the detailed reaction mechanism of PAD from Bacillus subtilis using quantum chemical methodology. A number of different mechanistic scenarios have been considered and evaluated on the basis of their energy profiles. The calculations support a mechanism in which a quinone methide intermediate is formed by protonation of the substrate double bond, followed by C-C bond cleavage. A different substrate orientation in the active site is suggested compared to the literature proposal. This suggestion is analogous to other enzymes with p-hydroxylated aromatic compounds as substrates, such as hydroxycinnamoyl-CoA hydratase-lyase and vanillyl alcohol oxidase. Furthermore, on the basis of the calculations, a different active site residue compared to previous proposals is suggested to act as the general acid in the reaction. The mechanism put forward here is consistent with the available mutagenesis experiments and the calculated energy barrier is in agreement with measured rate constants. The detailed mechanistic understanding developed here might be extended to other members of the family of PAD-type enzymes. It could also be useful to rationalize the recently developed alternative promiscuous reactivities of these enzymes. PMID:26408050

  9. A porphomethene inhibitor of uroporphyrinogen decarboxylase causes porphyria cutanea tarda

    PubMed Central

    Phillips, John D.; Bergonia, Hector A.; Reilly, Christopher A.; Franklin, Michael R.; Kushner, James P.

    2007-01-01

    Porphyria cutanea tarda (PCT), the most common form of porphyria in humans, is due to reduced activity of uroporphyrinogen decarboxylase (URO-D) in the liver. Previous studies have demonstrated that protein levels of URO-D do not change when catalytic activity is reduced, suggesting that an inhibitor of URO-D is generated in hepatocytes. Here, we describe the identification and characterization of an inhibitor of URO-D in liver cytosolic extracts from two murine models of PCT: wild-type mice treated with iron, δ-aminolevulinic acid, and polychlorinated biphenyls; and mice with one null allele of Uro-d and two null alleles of the hemochromatosis gene (Uro-d+/−, Hfe−/−) that develop PCT with no treatments. In both models, we identified an inhibitor of recombinant human URO-D (rhURO-D). The inhibitor was characterized by solid-phase extraction, chromatography, UV-visible spectroscopy, and mass spectroscopy and proved to be uroporphomethene, a compound in which one bridge carbon in the uroporphyrinogen macrocycle is oxidized. We synthesized uroporphomethene by photooxidation of enzymatically generated uroporphyrinogen I or III. Both uroporphomethenes inhibited rhURO-D, but the III isomer porphomethene was a more potent inhibitor. Finally, we detected an inhibitor of rhURO-D in cytosolic extracts of liver biopsy samples of patients with PCT. These studies define the mechanism underlying clinical expression of the PCT phenotype, namely oxidation of uroporphyrinogen to uroporphomethene, a competitive inhibitor of URO-D. The oxidation reaction is iron-dependent. PMID:17360334

  10. Chromosomal Integration and Expression of Two Bacterial α-Acetolactate Decarboxylase Genes in Brewer's Yeast

    PubMed Central

    Blomqvist, K.; Suihko, M.-L.; Knowles, J.; Penttilä, M.

    1991-01-01

    A bacterial gene encoding α-acetolactate decarboxylase, isolated from Klebsiella terrigena or Enterobacter aerogenes, was expressed in brewer's yeast. The genes were expressed under either the yeast phosphoglycerokinase (PGK1) or the alcohol dehydrogenase (ADH1) promoter and were integrated by gene replacement by using cotransformation into the PGK1 or ADH1 locus, respectively, of a brewer's yeast. The expression level of the α-acetolactate decarboxylase gene of the PGK1 integrant strains was higher than that of the ADH1 integrants. Under pilot-scale brewing conditions, the α-acetolactate decarboxylase activity of the PGK1 integrant strains was sufficient to reduce the formation of diacetyl below the taste threshold value, and no lagering was needed. The brewing properties of the recombinant yeast strains were otherwise unaltered, and the quality (most importantly, the flavor) of the trial beers produced was as good as that of the control beer. Images PMID:16348559

  11. Molecular Evolution and Functional Characterization of a Bifunctional Decarboxylase Involved in Lycopodium Alkaloid Biosynthesis1[OPEN

    PubMed Central

    Bunsupa, Somnuk; Hanada, Kousuke; Maruyama, Akira; Aoyagi, Kaori; Komatsu, Kana; Ueno, Hideki; Yamashita, Madoka; Sasaki, Ryosuke; Oikawa, Akira; Yamazaki, Mami

    2016-01-01

    Lycopodium alkaloids (LAs) are derived from lysine (Lys) and are found mainly in Huperziaceae and Lycopodiaceae. LAs are potentially useful against Alzheimer’s disease, schizophrenia, and myasthenia gravis. Here, we cloned the bifunctional lysine/ornithine decarboxylase (L/ODC), the first gene involved in LA biosynthesis, from the LA-producing plants Lycopodium clavatum and Huperzia serrata. We describe the in vitro and in vivo functional characterization of the L. clavatum L/ODC (LcL/ODC). The recombinant LcL/ODC preferentially catalyzed the decarboxylation of l-Lys over l-ornithine (l-Orn) by about 5 times. Transient expression of LcL/ODC fused with the amino or carboxyl terminus of green fluorescent protein, in onion (Allium cepa) epidermal cells and Nicotiana benthamiana leaves, showed LcL/ODC localization in the cytosol. Transgenic tobacco (Nicotiana tabacum) hairy roots and Arabidopsis (Arabidopsis thaliana) plants expressing LcL/ODC enhanced the production of a Lys-derived alkaloid, anabasine, and cadaverine, respectively, thus, confirming the function of LcL/ODC in plants. In addition, we present an example of the convergent evolution of plant Lys decarboxylase that resulted in the production of Lys-derived alkaloids in Leguminosae (legumes) and Lycopodiaceae (clubmosses). This convergent evolution event probably occurred via the promiscuous functions of the ancestral Orn decarboxylase, which is an enzyme involved in the primary metabolism of polyamine. The positive selection sites were detected by statistical analyses using phylogenetic trees and were confirmed by site-directed mutagenesis, suggesting the importance of those sites in granting the promiscuous function to Lys decarboxylase while retaining the ancestral Orn decarboxylase function. This study contributes to a better understanding of LA biosynthesis and the molecular evolution of plant Lys decarboxylase. PMID:27303024

  12. Molecular Evolution and Functional Characterization of a Bifunctional Decarboxylase Involved in Lycopodium Alkaloid Biosynthesis.

    PubMed

    Bunsupa, Somnuk; Hanada, Kousuke; Maruyama, Akira; Aoyagi, Kaori; Komatsu, Kana; Ueno, Hideki; Yamashita, Madoka; Sasaki, Ryosuke; Oikawa, Akira; Saito, Kazuki; Yamazaki, Mami

    2016-08-01

    Lycopodium alkaloids (LAs) are derived from lysine (Lys) and are found mainly in Huperziaceae and Lycopodiaceae. LAs are potentially useful against Alzheimer's disease, schizophrenia, and myasthenia gravis. Here, we cloned the bifunctional lysine/ornithine decarboxylase (L/ODC), the first gene involved in LA biosynthesis, from the LA-producing plants Lycopodium clavatum and Huperzia serrata We describe the in vitro and in vivo functional characterization of the L. clavatum L/ODC (LcL/ODC). The recombinant LcL/ODC preferentially catalyzed the decarboxylation of l-Lys over l-ornithine (l-Orn) by about 5 times. Transient expression of LcL/ODC fused with the amino or carboxyl terminus of green fluorescent protein, in onion (Allium cepa) epidermal cells and Nicotiana benthamiana leaves, showed LcL/ODC localization in the cytosol. Transgenic tobacco (Nicotiana tabacum) hairy roots and Arabidopsis (Arabidopsis thaliana) plants expressing LcL/ODC enhanced the production of a Lys-derived alkaloid, anabasine, and cadaverine, respectively, thus, confirming the function of LcL/ODC in plants. In addition, we present an example of the convergent evolution of plant Lys decarboxylase that resulted in the production of Lys-derived alkaloids in Leguminosae (legumes) and Lycopodiaceae (clubmosses). This convergent evolution event probably occurred via the promiscuous functions of the ancestral Orn decarboxylase, which is an enzyme involved in the primary metabolism of polyamine. The positive selection sites were detected by statistical analyses using phylogenetic trees and were confirmed by site-directed mutagenesis, suggesting the importance of those sites in granting the promiscuous function to Lys decarboxylase while retaining the ancestral Orn decarboxylase function. This study contributes to a better understanding of LA biosynthesis and the molecular evolution of plant Lys decarboxylase. PMID:27303024

  13. Ornithine Decarboxylase Activity Is Required for Prostatic Budding in the Developing Mouse Prostate

    PubMed Central

    Gamat, Melissa; Malinowski, Rita L.; Parkhurst, Linnea J.; Steinke, Laura M.; Marker, Paul C.

    2015-01-01

    The prostate is a male accessory sex gland that produces secretions in seminal fluid to facilitate fertilization. Prostate secretory function is dependent on androgens, although the mechanism by which androgens exert their effects is still unclear. Polyamines are small cationic molecules that play pivotal roles in DNA transcription, translation and gene regulation. The rate-limiting enzyme in polyamine biosynthesis is ornithine decarboxylase, which is encoded by the gene Odc1. Ornithine decarboxylase mRNA decreases in the prostate upon castration and increases upon administration of androgens. Furthermore, testosterone administered to castrated male mice restores prostate secretory activity, whereas administering testosterone and the ornithine decarboxylase inhibitor D,L-α-difluromethylornithine (DFMO) to castrated males does not restore prostate secretory activity, suggesting that polyamines are required for androgens to exert their effects. To date, no one has examined polyamines in prostate development, which is also androgen dependent. In this study, we showed that ornithine decarboxylase protein was expressed in the epithelium of the ventral, dorsolateral and anterior lobes of the adult mouse prostate. Ornithine decarboxylase protein was also expressed in the urogenital sinus (UGS) epithelium of the male and female embryo prior to prostate development, and expression continued in prostatic epithelial buds as they emerged from the UGS. Inhibiting ornithine decarboxylase using DFMO in UGS organ culture blocked the induction of prostatic buds by androgens, and significantly decreased expression of key prostate transcription factor, Nkx3.1, by androgens. DFMO also significantly decreased the expression of developmental regulatory gene Notch1. Other genes implicated in prostatic development including Sox9, Wif1 and Srd5a2 were unaffected by DFMO. Together these results indicate that Odc1 and polyamines are required for androgens to exert their effect in mediating

  14. Ornithine Decarboxylase Activity Is Required for Prostatic Budding in the Developing Mouse Prostate.

    PubMed

    Gamat, Melissa; Malinowski, Rita L; Parkhurst, Linnea J; Steinke, Laura M; Marker, Paul C

    2015-01-01

    The prostate is a male accessory sex gland that produces secretions in seminal fluid to facilitate fertilization. Prostate secretory function is dependent on androgens, although the mechanism by which androgens exert their effects is still unclear. Polyamines are small cationic molecules that play pivotal roles in DNA transcription, translation and gene regulation. The rate-limiting enzyme in polyamine biosynthesis is ornithine decarboxylase, which is encoded by the gene Odc1. Ornithine decarboxylase mRNA decreases in the prostate upon castration and increases upon administration of androgens. Furthermore, testosterone administered to castrated male mice restores prostate secretory activity, whereas administering testosterone and the ornithine decarboxylase inhibitor D,L-α-difluromethylornithine (DFMO) to castrated males does not restore prostate secretory activity, suggesting that polyamines are required for androgens to exert their effects. To date, no one has examined polyamines in prostate development, which is also androgen dependent. In this study, we showed that ornithine decarboxylase protein was expressed in the epithelium of the ventral, dorsolateral and anterior lobes of the adult mouse prostate. Ornithine decarboxylase protein was also expressed in the urogenital sinus (UGS) epithelium of the male and female embryo prior to prostate development, and expression continued in prostatic epithelial buds as they emerged from the UGS. Inhibiting ornithine decarboxylase using DFMO in UGS organ culture blocked the induction of prostatic buds by androgens, and significantly decreased expression of key prostate transcription factor, Nkx3.1, by androgens. DFMO also significantly decreased the expression of developmental regulatory gene Notch1. Other genes implicated in prostatic development including Sox9, Wif1 and Srd5a2 were unaffected by DFMO. Together these results indicate that Odc1 and polyamines are required for androgens to exert their effect in mediating

  15. Cloning and sequencing of pyruvate decarboxylase (PDC) genes from bacteria and uses therefor

    DOEpatents

    Maupin-Furlow, Julie A [Gainesville, FL; Talarico, Lee Ann [Gainesville, FL; Raj, Krishnan Chandra [Tamil Nadu, IN; Ingram, Lonnie O [Gainesville, FL

    2008-02-05

    The invention provides isolated nucleic acids molecules which encode pyruvate decarboxylase enzymes having improved decarboxylase activity, substrate affinity, thermostability, and activity at different pH. The nucleic acids of the invention also have a codon usage which allows for high expression in a variety of host cells. Accordingly, the invention provides recombinant expression vectors containing such nucleic acid molecules, recombinant host cells comprising the expression vectors, host cells further comprising other ethanologenic enzymes, and methods for producing useful substances, e.g., acetaldehyde and ethanol, using such host cells.

  16. Structure of PA4019, a putative aromatic acid decarboxylase from Pseudomonas aeruginosa

    PubMed Central

    Kopec, Jolanta; Schnell, Robert; Schneider, Gunter

    2011-01-01

    The ubiX gene (PA4019) of Pseudomonas aeruginosa has been annotated as encoding a putative 3-octaprenyl-4-hydroxybenzoate decarboxylase from the ubiquinone-biosynthesis pathway. Based on a transposon mutagenesis screen, this gene was also implicated as being essential for the survival of this organism. The crystal structure of recombinant UbiX determined to 1.5 Å resolution showed that the protein belongs to the superfamily of homo-oligomeric flavine-containing cysteine decarboxylases. The enzyme assembles into a dodecamer with 23 point symmetry. The subunit displays a typical Rossmann fold and contains one FMN molecule bound at the interface between two subunits. PMID:22102023

  17. Inhibition of erythromycin synthesis by disruption of malonyl-coenzyme A decarboxylase gene eryM in Saccharopolyspora erythraea.

    PubMed Central

    Hsieh, Y J; Kolattukudy, P E

    1994-01-01

    Malonyl-coenzyme A (malonyl-CoA) decarboxylase is widely distributed in prokaryotes and eukaryotes. However, the biological function of this enzyme has not been established in any organism. To elucidate the structure and function of this enzyme, the malonyl-CoA decarboxylase gene from Saccharopolyspora erythraea (formerly Streptomyces erythreaus) was cloned and sequenced. This gene would encode a polypeptide of 417 amino acids. The deduced amino acid sequence matched the experimentally determined amino acid sequences of 25 N-terminal residues each of the enzyme and of an internal peptide obtained by proteolysis of the purified enzyme. This decarboxylase showed homology with aminoglycoside N6'-acetyltransferases of Pseudomonas aeruginosa, Serratia marcescens, and Klebsiella pneumoniae. Northern (RNA) blot analysis revealed a single transcript. The transcription initiation site was 220 bp upstream of the start codon. When expressed in Escherichia coli, the S. erythraea malonyl-CoA decarboxylase gene yielded a protein that cross-reacted with antiserum prepared against S. erythraea malonyl-CoA decarboxylase and catalyzed decarboxylation of [3-14C]malonyl-CoA to acetyl-CoA and 14CO2. The S. erythraea malonyl-CoA decarboxylase gene was disrupted by homologous recombination using an integrating vector pWHM3. The gene-disrupted transformant did not produce immunologically cross-reacting 45-kDa decarboxylase, lacked malonyl-CoA decarboxylase activity, and could not produce erythromycin. Exogenous propionate restored the ability to produce erythromycin. These results strongly suggest that the decarboxylase provides propionyl-CoA for erythromycin synthesis probably via decarboxylation of methylmalonyl-CoA derived from succinyl-CoA, and therefore the malonyl-CoA decarboxylase gene is designated eryM. The gene disrupted mutants also did not produce pigments. Images PMID:8300527

  18. Biochemical and Structural Analysis of Inhibitors Targeting the ADC-7 Cephalosporinase of Acinetobacter baumannii

    PubMed Central

    2015-01-01

    β-Lactam resistance in Acinetobacter baumannii presents one of the greatest challenges to contemporary antimicrobial chemotherapy. Much of this resistance to cephalosporins derives from the expression of the class C β-lactamase enzymes, known as Acinetobacter-derived cephalosporinases (ADCs). Currently, β-lactamase inhibitors are structurally similar to β-lactam substrates and are not effective inactivators of this class C cephalosporinase. Herein, two boronic acid transition state inhibitors (BATSIs S02030 and SM23) that are chemically distinct from β-lactams were designed and tested for inhibition of ADC enzymes. BATSIs SM23 and S02030 bind with high affinity to ADC-7, a chromosomal cephalosporinase from Acinetobacter baumannii (Ki = 21.1 ± 1.9 nM and 44.5 ± 2.2 nM, respectively). The X-ray crystal structures of ADC-7 were determined in both the apo form (1.73 Å resolution) and in complex with S02030 (2.0 Å resolution). In the complex, S02030 makes several canonical interactions: the O1 oxygen of S02030 is bound in the oxyanion hole, and the R1 amide group makes key interactions with conserved residues Asn152 and Gln120. In addition, the carboxylate group of the inhibitor is meant to mimic the C3/C4 carboxylate found in β-lactams. The C3/C4 carboxylate recognition site in class C enzymes is comprised of Asn346 and Arg349 (AmpC numbering), and these residues are conserved in ADC-7. Interestingly, in the ADC-7/S02030 complex, the inhibitor carboxylate group is observed to interact with Arg340, a residue that distinguishes ADC-7 from the related class C enzyme AmpC. A thermodynamic analysis suggests that ΔH driven compounds may be optimized to generate new lead agents. The ADC-7/BATSI complex provides insight into recognition of non-β-lactam inhibitors by ADC enzymes and offers a starting point for the structure-based optimization of this class of novel β-lactamase inhibitors against a key resistance target. PMID:25380506

  19. 10-bit 20-Msample/s ADC for low-voltage low-power applications

    NASA Astrophysics Data System (ADS)

    Sou, Gerard; Lu, Guo N.; Klisnick, Geoffroy; Redon, Michel

    1998-09-01

    For the development of new low-voltage, low-power imaging microsystems, we have designed a 10-bit 20-Msample/s ADC. It is a 3-stage sub-ranging architecture and has a rail-to-rail dynamic input. To achieve low-voltage operation and low- power consumption, specific analog blocks such as op-amps and flash ADCs were required. Complementary CMOS comparators with no static consumption were used to build a new low- power 4-bit flash ADC structure with rail-to-rail input range. A new 1.7 volts, 120 dB op-amp structure was designed. To achieve 20 MHz sampling rate, the ADC makes use of time-interleaving, switched capacitor amplifiers, which perform dynamic frequency compensation to optimize speed and offset cancellation to meet resolution requirement. A 20- Msample/s rate has been obtained with supply voltages down to 2.4 volts to 2.4 volts and 60mW power consumption. This ADC has been fabricated and tested and will be integrated on the same chip with color image sensors in a BICMOS process.

  20. Histogram-based classification with Gaussian mixture modeling for GBM tumor treatment response using ADC map

    NASA Astrophysics Data System (ADS)

    Huo, Jing; Kim, Hyun J.; Pope, Whitney B.; Okada, Kazunori; Alger, Jeffery R.; Wang, Yang; Goldin, Jonathan G.; Brown, Matthew S.

    2009-02-01

    This study applied a Gaussian Mixture Model (GMM) to apparent diffusion coefficient (ADC) histograms to evaluate glioblastoma multiforme (GBM) tumor treatment response using diffusion weighted (DW) MR images. ADC mapping, calculated from DW images, has been shown to reveal changes in the tumor's microenvironment preceding morphologic tumor changes. In this study, we investigated the effectiveness of features that represent changes from pre- and post-treatment tumor ADC histograms to detect treatment response. The main contribution of this work is to model the ADC histogram as the composition of two components, fitted by GMM with expectation maximization (EM) algorithm. For both pre- and post-treatment scans taken 5-7 weeks apart, we obtained the tumor ADC histogram, calculated the two-component features, as well as the other standard histogram-based features, and applied supervised learning for classification. We evaluated our approach with data from 85 patients with GBM under chemotherapy, in which 33 responded and 52 did not respond based on tumor size reduction. We compared AdaBoost and random forests classification algorithms, using ten-fold cross validation, resulting in a best accuracy of 69.41%.

  1. A 15-bit incremental sigma-delta ADC for CMOS image sensor

    NASA Astrophysics Data System (ADS)

    Chen, Nan; Li, Zhengfen; Zhong, Shengyou; Zou, Mei; Yao, Libin

    2015-04-01

    An incremental sigma-delta ADC is designed for column-parallel ADC array in CMOS image sensor. Sigma-delta modulator with single-loop single-bit structure is chosen for power consumption and performance reasons. Second-order modulator is used to reduce conversion time, without stability problem and large area accompanied by higher order sigma-delta modulator. The asymmetric current mirror amplifier used in integrator reduces more than 30% power dissipation. The digital filter and decimator are implemented by counters and adders with significantly reduced chip area and power consumption. A Clock generator is shared by 8 ADCs for trade-off among power, area and clock loading. The ADC array is implemented in a 0.18-μm CMOS technology and clocked at 10 MHz, and the simulated resolution achieves 15-bit with 255 clock cycles. The average power consumption per ADC is 118 μW including clock generator, and the area is only 0.0053 μm2.

  2. Photoluminescence detection of alpha particle using DAM-ADC nuclear detector

    NASA Astrophysics Data System (ADS)

    Abdalla, Ayman M.; Harraz, Farid A.; Ali, Atif M.; Al-Sayari, S. A.; Al-Hajry, A.

    2016-09-01

    The photoluminescence (PL) and UV-vis spectral analysis of DAM-ADC (diallyl maleate: DAM, polyallyl diglycol carbonate: ADC) nuclear detector are demonstrated for the first time. The DAM-ADC surfaces were exposed to thin 241Am disk source that emits alpha particles with activity 333 kBq. It is found that the track density of the irradiated samples remarkably influences the PL characteristics of the DAM-ADC detector. The spectral peak heights and the integrated intensities under the peaks exhibit linear correlations with correlation coefficient R2=0.9636 and 0.9806, respectively for different alpha particle fluences ranging from 8.16-40.82×107 particles/cm2. Additionally, a correlation coefficient R2=0.9734 was achieved for the UV-vis spectral analysis. The linear fitting functions, along with the corresponding fitting parameters were evaluated in each case. Both the PL and the UV-vis data of the irradiated DAM-ADC samples showed considerable spectral differences, and hence they would be used to offer sensitive approaches for alpha particle detection.

  3. A low power 11-bit 100 MS/s SAR ADC IP

    NASA Astrophysics Data System (ADS)

    Ya, Wang; Chunying, Xue; Fule, Li; Chun, Zhang; Zhihua, Wang

    2015-02-01

    This paper presents a dual-channel 11-bit 100 MS/s hybrid SAR ADC IP. Each channel adopts flash-SAR architecture for high speed, low power and high linearity. Dynamic comparators in the coarse flash ADC and the fine SAR ADC further contribute to the reduction of power consumption. A gate-controlled ring oscillator generates a multi-phase clock for SAR logic, thereby allowing it to asynchronously trigger the comparator in the fine SAR ADC in high speed. MOM capacitors with a fully shielded structure provide enough matching accuracy without the need for calibration. This design was fabricated in SMIC 55 nm low leakage CMOS technology and the active area of dual-channel (I-Q) ADC is 0.35 mm2, while the core area is 0.046 mm2. It consumes 2.92 mA at a 1.2 V supply, for dual-channel too. The effective number of bits (ENOB) is 9.90 bits at 2.4 MHz input frequency, and 9.34 bits at 50 MHz, leading to a FOM of 18.3 fJ/conversion-step.

  4. Combined Self-Test of Analog Portion and ADCs in Integrated Mixed-Signal Circuits

    NASA Astrophysics Data System (ADS)

    Hu, Geng; Wang, Hong; Yang, Shiyuan

    Testing is a critical stage in integrated circuits production in order to guarantee reliability. The complexity and high integration level of mixed-signal ICs has put forward new challenges to circuit testing. This paper describes an oscillation-based combined self-test strategy for the analog portion and analog-to-digital converters (ADCs) in integrated mixed-signal circuits. In test mode, the analog portion under test is reconfigured into an oscillator, generating periodic signals as the test stimulus of ADC. By analyzing the A/D conversion results, a histogram test of ADC can be performed, and the oscillation frequency as well as amplitude can be checked, and in this way the oscillation test of the analog portion is realized simultaneously. For an analog benchmark circuit combined with an ADC, triangle oscillation and sinusoid oscillation schemes are both given to test their faults. Experimental results show that fault coverage of the analog portion is 92.2% and 94.3% in the two schemes respectively, and faults in the ADC can also be tested.

  5. High-Speed, Multi-Channel Serial ADC LVDS Interface for Xilinx Virtex-5 FPGA

    NASA Technical Reports Server (NTRS)

    Taylor, Gregory H.

    2012-01-01

    Analog-to-digital converters (ADCs) are used in scientific and communications instruments on all spacecraft. As data rates get higher, and as the transition is made from parallel ADC designs to high-speed, serial, low-voltage differential signaling (LVDS) designs, the need will arise to interface these in field programmable gate arrays (FPGAs). As Xilinx has released the radiation-hardened version of the Virtex-5, this will likely be used in future missions. High-speed serial ADCs send data at very high rates. A de-serializer instantiated in the fabric of the FPGA could not keep up with these high data rates. The Virtex-5 contains primitives designed specifically for high-speed, source-synchronous de-serialization, but as supported by Xilinx, can only support bitwidths of 10. Supporting bit-widths of 12 or more requires the use of the primitives in an undocumented configuration, a non-trivial task. A new SystemVerilog design was written that is simpler and uses fewer hardware resources than the reference design described in Xilinx Application Note XAPP866. It has been shown to work in a Xilinx XC5VSX24OT connected to a MAXIM MAX1438 12-bit ADC using a 50-MHz sample clock. The design can be replicated in the FPGA for multiple ADCs (four instantiations were used for a total of 28 channels).

  6. Adhesin competence repressor (AdcR) from Streptococcus pyogenes controls adaptive responses to zinc limitation and contributes to virulence

    PubMed Central

    Sanson, Misu; Makthal, Nishanth; Flores, Anthony R.; Olsen, Randall J.; Musser, James M.; Kumaraswami, Muthiah

    2015-01-01

    Altering zinc bioavailability to bacterial pathogens is a key component of host innate immunity. Thus, the ability to sense and adapt to the alterations in zinc concentrations is critical for bacterial survival and pathogenesis. To understand the adaptive responses of group A Streptococcus (GAS) to zinc limitation and its regulation by AdcR, we characterized gene regulation by AdcR. AdcR regulates the expression of 70 genes involved in zinc acquisition and virulence. Zinc-bound AdcR interacts with operator sequences in the negatively regulated promoters and mediates differential regulation of target genes in response to zinc deficiency. Genes involved in zinc mobilization and conservation are derepressed during mild zinc deficiency, whereas the energy-dependent zinc importers are upregulated during severe zinc deficiency. Further, we demonstrated that transcription activation by AdcR occurs by direct binding to the promoter. However, the repression and activation by AdcR is mediated by its interactions with two distinct operator sequences. Finally, mutational analysis of the metal ligands of AdcR caused impaired DNA binding and attenuated virulence, indicating that zinc sensing by AdcR is critical for GAS pathogenesis. Together, we demonstrate that AdcR regulates GAS adaptive responses to zinc limitation and identify molecular components required for GAS survival during zinc deficiency. PMID:25510500

  7. Inhibition of human ornithine decarboxylase activity by enantiomers of difluoromethylornithine.

    PubMed Central

    Qu, Ning; Ignatenko, Natalia A; Yamauchi, Phillip; Stringer, David E; Levenson, Corey; Shannon, Patrick; Perrin, Scott; Gerner, Eugene W

    2003-01-01

    Racemic difluoromethylornithine (D/L-DFMO) is an inhibitor of ODC (ornithine decarboxylase), the first enzyme in eukaryotic polyamine biosynthesis. D/L-DFMO is an effective anti-parasitic agent and inhibitor of mammalian cell growth and development. Purified human ODC-catalysed ornithine decarboxylation is highly stereospecific. However, both DFMO enantiomers suppressed ODC activity in a time- and concentration-dependent manner. ODC activity failed to recover after treatment with either L- or D-DFMO and dialysis to remove free inhibitor. The inhibitor dissociation constant (K(D)) values for the formation of enzyme-inhibitor complexes were 28.3+/-3.4, 1.3+/-0.3 and 2.2+/-0.4 microM respectively for D-, L- and D/L-DFMO. The differences in these K(D) values were statistically significant ( P <0.05). The inhibitor inactivation constants (K(inact)) for the irreversible step were 0.25+/-0.03, 0.15+/-0.03 and 0.15+/-0.03 min(-1) respectively for D-, L- and D/L-DFMO. These latter values were not statistically significantly different ( P >0.1). D-DFMO was a more potent inhibitor (IC50 approximately 7.5 microM) when compared with D-ornithine (IC50 approximately 1.5 mM) of ODC-catalysed L-ornithine decarboxylation. Treatment of human colon tumour-derived HCT116 cells with either L- or D-DFMO decreased the cellular polyamine contents in a concentration-dependent manner. These results show that both enantiomers of DFMO irreversibly inactivate ODC and suggest that this inactivation occurs by a common mechanism. Both enantiomers form enzyme-inhibitor complexes with ODC, but the probability of formation of these complexes is 20 times greater for L-DFMO when compared with D-DFMO. The rate of the irreversible reaction in ODC inactivation is similar for the L- and D-enantiomer. This unexpected similarity between DFMO enantiomers, in contrast with the high degree of stereospecificity of the substrate ornithine, appears to be due to the alpha-substituent of the inhibitor. The D

  8. Paraneoplastic Neurological Syndromes and Glutamic Acid Decarboxylase Antibodies

    PubMed Central

    Ariño, Helena; Höftberger, Romana; Gresa-Arribas, Nuria; Martínez-Hernandez, Eugenia; Armangue, Thaís; Kruer, Michael C.; Arpa, Javier; Domingo, Julio; Rojc, Bojan; Bataller, Luis; Saiz, Albert; Dalmau, Josep; Graus, Francesc

    2016-01-01

    IMPORTANCE Little is known of glutamic acid decarboxylase antibodies (GAD-abs) in the paraneoplastic context. Clinical recognition of such cases will lead to prompt tumor diagnosis and appropriate treatment. OBJECTIVE To report the clinical and immunological features of patients with paraneoplastic neurological syndromes (PNS) and GAD-abs. DESIGN, SETTING, AND PARTICIPANTS Retrospective case series study and immunological investigations conducted in February 2014 in a center for autoimmune neurological disorders. Fifteen cases with GAD65-abs evaluated between 1995 and 2013 who fulfilled criteria of definite or possible PNS without concomitant onconeural antibodies were included in this study. MAIN OUTCOMES AND MEASURES Analysis of the clinical records of 15 patients and review of 19 previously reported cases. Indirect immunofluorescence with rat hippocampal neuronal cultures and cell-based assays with known neuronal cell-surface antigens were used. One hundred six patients with GAD65-abs and no cancer served as control individuals. RESULTS Eight of the 15 patients with cancer presented as classic paraneoplastic syndromes (5 limbic encephalitis, 1 paraneoplastic encephalomyelitis, 1 paraneoplastic cerebellar degeneration, and 1 opsoclonus-myoclonus syndrome). When compared with the 106 non-PNS cases, those with PNS were older (median age, 60 years vs 48 years; P = .03), more frequently male (60% vs 13%; P < .001), and had more often coexisting neuronal cell-surface antibodies, mainly against γ-aminobutyric acid receptors (53%vs 11%; P < .001). The tumors more frequently involved were lung (n = 6) and thymic neoplasms (n = 4). The risk for an underlying tumor was higher if the presentation was a classic PNS, if it was different from stiff-person syndrome or cerebellar ataxia (odds ratio, 10.5; 95%CI, 3.2–34.5), or if the patient had coexisting neuronal cell-surface antibodies (odds ratio, 6.8; 95%CI, 1.1–40.5). Compared with the current series, the 19 previously

  9. Phosphorylation of Ser-204 and Tyr-405 in human malonyl-CoA decarboxylase expressed in silkworm Bombyx mori regulates catalytic decarboxylase activity.

    PubMed

    Hwang, In-Wook; Makishima, Yu; Suzuki, Tomohiro; Kato, Tatsuya; Park, Sungjo; Terzic, Andre; Chung, Shin-Kyo; Park, Enoch Y

    2015-11-01

    Decarboxylation of malonyl-CoA to acetyl-CoA by malonyl-CoA decarboxylase (MCD; EC 4.1.1.9) is a vital catalytic reaction of lipid metabolism. While it is established that phosphorylation of MCD modulates the enzymatic activity, the specific phosphorylation sites associated with the catalytic function have not been documented due to lack of sufficient production of MCD with proper post-translational modifications. Here, we used the silkworm-based Bombyx mori nucleopolyhedrovirus (BmNPV) bacmid system to express human MCD (hMCD) and mapped phosphorylation effects on enzymatic function. Purified MCD from silkworm displayed post-translational phosphorylation and demonstrated coherent enzymatic activity with high yield (-200 μg/silkworm). Point mutations in putative phosphorylation sites, Ser-204 or Tyr-405 of hMCD, identified by bioinformatics and proteomics analyses reduced the catalytic activity, underscoring the functional significance of phosphorylation in modulating decarboxylase-based catalysis. Identified phosphorylated residues are distinct from the decarboxylation catalytic site, implicating a phosphorylation-induced global conformational change of MCD as responsible in altering catalytic function. We conclude that phosphorylation of Ser-204 and Tyr-405 regulates the decarboxylase function of hMCD leveraging the silkworm-based BmNPV bacmid expression system that offers a fail-safe eukaryotic production platform implementing proper post-translational modification such as phosphorylation. PMID:26004805

  10. XML at the ADC: Steps to a Next Generation Data Repository

    NASA Astrophysics Data System (ADS)

    Shaya, E.; Gass, J.; Blackwell, J.; Thomas, B.; Holmes, B.; Cheung, C. Y.

    The staff of the Astronomical Data Center at GSFC (ADC, http://adc.gsfc.nasa.gov) is involved in a research project to define the XML format for the metadata of an astronomical repository and for large data tables. In the process, an XML tool box is being developed for importation, enhancement, and distribution of published data and their metadata documents. There is now a working draft Document Type Definition (DTD, http://messier.gsfc.nasa.gov/xml/dataset.dtd) which specifies the required elements of content and their attributes. The documentation for each data set will be viewable in several different styles via eXtensible Stylesheet Language Transformations (XSLT, (http://www.w3.org/TR/xslt) scripts. The ADC is actively creating designs for the flow of data through automated pipelines from authors and journal presses into an XML archive, as well as data retrieval through the web via the XML Query Language.

  11. Fast neutrons detection in CR-39 and DAM-ADC nuclear track detectors

    NASA Astrophysics Data System (ADS)

    Abdalla, A. M.; Ashraf, O.; Rammah, Y. S.; Ashry, A. H.; Eisa, M.; Tsuruta, T.

    2015-03-01

    Fast detection of neutrons in CR-39 and DAM-ADC nuclear track detectors were investigated using new etching conditions. The neutron irradiation is performed using a 5 mCi Am-Be source present at the National Institute of Standards (NIS) of Egypt. Using the new etching condition, irradiated CR-39 samples were etched for 4 h and DAM-ADC samples for 80 min. Suitable analyzing software has been used to analyze experimental data.The dependence of neutrons track density on the neutrons fluence is investigated. When etched under optimum conditions, the relationship between track density and fluence is determined which is found to be linear. Detection efficiency has been represented for both SSNTDs and found to be constant with fluence, which reflects the importance of using CR-39 and DAM-ADC detectors in the field of neutron dosimetry. Linear relationship between track density and effective dose is determined.

  12. Molecular analysis of the glutamate decarboxylase locus in Streptococcus thermophilus ST110

    Technology Transfer Automated Retrieval System (TEKTRAN)

    GABA ('-aminobutyric acid) is generated from glutamate by the action of glutamic acid decarboxylase (GAD) and characterized by hypotensive, diuretic and tranquilizing effects in humans and animals. The production of GABA by lactic acid starter bacteria would enhance the functionality of fermented da...

  13. Detection and transfer of the glutamate decarboxylase gene in Streptococcus thermophilus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    GABA (gamma-aminobutyric acid) is generated from glutamate by the action of glutamic acid decarboxylase (GAD) and characterized by hypotensive, diuretic and tranquilizing effects in humans and animals. The production of GABA by lactic acid starter bacteria would enhance the functionality of fermen...

  14. The ornithine decarboxylase gene of Caenorhabditis elegans: Cloning, mapping and mutagenesis

    SciTech Connect

    Macrae, M.; Coffino, P.; Plasterk, R.H.A.

    1995-06-01

    The gene (odc-1) encoding ornithine decarboxylase, a key enzyme in polyamine biosynthesis, was cloned and characterized. Two introns interrupt the coding sequence of the gene. The deduced protein contains 442 amino acids and is homologous to ornithine decarboxylases of other eukaryotic species. In vitro translation of a transcript of the cDNA yielded an enzymatically active product. The mRNA is 1.5 kb in size and is formed by trans-splicing to SL1, a common 5{prime} RNA segment. odc-1 maps to the middle of LG V, between dpy-11 and unc-42 and near a breakpoint of the nDf32 deficiency strain. Enzymatic activity is low in starved 1 (L1) larva and, after feeding, rises progressively as the worms develop. Targeted gene disruption was used to create a null allele. Homozygous mutants are normally viable and show no apparent defects, with the exception of a somewhat reduced brood size. In vitro assays for ornithine decarboxylase activity, however, show no detectable enzymatic activity, suggesting that ornithine decarboxylase is dispensible for nematode growth in the laboratory. 37 refs., 6 figs., 1 tab.

  15. The Degradation of 14C-Glutamic Acid by L-Glutamic Acid Decarboxylase.

    ERIC Educational Resources Information Center

    Dougherty, Charles M; Dayan, Jean

    1982-01-01

    Describes procedures and semi-micro reaction apparatus (carbon dioxide trap) to demonstrate how a particular enzyme (L-Glutamic acid decarboxylase) may be used to determine the site or sites of labeling in its substrate (carbon-14 labeled glutamic acid). Includes calculations, solutions, and reagents used. (Author/SK)

  16. An inhibitor of ornithine decarboxylase in the thymus and spleen of dexamethasone-treated rats.

    PubMed Central

    Bishop, P B; Young, J; Peng, T; Richards, J F

    1985-01-01

    A marked decrease in activity of ornithine decarboxylase in thymus and spleen occurs soon after treatment of rats with a glucocorticoid. In the present study, evidence was obtained that extracts of these tissues prepared 5 h after administration of dexamethasone, when the enzyme activity is very low, contain an inhibitor of ornithine decarboxylase. The inhibitor is also present at 12 h after treatment and, in lesser amount, at 2.5 h, but was not evident at 24 h. The inhibitory activity was destroyed by treatment with heat or with trypsin, and was not lost on dialysis of the extract. Preliminary experiments indicate that the Mr of the inhibitor is greater than 50 000, which differentiates it from antizyme, an inhibitor of ornithine decarboxylase found in several other cell types. The inhibitor seems to act by a non-catalytic and non-competitive mechanism. The inhibition is dependent on the amount of inhibitor and does not change with time. Since inhibition is not changed by dialysis of the inhibitory extract, its activity apparently does not require small-Mr substances. This differentiates it from inhibitors which inactivate ornithine decarboxylase by covalent modification, such as the polyamine-dependent protein kinase or transglutaminase. The formation of this inhibitor is an early event in lymphoid tissues in response to dexamethasone and may be important in causing the inhibition of cell division which precedes the destruction of lymphocytes. PMID:3977859

  17. Structural and Mechanistic Studies on Klebsiella pneumoniae 2-Oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline Decarboxylase

    SciTech Connect

    French, Jarrod B.; Ealick, Steven E.

    2010-11-12

    The stereospecific oxidative degradation of uric acid to (S)-allantoin was recently shown to proceed via three enzymatic steps. The final conversion is a decarboxylation of the unstable intermediate 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline (OHCU) and is catalyzed by OHCU decarboxylase. Here we present the structures of Klebsiella pneumoniae OHCU decarboxylase in unliganded form and with bound allantoin. These structures provide evidence that ligand binding organizes the active site residues for catalysis. Modeling of the substrate and intermediates provides additional support for this hypothesis. In addition we characterize the steady state kinetics of this enzyme and report the first OHCU decarboxylase inhibitor, allopurinol, a structural isomer of hypoxanthine. This molecule is a competitive inhibitor of K. pneumoniae OHCU decarboxylase with a K{sub i} of 30 {+-} 2 {micro}m. Circular dichroism measurements confirm structural observations that this inhibitor disrupts the necessary organization of the active site. Our structural and biochemical studies also provide further insights into the mechanism of catalysis of OHCU decarboxylation.

  18. A complementary dual-slope ADC with high frame rate and wide input range for fast X-ray imaging

    NASA Astrophysics Data System (ADS)

    Lee, Daehee; Cho, Minsik; Kang, Dong-Uk; Kim, Myung Soo; Kim, Hyunduk; Cho, Gyuseong

    2014-02-01

    The single-slope analog-to-digital converter (SS-ADC) is the most commonly used column-level ADC for high-speed industrial, complementary metal-oxide semiconductor (CMOS)-based X-ray image sensors because of its small chip area (the width of a pixel), its simple circuit structure, and its low power consumption. However, it generally has a long conversion time, so we propose an innovative design: a complimentary dual-slope ADC (CDS-ADC) that uses two opposite ramp signals instead of a single ramp to double the conversion speed. This CDS-ADC occupies only 15% more area than the original SS-ADC. A prototype 12-bit CDS-ADC and a 12-bit SS-ADC were fabricated using a 0.35-µm 1P 4M CMOS process. During comparison of the two, the measured maximum differential non-linearity (DNL) of the CDS-ADC was a 0.49 least significant bit (LSB), the maximum integral non-linearity (INL) was a 0.43 LSB, the effective number of bits (ENOB) was 9.18 bits, and the figure of merit (FOM) was 0.03 pJ/conversion. The total power consumption was 0.031 uW. The conversion time of the new CDS-ADC was half that of the SS-ADC. The proposed dual-slope concept can be extended to further multiply the conversion speed by using multiple pairs of dual-slope ramps.

  19. In-line inspection method with AIT-II and ADC

    NASA Astrophysics Data System (ADS)

    Terryll, Kathleen; Mateos, Carlos

    2001-04-01

    In this article, we emphasize the streamlined, in-line inspection methodology at Agere Systems, Madrid, Spain (formally Lucent Technologies, Microelectronics). This method includes the use of AIT-II with Impact ADC 2.0 to better focus and separate out excursion and baseline events. Real life examples demonstrating the potential of ADC are presented. In continuation, the shop reaction methodology and data flow scheme is described in detail. Currently, the Agere systems methodology is one of the most advanced in the European semiconductor industry.

  20. Front end processing for a 100 MHZ Flash-ADC-System

    SciTech Connect

    Eckerlin, G.; Elsen, E.; Schmitt, H.V.D.; Wagner, A.; Walter, P.V.

    1986-06-01

    An intelligent interface for readout of a high speed (100 MHz), multichannel Flash-ADC System is described. 3072 FADC channels are controlled and read by a system of 34 microprocessors M68000 placed at two different hierarchical levels. In addition to the readout itself, the processors perform a detailed pulse shape analysis necessary for a compact and manageable data format. The purpose of the system is to exploit the good double tract separation and time resolution provided by Flash-ADCs in conjunction with large drift chamber detectors such as JADE at PETRA and OPAL at LEP. Details of the system presently being installed at JADE are reviewed.

  1. UDP-Glucuronic Acid Decarboxylases of Bacteroides fragilis and Their Prevalence in Bacteria▿†

    PubMed Central

    Coyne, Michael J.; Fletcher, C. Mark; Reinap, Barbara; Comstock, Laurie E.

    2011-01-01

    Xylose is rarely described as a component of bacterial glycans. UDP-xylose is the nucleotide-activated form necessary for incorporation of xylose into glycans and is synthesized by the decarboxylation of UDP-glucuronic acid (UDP-GlcA). Enzymes with UDP-GlcA decarboxylase activity include those that lead to the formation of UDP-xylose as the end product (Uxs type) and those synthesizing UDP-xylose as an intermediate (ArnA and RsU4kpxs types). In this report, we identify and confirm the activities of two Uxs-type UDP-GlcA decarboxylases of Bacteroides fragilis, designated BfUxs1 and BfUxs2. Bfuxs1 is located in a conserved region of the B. fragilis genome, whereas Bfuxs2 is in the heterogeneous capsular polysaccharide F (PSF) biosynthesis locus. Deletion of either gene separately does not result in the loss of a detectable phenotype, but deletion of both genes abrogates PSF synthesis, strongly suggesting that they are functional paralogs and that the B. fragilis NCTC 9343 PSF repeat unit contains xylose. UDP-GlcA decarboxylases are often annotated incorrectly as NAD-dependent epimerases/dehydratases; therefore, their prevalence in bacteria is underappreciated. Using available structural and mutational data, we devised a sequence pattern to detect bacterial genes encoding UDP-GlcA decarboxylase activity. We identified 826 predicted UDP-GlcA decarboxylase enzymes in diverse bacterial species, with the ArnA and RsU4kpxs types confined largely to proteobacterial species. These data suggest that xylose, or a monosaccharide requiring a UDP-xylose intermediate, is more prevalent in bacterial glycans than previously appreciated. Genes encoding BfUxs1-like enzymes are highly conserved in Bacteroides species, indicating that these abundant intestinal microbes may synthesize a conserved xylose-containing glycan. PMID:21804000

  2. Substrate Specificity of Thiamine Pyrophosphate-Dependent 2-Oxo-Acid Decarboxylases in Saccharomyces cerevisiae

    PubMed Central

    Romagnoli, Gabriele; Luttik, Marijke A. H.; Kötter, Peter; Pronk, Jack T.

    2012-01-01

    Fusel alcohols are precursors and contributors to flavor and aroma compounds in fermented beverages, and some are under investigation as biofuels. The decarboxylation of 2-oxo acids is a key step in the Ehrlich pathway for fusel alcohol production. In Saccharomyces cerevisiae, five genes share sequence similarity with genes encoding thiamine pyrophosphate-dependent 2-oxo-acid decarboxylases (2ODCs). PDC1, PDC5, and PDC6 encode differentially regulated pyruvate decarboxylase isoenzymes; ARO10 encodes a 2-oxo-acid decarboxylase with broad substrate specificity, and THI3 has not yet been shown to encode an active decarboxylase. Despite the importance of fusel alcohol production in S. cerevisiae, the substrate specificities of these five 2ODCs have not been systematically compared. When the five 2ODCs were individually overexpressed in a pdc1Δ pdc5Δ pdc6Δ aro10Δ thi3Δ strain, only Pdc1, Pdc5, and Pdc6 catalyzed the decarboxylation of the linear-chain 2-oxo acids pyruvate, 2-oxo-butanoate, and 2-oxo-pentanoate in cell extracts. The presence of a Pdc isoenzyme was also required for the production of n-propanol and n-butanol in cultures grown on threonine and norvaline, respectively, as nitrogen sources. These results demonstrate the importance of pyruvate decarboxylases in the natural production of n-propanol and n-butanol by S. cerevisiae. No decarboxylation activity was found for Thi3 with any of the substrates tested. Only Aro10 and Pdc5 catalyzed the decarboxylation of the aromatic substrate phenylpyruvate, with Aro10 showing superior kinetic properties. Aro10, Pdc1, Pdc5, and Pdc6 exhibited activity with all branched-chain and sulfur-containing 2-oxo acids tested but with markedly different decarboxylation kinetics. The high affinity of Aro10 identified it as a key contributor to the production of branched-chain and sulfur-containing fusel alcohols. PMID:22904058

  3. Substrate specificity of thiamine pyrophosphate-dependent 2-oxo-acid decarboxylases in Saccharomyces cerevisiae.

    PubMed

    Romagnoli, Gabriele; Luttik, Marijke A H; Kötter, Peter; Pronk, Jack T; Daran, Jean-Marc

    2012-11-01

    Fusel alcohols are precursors and contributors to flavor and aroma compounds in fermented beverages, and some are under investigation as biofuels. The decarboxylation of 2-oxo acids is a key step in the Ehrlich pathway for fusel alcohol production. In Saccharomyces cerevisiae, five genes share sequence similarity with genes encoding thiamine pyrophosphate-dependent 2-oxo-acid decarboxylases (2ODCs). PDC1, PDC5, and PDC6 encode differentially regulated pyruvate decarboxylase isoenzymes; ARO10 encodes a 2-oxo-acid decarboxylase with broad substrate specificity, and THI3 has not yet been shown to encode an active decarboxylase. Despite the importance of fusel alcohol production in S. cerevisiae, the substrate specificities of these five 2ODCs have not been systematically compared. When the five 2ODCs were individually overexpressed in a pdc1Δ pdc5Δ pdc6Δ aro10Δ thi3Δ strain, only Pdc1, Pdc5, and Pdc6 catalyzed the decarboxylation of the linear-chain 2-oxo acids pyruvate, 2-oxo-butanoate, and 2-oxo-pentanoate in cell extracts. The presence of a Pdc isoenzyme was also required for the production of n-propanol and n-butanol in cultures grown on threonine and norvaline, respectively, as nitrogen sources. These results demonstrate the importance of pyruvate decarboxylases in the natural production of n-propanol and n-butanol by S. cerevisiae. No decarboxylation activity was found for Thi3 with any of the substrates tested. Only Aro10 and Pdc5 catalyzed the decarboxylation of the aromatic substrate phenylpyruvate, with Aro10 showing superior kinetic properties. Aro10, Pdc1, Pdc5, and Pdc6 exhibited activity with all branched-chain and sulfur-containing 2-oxo acids tested but with markedly different decarboxylation kinetics. The high affinity of Aro10 identified it as a key contributor to the production of branched-chain and sulfur-containing fusel alcohols. PMID:22904058

  4. ADC values in diffusion-weighted MRI and their relationship with age, gender and BMI in healthy people's pancreases

    PubMed Central

    Faeghi, F; Abdkarimi, M H; Asghari JafarAbadi, M

    2015-01-01

    Objective: The aim of this study is to use diffusion-weighted MRI to assess the apparent diffusion coefficient (ADC) values in head, body and tail sections of the pancreas in healthy subjects and the relationships between these values and age, gender and body mass index (BMI) of these cases. Methods: This study was conducted on 82 participants who were referred to the Tabesh Medical Imaging Center, Tabriz, Islamic Republic of Iran, during 2013. Echo-planar diffusion-weighted imaging of the pancreas was carried out with b-values of 50, 400 and 800 s mm−2, and ADC values were assessed for the head, body and tail sections of the pancreas. Results: The ADC values for the head, body and tail sections of the pancreas in female participants were significantly greater than those in male subjects (p < 0.05). ADC values for these parts among subjects with different BMI differed significantly (p < 0.05). Regarding age, there were no statistically meaningful differences among the ADC values for the three parts (p > 0.05). Conclusion: Gender and BMI effect the ADC values of the three sections of the pancreas. Thus, knowledge of the basic values based on gender and BMI can improve diagnostics. Having looked at age factor, it seems that the ADC values were not significantly different. Advances in knowledge: According to the results pancreatic ADC values appear to be influenced by gender and BMI but not by age. PMID:25471056

  5. A low-power column-parallel ADC for high-speed CMOS image sensor

    NASA Astrophysics Data System (ADS)

    Han, Ye; Li, Quanliang; Shi, Cong; Liu, Liyuan; Wu, Nanjian

    2013-08-01

    This paper presents a 10-bit low-power column-parallel cyclic analog-to-digital converter (ADC) used for high-speed CMOS image sensor (CIS). An opamp sharing technique is used to save power and area. Correlated double sampling (CDS) circuit and programmable gain amplifier (PGA) are integrated in the ADC, which avoids stand-alone circuit blocks. An offset cancellation technique is also introduced, which reduces the column fixed-pattern noise (FPN) effectively. One single channel ADC with an area less than 0.03mm2 was implemented in a 0.18μm 1P4M CMOS image sensor process. The resolution of the proposed ADC is 10-bit, and the conversion rate is 2MS/s. The measured differential nonlinearity (DNL) and integral nonlinearity (INL) are 0.62 LSB and 2.1 LSB together with CDS, respectively. The power consumption from 1.8V supply is only 0.36mW.

  6. XML at the ADC: Steps to a Next Generation Data Archive

    NASA Astrophysics Data System (ADS)

    Shaya, E.; Blackwell, J.; Gass, J.; Oliversen, N.; Schneider, G.; Thomas, B.; Cheung, C.; White, R. A.

    1999-05-01

    The eXtensible Markup Language (XML) is a document markup language that allows users to specify their own tags, to create hierarchical structures to qualify their data, and to support automatic checking of documents for structural validity. It is being intensively supported by nearly every major corporate software developer. Under the funds of a NASA AISRP proposal, the Astronomical Data Center (ADC, http://adc.gsfc.nasa.gov) is developing an infrastructure for importation, enhancement, and distribution of data and metadata using XML as the document markup language. We discuss the preliminary Document Type Definition (DTD, at http://adc.gsfc.nasa.gov/xml) which specifies the elements and their attributes in our metadata documents. This attempts to define both the metadata of an astronomical catalog and the `header' information of an astronomical table. In addition, we give an overview of the planned flow of data through automated pipelines from authors and journal presses into our XML archive and retrieval through the web via the XML-QL Query Language and eXtensible Style Language (XSL) scripts. When completed, the catalogs and journal tables at the ADC will be tightly hyperlinked to enhance data discovery. In addition one will be able to search on fragmentary information. For instance, one could query for a table by entering that the second author is so-and-so or that the third author is at such-and-such institution.

  7. Attitude Determination and Control Subsystem (ADCS) Preparations for the EPOXI Flyby of Comet Hartley 2

    NASA Technical Reports Server (NTRS)

    Luna, Michael E.; Collins, Steven M.

    2011-01-01

    On November 4, 2010 the former "Deep Impact" spacecraft, renamed "EPOXI" for its extended mission, flew within 700km of comet 103P/Hartley 2. In July 2005, the spacecraft had previously imaged a probe impact of comet Tempel 1. The EPOXI flyby was the fifth close encounter of a spacecraft with a comet nucleus and marked the first time in history that two comet nuclei were imaged at close range with the same suite of onboard science instruments. This challenging objective made the function of the attitude determination and control subsystem (ADCS) critical to the successful execution of the EPOXI flyby.As part of the spacecraft flyby preparations, the ADCS operations team had to perform meticulous sequence reviews, implement complex spacecraft engineering and science activities and perform numerous onboard calibrations. ADCS contributions included design and execution of 10 trajectory correction maneuvers, the science calibration of the two telescopic instruments, an in-flight demonstration of high-rate turns between Earth and comet point, and an ongoing assessment of reaction wheel health. The ADCS team was also responsible for command sequences that included updates to the onboard ephemeris and sun sensor coefficients and implementation of reaction wheel assembly (RWA) de-saturations.

  8. Meeting Active Start Guidelines in the ADC-Ridgecrest Program: Toddlers

    ERIC Educational Resources Information Center

    Wall, Sarah J.; Rudisill, Mary E.

    2004-01-01

    Through experiences with toddlers at the ADC-Ridgecrest Physical Activity Program, the authors have found there are many ways to encourage and promote the "Active Start" guidelines through play. Their research and collaboration with early childhood specialists suggests that toddlers like to play and that it is particularly important in the overall…

  9. Childhood attachment and schizophrenia: the "attachment-developmental-cognitive" (ADC) hypothesis.

    PubMed

    Rajkumar, Ravi Philip

    2014-09-01

    Schizophrenia is a complex psychiatric syndrome whose exact causes remain unclear. However, current scientific consensus has highlighted the importance of neurodevelopmental and neurocognitive processes in the development of schizophrenic symptoms. Research over the past three decades, motivated by the findings of the World Health Organization's large-scale studies, has highlighted the importance of psychosocial adversities - including childhood abuse and neglect - in this disorder. In this paper, I propose a hypothesis based on John Bowlby's framework of attachment theory, which I have termed the attachment-developmental-cognitive (ADC) hypothesis. The ADC hypothesis integrates recent developments related to (1) existing models of schizophrenia, (2) studies examining the effect of attachment on brain biology and cognitive development, and (3) various known facts about the course and outcome of this disorder. In doing so, it explains how disturbed childhood attachment leads to core psychological and neurochemical abnormalities which are implicated in the genesis of schizophrenia and also affect its outcome. The ADC hypothesis compasses and expands on earlier formulations, such as the "social defeat" and "traumagenic" models, and has important implications regarding the prevention and treatment of schizophrenia. Ways of testing and refining this hypothesis are outlined as avenues for future research. Though provisional, the ADC hypothesis is entirely consistent with both biological and psychosocial research into the origins of schizophrenia. PMID:24957505

  10. A Study of the Training Potential of a Select Group of ADC Mothers

    ERIC Educational Resources Information Center

    Packman, Jerrold B.

    1970-01-01

    Approximately 52 percept of ADC mothers are willing to attend orientation testing sessions for WIN Program. Of the above, approximately 10 percent have the skills for direct job placement. Remaining 90 percent on the job or instituional training, Special Works Project, and those not feasible for work. Success or failure of WIN Program relates to…

  11. A low-power time-domain VCO-based ADC in 65 nm CMOS

    NASA Astrophysics Data System (ADS)

    Chenluan, Wang; Shengxi, Diao; Fujiang, Lin

    2014-10-01

    A low-power, high-FoM (figure of merit), time-domain VCO (voltage controlled oscillator)-based ADC (analog-to-digital converter) in 65 nm CMOS technology is proposed. An asynchronous sigma—delta modulator (ASDM) is used to convert the voltage input signal to a square wave time signal, where the information is contained in its pulse-width. A time-domain quantizer, which uses VCO to convert voltage to frequency, is adopted, while the XOR (exclusive-OR) gate circuits convert the frequency information to digital representatives. The ASDM does not need an external clock, so there is no quantization noise. At the same time, the ASDM applies a harmonic-distortion-cancellation technique to its transconductance stage, which increases the SNDR (signal to noise and distortion ratio) performance of the ASDM. Since the output of the ASDM is a two-level voltage signal, the VCO's V—F (voltage to frequency) conversion curve is always linear. The XOR phase quantizer has an inherent feature of first-order noise-shaping. It puts the ADC's low-frequency output noise to high-frequency which is further filtered out by a low-pass filter. The proposed ADC achieves an SNR/SNDR of 54. dB/54.3 dB in the 8 MHz bandwidth, while consuming 2.8 mW. The FoM of the proposed ADC is a 334 fJ/conv-step.

  12. Communication Impairment in the AIDS Dementia Complex (ADC): A Case Report

    ERIC Educational Resources Information Center

    McCabe, Patricia J.; Sheard, Christine; Code, Chris

    2008-01-01

    This article details three examinations of communication impairment over 13 months in a man with AIDS dementia complex (ADC) and compares his performance on standardised language testing with that of two control participants. He had mild language impairments as measured on standardised tests but was severely impaired in pragmatic language skills.…

  13. Precision ADCS of a spinning spacecraft for the Mars Aeronomy Explorer Mission

    NASA Technical Reports Server (NTRS)

    Mungas, Greg S.; Shotwell, Robert; Gray, Andrew

    2005-01-01

    This paper discusses a precision attitude and control technique for meeting these requirements utilizing a similar architecture that was adopted for the Laboratory of Atmospheric and Space Physics (LASP) SNOE (Student Nitrous Oxide Explorer) spinning spacecraft; SNOE has been operating with its ADCS architecture in low earth orbit (LEO) for over two years.

  14. Volterra kernels measurement and the application in post calibration of ADCs

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Yueyang, Chen; Shun'an, Zhong; Minshu, Ma

    As the proper choice for the digital post-calibration of the Analog to Digital Converters (ADCs), Volterra series has developed on a firm mathematical and logical foundation for decades. The most important issue in the Volterra series method is how to measure the Volterra kernels. This paper describes how frequency domain Volterra kernels effectively separated by compounding the Vandermonde matrix.

  15. A sixteen channel peak sensing ADC for singles spectra in the FERA format

    SciTech Connect

    Maier, M.R.; Ludewigt, B.; Rossington, C.; Yaver, H.; Zaninovich, J.

    1996-06-01

    To read out multi-element small X-ray detectors for X-ray fluorescence applications with synchrotron radiation one needs the capability to record multiple singles spectra for each detector element at high rates. The authors have developed a sixteen channel 11 bit peak sensing ADC in a CAMAC module. They use the FERA readout bus to place the data into a commercially available histogramming module developed to generate multiple histograms from FERA ADCs. The sixteen channels digitize shaped pulses from the detectors without external gating. The digitizing time is 8 {micro}sec, the peak acquisition time is {ge}2 {micro}sec. The module contains a LIFO to permit block transfers in order to minimize dead times associated with the readout. There is a common CAMAC controlled analog threshold for noise suppression and a 16 bit mask to enable or disable individual ADCs. Differential nonlinearity is less than +8%/{minus}4%. A {gamma}-ray spectrum collected using this ADC is presented.

  16. A sixteen channel peak sensing ADC for singles spectra in the FERA format

    SciTech Connect

    Maier, M.R.; Ludewigt, B.A.; Rossington, C.S.; Yaver, H.; Zaninovich, J.J.

    1995-10-01

    To read out multi-element small X-ray detectors for X-ray fluorescence application with synchrotron radiation one needs the capability to record multiple singles spectra for each detector element at high rates. We have developed a sixteen channel 11 bit peak sensing ADC in a CAMAC module. We use the FERA readout bus to place the data into a commercially available histogramming module developed to generate multiple histograms from FERA ADCs. The sixteen channels digitize shaped pulses from the detectors without external gating. The digitizing time is 8 {mu}sec, the peak acquisition time is {>=} 2 {mu}sec. The module contains a LiFO to permit block transfers in order to minimize dead times associated with the readout. There is a common CAMAC controlled analog threshold for noise suppression and a 16 bit mask to enable or disable individual ADCs. Differential non-linearity is less than +8% / -4%. A {gamma}-ray spectrum collected using this ADC is presented.

  17. Model based on-chip 13bits ADC design dedicated to uncooled infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Dupont, Benoit; Robert, Patrick; Dupret, Antoine; Villard, Patrick; Pochic, David

    2007-10-01

    This paper presents an on-chip 13 bits 10 M/S Analog to Digital Converter (ADC) specifically designed for infrared bolometric image sensor. Bolometric infrared sensors are MEMs based thermal sensors, which covers a large spectrum of infrared applications, ranging from night vision to predictive industrial maintenance and medical imaging. With the current move towards submicron technologies, the demand for more integrated, smarter sensors and microsystems has dramatically increased. This trend has strengthened the need of on-chip ADC as the interface between the analog core and the digital processing electronic. However designing an on-chip ADC dedicated to focal plane array raises many questions about its architecture and its performance requirements. To take into account those specific needs, a high level model has been developed prior to the actual design. In this paper, we present the trade-offs of ADC design linked to infrared key performance parameters and bolometric technology detection method. The original development scheme, based on system level modeling, is also discussed. Finally we present the actual design and the measured performances.

  18. Detection, purification and identification of an endogenous inhibitor of L-Dopa decarboxylase activity from human placenta.

    PubMed

    Vassiliou, Alice-Georgia; Fragoulis, Emmanuel G; Vassilacopoulou, Dido

    2009-06-01

    An endogenous inhibitor of L-Dopa decarboxylase activity was identified and purified from human placenta. The endogenous inhibitor of L-Dopa decarboxylase (Ddc) was localized in the membrane fraction of placental tissue. Treatment of membranes with phosphatidylinositol-specific phospholipase C or proteinase K did not affect membrane-associated Ddc inhibitory activity, suggesting that a population of the inhibitor is embedded within membranes. Purification was achieved by extraction from a nondenaturing polyacrylamide gel. The purification scheme resulted in the isolation of a single 35 kDa band, bearing L-Dopa decarboxylase inhibitory activity. The purified inhibitor was identified as Annexin V. The elucidation of the biological importance of the presence of an L-Dopa decarboxylase activity inhibitor in normal human tissues could provide us with new information leading to the better understanding of the biological pathways that Ddc is involved in. PMID:19005753

  19. ADC texture—An imaging biomarker for high-grade glioma?

    SciTech Connect

    Brynolfsson, Patrik; Hauksson, Jón; Karlsson, Mikael; Garpebring, Anders; Nyholm, Tufve; Nilsson, David; Trygg, Johan; Henriksson, Roger; Birgander, Richard; Asklund, Thomas

    2014-10-15

    Purpose: Survival for high-grade gliomas is poor, at least partly explained by intratumoral heterogeneity contributing to treatment resistance. Radiological evaluation of treatment response is in most cases limited to assessment of tumor size months after the initiation of therapy. Diffusion-weighted magnetic resonance imaging (MRI) and its estimate of the apparent diffusion coefficient (ADC) has been widely investigated, as it reflects tumor cellularity and proliferation. The aim of this study was to investigate texture analysis of ADC images in conjunction with multivariate image analysis as a means for identification of pretreatment imaging biomarkers. Methods: Twenty-three consecutive high-grade glioma patients were treated with radiotherapy (2 Gy/60 Gy) with concomitant and adjuvant temozolomide. ADC maps and T1-weighted anatomical images with and without contrast enhancement were collected prior to treatment, and (residual) tumor contrast enhancement was delineated. A gray-level co-occurrence matrix analysis was performed on the ADC maps in a cuboid encapsulating the tumor in coronal, sagittal, and transversal planes, giving a total of 60 textural descriptors for each tumor. In addition, similar examinations and analyses were performed at day 1, week 2, and week 6 into treatment. Principal component analysis (PCA) was applied to reduce dimensionality of the data, and the five largest components (scores) were used in subsequent analyses. MRI assessment three months after completion of radiochemotherapy was used for classifying tumor progression or regression. Results: The score scatter plots revealed that the first, third, and fifth components of the pretreatment examinations exhibited a pattern that strongly correlated to survival. Two groups could be identified: one with a median survival after diagnosis of 1099 days and one with 345 days, p = 0.0001. Conclusions: By combining PCA and texture analysis, ADC texture characteristics were identified, which seems

  20. Pixelwise readout integrated circuits with pixel-level ADC for microbolometers

    NASA Astrophysics Data System (ADS)

    Hwang, C. H.; Kim, C. B.; Lee, Y. S.; Yu, B. G.; Lee, H. C.

    2007-04-01

    Pixelwise integrated circuits involving a pixel-level analog-to-digital converter (ADC) are studied for 320 × 240 microbolometer focal plane arrays (FPAs). It is necessary to use the pixelwise readout architecture for decreasing the thermal noise. However, it is hard to locate a sufficiently large integration capacitor in a unit pixel of FPAs because of the area limitation. To effectively overcome this problem, a two step integration method is proposed. First, after integrating the current of the microbolometer for 32μs, upper 5bits of the 13bit digital signal are output through a pixel-level ADC. Then, the current of the microbolometer is integrated during 1ms after the skimming current correction using upper 5bits in a field-programmable gate array (FPGA), and then lower 8bits are obtained through a pixel-level ADC. Finally, upper 5bits and lower 8bits are combined into the digital image signal after the gain and offset correction in digital signal processor (DSP) Each 2×2 pixel shares an readout circuit, including a current-mode background skimming circuit, an operational amplifier(op-Amp), an integration capacitor and a single slope ADC. When the current of a microbolometer is integrated, the integration capacitor is connected between a negative input and an output of the op-Amp. Therefore a capacitive transimpedance amplifier (CTIA) has been employed as the input circuit of the microbolometer. When the output of a microbolometer is converted to digital signal, the Op-Amp is used as a comparator of the single slope ADC. This readout circuit is designed to achieve 35×35μm2 pixel size in 0.35μm 2-poly 3-metal CMOS technology.

  1. Physiological characterization of the ARO10-dependent, broad-substrate-specificity 2-oxo acid decarboxylase activity of Saccharomyces cerevisiae.

    PubMed

    Vuralhan, Zeynep; Luttik, Marijke A H; Tai, Siew Leng; Boer, Viktor M; Morais, Marcos A; Schipper, Dick; Almering, Marinka J H; Kötter, Peter; Dickinson, J Richard; Daran, Jean-Marc; Pronk, Jack T

    2005-06-01

    Aerobic, glucose-limited chemostat cultures of Saccharomyces cerevisiae CEN.PK113-7D were grown with different nitrogen sources. Cultures grown with phenylalanine, leucine, or methionine as a nitrogen source contained high levels of the corresponding fusel alcohols and organic acids, indicating activity of the Ehrlich pathway. Also, fusel alcohols derived from the other two amino acids were detected in the supernatant, suggesting the involvement of a common enzyme activity. Transcript level analysis revealed that among the five thiamine-pyrophospate-dependent decarboxylases (PDC1, PDC5, PDC6, ARO10, and THI3), only ARO10 was transcriptionally up-regulated when phenylalanine, leucine, or methionine was used as a nitrogen source compared to growth on ammonia, proline, and asparagine. Moreover, 2-oxo acid decarboxylase activity measured in cell extract from CEN.PK113-7D grown with phenylalanine, methionine, or leucine displayed similar broad-substrate 2-oxo acid decarboxylase activity. Constitutive expression of ARO10 in ethanol-limited chemostat cultures in a strain lacking the five thiamine-pyrophosphate-dependent decarboxylases, grown with ammonia as a nitrogen source, led to a measurable decarboxylase activity with phenylalanine-, leucine-, and methionine-derived 2-oxo acids. Moreover, even with ammonia as the nitrogen source, these cultures produced significant amounts of the corresponding fusel alcohols. Nonetheless, the constitutive expression of ARO10 in an isogenic wild-type strain grown in a glucose-limited chemostat with ammonia did not lead to any 2-oxo acid decarboxylase activity. Furthermore, even when ARO10 was constitutively expressed, growth with phenylalanine as the nitrogen source led to increased decarboxylase activities in cell extracts. The results reported here indicate the involvement of posttranscriptional regulation and/or a second protein in the ARO10-dependent, broad-substrate-specificity decarboxylase activity. PMID:15933030

  2. HemQ: An iron-coproporphyrin oxidative decarboxylase for protoheme synthesis in Firmicutes and Actinobacteria

    SciTech Connect

    Dailey, Harry A.; Gerdes, Svetlana

    2015-02-21

    Genes for chlorite dismutase-like proteins are found widely among heme-synthesizing bacteria and some Archaea. It is now known that among the Firmicutes and Actinobacteria these proteins do not possess chlorite dismutase activity but instead are essential for heme synthesis. These proteins, named HemQ, are ironcoproporphyrin (coproheme) decarboxylases that catalyze the oxidative decarboxylation of coproheme III into protoheme IX. As purified, HemQs do not contain bound heme, but readily bind exogeneously supplied heme with low micromolar affinity. We find that the heme-bound form of HemQ has low peroxidase activity and in the presence of peroxide the bound heme may be destroyed. Furthermore, it is possible that HemQ may serve a dual role as a decarboxylase in heme biosynthesis and a regulatory protein in heme homeostasis.

  3. Observation of superoxide production during catalysis of Bacillus subtilis oxalate decarboxylase at pH 4.

    PubMed

    Twahir, Umar T; Stedwell, Corey N; Lee, Cory T; Richards, Nigel G J; Polfer, Nicolas C; Angerhofer, Alexander

    2015-03-01

    This contribution describes the trapping of the hydroperoxyl radical at a pH of 4 during turnover of wild-type oxalate decarboxylase and its T165V mutant using the spin-trap BMPO. Radicals were detected and identified by a combination of EPR and mass spectrometry. Superoxide, or its conjugate acid, the hydroperoxyl radical, is expected as an intermediate in the decarboxylation and oxidation reactions of the oxalate monoanion, both of which are promoted by oxalate decarboxylase. Another intermediate, the carbon dioxide radical anion was also observed. The quantitative yields of superoxide trapping are similar in the wild type and the mutant while it is significantly different for the trapping of the carbon dioxide radical anion. This suggests that the two radicals are released from different sites of the protein. PMID:25526893

  4. Unusual space-group pseudo symmetry in crystals of human phosphopantothenoylcysteine decarboxylase

    SciTech Connect

    Manoj, N.; Ealick, S.E.

    2010-12-01

    Phosphopantothenoylcysteine (PPC) decarboxylase is an essential enzyme in the biosynthesis of coenzyme A and catalyzes the decarboxylation of PPC to phosphopantetheine. Human PPC decarboxylase has been expressed in Escherichia coli, purified and crystallized. The Laue class of the diffraction data appears to be {bar 3}m, suggesting space group R32 with two monomers per asymmetric unit. However, the crystals belong to the space group R3 and the asymmetric unit contains four monomers. The structure has been solved using molecular replacement and refined to a current R factor of 29%. The crystal packing can be considered as two interlaced lattices, each consistent with space group R32 and with the corresponding twofold axes parallel to each other but separated along the threefold axis. Thus, the true space group is R3 with four monomers per asymmetric unit.

  5. HemQ: An iron-coproporphyrin oxidative decarboxylase for protoheme synthesis in Firmicutes and Actinobacteria.

    PubMed

    Dailey, Harry A; Gerdes, Svetlana

    2015-05-15

    Genes for chlorite dismutase-like proteins are found widely among heme-synthesizing bacteria and some Archaea. It is now known that among the Firmicutes and Actinobacteria these proteins do not possess chlorite dismutase activity but instead are essential for heme synthesis. These proteins, named HemQ, are iron-coproporphyrin (coproheme) decarboxylases that catalyze the oxidative decarboxylation of coproheme III into protoheme IX. As purified, HemQs do not contain bound heme, but readily bind exogeneously supplied heme with low micromolar affinity. The heme-bound form of HemQ has low peroxidase activity and in the presence of peroxide the bound heme may be destroyed. Thus, it is possible that HemQ may serve a dual role as a decarboxylase in heme biosynthesis and a regulatory protein in heme homeostasis. PMID:25711532

  6. HemQ: An iron-coproporphyrin oxidative decarboxylase for protoheme synthesis in Firmicutes and Actinobacteria

    DOE PAGESBeta

    Dailey, Harry A.; Gerdes, Svetlana

    2015-02-21

    Genes for chlorite dismutase-like proteins are found widely among heme-synthesizing bacteria and some Archaea. It is now known that among the Firmicutes and Actinobacteria these proteins do not possess chlorite dismutase activity but instead are essential for heme synthesis. These proteins, named HemQ, are ironcoproporphyrin (coproheme) decarboxylases that catalyze the oxidative decarboxylation of coproheme III into protoheme IX. As purified, HemQs do not contain bound heme, but readily bind exogeneously supplied heme with low micromolar affinity. We find that the heme-bound form of HemQ has low peroxidase activity and in the presence of peroxide the bound heme may be destroyed.more » Furthermore, it is possible that HemQ may serve a dual role as a decarboxylase in heme biosynthesis and a regulatory protein in heme homeostasis.« less

  7. Functional plasticity and allosteric regulation of α-ketoglutarate decarboxylase in central mycobacterial metabolism.

    PubMed

    Wagner, Tristan; Bellinzoni, Marco; Wehenkel, Annemarie; O'Hare, Helen M; Alzari, Pedro M

    2011-08-26

    The α-ketoglutarate dehydrogenase (KDH) complex is a major regulatory point of aerobic energy metabolism. Mycobacterium tuberculosis was reported to lack KDH activity, and the putative KDH E1o component, α-ketoglutarate decarboxylase (KGD), was instead assigned as a decarboxylase or carboligase. Here, we show that this protein does in fact sustain KDH activity, as well as the additional two reactions, and these multifunctional properties are shared by the Escherichia coli homolog, SucA. We also show that the mycobacterial enzyme is finely regulated by an additional acyltransferase-like domain and by the action of acetyl-CoA, a powerful allosteric activator able to enhance the concerted protein motions observed during catalysis. Our results uncover the functional plasticity of a crucial node in bacterial metabolism, which may be important for M. tuberculosis during host infection. PMID:21867916

  8. HemQ: an iron-coproporphyrin oxidative decarboxylase for protoheme synthesis in Firmicutes and Actinobacteria

    PubMed Central

    Dailey, Harry A.; Gerdes, Svetlana

    2015-01-01

    Genes for chlorite dismutase-like proteins are found widely among hemesynthesizing bacteria and some Archaea. It is now known that among the Firmicutes and Actinobacteria these proteins do not possess chlorite dismutase activity but instead are essential for heme synthesis. These proteins, named HemQ, are ironcoproporphyrin (coproheme) decarboxylases that catalyze the oxidative decarboxylation of coproheme III into protoheme IX. As purified, HemQs do not contain bound heme, but readily bind exogeneously supplied heme with low micromolar affinity. The heme-bound form of HemQ has low peroxidase activity and in the presence of peroxide the bound heme may be destroyed. Thus, it is possible that HemQ may serve a dual role as a decarboxylase in heme biosynthesis and a regulatory protein in heme homeostasis. PMID:25711532

  9. Observation of Superoxide Production During Catalysis of Bacillus subtilis Oxalate Decarboxylase at pH4

    PubMed Central

    Twahir, Umar T.; Stedwell, Corey N.; Lee, Cory T.; Richards, Nigel G. J.; Polfer, Nicolas C.; Angerhofer, Alexander

    2015-01-01

    This contribution describes the trapping of the hydroperoxyl radical at a pH of 4 during turnover of wild-type oxalate decarboxylase and its T165V mutant using the spin trap BMPO. Radicals were detected and identified by a combination of EPR and mass spectrometry. Superoxide, or its conjugate acid, the hydroperoxyl radical, is expected as an intermediate in the decarboxylation and oxidation reactions of the oxalate monoanion both of which are promoted by oxalate decarboxylase. Another intermediate, the carbon dioxide radical anion was also observed. The quantitative yields of superoxide trapping is similar in the wild type and the mutant while it is significantly different for the trapping of the carbon dioxide radical anion. This suggests that the two radicals are released from different sites of the protein. PMID:25526893

  10. The Regulation of the AdcR Regulon in Streptococcus pneumoniae Depends Both on Zn2+- and Ni2+-Availability

    PubMed Central

    Manzoor, Irfan; Shafeeq, Sulman; Afzal, Muhammad; Kuipers, Oscar P.

    2015-01-01

    By using a transcriptomic approach, we have elucidated the effect of Ni2+ on the global gene expression of S. pneumoniae D39 by identifying several differentially expressed genes/operons in the presence of a high extracellular concentration of Ni2+. The genes belonging to the AdcR regulon (adcRCBA, adcAII-phtD, phtA, phtB, and phtE) and the PsaR regulon (pcpA, prtA, and psaBCA) were highly upregulated in the presence of Ni2+. We have further studied the role of Ni2+ in the regulation of the AdcR regulon by using ICP-MS analysis, electrophoretic mobility shift assays and transcriptional lacZ-reporter studies, and demonstrate that Ni2+ is directly involved in the derepression of the AdcR regulon via the Zn2+-dependent repressor AdcR, and has an opposite effect on the expression of the AdcR regulon compared to Zn2+. PMID:26697415

  11. Perturbation of the Monomer-Monomer Interfaces of the Benzoylformate Decarboxylase Tetramer

    SciTech Connect

    Andrews, Forest H.; Rogers, Megan P.; Paul, Lake N.; McLeish, Michael J.

    2014-08-14

    The X-ray structure of benzoylformate decarboxylase (BFDC) from Pseudomonas putida ATCC 12633 shows it to be a tetramer. This was believed to be typical of all thiamin diphosphate-dependent decarboxylases until recently when the structure of KdcA, a branched-chain 2-keto acid decarboxylase from Lactococcus lactis, showed it to be a homodimer. This lent credence to earlier unfolding experiments on pyruvate decarboxylase from Saccharomyces cerevisiae that indicated that it might be active as a dimer. To investigate this possibility in BFDC, we sought to shift the equilibrium toward dimer formation. Point mutations were made in the noncatalytic monomer–monomer interfaces, but these had a minimal effect on both tetramer formation and catalytic activity. Subsequently, the R141E/Y288A/A306F variant was shown by analytical ultracentrifugation to be partially dimeric. It was also found to be catalytically inactive. Further experiments revealed that just two mutations, R141E and A306F, were sufficient to markedly alter the dimer–tetramer equilibrium and to provide an ~450-fold decrease in kcat. Equilibrium denaturation studies suggested that the residual activity was possibly due to the presence of residual tetramer. The structures of the R141E and A306F variants, determined to <1.5 Å resolution, hinted that disruption of the monomer interfaces will be accompanied by movement of a loop containing Leu109 and Leu110. As these residues contribute to the hydrophobicity of the active site and the correct positioning of the substrate, it seems that tetramer formation may well be critical to the catalytic activity of BFDC.

  12. Perturbation of the Monomer–Monomer Interfaces of the Benzoylformate Decarboxylase Tetramer

    PubMed Central

    2015-01-01

    The X-ray structure of benzoylformate decarboxylase (BFDC) from Pseudomonas putida ATCC 12633 shows it to be a tetramer. This was believed to be typical of all thiamin diphosphate-dependent decarboxylases until recently when the structure of KdcA, a branched-chain 2-keto acid decarboxylase from Lactococcus lactis, showed it to be a homodimer. This lent credence to earlier unfolding experiments on pyruvate decarboxylase from Saccharomyces cerevisiae that indicated that it might be active as a dimer. To investigate this possibility in BFDC, we sought to shift the equilibrium toward dimer formation. Point mutations were made in the noncatalytic monomer–monomer interfaces, but these had a minimal effect on both tetramer formation and catalytic activity. Subsequently, the R141E/Y288A/A306F variant was shown by analytical ultracentrifugation to be partially dimeric. It was also found to be catalytically inactive. Further experiments revealed that just two mutations, R141E and A306F, were sufficient to markedly alter the dimer–tetramer equilibrium and to provide an ∼450-fold decrease in kcat. Equilibrium denaturation studies suggested that the residual activity was possibly due to the presence of residual tetramer. The structures of the R141E and A306F variants, determined to <1.5 Å resolution, hinted that disruption of the monomer interfaces will be accompanied by movement of a loop containing Leu109 and Leu110. As these residues contribute to the hydrophobicity of the active site and the correct positioning of the substrate, it seems that tetramer formation may well be critical to the catalytic activity of BFDC. PMID:24956165

  13. Treatment with the C5a receptor antagonist ADC-1004 reduces myocardial infarction in a porcine ischemia-reperfusion model

    PubMed Central

    2010-01-01

    Background Polymorphonuclear neutrophils, stimulated by the activated complement factor C5a, have been implicated in cardiac ischemia/reperfusion injury. ADC-1004 is a competitive C5a receptor antagonist that has been shown to inhibit complement related neutrophil activation. ADC-1004 shields the neutrophils from C5a activation before they enter the reperfused area, which could be a mechanistic advantage compared to previous C5a directed reperfusion therapies. We investigated if treatment with ADC-1004, according to a clinically applicable protocol, would reduce infarct size and microvascular obstruction in a large animal myocardial infarct model. Methods In anesthetized pigs (42-53 kg), a percutaneous coronary intervention balloon was inflated in the left anterior descending artery for 40 minutes, followed by 4 hours of reperfusion. Twenty minutes after balloon inflation the pigs were randomized to an intravenous bolus administration of ADC-1004 (175 mg, n = 8) or saline (9 mg/ml, n = 8). Area at risk (AAR) was evaluated by ex vivo SPECT. Infarct size and microvascular obstruction were evaluated by ex vivo MRI. The observers were blinded to the treatment at randomization and analysis. Results ADC-1004 treatment reduced infarct size by 21% (ADC-1004: 58.3 ± 3.4 vs control: 74.1 ± 2.9%AAR, p = 0.007). Microvascular obstruction was similar between the groups (ADC-1004: 2.2 ± 1.2 vs control: 5.3 ± 2.5%AAR, p = 0.23). The mean plasma concentration of ADC-1004 was 83 ± 8 nM at sacrifice. There were no significant differences between the groups with respect to heart rate, mean arterial pressure, cardiac output and blood-gas data. Conclusions ADC-1004 treatment reduces myocardial ischemia-reperfusion injury and represents a novel treatment strategy of myocardial infarct with potential clinical applicability. PMID:20875134

  14. Different mRNAs code for dopa decarboxylase in tissues of neuronal and nonneuronal origin

    SciTech Connect

    Krieger, M.; Coge, F.; Gros, F.; Thibault, J. )

    1991-03-15

    A cDNA clone for dopa decarboxylase has been isolated from a rat pheochromocytoma cDNA library and the cDNA sequence has been determined. It corresponds to an mRNA of 2094 nucleotides. The length of the mRNA was measured by primer-extension of rat pheochromocytoma RNA and the 5{prime} end of the sequence of the mRNA was confirmed by the PCR. A probe spanning the translation initiation site of the mRNA was used to hybridize with mRNAs from various organs of the rat. S1 nuclease digestion of the mRNAs annealed with this probe revealed two classes of mRNAs. The comparison of the cDNA sequence and published sequences for rat liver, human pheochromocytoma, and Droxophila dopa decarboxylase supported the conclusion that two mRNAs are produced: one is specific for tissue of neuronal origin and the other is specific for tissues of nonneuronal (mesodermal or endodermal) origin. The neuronal mRNA contains a 5{prime} untranslated sequence that is highly conserved between human and rat pheochromocytoma including a GA stretch. The coding sequence and the 3{prime} untranslated sequence of mRNAs from rat liver and pheochromocytoma are identical. The rat mRNA differs only in the 5{prime} untranslated region. Thus a unique gene codes for dopa decarboxylase and this gene gives rise to at least two transcripts presumably in response to different signals during development.

  15. Cloning and characterization of indolepyruvate decarboxylase from Methylobacterium extorquens AM1.

    PubMed

    Fedorov, D N; Doronina, N V; Trotsenko, Yu A

    2010-12-01

    For the first time for methylotrophic bacteria an enzyme of phytohormone indole-3-acetic acid (IAA) biosynthesis, indole-3-pyruvate decarboxylase (EC 4.1.1.74), has been found. An open reading frame (ORF) was identified in the genome of facultative methylotroph Methylobacterium extorquens AM1 using BLAST. This ORF encodes thiamine diphosphate-dependent 2-keto acid decarboxylase and has similarity with indole-3-pyruvate decarboxylases, which are key enzymes of IAA biosynthesis. The ORF of the gene, named ipdC, was cloned into overexpression vector pET-22b(+). Recombinant enzyme IpdC was purified from Escherichia coli BL21(DE3) and characterized. The enzyme showed the highest k(cat) value for benzoylformate, albeit the indolepyruvate was decarboxylated with the highest catalytic efficiency (k(cat)/K(m)). The molecular mass of the holoenzyme determined using gel-permeation chromatography corresponds to a 245-kDa homotetramer. An ipdC-knockout mutant of M. extorquens grown in the presence of tryptophan had decreased IAA level (46% of wild type strain). Complementation of the mutation resulted in 6.3-fold increase of IAA concentration in the culture medium compared to that of the mutant strain. Thus involvement of IpdC in IAA biosynthesis in M. extorquens was shown. PMID:21314613

  16. EPR Spin Trapping of an Oxalate-Derived Free Radical in the Oxalate Decarboxylase Reaction

    PubMed Central

    Imaram, Witcha; Saylor, Benjamin T.; Centonze, Christopher P.; Richards, Nigel G. J.; Angerhofer, Alexander

    2011-01-01

    EPR spin trapping experiments on bacterial oxalate decarboxylase from Bacillus subtilis under turn-over conditions are described. The use of doubly 13C-labeled oxalate leads to a characteristic splitting of the observed radical adducts using the spin trap N-tert-butyl-α-phenylnitrone linking them directly to the substrate. The radical was identified as the carbon dioxide radical anion which is a key intermediate in the hypothetical reaction mechanism of both decarboxylase and oxidase activities. X-ray crystallography had identified a flexible loop, SENS161-4, which acts as a lid to the putative active site. Site directed mutagenesis of the hinge amino acids, S161 and T165 was explored and showed increased radical trapping yields compared to the wild type. In particular, T165V shows approximately ten times higher radical yields while at the same time its decarboxylase activity was reduced by about a factor of ten. This mutant lacks a critical H-bond between T165 and R92 resulting in compromised control over its radical chemistry allowing the radical intermediate to leak into the surrounding solution. PMID:21277974

  17. Novel protein–protein interaction between spermidine synthase and S-adenosylmethionine decarboxylase from Leishmania donovani

    SciTech Connect

    Mishra, Arjun K.; Agnihotri, Pragati; Srivastava, Vijay Kumar; Pratap, J. Venkatesh

    2015-01-09

    Highlights: • L. donovani spermidine synthase and S-adenosylmethionine decarboxylase have been cloned and purified. • S-adenosylmethionine decarboxylase has autocatalytic property. • GST pull down assay shows the two proteins to form a metabolon. • Isothermal titration calorimetry shows that binding was exothermic having K{sub d} value of 0.4 μM. • Interaction confirmed by fluorescence spectroscopy and size exclusion chromatography. - Abstract: Polyamine biosynthesis pathway has long been considered an essential drug target for trypanosomatids including Leishmania. S-adenosylmethionine decarboxylase (AdoMetDc) and spermidine synthase (SpdSyn) are enzymes of this pathway that catalyze successive steps, with the product of the former, decarboxylated S-adenosylmethionine (dcSAM), acting as an aminopropyl donor for the latter enzyme. Here we have explored the possibility of and identified the protein–protein interaction between SpdSyn and AdoMetDc. The protein–protein interaction has been identified using GST pull down assay. Isothermal titration calorimetry reveals that the interaction is thermodynamically favorable. Fluorescence spectroscopy studies also confirms the interaction, with SpdSyn exhibiting a change in tertiary structure with increasing concentrations of AdoMetDc. Size exclusion chromatography suggests the presence of the complex as a hetero-oligomer. Taken together, these results suggest that the enzymes indeed form a heteromer. Computational analyses suggest that this complex differs significantly from the corresponding human complex, implying that this complex could be a better therapeutic target than the individual enzymes.

  18. Analysis and comparison of CVS-ADC approaches up to third order for the calculation of core-excited states

    SciTech Connect

    Wenzel, Jan Holzer, Andre; Wormit, Michael; Dreuw, Andreas

    2015-06-07

    The extended second order algebraic-diagrammatic construction (ADC(2)-x) scheme for the polarization operator in combination with core-valence separation (CVS) approximation is well known to be a powerful quantum chemical method for the calculation of core-excited states and the description of X-ray absorption spectra. For the first time, the implementation and results of the third order approach CVS-ADC(3) are reported. Therefore, the CVS approximation has been applied to the ADC(3) working equations and the resulting terms have been implemented efficiently in the adcman program. By treating the α and β spins separately from each other, the unrestricted variant CVS-UADC(3) for the treatment of open-shell systems has been implemented as well. The performance and accuracy of the CVS-ADC(3) method are demonstrated with respect to a set of small and middle-sized organic molecules. Therefore, the results obtained at the CVS-ADC(3) level are compared with CVS-ADC(2)-x values as well as experimental data by calculating complete basis set limits. The influence of basis sets is further investigated by employing a large set of different basis sets. Besides the accuracy of core-excitation energies and oscillator strengths, the importance of cartesian basis functions and the treatment of orbital relaxation effects are analyzed in this work as well as computational timings. It turns out that at the CVS-ADC(3) level, the results are not further improved compared to CVS-ADC(2)-x and experimental data, because the fortuitous error compensation inherent in the CVS-ADC(2)-x approach is broken. While CVS-ADC(3) overestimates the core excitation energies on average by 0.61% ± 0.31%, CVS-ADC(2)-x provides an averaged underestimation of −0.22% ± 0.12%. Eventually, the best agreement with experiments can be achieved using the CVS-ADC(2)-x method in combination with a diffuse cartesian basis set at least at the triple-ζ level.

  19. Analysis and comparison of CVS-ADC approaches up to third order for the calculation of core-excited states

    NASA Astrophysics Data System (ADS)

    Wenzel, Jan; Holzer, Andre; Wormit, Michael; Dreuw, Andreas

    2015-06-01

    The extended second order algebraic-diagrammatic construction (ADC(2)-x) scheme for the polarization operator in combination with core-valence separation (CVS) approximation is well known to be a powerful quantum chemical method for the calculation of core-excited states and the description of X-ray absorption spectra. For the first time, the implementation and results of the third order approach CVS-ADC(3) are reported. Therefore, the CVS approximation has been applied to the ADC(3) working equations and the resulting terms have been implemented efficiently in the adcman program. By treating the α and β spins separately from each other, the unrestricted variant CVS-UADC(3) for the treatment of open-shell systems has been implemented as well. The performance and accuracy of the CVS-ADC(3) method are demonstrated with respect to a set of small and middle-sized organic molecules. Therefore, the results obtained at the CVS-ADC(3) level are compared with CVS-ADC(2)-x values as well as experimental data by calculating complete basis set limits. The influence of basis sets is further investigated by employing a large set of different basis sets. Besides the accuracy of core-excitation energies and oscillator strengths, the importance of cartesian basis functions and the treatment of orbital relaxation effects are analyzed in this work as well as computational timings. It turns out that at the CVS-ADC(3) level, the results are not further improved compared to CVS-ADC(2)-x and experimental data, because the fortuitous error compensation inherent in the CVS-ADC(2)-x approach is broken. While CVS-ADC(3) overestimates the core excitation energies on average by 0.61% ± 0.31%, CVS-ADC(2)-x provides an averaged underestimation of -0.22% ± 0.12%. Eventually, the best agreement with experiments can be achieved using the CVS-ADC(2)-x method in combination with a diffuse cartesian basis set at least at the triple-ζ level.

  20. In-pixel conversion with a 10 bit SAR ADC for next generation X-ray FELs

    NASA Astrophysics Data System (ADS)

    Lodola, L.; Batignani, G.; Benkechkache, M. A.; Bettarini, S.; Casarosa, G.; Comotti, D.; Dalla Betta, G. F.; Fabris, L.; Forti, F.; Grassi, M.; Latreche, S.; Malcovati, P.; Manghisoni, M.; Mendicino, R.; Morsani, F.; Paladino, A.; Pancheri, L.; Paoloni, E.; Ratti, L.; Re, V.; Rizzo, G.; Traversi, G.; Vacchi, C.; Verzellesi, G.; Xu, H.

    2016-07-01

    This work presents the design of an interleaved Successive Approximation Register (SAR) ADC, part of the readout channel for the PixFEL detector. The PixFEL project aims at substantially advancing the state-of-the-art in the field of 2D X-ray imaging for applications at the next generation Free Electron Laser (FEL) facilities. For this purpose, the collaboration is developing the fundamental microelectronic building blocks for the readout channel. This work focuses on the design of the ADC carried out in a 65 nm CMOS technology. To obtain a good tradeoff between power consumption, conversion speed and area occupation, an interleaved SAR ADC architecture was adopted.

  1. Analysis and comparison of CVS-ADC approaches up to third order for the calculation of core-excited states.

    PubMed

    Wenzel, Jan; Holzer, Andre; Wormit, Michael; Dreuw, Andreas

    2015-06-01

    The extended second order algebraic-diagrammatic construction (ADC(2)-x) scheme for the polarization operator in combination with core-valence separation (CVS) approximation is well known to be a powerful quantum chemical method for the calculation of core-excited states and the description of X-ray absorption spectra. For the first time, the implementation and results of the third order approach CVS-ADC(3) are reported. Therefore, the CVS approximation has been applied to the ADC(3) working equations and the resulting terms have been implemented efficiently in the adcman program. By treating the α and β spins separately from each other, the unrestricted variant CVS-UADC(3) for the treatment of open-shell systems has been implemented as well. The performance and accuracy of the CVS-ADC(3) method are demonstrated with respect to a set of small and middle-sized organic molecules. Therefore, the results obtained at the CVS-ADC(3) level are compared with CVS-ADC(2)-x values as well as experimental data by calculating complete basis set limits. The influence of basis sets is further investigated by employing a large set of different basis sets. Besides the accuracy of core-excitation energies and oscillator strengths, the importance of cartesian basis functions and the treatment of orbital relaxation effects are analyzed in this work as well as computational timings. It turns out that at the CVS-ADC(3) level, the results are not further improved compared to CVS-ADC(2)-x and experimental data, because the fortuitous error compensation inherent in the CVS-ADC(2)-x approach is broken. While CVS-ADC(3) overestimates the core excitation energies on average by 0.61% ± 0.31%, CVS-ADC(2)-x provides an averaged underestimation of -0.22% ± 0.12%. Eventually, the best agreement with experiments can be achieved using the CVS-ADC(2)-x method in combination with a diffuse cartesian basis set at least at the triple-ζ level. PMID:26049476

  2. Recent Developments in Catalog Data Viewing and Visualization at the ADC

    NASA Astrophysics Data System (ADS)

    White, R. A.; Cheung, C. Y.; Gass, J. E.; Roman, N. G.; Schneider, G. L.; Blackwell, J. H.; Weiland, J. L.; Shaya, E. J.; Kargatis, V. E.; Reichert, G.; Digel, S. W.; de La Beaujardiere, J.

    1997-12-01

    The Astronomical Data Center (ADC) at the NASA Goddard Space Flight Center is a major archive and distribution center for computer-readable versions of astronomical catalogs and journal data tables. The ADC's archives contain more than 2100 catalogs and tables of astrometry, photometry, spectroscopy, radio, high energy, and other miscellaneous data for stellar and non-stellar objects. To improve the usability of these data holdings, we have developed a simple data viewing and visualization capability by building on work done for the Global Learning and Observations to Benefit the Environment (GLOBE) program. This capability allows researchers to subset, resort, select table columns for display, and view or plot the selected data via the Web. Related developments, notably linkage and display of NASA mission data are discussed. These capabilities can be accessed from the Web page http://adf.gsfc.nasa.gov/adf/visualization.

  3. Development of multichannel analyzer using sound card ADC for nuclear spectroscopy system

    SciTech Connect

    Ibrahim, Maslina Mohd; Yussup, Nolida; Lombigit, Lojius; Rahman, Nur Aira Abdul; Jaafar, Zainudin

    2014-02-12

    This paper describes the development of Multi-Channel Analyzer (MCA) using sound card analogue to digital converter (ADC) for nuclear spectroscopy system. The system was divided into a hardware module and a software module. Hardware module consist of detector NaI (Tl) 2” by 2”, Pulse Shaping Amplifier (PSA) and a build in ADC chip from readily available in any computers’ sound system. The software module is divided into two parts which are a pre-processing of raw digital input and the development of the MCA software. Band-pass filter and baseline stabilization and correction were implemented for the pre-processing. For the MCA development, the pulse height analysis method was used to process the signal before displaying it using histogram technique. The development and tested result for using the sound card as an MCA are discussed.

  4. A 13-bit Noise Shaping SAR-ADC with Dual-Polarity Digital Calibration.

    PubMed

    Park, Hangue; Ghovanloo, Maysam

    2013-06-01

    We present a new noise shaping method and a dual polarity calibration technique suited for successive approximation register type analog to digital converters (SAR-ADC). Noise is pushed to higher frequencies with the noise shaping by adding a switched capacitor. The SAR capacitor array mismatch has been compensated by the dual-polarity digital calibration with minimum circuit overhead. A proof-of-concept prototype SAR-ADC using the proposed techniques has been fabricated in a 0.5-μm standard CMOS technology. It achieves 67.7 dB SNDR at 62.5 kHz sampling frequency, while consuming 38.3μW power with 1.8 V supply. PMID:23682207

  5. Ethernet-based flash ADC for a plant PET detector system

    SciTech Connect

    Lee, Seung Joon; Dong, Hai T.; McKisson, John E.; Weisenberger, Andrew G.; Xi, Wenze; Howell, C. R.; Reid, C. D.; Smith, Mark F.

    2012-11-01

    We have developed a flash analog to digital (ADC) based read out system to be used for a Positron Emission Tomography (PET) system. The custom designed 16 channel 12-bit Ethernet-based flash ADC (EFADC-16) unit operates at 250 MHzls/channel utilizing a gigabit Ethernet interface to parse time-stamped event signals. Each unit allows the user to define a custom coincidence table for triggering. Each EFADC-16 unit can digitize four H8500 position sensitive photomultiplier tubes (PSPMT) equipped with a Jefferson Lab designed 4 channel resistive readout (a total of 16 channels). We present initial performance results of the EFADC-16 with four PET detector modules in a plant biology application to acquire tomographic images of the translocation of {sup 11}C within an oak seedling.

  6. Development of multichannel analyzer using sound card ADC for nuclear spectroscopy system

    NASA Astrophysics Data System (ADS)

    Ibrahim, Maslina Mohd; Yussup, Nolida; Lombigit, Lojius; Rahman, Nur Aira Abdul; Jaafar, Zainudin

    2014-02-01

    This paper describes the development of Multi-Channel Analyzer (MCA) using sound card analogue to digital converter (ADC) for nuclear spectroscopy system. The system was divided into a hardware module and a software module. Hardware module consist of detector NaI (Tl) 2" by 2", Pulse Shaping Amplifier (PSA) and a build in ADC chip from readily available in any computers' sound system. The software module is divided into two parts which are a pre-processing of raw digital input and the development of the MCA software. Band-pass filter and baseline stabilization and correction were implemented for the pre-processing. For the MCA development, the pulse height analysis method was used to process the signal before displaying it using histogram technique. The development and tested result for using the sound card as an MCA are discussed.

  7. A mixed signal ECG processing platform with an adaptive sampling ADC for portable monitoring applications.

    PubMed

    Kim, Hyejung; Van Hoof, Chris; Yazicioglu, Refet Firat

    2011-01-01

    This paper describes a mixed-signal ECG processing platform with an 12-bit ADC architecture that can adapt its sampling rate according to the input signals rate of change. This enables the sampling of ECG signals with significantly reduced data rate without loss of information. The presented adaptive sampling scheme reduces the ADC power consumption, enables the processing of ECG signals with lower power consumption, and reduces the power consumption of the radio while streaming the ECG signals. The test results show that running a CWT-based R peak detection algorithm using the adaptively sampled ECG signals consumes only 45.6 μW and it leads to 36% less overall system power consumption. PMID:22254775

  8. Enhancing muconic acid production from glucose and lignin-derived aromatic compounds via increased protocatechuate decarboxylase activity

    DOE PAGESBeta

    Johnson, Christopher W.; Salvachua, Davinia; Khanna, Payal; Smith, Holly; Peterson, Darren J.; Beckham, Gregg T.

    2016-04-22

    The conversion of biomass-derived sugars and aromatic molecules to cis,cis-muconic acid (referred to hereafter as muconic acid or muconate) has been of recent interest owing to its facile conversion to adipic acid, an important commodity chemical. Metabolic routes to produce muconate from both sugars and many lignin-derived aromatic compounds require the use of a decarboxylase to convert protocatechuate (PCA, 3,4-dihydroxybenzoate) to catechol (1,2-dihydroxybenzene), two central aromatic intermediates in this pathway. Several studies have identified the PCA decarboxylase as a metabolic bottleneck, causing an accumulation of PCA that subsequently reduces muconate production. A recent study showed that activity of the PCAmore » decarboxylase is enhanced by co-expression of two genetically associated proteins, one of which likely produces a flavin-derived cofactor utilized by the decarboxylase. Using entirely genome-integrated gene expression, we have engineered Pseudomonas putida KT2440-derived strains to produce muconate from either aromatic molecules or sugars and demonstrate in both cases that co-expression of these decarboxylase associated proteins reduces PCA accumulation and enhances muconate production relative to strains expressing the PCA decarboxylase alone. In bioreactor experiments, co-expression increased the specific productivity (mg/g cells/h) of muconate from the aromatic lignin monomer p-coumarate by 50% and resulted in a titer of >15 g/L. In strains engineered to produce muconate from glucose, co-expression more than tripled the titer, yield, productivity, and specific productivity, with the best strain producing 4.92+/-0.48 g/L muconate. Furthermore, this study demonstrates that overcoming the PCA decarboxylase bottleneck can increase muconate yields from biomass-derived sugars and aromatic molecules in industrially relevant strains and cultivation conditions.« less

  9. Extension of the ADC Charge-Collection Model to Include Multiple Junctions

    NASA Technical Reports Server (NTRS)

    Edmonds, Larry D.

    2011-01-01

    The ADC model is a charge-collection model derived for simple p-n junction silicon diodes having a single reverse-biased p-n junction at one end and an ideal substrate contact at the other end. The present paper extends the model to include multiple junctions, and the goal is to estimate how collected charge is shared by the different junctions.

  10. "Clues on Balo's concentric sclerosis evolution from serial analysis of ADC values".

    PubMed

    Ripellino, Paolo; Khonsari, Roman; Stecco, Alessandro; Filippi, Massimo; Perchinunno, Marco; Cantello, Roberto

    2016-01-01

    Balò's sclerosis is considered a rare variant of multiple sclerosis characterized by demyelination with concentric rings. Advanced magnetic resonance studies allow nowadays early diagnosis and prompt treatment. However, the pathophysiology of lesion evolution is still matter of debate, as detailed in our literature review. Based on a clear-cut Balò's lesion analysis, we describe early changes in DWI and ADC values within the different layers, favoring the concept of a centrifugal growth. PMID:25405537

  11. Adaptive Readout Technique For A Sixteen Channel Peak Sensing ADC In the FERA Format

    SciTech Connect

    Yaver, H.; Maier, M.R.; Lindstrom, D.; Ludewigt, B.A.

    1998-11-01

    An adaptive, variable block-size readout technique for use with multiple, sixteen-channel CAMAC ADCs with a FERA-bus readout has been developed and designed. It can be used to read data from experiments with or without coincidence, i.e. singles, without having to change the readout protocol. Details of the implementation are discussed and initial results are presented. Further applications of the adaptive readout are also discussed.

  12. Adaptive readout technique for a sixteen channel peak sensing ADC in the FERA format

    SciTech Connect

    Yaver, H.; Maier, M.R.; Ludewigt, B.A.; Lindstroem, D.

    1999-08-01

    An adaptive variable block size readout technique for use with multiple sixteen channel CAMAC ADCs with a FERA-bus readout has been developed and designed. It can be used to read data from experiments with or without coincidence, i.e. singles, without having to change the readout protocol. Details of the implementation are discussed and initial results are presented. Further applications of the adaptive readout are also discussed.

  13. Chandra and XMM Observations of the ADC Source 0921-630

    NASA Technical Reports Server (NTRS)

    Kallman, T. R.; Angelini, L.; Boroson, B.; Cottam, J.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We analyze observations of the low mass X-ray binary 2S0921-63 obtained with the gratings and CCDs on Chandra and XMM. This object is a high inclination system showing evidence for an accretion disk corona (ADC). Such a corona has the potential to constrain the properties of the heated accretion disk in this system, and other LMXBs by extension. We find evidence for line emission which is generally consistent with that found by previous experiments, although we are able to detect more lines. For the first time in this source, we find that the iron K line has multiple components. We set limits on the line widths and velocity offsets, and we fit the spectra to photoionization models and discuss the implications for accretion disk corona models. For the first time in any ADC source we use these fits, together with density constraints based on the O VII line ratio, in order to constrain the flux in the medium-ionization region of the ADC. Under various assumptions about the source luminosity this constrains the location of the emitting region. These estimates, together with estimates for the emission measure, favor a scenario in which the intrinsic luminosity of the source is comparable to what we observe.

  14. Iterative current mode per pixel ADC for 3D SoftChip implementation in CMOS

    NASA Astrophysics Data System (ADS)

    Lachowicz, Stefan W.; Rassau, Alexander; Lee, Seung-Minh; Eshraghian, Kamran; Lee, Mike M.

    2003-04-01

    Mobile multimedia communication has rapidly become a significant area of research and development constantly challenging boundaries on a variety of technological fronts. The processing requirements for the capture, conversion, compression, decompression, enhancement, display, etc. of increasingly higher quality multimedia content places heavy demands even on current ULSI (ultra large scale integration) systems, particularly for mobile applications where area and power are primary considerations. The ADC presented in this paper is designed for a vertically integrated (3D) system comprising two distinct layers bonded together using Indium bump technology. The top layer is a CMOS imaging array containing analogue-to-digital converters, and a buffer memory. The bottom layer takes the form of a configurable array processor (CAP), a highly parallel array of soft programmable processors capable of carrying out complex processing tasks directly on data stored in the top plane. This paper presents a ADC scheme for the image capture plane. The analogue photocurrent or sampled voltage is transferred to the ADC via a column or a column/row bus. In the proposed system, an array of analogue-to-digital converters is distributed, so that a one-bit cell is associated with one sensor. The analogue-to-digital converters are algorithmic current-mode converters. Eight such cells are cascaded to form an 8-bit converter. Additionally, each photo-sensor is equipped with a current memory cell, and multiple conversions are performed with scaled values of the photocurrent for colour processing.

  15. Development of COTS ADC SEE Test System for the ATLAS LArCalorimeter Upgrade

    SciTech Connect

    Hu, Xue -Ye; Chen, Hu -Cheng; Chen, Kai; Mead, Joseph; Liu, Shu -Bin; An, Qi

    2014-12-01

    Radiation-tolerant, high speed, high density and low power commercial off-the-shelf (COTS) analog-to-digital converters (ADCs) are planned to be used in the upgrade to the Liquid Argon (LAr) calorimeter front end (FE) trigger readout electronics. Total ionization dose (TID) and single event effect (SEE) are two important radiation effects which need to be characterized on COTS ADCs. In our initial TID test, Texas Instruments (TI) ADS5272 was identified to be the top performer after screening a total 17 COTS ADCs from different manufacturers with dynamic range and sampling rate meeting the requirements of the FE electronics. Another interesting feature of ADS5272 is its 6.5 clock cycles latency, which is the shortest among the 17 candidates. Based on the TID performance, we have designed a SEE evaluation system for ADS5272, which allows us to further assess its radiation tolerance. In this paper, we present a detailed design of ADS5272 SEE evaluation system and show the effectiveness of this system while evaluating ADS5272 SEE characteristics in multiple irradiation tests. According to TID and SEE test results, ADS5272 was chosen to be implemented in the full-size LAr Trigger Digitizer Board (LTDB) demonstrator, which will be installed on ATLAS calorimeter during the 2014 Long Shutdown 1 (LS1).

  16. PEALL4: a 4-channel, 12-bit, 40-MSPS, Power Efficient and Low Latency SAR ADC

    NASA Astrophysics Data System (ADS)

    Rarbi, F.; Dzahini, D.; Gallin-Martel, L.; Bouvier, J.; Zeloufi, M.; Trocme, B.; Gabaldon Ruiz, C.

    2015-01-01

    The PEALL4 chip is a Power Efficient And Low Latency 4-channels, 12-bit and 40-MSPS successive approximation register (SAR) ADC. It was designed featuring a very short latency time in the context of ATLAS Liquid Argon Calorimeter phase I upgrade. Moreover this design could be a good option for ATLAS phase II and other High Energy Physics (HEP) projects. The full functionality of the converter is achieved by an embedded high-speed clock frequency conversion generated by the ADC itself. The design and testing results of the PEALL4 chip implemented in a commercial 130nm CMOS process are presented. The size of this 4-channel ADC with embedded voltage references and sLVS output serializer is 2.8x3.4 mm2. The chip presents a short latency time less than 25 ns defined from the very beginning of the sampling to the last conversion bit made available. A total power consumption below 27mW per channel is measured including the reference buffer and the sLVS serializer.

  17. Development of COTS ADC SEE Test System for the ATLAS LArCalorimeter Upgrade

    DOE PAGESBeta

    Hu, Xue -Ye; Chen, Hu -Cheng; Chen, Kai; Mead, Joseph; Liu, Shu -Bin; An, Qi

    2014-12-01

    Radiation-tolerant, high speed, high density and low power commercial off-the-shelf (COTS) analog-to-digital converters (ADCs) are planned to be used in the upgrade to the Liquid Argon (LAr) calorimeter front end (FE) trigger readout electronics. Total ionization dose (TID) and single event effect (SEE) are two important radiation effects which need to be characterized on COTS ADCs. In our initial TID test, Texas Instruments (TI) ADS5272 was identified to be the top performer after screening a total 17 COTS ADCs from different manufacturers with dynamic range and sampling rate meeting the requirements of the FE electronics. Another interesting feature of ADS5272more » is its 6.5 clock cycles latency, which is the shortest among the 17 candidates. Based on the TID performance, we have designed a SEE evaluation system for ADS5272, which allows us to further assess its radiation tolerance. In this paper, we present a detailed design of ADS5272 SEE evaluation system and show the effectiveness of this system while evaluating ADS5272 SEE characteristics in multiple irradiation tests. According to TID and SEE test results, ADS5272 was chosen to be implemented in the full-size LAr Trigger Digitizer Board (LTDB) demonstrator, which will be installed on ATLAS calorimeter during the 2014 Long Shutdown 1 (LS1).« less

  18. Continuous Time Level Crossing Sampling ADC for Bio-Potential Recording Systems

    PubMed Central

    Tang, Wei; Osman, Ahmad; Kim, Dongsoo; Goldstein, Brian; Huang, Chenxi; Martini, Berin; Pieribone, Vincent A.

    2013-01-01

    In this paper we present a fixed window level crossing sampling analog to digital convertor for bio-potential recording sensors. This is the first proposed and fully implemented fixed window level crossing ADC without local DACs and clocks. The circuit is designed to reduce data size, power, and silicon area in future wireless neurophysiological sensor systems. We built a testing system to measure bio-potential signals and used it to evaluate the performance of the circuit. The bio-potential amplifier offers a gain of 53 dB within a bandwidth of 200 Hz-20 kHz. The input-referred rms noise is 2.8 µV. In the asynchronous level crossing ADC, the minimum delta resolution is 4 mV. The input signal frequency of the ADC is up to 5 kHz. The system was fabricated using the AMI 0.5 µm CMOS process. The chip size is 1.5 mm by 1.5 mm. The power consumption of the 4-channel system from a 3.3 V supply is 118.8 µW in the static state and 501.6 µW with a 240 kS/s sampling rate. The conversion efficiency is 1.6 nJ/conversion. PMID:24163640

  19. Continuous Time Level Crossing Sampling ADC for Bio-Potential Recording Systems.

    PubMed

    Tang, Wei; Osman, Ahmad; Kim, Dongsoo; Goldstein, Brian; Huang, Chenxi; Martini, Berin; Pieribone, Vincent A; Culurciello, Eugenio

    2013-06-01

    In this paper we present a fixed window level crossing sampling analog to digital convertor for bio-potential recording sensors. This is the first proposed and fully implemented fixed window level crossing ADC without local DACs and clocks. The circuit is designed to reduce data size, power, and silicon area in future wireless neurophysiological sensor systems. We built a testing system to measure bio-potential signals and used it to evaluate the performance of the circuit. The bio-potential amplifier offers a gain of 53 dB within a bandwidth of 200 Hz-20 kHz. The input-referred rms noise is 2.8 µV. In the asynchronous level crossing ADC, the minimum delta resolution is 4 mV. The input signal frequency of the ADC is up to 5 kHz. The system was fabricated using the AMI 0.5 µm CMOS process. The chip size is 1.5 mm by 1.5 mm. The power consumption of the 4-channel system from a 3.3 V supply is 118.8 µW in the static state and 501.6 µW with a 240 kS/s sampling rate. The conversion efficiency is 1.6 nJ/conversion. PMID:24163640

  20. A fast, low-power, 6-bit SAR ADC for readout of strip detectors in the LHCb Upgrade experiment

    NASA Astrophysics Data System (ADS)

    Firlej, M.; Fiutowski, T.; Idzik, M.; Moron, J.; Swientek, K.

    2014-07-01

    The readout of silicon strip sensors in the upgraded Tracker System of Large Hadron Collider beauty (LHCb) experiment will require a novel complex Application Specific Integrated Circuit (ASIC). The ASIC will extract and digitise analogue signal from the sensor and subsequently will perform digital processing and serial data transmission. One of the key processing blocks, placed in each channel, will be an Analogue to Digital Converter (ADC). A prototype of fast, low-power 6-bit Successive Approximation Register (SAR) ADC was designed, fabricated and tested. The measurements of ADC prototypes confirmed simulation results showing excellent overall performance. In particular, very good resolution with Effective Number Of Bits (ENOB) 5.85 was obtained together with very low power consumption of 0.35 mW at 40 MS/s sampling rate. The results of the performed static and dynamic measurements confirm excellent ADC operation for higher sampling rates up to 80 MS/s.

  1. A 72-dB-SNDR rail-to-rail successive approximation ADC using mismatch calibration techniques

    NASA Astrophysics Data System (ADS)

    Yan, Liu; Siliang, Hua; Donghui, Wang; Chaohuan, Hou

    2012-12-01

    When the voltage of an analog input signal is equal to the supply voltage, it is difficult for a conventional successive approximation ADC to correctly convert the analog signal into digital signal. This paper introduces an improved successive approximation ADC, which can convert the rail-to-rail input range and reduce sampling time through a track-and-hold circuit. Comparator offset cancellation and capacitor self-calibration techniques are used in this ADC. Measurement results show that the peak SNDR of this ADC reaches 72 dB and the signal effective bandwidth is up to 1.25 MHz. It consumes 1 mW in the test, and the figure of merit is 123 fJ/conversion-step.

  2. Parasite-specific inserts in the bifunctional S-adenosylmethionine decarboxylase/ornithine decarboxylase of Plasmodium falciparum modulate catalytic activities and domain interactions.

    PubMed Central

    Birkholtz, Lyn-Marie; Wrenger, Carsten; Joubert, Fourie; Wells, Gordon A; Walter, Rolf D; Louw, Abraham I

    2004-01-01

    Polyamine biosynthesis of the malaria parasite, Plasmodium falciparum, is regulated by a single, hinge-linked bifunctional PfAdoMetDC/ODC [ P. falciparum AdoMetDC (S-adenosylmethionine decarboxylase)/ODC (ornithine decarboxylase)] with a molecular mass of 330 kDa. The bifunctional nature of AdoMetDC/ODC is unique to Plasmodia and is shared by at least three species. The PfAdoMetDC/ODC contains four parasite-specific regions ranging in size from 39 to 274 residues. The significance of the parasite-specific inserts for activity and protein-protein interactions of the bifunctional protein was investigated by a single- and multiple-deletion strategy. Deletion of these inserts in the bifunctional protein diminished the corresponding enzyme activity and in some instances also decreased the activity of the neighbouring, non-mutated domain. Intermolecular interactions between AdoMetDC and ODC appear to be vital for optimal ODC activity. Similar results have been reported for the bifunctional P. falciparum dihydrofolate reductase-thymidylate synthase [Yuvaniyama, Chitnumsub, Kamchonwongpaisan, Vanichtanankul, Sirawaraporn, Taylor, Walkinshaw and Yuthavong (2003) Nat. Struct. Biol. 10, 357-365]. Co-incubation of the monofunctional, heterotetrameric approximately 150 kDa AdoMetDC domain with the monofunctional, homodimeric ODC domain (approximately 180 kDa) produced an active hybrid complex of 330 kDa. The hinge region is required for bifunctional complex formation and only indirectly for enzyme activities. Deletion of the smallest, most structured and conserved insert in the ODC domain had the biggest impact on the activities of both decarboxylases, homodimeric ODC arrangement and hybrid complex formation. The remaining large inserts are predicted to be non-globular regions located on the surface of these proteins. The large insert in AdoMetDC in contrast is not implicated in hybrid complex formation even though distinct interactions between this insert and the two domains

  3. A fast, ultra-low and frequency-scalable power consumption, 10-bit SAR ADC for particle physics detectors

    NASA Astrophysics Data System (ADS)

    Firlej, M.; Fiutowski, T.; Idzik, M.; Kulis, S.; Moron, J.; Swientek, K.

    2015-11-01

    The design and measurements results of a fast 10-bit SAR ADC with ultra-low and scalable with frequency power consumption, developed for readout systems for detectors at future particle physics colliders (ILC, CLIC, LHC Upgrade), are described. A prototype ASIC was designed and fabricated in 130 nm CMOS technology and a wide spectrum of static (INLlesssim0.5 LSB, DNLlesssim0.5 LSB) and dynamic (SINAD ~58 dB, ENOB~9.3) measurements was performed to study and quantify the ADC performance. The ADC works in wide 10 kS/s - 40 MS/s sampling frequency range, covering more than three orders of magnitude. In most of the range the power consumption scales linearly with sampling rate with a factor of about 22 μW/MS/s. A dynamic and asynchronous internal logic makes the ADC very well suited not only for commonly used synchronous sampling but also for applications with asynchronous sampling and/or the ones requiring power cycling, like the experiments at future linear collider (ILC/CLIC). The ADC layout is drawn with a small pitch of 146 μm to facilitate multi-channel integration. The obtained figure of Merit is in range 32-37 fJ/conversion for sampling frequencies 10-40 MS/s, placing the ADC among the best State of the Art designs with similar technology and specifications.

  4. Carbon Dioxide Effects on Ethanol Production, Pyruvate Decarboxylase, and Alcohol Dehydrogenase Activities in Anaerobic Sweet Potato Roots 1

    PubMed Central

    Chang, Ling A.; Hammett, Larry K.; Pharr, David M.

    1983-01-01

    The effect of varied anaerobic atmospheres on the metabolism of sweet potato (Ipomoea batatas [L.] Lam.) roots was studied. The internal gas atmospheres of storage roots changed rapidly when the roots were submerged under water. O2 and N2 gases disappeared quickly and were replaced by CO2. There were no appreciable differences in gas composition among the four cultivars that were studied. Under different anaerobic conditions, ethanol concentration in the roots was highest in a CO2 environment, followed by submergence and a N2 environment in all the cultivars except one. A positive relationship was found between ethanol production and pyruvate decarboxylase activity from both 100% CO2-treated and 100% N2-treated roots. CO2 atmospheres also resulted in higher pyruvate decarboxylase activity than did N2 atmospheres. Concentrations of CO2 were higher within anaerobic roots than those in the ambient anaerobic atmosphere. The level of pyruvate decarboxylase and ethanol in anaerobic roots was proportional to the ambient CO2 concentration. The measurable activity of pyruvate decarboxylase that was present in the roots was about 100 times less than that of alcohol dehydrogenase. Considering these observations, it is suggested that the rate-limiting enzyme for ethanol biosynthesis in sweet potato storage roots under anoxia is likely to be pyruvate decarboxylase rather than alcohol dehydrogenase. PMID:16662798

  5. Kinetic, Mutational, and Structural Analysis of Malonate Semialdehyde Decarboxylase from Coryneform bacterium strain FG41: Mechanistic Implications for the Decarboxylase and Hydratase Activities

    PubMed Central

    Guo, Youzhong; Serrano, Hector; Poelarends, Gerrit J.; Johnson, William H.; Hackert, Marvin L.; Whitman, Christian P.

    2013-01-01

    Malonate semialdehyde decarboxylase from Pseudomonas pavonaceae 170 (designated Pp MSAD) is in a bacterial catabolic pathway for the nematicide 1,3-dichloropropene. MSAD has two known activities: it catalyzes the metal-ion independent decarboxylation of malonate semialdehyde to produce acetaldehyde and carbon dioxide, as well as a low-level hydration of 2-oxo-3-pentynoate to yield acetopyruvate. The latter activity is not known to be biologically relevant. Previous studies identified Pro-1, Asp-37, and a pair of arginines (Arg-73 and Arg-75) as critical residues in these activities. MSAD from Coryneform bacterium strain FG41 (designated FG41 MSAD) shares 38% pairwise sequence identity with the Pseudomonas enzyme including Pro-1 and Asp-37. However, Gln-73 replaces Arg-73, and the second arginine is shifted to Arg-76 by the insertion of a glycine. In order to determine how these changes relate to the activities of FG41 MSAD, the gene was cloned and the enzyme expressed and characterized. The enzyme has a comparable decarboxylase activity, but a significantly reduced hydratase activity. Mutagenesis along with crystal structures of the native enzyme (2.0 Å resolution) and the enzyme modified by a 3-oxopropanoate moiety (resulting from the incubation of enzyme and 3-bromopropiolate) (2.2 Å resolution) provided a structural basis. The roles of Pro-1 and Asp-37 are likely the same as those proposed for MSAD. However, the side chains of Thr-72, Gln-73, and Tyr-123 replace those of Arg-73 and Arg-75 in the mechanism and play a role in binding and catalysis. The structures also show that Arg-76 is likely too distant to play a direct role in the mechanism. FG41 MSAD is the second functionally annotated homologue in the MSAD family of the tautomerase superfamily and could represent a new subfamily. PMID:23781927

  6. Biochemical Evaluation of the Decarboxylation and Decarboxylation-Deamination Activities of Plant Aromatic Amino Acid Decarboxylases*

    PubMed Central

    Torrens-Spence, Michael P.; Liu, Pingyang; Ding, Haizhen; Harich, Kim; Gillaspy, Glenda; Li, Jianyong

    2013-01-01

    Plant aromatic amino acid decarboxylase (AAAD) enzymes are capable of catalyzing either decarboxylation or decarboxylation-deamination on various combinations of aromatic amino acid substrates. These two different activities result in the production of arylalkylamines and the formation of aromatic acetaldehydes, respectively. Variations in product formation enable individual enzymes to play different physiological functions. Despite these catalytic variations, arylalkylamine and aldehyde synthesizing AAADs are indistinguishable without protein expression and characterization. In this study, extensive biochemical characterization of plant AAADs was performed to identify residues responsible for differentiating decarboxylation AAADs from aldehyde synthase AAADs. Results demonstrated that a tyrosine residue located on a catalytic loop proximal to the active site of plant AAADs is primarily responsible for dictating typical decarboxylase activity, whereas a phenylalanine at the same position is primarily liable for aldehyde synthase activity. Mutagenesis of the active site phenylalanine to tyrosine in Arabidopsis thaliana and Petroselinum crispum aromatic acetaldehyde synthases primarily converts the enzymes activity from decarboxylation-deamination to decarboxylation. The mutation of the active site tyrosine to phenylalanine in the Catharanthus roseus and Papaver somniferum aromatic amino acid decarboxylases changes the enzymes decarboxylation activity to a primarily decarboxylation-deamination activity. Generation of these mutant enzymes enables the production of unusual AAAD enzyme products including indole-3-acetaldehyde, 4-hydroxyphenylacetaldehyde, and phenylethylamine. Our data indicates that the tyrosine and phenylalanine in the catalytic loop region could serve as a signature residue to reliably distinguish plant arylalkylamine and aldehyde synthesizing AAADs. Additionally, the resulting data enables further insights into the mechanistic roles of active site

  7. Apraxia in anti-glutamic acid decarboxylase-associated stiff person syndrome: link to corticobasal degeneration?

    PubMed

    Bowen, Lauren N; Subramony, S H; Heilman, Kenneth M

    2015-01-01

    Corticobasal syndrome (CBS) is associated with asymmetrical rigidity as well as asymmetrical limb-kinetic and ideomotor apraxia. Stiff person syndrome (SPS) is characterized by muscle stiffness and gait difficulties. Whereas patients with CBS have several forms of pathology, many patients with SPS have glutamic acid decarboxylase antibodies (GAD-ab), but these 2 disorders have not been reported to coexist. We report 2 patients with GAD-ab-positive SPS who also had signs suggestive of CBS, including asymmetrical limb rigidity associated with both asymmetrical limb-kinetic and ideomotor apraxia. Future studies should evaluate patients with CBS for GAD-ab and people with SPS for signs of CBS. PMID:25100431

  8. Changes in activity of lysine decarboxylase in winter triticale in response to grain aphid feeding.

    PubMed

    Sempruch, C; Leszczyński, B; Wójcicka, Agnieszka; Makosz, M; Matok, H; Chrzanowski, G

    2010-12-01

    Changes in lysine decarboxylase (LDC) activity caused by Sitobion avenae (F.) feeding on two winter triticale cultivars (cvs) were studied. The aphid fecundity and values of intrinsic rate of natural increase showed that cv Witon was less susceptible to S. avenae than cv Tornado. The grain aphid feeding on more susceptible triticale caused a decrease in the LDC activity, with exceptions of root tissues after two weeks of the feeding. In case of less susceptible cv Witon reduction of the LDC activity was observed only during initial period of S. avenae feeding. Later the aphid infestation induced activity of the LDC within tissues of cv Witon. PMID:21112841

  9. Cloning of aldB, which encodes alpha-acetolactate decarboxylase, an exoenzyme from Bacillus brevis.

    PubMed Central

    Diderichsen, B; Wedsted, U; Hedegaard, L; Jensen, B R; Sjøholm, C

    1990-01-01

    A gene for alpha-acetolactate decarboxylase (ALDC) was cloned from Bacillus brevis in Escherichia coli and in Bacillus subtilis. The 1.3-kilobase-pair nucleotide sequence of the gene, aldB, encoding ALDC and its flanking regions was determined. An open reading frame of 285 amino acids included a typical N-terminal signal peptide of 24 or 27 amino acids. A B. subtilis strain harboring the aldB gene on a recombinant plasmid processed and secreted ALDC. In contrast, a similar enzyme from Enterobacter aerogenes is intracellular. Images PMID:2198252

  10. Automatic Analysis of Cellularity in Glioblastoma and Correlation with ADC Using Trajectory Analysis and Automatic Nuclei Counting

    PubMed Central

    Burth, Sina; Kieslich, Pascal J.; Jungk, Christine; Sahm, Felix; Kickingereder, Philipp; Kiening, Karl; Unterberg, Andreas; Wick, Wolfgang; Schlemmer, Heinz-Peter; Bendszus, Martin; Radbruch, Alexander

    2016-01-01

    Objective Several studies have analyzed a correlation between the apparent diffusion coefficient (ADC) derived from diffusion-weighted MRI and the tumor cellularity of corresponding histopathological specimens in brain tumors with inconclusive findings. Here, we compared a large dataset of ADC and cellularity values of stereotactic biopsies of glioblastoma patients using a new postprocessing approach including trajectory analysis and automatic nuclei counting. Materials and Methods Thirty-seven patients with newly diagnosed glioblastomas were enrolled in this study. ADC maps were acquired preoperatively at 3T and coregistered to the intraoperative MRI that contained the coordinates of the biopsy trajectory. 561 biopsy specimens were obtained; corresponding cellularity was calculated by semi-automatic nuclei counting and correlated to the respective preoperative ADC values along the stereotactic biopsy trajectory which included areas of T1-contrast-enhancement and necrosis. Results There was a weak to moderate inverse correlation between ADC and cellularity in glioblastomas that varied depending on the approach towards statistical analysis: for mean values per patient, Spearman’s ρ = -0.48 (p = 0.002), for all trajectory values in one joint analysis Spearman’s ρ = -0.32 (p < 0.001). The inverse correlation was additionally verified by a linear mixed model. Conclusions Our data confirms a previously reported inverse correlation between ADC and tumor cellularity. However, the correlation in the current article is weaker than the pooled correlation of comparable previous studies. Hence, besides cell density, other factors, such as necrosis and edema might influence ADC values in glioblastomas. PMID:27467557

  11. ADC histograms predict response to anti-angiogenic therapy in patients with recurrent high-grade glioma

    PubMed Central

    2011-01-01

    Introduction The purpose of this study is to evaluate apparent diffusion coefficient (ADC) maps to distinguish anti-vascular and anti-tumor effects in the course of anti-angiogenic treatment of recurrent high-grade gliomas (rHGG) as compared to standard magnetic resonance imaging (MRI). Methods This retrospective study analyzed ADC maps from diffusion-weighted MRI in 14 rHGG patients during bevacizumab/irinotecan (B/I) therapy. Applying image segmentation, volumes of contrast-enhanced lesions in T1 sequences and of hyperintense T2 lesions (hT2) were calculated. hT2 were defined as regions of interest (ROI) and registered to corresponding ADC maps (hT2-ADC). Histograms were calculated from hT2-ADC ROIs. Thereafter, histogram asymmetry termed “skewness” was calculated and compared to progression-free survival (PFS) as defined by the Response Assessment Neuro-Oncology (RANO) Working Group criteria. Results At 8–12 weeks follow-up, seven (50%) patients showed a partial response, three (21.4%) patients were stable, and four (28.6%) patients progressed according to RANO criteria. hT2-ADC histograms demonstrated statistically significant changes in skewness in relation to PFS at 6 months. Patients with increasing skewness (n=11) following B/I therapy had significantly shorter PFS than did patients with decreasing or stable skewness values (n=3, median percentage change in skewness 54% versus −3%, p=0.04). Conclusion In rHGG patients, the change in ADC histogram skewness may be predictive for treatment response early in the course of anti-angiogenic therapy and more sensitive than treatment assessment based solely on RANO criteria. PMID:21125399

  12. Polyamine formation by arginine decarboxylase as a transducer of hormonal, environmental and stress stimuli in higher plants

    NASA Technical Reports Server (NTRS)

    Galston, A. W.; Flores, H. E.; Kaur-Sawhney, R.

    1982-01-01

    Recent evidence implicates polyamines including putrescine in the regulation of such diverse plant processes as cell division, embryogenesis and senescence. We find that the enzyme arginine decarboxylase, which controls the rate of putrescine formation in some plant systems, is activated by light acting through P(r) phytochrome as a receptor, by the plant hormone gibberellic acid, by osmotic shock and by other stress stimuli. We therefore propose arginine decarboxylase as a possible transducer of the various initially received tropistic stimuli in plants. The putrescine formed could act by affecting cytoskeletal components.

  13. Subcellular localization of tryptophan decarboxylase, strictosidine synthase and strictosidine glucosidase in suspension cultured cells of Catharanthus roseus and Tabernaemontana divaricata.

    PubMed

    Stevens, L H; Blom, T J; Verpoorte, R

    1993-08-01

    The subcellular localization of tryptophan decarboxylase, strictosidine synthase and strictosidine glucosidase in suspension cultured cells of Catharanthus roseus (L.) G. Don and Tabernaemontana divaricata (L.) R. Br. ex Roem. et Schult, was investigated. It was found that tryptophan decarboxylase is an extra-vacuolar enzyme, whereas strictosidine synthase is active inside the vacuole. Strong indications were obtained for the localization of strictosidine glucosidase on the outside of the tonoplast. The results suggest that tryptamine is transported into the vacuole where it is condensed with secologanin to form strictosidine, and that strictosidine passes the tonoplast and is subsequently hydrolysed outside the vacuole. PMID:24201788

  14. NI-20ADC HISTOGRAM ANALYSIS FOLLOWING RADIOTHERAPY PREDICTS RESPONSE TO ADJUVANT TEMOZOLOMIDE IN NEWLY DIAGNOSED GBM

    PubMed Central

    Ellingson, Benjamin; Chang, Warren; Harris, Robert; Mody, Reema; Lai, Albert; Nghiemphu, Phioanh; Cloughesy, Timothy; Pope, Whitney

    2014-01-01

    INTRODUCTION: The current standard of care for newly diagnosed GBM consists of concurrent radiotherapy and temozolomide (TMZ) plus adjuvant TMZ. We hypothesize there is a subset of patients that will have a significant benefit from this adjuvant therapy. Therefore, the purpose of the current study was to identify a diffusion imaging phenotype for patients with newly diagnosed GBM that will benefit from adjuvant TMZ following concurrent radiotherapy and TMZ. METHODS: A total of 120 patients with: 1) histologically confirmed glioblastoma, 2) treated with concurrent radiotherapy and TMZ followed by adjuvant TMZ; and 3) high quality diffusion MR data were included in the current study. Diffusion and standard structural MRI were performed approximately 10 weeks after the start of radiotherapy and concurrent TMZ. ADC histogram analysis was performed by fitting a double Gaussian mixed model to ADC data extracted from contrast enhancement tumor. ADCL was defined as the mean ADC of the lower Gaussian distribution. We hypothesize that patients with a high ADCL have a lower tumor burden and thus favorable response to adjuvant TMZ in terms of TTP and OS. RESULTS: Results demonstrate that patients with an ADCL lower than 1 um2/ms has a significantly shorter PFS compared with patients having a higher ADCL (Log-rank, P < 0.0001), showing almost twice the median PFS (297 days vs. 156 days). Additionally, patients with a high ADCL had a significantly longer OS (Log-rank, P = 0.0049). Patients with a high ADCL had a median OS of 648 days while patients with a low ADCL had a median OS of only 407 days from the start of adjuvant TMZ. CONCLUSION: Newly diagnosed GBM patients with elevated tumor diffusivity after completion of radiotherapy and concurrent TMZ have a favorable prognosis.

  15. Fast processing of optical fringe movement in displacement sensors without using an ADC

    NASA Astrophysics Data System (ADS)

    Hussain, Babar; Muhammad, Taj; Rehan, Muhammad; Aman, Haroon; Aslam, Muhammad; Ikram, Masroor; Raja, M. Yasin Akhtar

    2013-09-01

    An interferometer based optical sensor for displacement measurement is reported. This method requires quite simple signal processing as well as least electronic components. Referring to this technique, two photodiodes spatially shifted by 90 degrees were used. The output of photodiodes was converted into rectangular signals which were extracted in LabVIEW using the data acquisition card without using an analog to digital converters (ADC). We have also processed the signals in C++ after acquiring via parallel port. A Michelson interferometer configuration was used to produce linear fringes for the detection of displacements. The displacement less than 100 nm could be measured using this technique.

  16. Increasing the Accuracy of Volume and ADC Delineation for Heterogeneous Tumor on Diffusion-Weighted MRI: Correlation with PET/CT

    SciTech Connect

    Gong, Nan-Jie; Wong, Chun-Sing; Chu, Yiu-Ching; Guo, Hua; Huang, Bingsheng; Chan, Queenie

    2013-10-01

    Purpose: To improve the accuracy of volume and apparent diffusion coefficient (ADC) measurements in diffusion-weighted magnetic resonance imaging (MRI), we proposed a method based on thresholding both the b0 images and the ADC maps. Methods and Materials: In 21 heterogeneous lesions from patients with metastatic gastrointestinal stromal tumors (GIST), gross lesion were manually contoured, and corresponding volumes and ADCs were denoted as gross tumor volume (GTV) and gross ADC (ADC{sub g}), respectively. Using a k-means clustering algorithm, the probable high-cellularity tumor tissues were selected based on b0 images and ADC maps. ADC and volume of the tissues selected using the proposed method were denoted as thresholded ADC (ADC{sub thr}) and high-cellularity tumor volume (HCTV), respectively. The metabolic tumor volume (MTV) in positron emission tomography (PET)/computed tomography (CT) was measured using 40% maximum standard uptake value (SUV{sub max}) as the lower threshold, and corresponding mean SUV (SUV{sub mean}) was also measured. Results: HCTV had excellent concordance with MTV according to Pearson's correlation (r=0.984, P<.001) and linear regression (slope = 1.085, intercept = −4.731). In contrast, GTV overestimated the volume and differed significantly from MTV (P=.005). ADC{sub thr} correlated significantly and strongly with SUV{sub mean} (r=−0.807, P<.001) and SUV{sub max} (r=−0.843, P<.001); both were stronger than those of ADC{sub g}. Conclusions: The proposed lesion-adaptive semiautomatic method can help segment high-cellularity tissues that match hypermetabolic tissues in PET/CT and enables more accurate volume and ADC delineation on diffusion-weighted MR images of GIST.

  17. Evolutionary Trails of Plant Group II Pyridoxal Phosphate-Dependent Decarboxylase Genes.

    PubMed

    Kumar, Rahul

    2016-01-01

    Type II pyridoxal phosphate-dependent decarboxylase (PLP_deC) enzymes play important metabolic roles during nitrogen metabolism. Recent evolutionary profiling of these genes revealed a sharp expansion of histidine decarboxylase genes in the members of Solanaceae family. In spite of the high sequence homology shared by PLP_deC orthologs, these enzymes display remarkable differences in their substrate specificities. Currently, limited information is available on the gene repertoires and substrate specificities of PLP_deCs which renders their precise annotation challenging and offers technical challenges in the immediate identification and biochemical characterization of their full gene complements in plants. Herein, we explored their evolutionary trails in a comprehensive manner by taking advantage of high-throughput data accessibility and computational approaches. We discussed the premise that has enabled an improved reconstruction of their evolutionary lineage and evaluated the factors offering constraints in their rapid functional characterization, till date. We envisage that the synthesized information herein would act as a catalyst for the rapid exploration of their biochemical specificity and physiological roles in more plant species. PMID:27602045

  18. A glutamic acid decarboxylase (CgGAD) highly expressed in hemocytes of Pacific oyster Crassostrea gigas.

    PubMed

    Li, Meijia; Wang, Lingling; Qiu, Limei; Wang, Weilin; Xin, Lusheng; Xu, Jiachao; Wang, Hao; Song, Linsheng

    2016-10-01

    Glutamic acid decarboxylase (GAD), a rate-limiting enzyme to catalyze the reaction converting the excitatory neurotransmitter glutamate to inhibitory neurotransmitter γ-aminobutyric acid (GABA), not only functions in nervous system, but also plays important roles in immunomodulation in vertebrates. However, GAD has rarely been reported in invertebrates, and never in molluscs. In the present study, one GAD homologue (designed as CgGAD) was identified from Pacific oyster Crassostrea gigas. The full length cDNA of CgGAD was 1689 bp encoding a polypeptide of 562 amino acids containing a conserved pyridoxal-dependent decarboxylase domain. CgGAD mRNA and protein could be detected in ganglion and hemocytes of oysters, and their abundance in hemocytes was unexpectedly much higher than those in ganglion. More importantly, CgGAD was mostly located in those granulocytes without phagocytic capacity in oysters, and could dynamically respond to LPS stimulation. Further, after being transfected into HEK293 cells, CgGAD could promote the production of GABA. Collectively, these findings suggested that CgGAD, as a GABA synthase and molecular marker of GABAergic system, was mainly distributed in hemocytes and ganglion and involved in neuroendocrine-immune regulation network in oysters, which also provided a novel insight to the co-evolution between nervous system and immune system. PMID:27208883

  19. Dual role of alpha-acetolactate decarboxylase in Lactococcus lactis subsp. lactis.

    PubMed Central

    Goupil-Feuillerat, N; Cocaign-Bousquet, M; Godon, J J; Ehrlich, S D; Renault, P

    1997-01-01

    The alpha-acetolactate decarboxylase gene aldB is clustered with the genes for the branched-chain amino acids (BCAA) in Lactococcus lactis subsp. lactis. It can be transcribed with BCAA genes under isoleucine regulation or independently of BCAA synthesis under the control of its own promoter. The product of aldB is responsible for leucine sensibility under valine starvation. In the presence of more than 10 microM leucine, the alpha-acetolactate produced by the biosynthetic acetohydroxy acid synthase IlvBN is transformed to acetoin by AldB and, consequently, is not available for valine synthesis. AldB is also involved in acetoin formation in the 2,3-butanediol pathway, initiated by the catabolic acetolactate synthase, AlsS. The differences in the genetic organization, the expression, and the kinetics parameters of these enzymes between L. lactis and Klebsiella terrigena, Bacillus subtilis, or Leuconostoc oenos suggest that this pathway plays a different role in the metabolism in these bacteria. Thus, the alpha-acetolactate decarboxylase from L. lactis plays a dual role in the cell: (i) as key regulator of valine and leucine biosynthesis, by controlling the acetolactate flux by a shift to catabolism; and (ii) as an enzyme catalyzing the second step of the 2,3-butanediol pathway. PMID:9335274

  20. Glutamate decarboxylase from barley embryos and roots. General properties and the occurrence of three enzymic forms.

    PubMed Central

    Inatomi, K; Slaughter, J C

    1975-01-01

    Glutamate decarboxylase in extracts of barley has a Km value for L-glutamate of 22 mM and is activated by the addition of pyridoxal phosphate by up to 3.5 times. Sucrose-density-gradient experiments indicate the presence of two enzyme forms with molecular weights 256000 and 120000. The lower-molecular-weight form appears to be relatively inactive and spontaneously associates to the higher-molecular-weight form on storage. The enzyme is inhibited by thiol reagents and the distribution of activity on density gradients is altered in favour of the lower-molecular-weight form by the presence of 2-mercaptoethanol. After removal of the 2-mercaptoethanol spontaneous association to the higher-molecular-weight form occurs. The presence of oxygen in the extraction buffer and in the water during imbibition leads to a relative increase in the higher-molecular-weight form compared with situations where oxygen is excluded. In contrast, glutamate decarboxylase in extracts of 3-day-old barley roots has a Km value for L-glutamate of 3.1 mM and is activated up to 10% by addition of pyridoxal phosphate. The root enzyme occurs as a single species with molecular weight 310000 and this is unaffected by 2-mercaptoethanol although thiol reagents do act as weak inhibitors. The molecular weight is also unaffected by the presence or absence of oxygen in the extraction buffers. PMID:1167156

  1. Immunological Detection and Quantitation of Tryptophan Decarboxylase in Developing Catharanthus roseus Seedlings 1

    PubMed Central

    Fernandez, Jesus Alvarez; Owen, Terence G.; Kurz, Wolfgang G. W.; De Luca, Vincenzo

    1989-01-01

    l-Tryptophan decarboxylase (TDC) (EC 4.2.1.27) enzyme activity was induced in cell suspension cultures of Catharanthus roseus after treatment with a Pythium aphanidermatum elicitor preparation. The enzyme was extracted from lyophilized cells containing high levels of TDC and the protein was purified to homogeneity. The pure protein was used to produce highly specific polyclonal antibodies, and an enzyme-linked immunosorbent assay (ELISA) was developed to quantitate the level of TDC antigen during seedling development and in leaves of the mature plant. Western immunoblotting of proteins after SDS-PAGE with anti-TDC antibodies detected several immunoreactive proteins (40, 44, 54.8, 55, and 67 kilodaltons) which appeared at different stages during seedling development and in leaves of the mature plant. The major 54.8 and 55 kilodalton antigenic proteins in immunoblots appeared transiently between days 1 to 5 and 5 to 8 of seedling development, respectively. The 54.8 kilodalton protein was devoid of TDC enzyme activity, whereas the appearance of the 55 kilodalton protein coincided with the appearance of this decarboxylase activity. The minor immunoreactive proteins (40, 44, and 67 kilodaltons) appeared after day 5 of seedling development and in older leaves of the mature plant, and their relationship, if any, to TDC is presently unknown. Results suggest that the synthesis and degradation of TDC protein is highly regulated in Catharanthus roseus and that this regulation follows a preset developmental program. Images Figure 3 Figure 5 PMID:16667047

  2. Structural analysis of mevalonate-3-kinase provides insight into the mechanisms of isoprenoid pathway decarboxylases

    PubMed Central

    Vinokur, Jeffrey M; Korman, Tyler P; Sawaya, Michael R; Collazo, Michael; Cascio, Duillio; Bowie, James U

    2015-01-01

    In animals, cholesterol is made from 5-carbon building blocks produced by the mevalonate pathway. Drugs that inhibit the mevalonate pathway such as atorvastatin (lipitor) have led to successful treatments for high cholesterol in humans. Another potential target for the inhibition of cholesterol synthesis is mevalonate diphosphate decarboxylase (MDD), which catalyzes the phosphorylation of (R)-mevalonate diphosphate, followed by decarboxylation to yield isopentenyl pyrophosphate. We recently discovered an MDD homolog, mevalonate-3-kinase (M3K) from Thermoplasma acidophilum, which catalyzes the identical phosphorylation of (R)-mevalonate, but without concomitant decarboxylation. Thus, M3K catalyzes half the reaction of the decarboxylase, allowing us to separate features of the active site that are required for decarboxylation from features required for phosphorylation. Here we determine the crystal structure of M3K in the apo form, and with bound substrates, and compare it to MDD structures. Structural and mutagenic analysis reveals modifications that allow M3K to bind mevalonate rather than mevalonate diphosphate. Comparison to homologous MDD structures show that both enzymes employ analogous Arg or Lys residues to catalyze phosphate transfer. However, an invariant active site Asp/Lys pair of MDD previously thought to play a role in phosphorylation is missing in M3K with no functional replacement. Thus, we suggest that the invariant Asp/Lys pair in MDD may be critical for decarboxylation rather than phosphorylation. PMID:25422158

  3. Pyridoxal phosphate-sensitized photoinactivation of glutamate decarboxylase from Clostridium perfringens

    PubMed Central

    Cozzani, Ivo; Santoni, Costantino; Jori, Giulio; Gennari, Giorgio; Tamburro, Antonio Mario

    1974-01-01

    1. l-Glutamate decarboxylase (EC 4.1.1.15) from Clostridium perfringens was inactivated by exposure to visible light at pH6.2. 2. Inactivation does not occur at pH4.6 or in the absence of bound pyridoxal phosphate. 3. On prolonged photo-oxidation six histidine residues per molecule of enzyme were destroyed. 4. The loss of six cysteine residues per molecule occurred both in irradiated samples and in controls oxygenated in the dark. 5. This dark-oxidation of cysteine residues is apparently required before the photo-oxidation process. 6. The absorbance, fluorescence and circular-dichroism properties of the enzyme as well as its elution volume during Sephadex gel-filtration were unaffected by prolonged irradiation. 7. However, an apparently homogeneous product of photo-oxidation could be separated from the control enzyme by ion-exchange chromatography. 8. The Km for l-glutamate was unchanged in an irradiated sample retaining 22% of control activity. 9. These data and the catalytic role of imidazole residues at the active sites of amino acid decarboxylases are discussed. PMID:4375980

  4. Evolutionary Trails of Plant Group II Pyridoxal Phosphate-Dependent Decarboxylase Genes

    PubMed Central

    Kumar, Rahul

    2016-01-01

    Type II pyridoxal phosphate-dependent decarboxylase (PLP_deC) enzymes play important metabolic roles during nitrogen metabolism. Recent evolutionary profiling of these genes revealed a sharp expansion of histidine decarboxylase genes in the members of Solanaceae family. In spite of the high sequence homology shared by PLP_deC orthologs, these enzymes display remarkable differences in their substrate specificities. Currently, limited information is available on the gene repertoires and substrate specificities of PLP_deCs which renders their precise annotation challenging and offers technical challenges in the immediate identification and biochemical characterization of their full gene complements in plants. Herein, we explored their evolutionary trails in a comprehensive manner by taking advantage of high-throughput data accessibility and computational approaches. We discussed the premise that has enabled an improved reconstruction of their evolutionary lineage and evaluated the factors offering constraints in their rapid functional characterization, till date. We envisage that the synthesized information herein would act as a catalyst for the rapid exploration of their biochemical specificity and physiological roles in more plant species. PMID:27602045

  5. Crystal Structure and Substrate Specificity of Drosophila 3,4-Dihydroxyphenylalanine Decarboxylase

    SciTech Connect

    Han, Q.; Ding, H; Robinson, H; Christensen, B; Li, J

    2010-01-01

    3,4-Dihydroxyphenylalanine decarboxylase (DDC), also known as aromatic L-amino acid decarboxylase, catalyzes the decarboxylation of a number of aromatic L-amino acids. Physiologically, DDC is responsible for the production of dopamine and serotonin through the decarboxylation of 3,4-dihydroxyphenylalanine and 5-hydroxytryptophan, respectively. In insects, both dopamine and serotonin serve as classical neurotransmitters, neuromodulators, or neurohormones, and dopamine is also involved in insect cuticle formation, eggshell hardening, and immune responses. In this study, we expressed a typical DDC enzyme from Drosophila melanogaster, critically analyzed its substrate specificity and biochemical properties, determined its crystal structure at 1.75 Angstrom resolution, and evaluated the roles residues T82 and H192 play in substrate binding and enzyme catalysis through site-directed mutagenesis of the enzyme. Our results establish that this DDC functions exclusively on the production of dopamine and serotonin, with no activity to tyrosine or tryptophan and catalyzes the formation of serotonin more efficiently than dopamine. The crystal structure of Drosophila DDC and the site-directed mutagenesis study of the enzyme demonstrate that T82 is involved in substrate binding and that H192 is used not only for substrate interaction, but for cofactor binding of drDDC as well. Through comparative analysis, the results also provide insight into the structure-function relationship of other insect DDC-like proteins.

  6. Crystal Structure and Substrate Specificity of Drosophila 3,4-Dihydroxyphenylalanine Decarboxylase

    PubMed Central

    Han, Qian; Ding, Haizhen; Robinson, Howard; Christensen, Bruce M.; Li, Jianyong

    2010-01-01

    Background 3,4-Dihydroxyphenylalanine decarboxylase (DDC), also known as aromatic L-amino acid decarboxylase, catalyzes the decarboxylation of a number of aromatic L-amino acids. Physiologically, DDC is responsible for the production of dopamine and serotonin through the decarboxylation of 3,4-dihydroxyphenylalanine and 5-hydroxytryptophan, respectively. In insects, both dopamine and serotonin serve as classical neurotransmitters, neuromodulators, or neurohormones, and dopamine is also involved in insect cuticle formation, eggshell hardening, and immune responses. Principal Findings In this study, we expressed a typical DDC enzyme from Drosophila melanogaster, critically analyzed its substrate specificity and biochemical properties, determined its crystal structure at 1.75 Angstrom resolution, and evaluated the roles residues T82 and H192 play in substrate binding and enzyme catalysis through site-directed mutagenesis of the enzyme. Our results establish that this DDC functions exclusively on the production of dopamine and serotonin, with no activity to tyrosine or tryptophan and catalyzes the formation of serotonin more efficiently than dopamine. Conclusions The crystal structure of Drosophila DDC and the site-directed mutagenesis study of the enzyme demonstrate that T82 is involved in substrate binding and that H192 is used not only for substrate interaction, but for cofactor binding of drDDC as well. Through comparative analysis, the results also provide insight into the structure-function relationship of other insect DDC-like proteins. PMID:20098687

  7. Characterization of Plasmodium phosphatidylserine decarboxylase expressed in yeast and application for inhibitor screening

    PubMed Central

    Choi, Jae-Yeon; Lawres, Lauren; Toh, Justin Y.; Voelker, Dennis R.; Ben Mamoun, Choukri

    2016-01-01

    Summary Phospholipid biosynthesis is critical for the development, differentiation and pathogenesis of several eukaryotic pathogens. Genetic studies have validated the pathway for phosphatidylethanolamine synthesis from phosphatidylserine catalyzed by phosphatidylserine decarboxylase enzymes (PSD) as a suitable target for development of antimicrobials; however no inhibitors of this class of enzymes have been discovered. We show that the Plasmodium falciparum PSD can restore the essential function of the yeast gene in strains requiring PSD for growth. Genetic, biochemical and metabolic analyses demonstrate that amino acids between positions 40 and 70 of the parasite enzyme are critical for proenzyme processing and decarboxylase activity. We used the essential role of Plasmodium PSD in yeast as a tool for screening a library of anti-malarials. One of these compounds is 7-chloro-N-(4-ethoxyphenyl)-4-quinolinamine, an inhibitor with potent activity against P. falciparum, and low toxicity toward mammalian cells. We synthesized an analog of this compound and showed that it inhibits PfPSD activity and eliminates Plasmodium yoelii infection in mice. These results highlight the importance of 4-quinolinamines as a novel class of drugs targeting membrane biogenesis via inhibition of PSD activity PMID:26585333

  8. Purification and characterization of a ferulic acid decarboxylase from Pseudomonas fluorescens.

    PubMed Central

    Huang, Z; Dostal, L; Rosazza, J P

    1994-01-01

    A ferulic acid decarboxylase enzyme which catalyzes the decarboxylation of ferulic acid to 4-hydroxy-3-methoxystyrene was purified from Pseudomonas fluorescens UI 670. The enzyme requires no cofactors and contains no prosthetic groups. Gel filtration estimated an apparent molecular mass of 40.4 (+/- 6%) kDa, whereas sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a molecular mass of 20.4 kDa, indicating that ferulic acid decarboxylase is a homodimer in solution. The purified enzyme displayed an optimum temperature range of 27 to 30 degrees C, exhibited an optimum pH of 7.3 in potassium phosphate buffer, and had a Km of 7.9 mM for ferulic acid. This enzyme also decarboxylated 4-hydroxycinnamic acid but not 2- or 3-hydroxycinnamic acid, indicating that a hydroxy group para to the carboxylic acid-containing side chain is required for the enzymatic reaction. The enzyme was inactivated by Hg2+, Cu2+, p-chloromercuribenzoic acid, and N-ethylmaleimide, suggesting that sulfhydryl groups are necessary for enzyme activity. Diethyl pyrocarbonate, a histidine-specific inhibitor, did not affect enzyme activity. Images PMID:7928951

  9. Stereochemistry of 4-carboxymuconolactone decarboxylase and muconolactone isomerase in the. beta. -ketoadipate pathway

    SciTech Connect

    Whitman, C.P.; Chari, R.V.J.; Ngai, K.L.; Kozarich, J.W.

    1986-05-01

    The protocatechuate and catechol pathways, two separate and parallel branches of the ..beta..-ketoadipate pathway in Pseudomonas putida, converge at a common intermediate - ..beta..-ketoadipate enol-lactone. The enol-lactone is generated by 4-carboxymuconolactone decarboxylase in the protocatechuate pathway while muconolactone isomerase produces it in the catechol pathway. The presence of these enzymes as well as ..beta..-carboxymuconate cycloisomerase and its substrate, ..beta..-carboxy-cis,cis-muconate, in a NMR tube, leads to the following sequence of events. Lactonization of ..beta..-carboxy-cis,cis-muconate produces 4-carboxymuconolactone which decarboxylates enzymatically with deuteration by D/sub 2/O to afford 2-(/sup 2/H)-4-ketoadipate enol-lactone - the substrate for muconolactone isomerase. Further conversion of the monodeuterated enol-lactone by muconolactone isomerase affords muconolactone which is nearly completely deuterated at the 4 position. The proton ricochets between the 2 and 4 positions with concurrent washout while in the 2 position. Based on the known absolute stereochemistry of 4-carboxymuconolactone and muconolactone, these results suggest that both the decarboxylase and isomerase proceed by syn mechanisms, but operate on opposite faces of the common enol-lactone substrate.

  10. Influence of ornithine decarboxylase antizymes and antizyme inhibitors on agmatine uptake by mammalian cells.

    PubMed

    Ramos-Molina, Bruno; López-Contreras, Andrés J; Lambertos, Ana; Dardonville, Christophe; Cremades, Asunción; Peñafiel, Rafael

    2015-05-01

    Agmatine (4-aminobutylguanidine), a dicationic molecule at physiological pH, exerts relevant modulatory actions at many different molecular target sites in mammalian cells, having been suggested that the administration of this compound may have therapeutic interest. Several plasma membrane transporters have been implicated in agmatine uptake by mammalian cells. Here we report that in kidney-derived COS-7 cell line, at physiological agmatine levels, the general polyamine transporter participates in the plasma membrane translocation of agmatine, with an apparent Km of 44 ± 7 µM and Vmax of 17.3 ± 3.3 nmol h(-1) mg(-1) protein, but that at elevated concentrations, agmatine can be also taken up by other transport systems. In the first case, the physiological polyamines (putrescine, spermidine and spermine), several diguanidines and bis(2-aminoimidazolines) and the polyamine transport inhibitor AMXT-1501 markedly decreased agmatine uptake. In cells transfected with any of the three ornithine decarboxylase antizymes (AZ1, AZ2 and AZ3), agmatine uptake was dramatically reduced. On the contrary, transfection with antizyme inhibitors (AZIN1 and AZIN2) markedly increased the transport of agmatine. Furthermore, whereas putrescine uptake was significantly decreased in cells transfected with ornithine decarboxylase (ODC), the accumulation of agmatine was stimulated, suggesting a trans-activating effect of intracellular putrescine on agmatine uptake. All these results indicate that ODC and its regulatory proteins (antizymes and antizyme inhibitors) may influence agmatine homeostasis in mammalian tissues. PMID:25655388

  11. A coenzyme-independent decarboxylase/oxygenase cascade for the efficient synthesis of vanillin.

    PubMed

    Furuya, Toshiki; Miura, Misa; Kino, Kuniki

    2014-10-13

    Vanillin is one of the most widely used flavor compounds in the world as well as a promising versatile building block. The biotechnological production of vanillin from plant-derived ferulic acid has attracted much attention as a new alternative to chemical synthesis. One limitation of the known metabolic pathway to vanillin is its requirement for expensive coenzymes. Here, we developed a novel route to vanillin from ferulic acid that does not require any coenzymes. This artificial pathway consists of a coenzyme-independent decarboxylase and a coenzyme-independent oxygenase. When Escherichia coli cells harboring the decarboxylase/oxygenase cascade were incubated with ferulic acid, the cells efficiently synthesized vanillin (8.0 mM, 1.2 g L(-1) ) via 4-vinylguaiacol in one pot, without the generation of any detectable aromatic by-products. The efficient method described here might be applicable to the synthesis of other high-value chemicals from plant-derived aromatics. PMID:25164030

  12. Production of pyruvate from mannitol by mannitol-assimilating pyruvate decarboxylase-negative Saccharomyces cerevisiae.

    PubMed

    Yoshida, Shiori; Tanaka, Hideki; Hirayama, Makoto; Murata, Kousaku; Kawai, Shigeyuki

    2015-01-01

    Mannitol is contained in brown macroalgae up to 33% (w/w, dry weight), and thus is a promising carbon source for white biotechnology. However, Saccharomyces cerevisiae, a key cell factory, is generally regarded to be unable to assimilate mannitol for growth. We have recently succeeded in producing S. cerevisiae that can assimilate mannitol through spontaneous mutations of Tup1-Cyc8, each of which constitutes a general corepressor complex. In this study, we demonstrate production of pyruvate from mannitol using this mannitol-assimilating S. cerevisiae through deletions of all 3 pyruvate decarboxylase genes. The resultant mannitol-assimilating pyruvate decarboxylase-negative strain produced 0.86 g/L pyruvate without use of acetate after cultivation for 4 days, with an overall yield of 0.77 g of pyruvate per g of mannitol (the theoretical yield was 79%). Although acetate was not needed for growth of this strain in mannitol-containing medium, addition of acetate had a significant beneficial effect on production of pyruvate. This is the first report of production of a valuable compound (other than ethanol) from mannitol using S. cerevisiae, and is an initial platform from which the productivity of pyruvate from mannitol can be improved. PMID:26588105

  13. A low-power and small-area column-level ADC for high frame-rate CMOS pixel sensor

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Morel, F.; Hu-Guo, C.; Hu, Y.

    2014-07-01

    CMOS pixel sensors (CPS) have demonstrated performances meeting the specifications of the International Linear Collider (ILC) vertex detector (VTX). This paper presents a low-power and small-area 4-bit column-level analog-to-digital converter (ADC) for CMOS pixel sensors. The ADC employs a self-timed trigger and completes the conversion by performing a multi-bit/step approximation. As in the outer layers of the ILC vertex detector hit density is of the order of a few per thousand, in order to reduce power consumption, the ADC is designed to work in two modes: active mode and idle mode. The ADC is fabricated in a 0.35 μm CMOS process with a pixel pitch of 35 μm. It is implemented with 48 columns in a sensor prototype. Each column ADC covers an area of 35 ×545 μm2. The measured temporal noise and Fixed Pattern Noise (FPN) are 0.96 mV and 0.40 mV, respectively. The power consumption, for a 3 V supply and 6.25 MS/s sampling rate, is 486 μW during idle time, which is by far the most frequently employed one. This value rises to 714 μW in the case of the active mode. The measured differential nonlinearity (DNL) and integral nonlinearity (INL) are 0.49/-0.28 LSB and 0.29/-0.20 LSB, respectively.

  14. A SAR-ADC using unit bridge capacitor and with calibration for the front-end electronics of PET imaging

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Wei, Tingcun; Li, Bo; Yang, Lifeng; Xue, Feifei; Hu, Yongcai

    2016-05-01

    This paper presents a 12-bit 1 MS/s successive approximation register-analog to digital converter (SAR-ADC) for the 32-channel front-end electronics of CZT-based PET imaging system. To reduce the capacitance mismatch, instead of the fractional capacitor, the unit capacitor is used as the bridge capacitor in the split-capacitor digital to analog converter (DAC) circuit. In addition, in order to eliminate the periodical DNL errors of -1 LSB which often exists in the SAR-ADC using the charge-redistributed DAC, a calibration algorithm is proposed and verified by the experiments. The proposed 12-bit 1 MS/s SAR-ADC is designed and implemented using a 0.35 μm CMOS technology, it occupies only an active area of 986×956 μm2. The measurement results show that, at the power supply of 3.3/5.0 V and the sampling rate of 1 MS/s, the ADC with calibration has a signal-to-noise-and-distortion ratio (SINAD) of 67.98 dB, the power dissipation of 5 mW, and a figure of merit (FOM) of 2.44 pJ/conv.-step. This ADC is with the features of high accuracy, low power and small layout area, it is especially suitable to the one-chip integration of the front-end readout electronics.

  15. A 10-bit 250 MSPS charge-domain pipelined ADC with replica controlled PVT insensitive BCT circuit

    NASA Astrophysics Data System (ADS)

    Songren, Huang; Hong, Zhang; Zhenhai, Chen; Shuang, Zhu; Zongguang, Yu; Hongwen, Qian; Yue, Hao

    2015-05-01

    A low power 10-bit 250 MSPS charge-domain (CD) pipelined analog-to-digital converter (ADC) is introduced. The ADC is implemented in MOS bucket-brigade devices (BBDs) based CD pipelined architecture. A replica controlled boosted charge transfer (BCT) circuit is introduced to reject the influence of PVT variations on the charge transfer process. Based on replica controlled BCT, the CD pipelined ADC is designed and realized in a 1P6M 0.18 μm CMOS process. The ADC achieves an SFDR of 64.4 dB, an SNDR of 56.9 dB and an ENOB of 9.2 for a 9.9 MHz input; and an SFDR of 63.1 dB, an SNR of 55.2 dB, an SNDR of 54.5 dB and an ENOB of 8.7 for a 220.5 MHz input at full sampling rate. The DNL is +0.5/ -0.55 LSB and INL is +0.8/ -0.85 LSB. The power consumption of the prototype ADC is only 45 mW at 1.8 V supply and it occupies an active die area of 1.56 mm2. Project supported by the National Natural Science Foundation of China (No. 61106027).

  16. Relativistic decay widths of autoionization processes: The relativistic FanoADC-Stieltjes method

    SciTech Connect

    Fasshauer, Elke; Kolorenč, Přemysl; Pernpointner, Markus

    2015-04-14

    Electronic decay processes of ionized systems are, for example, the Auger decay or the Interatomic/ Intermolecular Coulombic Decay. In both processes, an energetically low lying vacancy is filled by an electron of an energetically higher lying orbital and a secondary electron is instantaneously emitted to the continuum. Whether or not such a process occurs depends both on the energetic accessibility and the corresponding lifetime compared to the lifetime of competing decay mechanisms. We present a realization of the non-relativistically established FanoADC-Stieltjes method for the description of autoionization decay widths including relativistic effects. This procedure, being based on the Algebraic Diagrammatic Construction (ADC), was adapted to the relativistic framework and implemented into the relativistic quantum chemistry program package Dirac. It is, in contrast to other existing relativistic atomic codes, not limited to the description of autoionization lifetimes in spherically symmetric systems, but is instead also applicable to molecules and clusters. We employ this method to the Auger processes following the Kr3d{sup −1}, Xe4d{sup −1}, and Rn5d{sup −1} ionization. Based on the results, we show a pronounced influence of mainly scalar-relativistic effects on the decay widths of autoionization processes.

  17. Continuous-time ΣΔ ADC with implicit variable gain amplifier for CMOS image sensor.

    PubMed

    Tang, Fang; Bermak, Amine; Abbes, Amira; Benammar, Mohieddine Amor

    2014-01-01

    This paper presents a column-parallel continuous-time sigma delta (CTSD) ADC for mega-pixel resolution CMOS image sensor (CIS). The sigma delta modulator is implemented with a 2nd order resistor/capacitor-based loop filter. The first integrator uses a conventional operational transconductance amplifier (OTA), for the concern of a high power noise rejection. The second integrator is realized with a single-ended inverter-based amplifier, instead of a standard OTA. As a result, the power consumption is reduced, without sacrificing the noise performance. Moreover, the variable gain amplifier in the traditional column-parallel read-out circuit is merged into the front-end of the CTSD modulator. By programming the input resistance, the amplitude range of the input current can be tuned with 8 scales, which is equivalent to a traditional 2-bit preamplification function without consuming extra power and chip area. The test chip prototype is fabricated using 0.18 μm CMOS process and the measurement result shows an ADC power consumption lower than 63.5 μW under 1.4 V power supply and 50 MHz clock frequency. PMID:24772012

  18. Attitude Determination and Control Subsystem (ADCS) Preparations for the EPOXI Flyby of Comet Haley 2

    NASA Technical Reports Server (NTRS)

    Luna, Michael E.; Collins, Stephen M.

    2011-01-01

    On November 4, 2010 the already "in-flight" Deep Impact spacecraft flew within 700km of comet 103P/Hartley 2 as part of its extended mission EPOXI, the 5th time to date any spacecraft visited a comet. In 2005, the spacecraft had previously imaged a probe impact comet Tempel 1. The EPOXI flyby marked the first time in history that two comets were explored with the same instruments on a re-used spacecraft-with hardware and software originally designed and optimized for a different mission. This made the function of the attitude determination and control subsystem (ADCS) critical to the successful execution of the EPOXI flyby. As part of the spacecraft team preparations, the ADCS team had to perform thorough sequence reviews, key spacecraft activities and onboard calibrations. These activities included: review of background sequences for the initial conditions vector, sun sensor coefficients, and reaction wheel assembly (RWA) de-saturations; design and execution of 10 trajectory correction maneuvers; science calibration of the two telescope instruments; a flight demonstration of the fastest turns conducted by the spacecraft between Earth and comet point; and assessment of RWA health (given RWA problems on other spacecraft).

  19. Fast Imaging Detector Readout Circuits with In-Pixel ADCs for Fourier Transform Imaging Spectrometers

    NASA Technical Reports Server (NTRS)

    Rider, D.; Blavier, J-F.; Cunningham, T.; Hancock, B.; Key, R.; Pannell, Z.; Sander, S.; Seshadri, S.; Sun, C.; Wrigley, C.

    2011-01-01

    Focal plane arrays (FPAs) with high frame rates and many pixels benefit several upcoming Earth science missions including GEO-CAPE, GACM, and ACE by enabling broader spatial coverage and higher spectral resolution. FPAs for the PanFTS, a high spatial resolution Fourier transform spectrometer and a candidate instrument for the GEO-CAPE mission are the focus of the developments reported here, but this FPA technology has the potential to enable a variety of future measurements and instruments. The ESTO ACT Program funded the developed of a fast readout integrated circuit (ROIC) based on an innovative in-pixel analog-to-digital converter (ADC). The 128 X 128 pixel ROIC features 60 ?m pixels, a 14-bit ADC in each pixel and operates at a continuous frame rate of 14 kHz consuming only 1.1 W of power. The ROIC outputs digitized data completely eliminating the bulky, power consuming signal chains needed by conventional FPAs. The 128 X 128 pixel ROIC has been fabricated in CMOS and tested at the Jet Propulsion Laboratory. The current version is designed to be hybridized with PIN photodiode arrays via indium bump bonding for light detection in the visible and ultraviolet spectral regions. However, the ROIC design incorporates a small photodiode in each cell to permit detailed characterization of the ROICperformance without the need for hybridization. We will describe the essential features of the ROIC design and present results of ROIC performance measurements.

  20. A low power 12-bit 1 Msps successive approximation register ADC with an improved switching procedure

    NASA Astrophysics Data System (ADS)

    Fubin, Xin; Tao, Yin; Qisong, Wu; Yuanlong, Yang; Fei, Liu; Haigang, Yang

    2015-08-01

    As a key building block of data acquisition systems, power dissipation of the successive approximation register (SAR) ADC determines the total power consumption of the system. In this paper, a low power 12-bit 1 Msps SAR ADC with an improved switching procedure is presented. Power consumption and area occupation could be significantly reduced by using the proposed switching procedure. Compared to converters that use the conventional switching procedure, the average switching energy could be reduced by about 80% and the total capacitance could be reduced by 50%. A simplified digital control logic is utilized to reduce power dissipation and area occupation of the digital control circuits. Simulation results show that the power dissipated by the proposed digital control circuits could be reduced by about 50% compared to the power dissipated by conventional control circuits. The chip has been processed in a standard 0.35 μm CMOS technology and has a core die area of 1.12 mm2. A signal-to-noise-and-distortion-ratio of 64.2 dB has been measured with a 100 kHz signal input under a wide range variation of temperature from -55 to 150 °C. The total power consumption of the prototype is only 0.72 mW with a 3.3 V supply voltage. Project supported by the National Basic Research Program of China (No. 2014CB744600) and the National Natural Science Foundation of China (No. 61474120).

  1. Realizing Low-Energy Classification Systems by Implementing Matrix Multiplication Directly Within an ADC.

    PubMed

    Wang, Zhuo; Zhang, Jintao; Verma, Naveen

    2015-12-01

    In wearable and implantable medical-sensor applications, low-energy classification systems are of importance for deriving high-quality inferences locally within the device. Given that sensor instrumentation is typically followed by A-D conversion, this paper presents a system implementation wherein the majority of the computations required for classification are implemented within the ADC. To achieve this, first an algorithmic formulation is presented that combines linear feature extraction and classification into a single matrix transformation. Second, a matrix-multiplying ADC (MMADC) is presented that enables multiplication between an analog input sample and a digital multiplier, with negligible additional energy beyond that required for A-D conversion. Two systems mapped to the MMADC are demonstrated: (1) an ECG-based cardiac arrhythmia detector; and (2) an image-pixel-based facial gender detector. The RMS error over all multiplication performed, normalized to the RMS of ideal multiplication results is 0.018. Further, compared to idealized versions of conventional systems, the energy savings obtained are estimated to be 13× and 29×, respectively, while achieving similar level of performance. PMID:26849205

  2. CMOS Amperometric ADC With High Sensitivity, Dynamic Range and Power Efficiency for Air Quality Monitoring.

    PubMed

    Li, Haitao; Boling, C Sam; Mason, Andrew J

    2016-08-01

    Airborne pollutants are a leading cause of illness and mortality globally. Electrochemical gas sensors show great promise for personal air quality monitoring to address this worldwide health crisis. However, implementing miniaturized arrays of such sensors demands high performance instrumentation circuits that simultaneously meet challenging power, area, sensitivity, noise and dynamic range goals. This paper presents a new multi-channel CMOS amperometric ADC featuring pixel-level architecture for gas sensor arrays. The circuit combines digital modulation of input currents and an incremental Σ∆ ADC to achieve wide dynamic range and high sensitivity with very high power efficiency and compact size. Fabricated in 0.5 [Formula: see text] CMOS, the circuit was measured to have 164 dB cross-scale dynamic range, 100 fA sensitivity while consuming only 241 [Formula: see text] and 0.157 [Formula: see text] active area per channel. Electrochemical experiments with liquid and gas targets demonstrate the circuit's real-time response to a wide range of analyte concentrations. PMID:27352395

  3. A power scalable PLL frequency synthesizer for high-speed Δ—Σ ADC

    NASA Astrophysics Data System (ADS)

    Siyang, Han; Baoyong, Chi; Xinwang, Zhang; Zhihua, Wang

    2014-08-01

    A 35-130 MHz/300-360 MHz phase-locked loop frequency synthesizer for Δ—Σ analog-to-digital converter (ADC) in 65 nm CMOS is presented. The frequency synthesizer can work in low phase-noise mode (300-360 MHz) or in low-power mode (35-130 MHz) to satisfy the ADC's requirements. To switch between these two modes, a high frequency GHz LC VCO followed by a divided-by-four frequency divider and a low frequency ring VCO followed by a divided-by-two frequency divider are integrated on-chip. The measured results show that the frequency synthesizer achieves a phase-noise of -132 dBc/Hz at 1 MHz offset and an integrated RMS jitter of 1.12 ps with 1.74 mW power consumption from a 1.2 V power supply in low phase-noise mode. In low-power mode, the frequency synthesizer achieves a phase-noise of -112 dBc/Hz at 1 MHz offset and an integrated RMS jitter of 7.23 ps with 0.92 mW power consumption from a 1.2 V power supply.

  4. A 12-bit SAR ADC integrated on a multichannel silicon drift detector readout IC

    NASA Astrophysics Data System (ADS)

    Schembari, F.; Bellotti, G.; Fiorini, C.

    2016-07-01

    A 12-bit analog-to-digital converter (ADC) addressed to Silicon-Drift Detectors (SDDs) multichannel readout ASICs for X- and gamma-ray applications is presented. Aiming at digitizing output multiplexed data from the upstream analog filters banks, the converter must ensure 11-bit accuracy and a sampling frequency of about 5 MS/s. The ADC architecture is the charge-redistribution (CR) successive-approximation register (SAR). A fully differential topology has also been chosen for better rejection of common-mode noise and disturbances. The internal DAC is made of binary-scaled capacitors, whose bottom plates are switched by the SAR logic to perform the binary search of the analog input value by means of the monotonic switching scheme. The A/D converter is integrated on SFERA, a multichannel ASIC fabricated in a standard CMOS 0.35 μm 3.3 V technology and it occupies an area of 0.42 mm2. Simulated static performance shows monotonicity over the whole input-output characteristic. The description of the circuit topology and of inner blocks architectures together with the experimental characterization is here presented.

  5. CMOS readout integrated circuit involving pixel-level ADC for microbolometer FPAs

    NASA Astrophysics Data System (ADS)

    Hwang, C. H.; Kwon, I. W.; Lee, Y. S.; Lee, H. C.

    2008-04-01

    The function of most readout integrated circuits (ROIC) for microbolometer focal plane arrays (FPAs) is supplying a bias voltage to a microbolometer of each pixel, integrating the current of a microbolometer, and transferring the signals from pixels to the output of a chip. However, the scale down of CMOS technology allows the integration of other functions. In this paper, we proposed a CMOS ROIC involving a pixel-level analog-to-digital converter (ADC) for 320 × 240 microbolometer FPAs. Such integration would improve the performance of a ROIC at the reduced system cost and power consumption. The noise performance of a microbolometer is improved by using the pixelwise readout structure because integration time can be increased up to 1ms. A Pixel circuit is consisted of a background skimming circuit, a differential amplifier, an integration capacitor and a 10-bit DRAM. First, the microbolometer current is integrated for 1ms after the skimming current correction. The differential amplifier operates as an op-Amp and the integration capacitor makes negative feedback loop between an output and a negative input of the op-Amp. And then, the integrated signal voltage is converted to digital signals using a modified single slope ADC in a pixel when the differential amplifier operates as a comparator and the 10-bit DRAM stores values of a counter. This readout circuit is designed and fabricated using a standard 0.35μm 2-poly 3-metal CMOS technology.

  6. In vitro Characterization of Phenylacetate Decarboxylase, a Novel Enzyme Catalyzing Toluene Biosynthesis in an Anaerobic Microbial Community

    PubMed Central

    Zargar, K.; Saville, R.; Phelan, R. M.; Tringe, S. G.; Petzold, C. J.; Keasling, J. D.; Beller, H. R.

    2016-01-01

    Anaerobic bacterial biosynthesis of toluene from phenylacetate was reported more than two decades ago, but the biochemistry underlying this novel metabolism has never been elucidated. Here we report results of in vitro characterization studies of a novel phenylacetate decarboxylase from an anaerobic, sewage-derived enrichment culture that quantitatively produces toluene from phenylacetate; complementary metagenomic and metaproteomic analyses are also presented. Among the noteworthy findings is that this enzyme is not the well-characterized clostridial p-hydroxyphenylacetate decarboxylase (CsdBC). However, the toluene synthase under study appears to be able to catalyze both phenylacetate and p-hydroxyphenylacetate decarboxylation. Observations suggesting that phenylacetate and p-hydroxyphenylacetate decarboxylation in complex cell-free extracts were catalyzed by the same enzyme include the following: (i) the specific activity for both substrates was comparable in cell-free extracts, (ii) the two activities displayed identical behavior during chromatographic separation of cell-free extracts, (iii) both activities were irreversibly inactivated upon exposure to O2, and (iv) both activities were similarly inhibited by an amide analog of p-hydroxyphenylacetate. Based upon these and other data, we hypothesize that the toluene synthase reaction involves a glycyl radical decarboxylase. This first-time study of the phenylacetate decarboxylase reaction constitutes an important step in understanding and ultimately harnessing it for making bio-based toluene. PMID:27506494

  7. Recombinant oxalate decarboxylase: enhancement of a hybrid catalytic cascade for the complete electro-oxidation of glycerol.

    PubMed

    Abdellaoui, Sofiene; Hickey, David P; Stephens, Andrew R; Minteer, Shelley D

    2015-10-01

    The complete electro-oxidation of glycerol to CO2 is performed through an oxidation cascade using a hybrid catalytic system combining a recombinant enzyme, oxalate decarboxylase from Bacillus subtilis, and an organic oxidation catalyst, 4-amino-TEMPO. This system is capable of electrochemically oxidizing glycerol at a carbon electrode collecting all 14 electrons per molecule. PMID:26271633

  8. COMPARISON OF ENHANCEMENT OF GGTASE-POSITIVE FOCI AND INDUCTION OF ORNITHINE DECARBOXYLASE IN RAT LIVER BY BARBITURATES

    EPA Science Inventory

    The induction of ornithine decarboxylase (ODC) by barbiturates and the ability of barbiturates to enhance neoplastic progression of chemically initiated cancer was examined in rat liver. All seven barbiturates induced ODC with barbital (7.7 fold increase) and phenobarbital (5.7 f...

  9. 21 CFR 173.115 - Alpha-acetolactate decarboxylase (α-ALDC) enzyme preparation derived from a recombinant Bacillus...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) and 1 CFR part 51. Copies may be obtained from the National Academy Press, 2101 Constitution Ave. NW... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Alpha-acetolactate decarboxylase (α-ALDC) enzyme... FOOD FOR HUMAN CONSUMPTION Enzyme Preparations and Microorganisms § 173.115...

  10. 21 CFR 173.115 - Alpha-acetolactate decarboxylase (α-ALDC) enzyme preparation derived from a recombinant Bacillus...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the National... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Alpha-acetolactate decarboxylase (α-ALDC) enzyme...) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations...

  11. 21 CFR 173.115 - Alpha-acetolactate decarboxylase (α-ALDC) enzyme preparation derived from a recombinant Bacillus...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the National... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Alpha-acetolactate decarboxylase (α-ALDC) enzyme...) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations...

  12. 21 CFR 173.115 - Alpha-acetolactate decarboxylase (α-ALDC) enzyme preparation derived from a recombinant Bacillus...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the National... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Alpha-acetolactate decarboxylase (α-ALDC) enzyme...) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations...

  13. 21 CFR 173.115 - Alpha-acetolactate decarboxylase (α-ALDC) enzyme preparation derived from a recombinant Bacillus...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the National... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Alpha-acetolactate decarboxylase (α-ALDC) enzyme...) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations...

  14. CONFIRMATIONAL IDENTIFICATION OF ESCHERICHIA COLI, A COMPARISON OF GENOTYPIC AND PHENOTYPIC ASSAYS FOR GLUTAMATE DECARBOXYLASE AND B-D-GLUCURONIDASE

    EPA Science Inventory

    Genotypic and phenotypic assays for glutamate decarboxylase (GAD) and B-D-glucuronidase (GUD) were compared for their abilities to detect various strains of Escherichia coli and to discriminate among other bacterial species. Test strains included nonpathogenic E.coli, three major...

  15. In vitro Characterization of Phenylacetate Decarboxylase, a Novel Enzyme Catalyzing Toluene Biosynthesis in an Anaerobic Microbial Community.

    PubMed

    Zargar, K; Saville, R; Phelan, R M; Tringe, S G; Petzold, C J; Keasling, J D; Beller, H R

    2016-01-01

    Anaerobic bacterial biosynthesis of toluene from phenylacetate was reported more than two decades ago, but the biochemistry underlying this novel metabolism has never been elucidated. Here we report results of in vitro characterization studies of a novel phenylacetate decarboxylase from an anaerobic, sewage-derived enrichment culture that quantitatively produces toluene from phenylacetate; complementary metagenomic and metaproteomic analyses are also presented. Among the noteworthy findings is that this enzyme is not the well-characterized clostridial p-hydroxyphenylacetate decarboxylase (CsdBC). However, the toluene synthase under study appears to be able to catalyze both phenylacetate and p-hydroxyphenylacetate decarboxylation. Observations suggesting that phenylacetate and p-hydroxyphenylacetate decarboxylation in complex cell-free extracts were catalyzed by the same enzyme include the following: (i) the specific activity for both substrates was comparable in cell-free extracts, (ii) the two activities displayed identical behavior during chromatographic separation of cell-free extracts, (iii) both activities were irreversibly inactivated upon exposure to O2, and (iv) both activities were similarly inhibited by an amide analog of p-hydroxyphenylacetate. Based upon these and other data, we hypothesize that the toluene synthase reaction involves a glycyl radical decarboxylase. This first-time study of the phenylacetate decarboxylase reaction constitutes an important step in understanding and ultimately harnessing it for making bio-based toluene. PMID:27506494

  16. Repeated immobilization stress alters rat hippocampal and prefrontal cortical morphology in parallel with endogenous agmatine and arginine decarboxylase levels

    PubMed Central

    Zhu, Meng-Yang; Wang, Wei-Ping; Huang, Jingjing; Feng, Yang-Zheng; Regunathan, Soundar; Bissette, Garth

    2008-01-01

    Agmatine, an endogenous amine derived from decarboxylation of L-arginine catalyzed by arginine decarboxylase, has been proposed as a neurotransmitter or neuromodulator in the brain. In the present study we examined whether agmatine has neuroprotective effects against repeated immobilization-induced morphological changes in brain tissues and possible effects of immobilization stress on endogenous agmatine levels and arginine decarboxylase expression in rat brains. Sprague-Dawley rats were subjected to two hour immobilization stress daily for seven days. This paradigm significantly increased plasma corticosterone levels, and the glutamate efflux in the hippocampus as measured by in vivo microdialysis. Immunohistochemical staining with β-tubulin III showed that repeated immobilization caused marked morphological alterations in the hippocampus and medial prefrontal cortex that were prevented by simultaneous treatment with agmatine (50 mg/kg/day, i.p.). Likewise, endogenous agmatine levels measured by high performance liquid chromatography in the prefrontal cortex, hippocampus, striatum and hypothalamus were significantly increased by immobilization, as compared to controls. The increased endogenous agmatine levels, ranging from 92% to 265% of controls, were accompanied by a significant increase of arginine decarboxylase protein levels in the same regions. These results demonstrate that administration of exogenous agmatine protects the hippocampus and medial prefrontal cortex against neuronal insults caused by repeated immobilization. The parallel increase in endogenous brain agmatine and arginine decarboxylase protein levels triggered by repeated immobilization indicates that the endogenous agmatine system may play an important role in adaptation to stress as a potential neuronal self-protection mechanism. PMID:18832001

  17. POSTNATAL METHYL MERCURY EXPOSURE: EFFECTS ON ONTOGENY OF RENAL AND HEPATIC ORNITHINE DECARBOXYLASE RESPONSES TO TROPHIC STIMULI

    EPA Science Inventory

    The effects of postnatal methylmercury exposure on the ongoteny of kidney and liver responsiveness to trophic stimuli were examined. Increased ornithine decarboxylase (ODC) activity was used as an index of tissue stimulation. In the rat, kidney ODC responsiveness to growth hormon...

  18. Absence of malonyl coenzyme A decarboxylase in mice increases cardiac glucose oxidation and protects the heart from ischemic injury

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acute pharmacological inhibition of cardiac malonyl coenzyme A decarboxylase (MCD) protects the heart from ischemic damage by inhibiting fatty acid oxidation and stimulating glucose oxidation. However, it is unknown whether chronic inhibition of MCD results in altered cardiac function, energy metabo...

  19. Monitoring T2 and ADC at 9.4 T following fractionated external beam radiation therapy in a mouse model

    NASA Astrophysics Data System (ADS)

    Larocque, Matthew P.; Syme, Alasdair; Yahya, Atiyah; Wachowicz, Keith; Allalunis-Turner, Joan; Fallone, B. Gino

    2010-03-01

    The purpose of this study is to investigate the response of transverse relaxation time (T2) and apparent diffusion coefficient (ADC) in human glioma tumor xenografts during and after fractionated radiotherapy. Tumor-bearing mice were divided into four treatment groups (n = 6 per group) that received a total dose of 800 cGy of 200 kVp x-rays, given over two or three fractions, with a fraction spacing of either 24 or 72 h. A fifth treatment group received 800 cGy in a single fraction, and a sixth group of mice served as an untreated control. All mice were scanned pretreatment, before each fraction and at multiple points after treatment using a 9.4 T magnetic resonance imaging (MRI) system. Quantitative T2 and ADC maps were produced. All treated groups showed an increase in mean tumor ADC, though the time for this response to reach a maximum and return toward baseline was delayed in the fractionated groups. The highest ADC was measured 7 days after the final fraction of treatment for all groups. There were no significant differences in the maximum measured change in ADC between any of the treated groups, with the average measured maximum value being 20.5% above baseline. After treatment, all groups showed an increase in mean tumor T2, with the average measured maximum T2 being 4.7% above baseline. This increase was followed by a transition to mean T2 values below baseline values, with the average measured tumor T2 being 92.4% of the pretreatment value. The transition between elevated and depressed T2 values was delayed in the cases of fractionated therapies and occurred between 3.6 and 7.3 days after the last fraction of treatment. These results further the understanding of the temporal evolution of T2 and ADC during fractionated radiotherapy and support their potential use as time-sensitive biomarkers for tumor response.

  20. Influence of image registration on ADC images computed from free-breathing diffusion MRIs of the abdomen

    NASA Astrophysics Data System (ADS)

    Guyader, Jean-Marie; Bernardin, Livia; Douglas, Naomi H. M.; Poot, Dirk H. J.; Niessen, Wiro J.; Klein, Stefan

    2014-03-01

    The apparent diffusion coefficient (ADC) is an imaging biomarker providing quantitative information on the diffusion of water in biological tissues. This measurement could be of relevance in oncology drug development, but it suffers from a lack of reliability. ADC images are computed by applying a voxelwise exponential fitting to multiple diffusion-weighted MR images (DW-MRIs) acquired with different diffusion gradients. In the abdomen, respiratory motion induces misalignments in the datasets, creating visible artefacts and inducing errors in the ADC maps. We propose a multistep post-acquisition motion compensation pipeline based on 3D non-rigid registrations. It corrects for motion within each image and brings all DW-MRIs to a common image space. The method is evaluated on 10 datasets of free-breathing abdominal DW-MRIs acquired from healthy volunteers. Regions of interest (ROIs) are segmented in the right part of the abdomen and measurements are compared in the three following cases: no image processing, Gaussian blurring of the raw DW-MRIs and registration. Results show that both blurring and registration improve the visual quality of ADC images, but compared to blurring, registration yields visually sharper images. Measurement uncertainty is reduced both by registration and blurring. For homogeneous ROIs, blurring and registration result in similar median ADCs, which are lower than without processing. In a ROI at the interface between liver and kidney, registration and blurring yield different median ADCs, suggesting that uncorrected motion introduces a bias. Our work indicates that averaging procedures on the scanner should be avoided, as they remove the opportunity to perform motion correction.

  1. Integration of quantitative DCE-MRI and ADC mapping to monitor treatment response in human breast cancer

    PubMed Central

    Yankeelov, Thomas E.; Lepage, Martin; Chakravarthy, Anuradha; Broome, Elizabeth E.; Niermann, Kenneth J.; Kelley, Mark C.; Meszoely, Ingrid; Mayer, Ingrid A.; Herman, Cheryl R.; McManus, Kevin; Price, Ronald R.; Gore, John C.

    2009-01-01

    Purpose The objective of this study was to assess changes in the water apparent diffusion coefficient (ADC) and in pharmacokinetic parameters obtained from the fast-exchange regime (FXR) modeling of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) during neoadjuvant chemotherapy in breast cancer. Materials and Methods Eleven patients with locally advanced breast cancer underwent MRI examination prior to and after chemotherapy but prior to surgery. A 1.5-T scanner was used to obtain T1, ADC and DCE-MRI data. DCE-MRI data were analyzed by the FXR model returning estimates of Ktrans (volume transfer constant), νe (extravascular extracellular volume fraction) and τsi (average intracellular water lifetime). Histogram and correlation analyses assessed parameter changes post-treatment. Results Significant ( P <.05) changes or trends towards significance ( P <.10) were seen in all parameters except τi, although there was qualitative reduction in τi values post-treatment. In particular, there was reduction ( P <.035) in voxels with Ktrans values in the range 0.2–0.5 min-1 and a decrease ( P <.05) in voxels with ADC values in the range 0.99×10-3 to 1.35×10-3 mm2/s. ADC and νe were negatively correlated (r = -.60, P <.02). Parameters sensitive to water distribution and geometry (T1, νe,τsi and ADC) correlated with a multivariable linear regression model. Conclusion The analysis presented here is sensitive to longitudinal changes in breast tumor status; Ktrans and ADC are most sensitive to these changes. Relationships between parameters provide information on water distribution and geometry in the tumor environment. PMID:17222711

  2. Isolation and characterization of the orotidine 5'-monophosphate decarboxylase domain of the multifunctional protein uridine 5'-monophosphate synthase.

    PubMed

    Floyd, E E; Jones, M E

    1985-08-01

    The multifunctional protein uridine 5'-monophosphate (UMP) synthase catalyzes the final two reactions of the de novo biosynthesis of UMP in mammalian cells by the sequential action of orotate phosphoribosyltransferase (EC 2.4.2.10) and orotidine 5'-monophosphate (OMP) decarboxylase (EC 4.1.1.23). This protein is composed of one or two identical subunits; the monomer weighs of 51,500 daltons. UMP synthase from mouse Ehrlich ascites cells can exist as three distinct species as determined by sucrose density gradient centrifugation: a 3.6 S monomer, a 5.1 S dimer, and a 5.6 S conformationally altered dimer. Limited digestion of each of these three species with trypsin produced a 28,500-dalton peptide that was relatively resistant to further proteolysis. The peptide appears to be one of the two enzyme domains of UMP synthase for it retained only OMP decarboxylase activity. Similar results were obtained when UMP synthase was digested with elastase. OMP decarboxylase activity was less stable for the domain than for UMP synthase; the domain can rapidly lose activity upon storage or upon dilution. The size of the mammalian OMP decarboxylase domain is similar to that of yeast OMP decarboxylase. If the polypeptides which are cleaved from UMP synthase by trypsin are derived exclusively from either the amino or the carboxyl end of UMP synthase, then the size of a fragment possessing the orotate phosphoribosyltransferase domain could be as large as 23,000 daltons which is similar in size to the orotate phosphoribosyltransferase of yeast and of Escherichia coli. PMID:3839509

  3. Expression, immobilization and enzymatic properties of glutamate decarboxylase fused to a cellulose-binding domain.

    PubMed

    Park, Hyemin; Ahn, Jungoh; Lee, Juwhan; Lee, Hyeokwon; Kim, Chunsuk; Jung, Joon-Ki; Lee, Hongweon; Lee, Eun Gyo

    2012-01-01

    Escherichia coli-derived glutamate decarboxylase (GAD), an enzyme that catalyzes the conversion of glutamic acid to gamma-aminobutyric acid (GABA), was fused to the cellulose-binding domain (CBD) and a linker of Trichoderma harzianum endoglucanase II. To prevent proteolysis of the fusion protein, the native linker was replaced with a S(3)N(10) peptide known to be completely resistant to E. coli endopeptidase. The CBD-GAD expressed in E. coli was successfully immobilized on Avicel, a crystalline cellulose, with binding capacity of 33 ± 2 nmol(CBD-GAD)/g(Avicel) and the immobilized enzymes retained 60% of their initial activities after 10 uses. The results of this report provide a feasible alternative to produce GABA using immobilized GAD through fusion to CBD. PMID:22312257

  4. Inhibitory activity of Filipendula ulmaria constituents on recombinant human histidine decarboxylase.

    PubMed

    Nitta, Yoko; Kikuzaki, Hiroe; Azuma, Toshiaki; Ye, Yuan; Sakaue, Motoyoshi; Higuchi, Yoshiki; Komori, Hirohumi; Ueno, Hiroshi

    2013-06-01

    Histidine decarboxylase (HDC) catalyses the formation of histamine, a bioactive amine. Agents that control HDC activity are beneficial for treating histamine-mediated symptoms, such as allergies and stomach ulceration. We searched for inhibitors of HDC from the ethyl acetate extract of the petal of Filipendula ulmaria, also called meadowsweet. Rugosin D, rugosin A, rugosin A methyl ester (a novel compound), and tellimagrandin II were the main components; these 4 ellagitannins exhibited a non-competitive type of inhibition, with K(i) values of approximately 0.35-1 μM. These K(i) values are nearly equal to that of histidine methyl ester (K(i)=0.46 μM), an existing substrate analogue inhibitor. Our results show that food products contain potent HDC inhibitors and that these active food constituents might be useful for designing clinically available HDC inhibitors. PMID:23411280

  5. Structural determinants for the inhibitory ligands of orotidine-5′-monophosphate decarboxylase

    SciTech Connect

    Meza-Avina, Maria Elena; Wei, Lianhu; Liu, Yan; Poduch, Ewa; Bello, Angelica M.; Mishra, Ram K.; Pai, Emil F.; Kotra, Lakshmi P.

    2010-06-14

    In recent years, orotidine-5{prime}-monophosphate decarboxylase (ODCase) has gained renewed attention as a drug target. As a part of continuing efforts to design novel inhibitors of ODCase, we undertook a comprehensive study of potent, structurally diverse ligands of ODCase and analyzed their structural interactions in the active site of ODCase. These ligands comprise of pyrazole or pyrimidine nucleotides including the mononucleotide derivatives of pyrazofurin, barbiturate ribonucleoside, and 5-cyanouridine, as well as, in a computational approach, 1,4-dihydropyridine-based non-nucleoside inhibitors such as nifedipine and nimodipine. All these ligands bind in the active site of ODCase exhibiting distinct interactions paving the way to design novel inhibitors against this interesting enzyme. We propose an empirical model for the ligand structure for rational modifications in new drug design and potentially new lead structures.

  6. Oral putrescine restores virulence of ornithine decarboxylase-deficient Leishmania donovani in mice

    PubMed Central

    Olenyik, Tamara; Gilroy, Caslin; Ullman, Buddy

    2011-01-01

    Administration of putrescine as a 1% solution in the drinking water ameliorated the profound loss of virulence exhibited by ornithine decarboxylase (ODC) deficient Leishmania donovani in mice. Furthermore, supplying α-difluoromethylornithine, an ODC inhibitor, at 2% in the drinking water reduced but did not eliminate infection with wild type L. donovani in the mouse model. Taken collectively, these findings: 1) demonstrate that oral putrescine can access the phagolysosome of macrophages in which the parasite resides in mice; 2) establish that the loss of virulence due to the Δodc lesion is a consequence of the inability of the mutant parasite to synthesize sufficient polyamines de novo; 3) imply that the L. donovani amastigote cannot access host polyamines in sufficient amounts for survival and growth; 4) and validate ODC as a drug target, although oral administration of DFMO is an unlikely therapeutic paradigm for visceral leishmaniasis. PMID:21182873

  7. Glycine decarboxylase in C3, C4 and C3-C4 intermediate species.

    PubMed

    Schulze, Stefanie; Westhoff, Peter; Gowik, Udo

    2016-06-01

    The glycine decarboxylase complex (GDC) plays a central role in photorespiration. GDC is localized in the mitochondria and together with serine hydroxymethyltransferase it converts two molecules of glycine to one molecule of serine, CO2 and NH3. Overexpression of GDC subunits in the C3 species Arabidopsis thaliana can increase the metabolic flux through the photorespiratory pathway leading to enhanced photosynthetic efficiency and consequently to an enhanced biomass production of the transgenic plants. Changing the spatial expression patterns of GDC subunits was an important step during the evolution of C3-C4 intermediate and likely also C4 plants. Restriction of the GDC activity to the bundle sheath cells led to the establishment of a photorespiratory CO2 pump. PMID:27038285

  8. The effect of pyruvate decarboxylase gene knockout in Saccharomyces cerevisiae on L-lactic acid production.

    PubMed

    Ishida, Nobuhiro; Saitoh, Satoshi; Onishi, Toru; Tokuhiro, Kenro; Nagamori, Eiji; Kitamoto, Katsuhiko; Takahashi, Haruo

    2006-05-01

    A plant- and crop-based renewable plastic, poly-lactic acid (PLA), is receiving attention as a new material for a sustainable society in place of petroleum-based plastics. We constructed a metabolically engineered Saccharomyces cerevisiae that has both pyruvate decarboxylase genes (PDC1 and PDC5) disrupted in the genetic background to express two copies of the bovine L-lactate dehydrogenase (LDH) gene. With this recombinant, the yield of lactate was 82.3 g/liter, up to 81.5% of the glucose being transformed into lactic acid on neutralizing cultivation, although pdc1 pdc5 double disruption led to ineffective decreases in cell growth and fermentation speed. This strain showed lactate productivity improvement as much as 1.5 times higher than the previous strain. This production yield is the highest value for a lactic acid-producing yeast yet reported. PMID:16717415

  9. Structural Determinants for Inhibitory Ligands of Orotidine-5′-Monophosphate Decarboxylase

    PubMed Central

    Meza-Avina, Maria Elena; Wei, Lianhu; Liu, Yan; Poduch, Ewa; Bello, Angelica M.; Mishra, Ram K.; Pai, Emil F.; Kotra, Lakshmi P.

    2011-01-01

    In recent years, orotidine-5′-monophosphate decarboxylase (ODCase) has gained renewed attention as a drug target. As a part of continuing efforts to design novel inhibitors of ODCase, we undertook a comprehensive study of potent, structurally diverse ligands of ODCase and analyzed their structural interactions in the active site of ODCase. These ligands comprise of pyrazole or pyrimidine nucleotides including the mononucleotide derivatives of pyrazofurin, barbiturate ribonucleoside, and 5-cyanouridine, as well as, in a computational approach, 1,4-dihydropyridine-based non-nucleoside inhibitors such as nifedipine and nimodipine. All these ligands bind in the active site of ODCase exhibiting distinct interactions paving the way to design novel inhibitors against this interesting enzyme. We propose an empirical model for the ligand structure for rational modifications in new drug design and potentially new lead structures. PMID:20452222

  10. Discovery and characterization of gut microbiota decarboxylases that can produce the neurotransmitter tryptamine

    PubMed Central

    Williams, Brianna B.; Van Benschoten, Andrew H.; Cimermancic, Peter; Donia, Mohamed S.; Zimmermann, Michael; Taketani, Mao; Ishihara, Atsushi; Kashyap, Purna C.; Fraser, James S.; Fischbach, Michael A.

    2014-01-01

    Summary Several recent studies describe the influence of the gut microbiota on host brain and behavior. However, the mechanisms responsible for microbiota-nervous system interactions are unknown. Using a combination of genetics, biochemistry, and crystallography, we identify and characterize two phylogenetically distinct enzymes found in the human microbiome that decarboxylate tryptophan to form the β-arylamine neurotransmitter tryptamine. Although this enzymatic activity is exceedingly rare among bacteria more broadly, analysis of the Human Microbiome Project data demonstrates that at least 10% of the human population harbors at least one bacterium encoding a tryptophan decarboxylase in their gut community. Our results uncover a previously unrecognized enzymatic activity that can give rise to host-modulatory compounds and suggests a potential direct mechanism by which gut microbiota can influence host physiology, including behavior. PMID:25263219

  11. Regioselective Enzymatic β-Carboxylation of para-Hydroxy- styrene Derivatives Catalyzed by Phenolic Acid Decarboxylases

    PubMed Central

    Wuensch, Christiane; Pavkov-Keller, Tea; Steinkellner, Georg; Gross, Johannes; Fuchs, Michael; Hromic, Altijana; Lyskowski, Andrzej; Fauland, Kerstin; Gruber, Karl; Glueck, Silvia M; Faber, Kurt

    2015-01-01

    We report on a ‘green’ method for the utilization of carbon dioxide as C1 unit for the regioselective synthesis of (E)-cinnamic acids via regioselective enzymatic carboxylation of para-hydroxystyrenes. Phenolic acid decarboxylases from bacterial sources catalyzed the β-carboxylation of para-hydroxystyrene derivatives with excellent regio- and (E/Z)-stereoselectivity by exclusively acting at the β-carbon atom of the C=C side chain to furnish the corresponding (E)-cinnamic acid derivatives in up to 40% conversion at the expense of bicarbonate as carbon dioxide source. Studies on the substrate scope of this strategy are presented and a catalytic mechanism is proposed based on molecular modelling studies supported by mutagenesis of amino acid residues in the active site. PMID:26190963

  12. Suppression of ornithine decarboxylase promotes osteogenic differentiation of human bone marrow-derived mesenchymal stem cells.

    PubMed

    Tsai, Yo-Hsian; Lin, Kuan-Lian; Huang, Yuan-Pin; Hsu, Yi-Chiang; Chen, Chung-Hwan; Chen, Yuhsin; Sie, Min-Hua; Wang, Gwo-Jaw; Lee, Mon-Juan

    2015-07-22

    Ornithine decarboxylase (ODC) is the rate-limiting enzyme for polyamine biosynthesis. Suppression of ODC by its irreversible inhibitor, α-difluoromethylornithine (DFMO), or by RNA interference through siRNA, enhanced osteogenic gene expression and alkaline phosphatase activity, and accelerated matrix mineralization of human bone marrow-derived mesenchymal stem cells (hBMSCs). Besides, adipogenic gene expression and lipid accumulation was attenuated, indicating that the enhanced osteogenesis was accompanied by down-regulation of adipogenesis when ODC was suppressed. A decrease in the intracellular polyamine content of hBMSCs during osteogenic induction was observed, suggesting that the level of endogenous polyamines is regulated during differentiation of hBMSCs. This study elucidates the role of polyamine metabolism in the lineage commitment of stem cells and provides a potential new indication for DFMO as bone-stimulating drug. PMID:26140984

  13. Targeting ornithine decarboxylase in Myc-induced lymphomagenesis prevents tumor formation.

    PubMed

    Nilsson, Jonas A; Keller, Ulrich B; Baudino, Troy A; Yang, Chunying; Norton, Sara; Old, Jennifer A; Nilsson, Lisa M; Neale, Geoffrey; Kramer, Debora L; Porter, Carl W; Cleveland, John L

    2005-05-01

    Checkpoints that control Myc-mediated proliferation and apoptosis are bypassed during tumorigenesis. Genes encoding polyamine biosynthetic enzymes are overexpressed in B cells from E mu-Myc transgenic mice. Here, we report that disabling one of these Myc targets, Ornithine decarboxylase (Odc), abolishes Myc-induced suppression of the Cdk inhibitors p21(Cip1) and p27(Kip1), thereby impairing Myc's proliferative, but not apoptotic, response. Moreover, lymphoma development was markedly delayed in E mu-Myc;Odc(+/-) transgenic mice and in E mu-Myc mice treated with the Odc inhibitor difluoromethylornithine (DFMO). Strikingly, tumors ultimately arising in E mu-Myc;Odc(+/-) transgenics lacked deletions of Arf, suggesting that targeting Odc forces other routes of transformation. Therefore, Odc is a critical Myc transcription target that regulates checkpoints that guard against tumorigenesis and is an effective target for cancer chemoprevention. PMID:15894264

  14. OMP decarboxylase: phosphodianion binding energy is used to stabilize a vinyl carbanion intermediate.

    PubMed

    Goryanova, Bogdana; Amyes, Tina L; Gerlt, John A; Richard, John P

    2011-05-01

    Orotidine 5'-monophosphate decarboxylase (OMPDC) catalyzes the exchange for deuterium from solvent D(2)O of the C-6 proton of 1-(β-d-erythrofuranosyl)-5-fluorouracil (FEU), a phosphodianion truncated product analog. The deuterium exchange reaction of FEU is accelerated 1.8 × 10(4)-fold by 1 M phosphite dianion (HPO(3)(2-)). This corresponds to a 5.8 kcal/mol stabilization of the vinyl carbanion-like transition state, which is similar to the 7.8 kcal/mol stabilization of the transition state for OMPDC-catalyzed decarboxylation of a truncated substrate analog by bound HPO(3)(2-). These results show that the intrinsic binding energy of phosphite dianion is used in the stabilization of the vinyl carbanion-like transition state common to the decarboxylation and deuterium exchange reactions. PMID:21486036

  15. Histidine decarboxylase deficiency causes Tourette syndrome: parallel findings in humans and mice

    PubMed Central

    Baldan, Lissandra Castellan; Rapanelli, Maximiliano; Crowley, Michael; Anderson, George M.; Loring, Erin; Gorczyca, Roxanne; Billingslea, Eileen; Wasylink, Suzanne; Panza, Kaitlyn E.; Ercan-Sencicek, A. Gulhan; Krusong, Kuakarun; Leventhal, Bennett L.; Ohtsu, Hiroshi; Bloch, Michael H.; Hughes, Zoë A.; Krystal, John H.; Mayes, Linda; de Araujo, Ivan; Ding, Yu-Shin; State, Matthew W.; Pittenger, Christopher

    2013-01-01

    Tourette syndrome (TS) is characterized by tics, sensorimotor gating deficiencies, and abnormalities of cortico-basal ganglia circuits. A mutation in histidine decarboxylase (Hdc), the key enzyme for the biosynthesis of histamine (HA), has been implicated as a rare genetic cause. Hdc knockout mice exhibited potentiated tic-like stereotypies, recapitulating core phenomenology of TS; these were mitigated by the dopamine D2 antagonist haloperidol, a proven pharmacotherapy, and by HA infusion into the brain. Prepulse inhibition was impaired in both mice and humans carrying Hdc mutations. HA infusion reduced striatal dopamine (DA) levels; in Hdc knockout mice, striatal DA was increased and the DA-regulated immediate early gene Fos was upregulated. Dopamine D2/D3 receptor binding was altered both in mice and in humans carrying the Hdc mutation. These data confirm HDC deficiency as a rare cause of TS and identify histamine-dopamine interactions in the basal ganglia as an important locus of pathology. PMID:24411733

  16. Intrathecal-specific glutamic acid decarboxylase antibodies at low titers in autoimmune neurological disorders.

    PubMed

    Sunwoo, Jun-Sang; Chu, Kon; Byun, Jung-Ick; Moon, Jangsup; Lim, Jung-Ah; Kim, Tae-Joon; Lee, Soon-Tae; Jung, Keun-Hwa; Park, Kyung-Il; Jeon, Daejong; Jung, Ki-Young; Kim, Manho; Lee, Sang Kun

    2016-01-15

    Autoantibodies to glutamic acid decarboxylase (Gad-Abs) are implicated in various neurological syndromes. The present study aims to identify intrathecal-specific GAD-Abs and to determine clinical manifestations and treatment outcomes. Nineteen patients had GAD-Abs in cerebrospinal fluid but not in paired serum samples. Neurological syndromes included limbic encephalitis, temporal lobe epilepsy, cerebellar ataxia, autonomic dysfunction, and stiff-person syndrome. Immunotherapy had beneficial effects in 57.1% of patients, and the patients with limbic encephalitis responded especially well to immunotherapy. Intrathecal-specific antibodies to GAD at low titers may appear as nonspecific markers of immune activation within the central nervous system rather than pathogenic antibodies causing neuronal dysfunction. PMID:26711563

  17. Genetic Confirmation of the Role of Sulfopyruvate Decarboxylase in Coenzyme M Biosynthesis in Methanococcus maripaludis

    DOE PAGESBeta

    Sarmiento, Felipe; Ellison, Courtney K.; Whitman, William B.

    2013-01-01

    Coenzyme M is an essential coenzyme for methanogenesis. The proposed biosynthetic pathway consists of five steps, of which the fourth step is catalyzed by sulfopyruvate decarboxylase (ComDE). Disruption of the gene comE by transposon mutagenesis resulted in a partial coenzyme M auxotroph, which grew poorly in the absence of coenzyme M and retained less than 3% of the wild type level of coenzyme M biosynthesis. Upon coenzyme M addition, normal growth of the mutant was restored. Moreover, complementation of the mutation with the wild type comE gene in trans restored full growth in the absence of coenzyme M. Thesemore » results confirm that ComE plays an important role in coenzyme M biosynthesis. The inability to yield a complete CoM auxotroph suggests that either the transposon insertion failed to completely inactivate the gene or M. maripaludis possesses a promiscuous activity that partially complemented the mutation.« less

  18. Crystallization and preliminary X-ray analysis of the inducible lysine decarboxylase from Escherichia coli

    SciTech Connect

    Alexopoulos, E.; Kanjee, U.; Snider, J.; Houry, W.A.; Pai, E.F.

    2010-02-11

    The decameric inducible lysine decarboxylase (LdcI) from Escherichia coli has been crystallized in space groups C2 and C222{sub 1}; the Ta{sub 6}Br{sub 12}{sup 2+} cluster was used to derivatize the C2 crystals. The method of single isomorphous replacement with anomalous scattering (SIRAS) as implemented in SHELXD was used to solve the Ta{sub 6}Br{sub 12}{sup 2+}-derivatized structure to 5 {angstrom} resolution. Many of the Ta{sub 6}Br{sub 12}{sup 2+}-binding sites had twofold and fivefold noncrystallographic symmetry. Taking advantage of this feature, phase modification was performed in DM. The electron-density map of LdcI displays many features in agreement with the low-resolution negative-stain electron-density map [Snider et al. (2006), J. Biol. Chem. 281, 1532-1546].

  19. Pristane-induced effects on cytochrome P-4501A, ornithine decarboxylase and putrescine in rats.

    PubMed

    Harper, C M; Soni, M G; Mehendale, H M; Cuchens, M A

    1995-08-16

    The effects of pristane (2,6,10,14-tetramethylpentadecane) on cytochrome P-4501A (cP4501A) activity in microsomes, as well as on ornithine decarboxylase (ODC) activity and concomitant putrescine levels were examined in Copenhagen rats. In general, pristane treatment led to increased cP4501A levels when compared to basal levels, while co-treatment with 3-methylcholanthrene (3-MC) and pristane elicited augmented cP4501A responses when compared to responses induced by 3-MC alone. Increases in both ODC activity and putrescine levels were also observed in pristane treated rats. Collectively, these results indicate that pristane influences cP4501A activity and elicits promoter-like responses as reflected in elevated ODC activity and increased amount of putrescine. PMID:7656217

  20. Active-site mobility revealed by the crystal structure of arylmalonate decarboxylase from Bordetella bronchiseptica.

    PubMed

    Kuettner, E Bartholomeus; Keim, Antje; Kircher, Markus; Rosmus, Susann; Sträter, Norbert

    2008-03-21

    Arylmalonate decarboxylase (AMDase) from Bordetella bronchiseptica catalyzes the enantioselective decarboxylation of arylmethylmalonates without the need for an organic cofactor or metal ion. The decarboxylation reaction is of interest for the synthesis of fine chemicals. As basis for an analysis of the catalytic mechanism of AMDase and for a rational enzyme design, we determined the X-ray structure of the enzyme up to 1.9 A resolution. Like the distantly related aspartate or glutamate racemases, AMDase has an aspartate transcarbamoylase fold consisting of two alpha/beta domains related by a pseudo dyad. However, the domain orientation of AMDase differs by about 30 degrees from that of the glutamate racemases, and also significant differences in active-site structures are observed. In the crystals, four independent subunits showing different conformations of active-site loops are present. This finding is likely to reflect the active-site mobility necessary for catalytic activity. PMID:18258259

  1. A 1 V 186-μW 50-MS/s 10-bit subrange SAR ADC in 130-nm CMOS process

    NASA Astrophysics Data System (ADS)

    Mingyuan, Yu; Ting, Li; Jiaqi, Yang; Shuangshuang, Zhang; Fujiang, Lin; Lin, He

    2016-07-01

    This paper presents a 10-bit 50-MS/s subrange successive-approximation register (SAR) analog-to-digital converter (ADC) composed of a 4-bit SAR coarse ADC and a 6-bit SAR fine ADC. In the coarse ADC, multi-comparator SAR architecture is used to reduce the digital logic propagation delay, and a traditional asynchronous SAR ADC with monotonic switching method is used as the fine ADC. With that combination, power dissipation also can be much reduced. Meanwhile, a modified SAR control logic is adopted in the fine ADC to speed up the conversion and other techniques, such as splitting capacitors array, are borrowed to reduce the power consumption. Fabricated with 1P8M 130-nm CMOS technology, the proposed SAR ADC achieves 51.6-dB signal to noise and distortion ratio (SNDR) and consumes 186 μW at 50 MS/s with a 1-V supply, resulting in a figure of merit (FOM) of 12 fJ/conversion-step. The core area is only 0.045 mm2. Project supported by the National Natural Science Foundation of China (Nos. 61204033, 61331015), the Fundamental Research Funds for the Central Universities (No. WK2100230015), and the Funds of Science and Technology on Analog Integrated Circuit Laboratory (No. 9140C090111150C09041).

  2. Structure and Mechanism of Ferulic Acid Decarboxylase (FDC1) from Saccharomyces cerevisiae.

    PubMed

    Bhuiya, Mohammad Wadud; Lee, Soon Goo; Jez, Joseph M; Yu, Oliver

    2015-06-15

    The nonoxidative decarboxylation of aromatic acids occurs in a range of microbes and is of interest for bioprocessing and metabolic engineering. Although phenolic acid decarboxylases provide useful tools for bioindustrial applications, the molecular bases for how these enzymes function are only beginning to be examined. Here we present the 2.35-Å-resolution X-ray crystal structure of the ferulic acid decarboxylase (FDC1; UbiD) from Saccharomyces cerevisiae. FDC1 shares structural similarity with the UbiD family of enzymes that are involved in ubiquinone biosynthesis. The position of 4-vinylphenol, the product of p-coumaric acid decarboxylation, in the structure identifies a large hydrophobic cavity as the active site. Differences in the β2e-α5 loop of chains in the crystal structure suggest that the conformational flexibility of this loop allows access to the active site. The structure also implicates Glu285 as the general base in the nonoxidative decarboxylation reaction catalyzed by FDC1. Biochemical analysis showed a loss of enzymatic activity in the E285A mutant. Modeling of 3-methoxy-4-hydroxy-5-decaprenylbenzoate, a partial structure of the physiological UbiD substrate, in the binding site suggests that an ∼30-Å-long pocket adjacent to the catalytic site may accommodate the isoprenoid tail of the substrate needed for ubiquinone biosynthesis in yeast. The three-dimensional structure of yeast FDC1 provides a template for guiding protein engineering studies aimed at optimizing the efficiency of aromatic acid decarboxylation reactions in bioindustrial applications. PMID:25862228

  3. [Cloning, prokaryotic expression and characterization of lysine decarboxylase gene from Huperzia serrata].

    PubMed

    Di, Ci; Li, Jing; Tang, Yuntao; Peng, Qingzhong

    2014-08-01

    Huperzine A is a promising drug to treat Alzheimer's disease (AD). To date, its biosynthetic pathway is still unknown. Lysine decarboxylase (LDC) has been proposed to catalyze the first-step of the biosynthesis of huperzine A. To identify and characterize LDCs from Huperzia serrata, we isolated two LDC fragments (LDC1 and LDC2) from leaves of H. serrata by RT-PCR and then cloned them into pMD 19-T vector. Sequence analysis showed that LDC1 and LDC2 genes shared 95.3% identity and encoded the protein of 212 and 202 amino acid residues respectively. Thus, we ligated LDC genes into pET-32a(+) to obtain recombinant expressing vectors pET-32a(+)/LDC1 and pET-32a(+)/LDC2 respectively. We further introduced two expression vectors into Escherichia coli BL21(DE3) and cultured positive colonies of E. coli in liquid LB medium. After inducing for 4 hours with 260 μg/mL IPTG at 30 degrees C, soluble recombinant Trx-LDC1 and Trx-LDC2 were obtained and isolated for purification using a Ni-NTA affinity chromatography. We incubated purified recombinant proteins with L-lysine in the enzyme reaction buffer at 37 degrees C and then derived the reaction products using dansyl chloride. It was found that both Trx-LDC1 and Trx-LDC2 had decarboxylase activity, could convert L-lysine into cadaverine by way of thin layer chromatography assay. Further, bioinformatics analysis indicated that deduced LDC1 and LDC2 had different physicochemical properties, but similar secondary and three-dimensional structures. PMID:25423760

  4. [Cloning, prokaryotic expression and characterization of lysine decarboxylase gene from Huperzia serrata].

    PubMed

    Di, Ci; Li, Jing; Tang, Yuntao; Peng, Qingzhong

    2014-08-01

    Huperzine A is a promising drug to treat Alzheimer's disease (AD). To date, its biosynthetic pathway is still unknown. Lysine decarboxylase (LDC) has been proposed to catalyze the first-step of the biosynthesis of huperzine A. To identify and characterize LDCs from Huperzia serrata, we isolated two LDC fragments (LDC1 and LDC2) from leaves of H. serrata by RT-PCR and then cloned them into pMD 19-T vector. Sequence analysis showed that LDC1 and LDC2 genes shared 95.3% identity and encoded the protein of 212 and 202 amino acid residues respectively. Thus, we ligated LDC genes into pET-32a(+) to obtain recombinant expressing vectors pET-32a(+)/LDC1 and pET-32a(+)/LDC2 respectively. We further introduced two expression vectors into Escherichia coli BL21(DE3) and cultured positive colonies of E. coli in liquid LB medium. After inducing for 4 hours with 260 μg/mL IPTG at 30 degrees C, soluble recombinant Trx-LDC1 and Trx-LDC2 were obtained and isolated for purification using a Ni-NTA affinity chromatography. We incubated purified recombinant proteins with L-lysine in the enzyme reaction buffer at 37 degrees C and then derived the reaction products using dansyl chloride. It was found that both Trx-LDC1 and Trx-LDC2 had decarboxylase activity, could convert L-lysine into cadaverine by way of thin layer chromatography assay. Further, bioinformatics analysis indicated that deduced LDC1 and LDC2 had different physicochemical properties, but similar secondary and three-dimensional structures. PMID:25507483

  5. Structure and Mechanism of Ferulic Acid Decarboxylase (FDC1) from Saccharomyces cerevisiae

    PubMed Central

    Bhuiya, Mohammad Wadud; Lee, Soon Goo

    2015-01-01

    The nonoxidative decarboxylation of aromatic acids occurs in a range of microbes and is of interest for bioprocessing and metabolic engineering. Although phenolic acid decarboxylases provide useful tools for bioindustrial applications, the molecular bases for how these enzymes function are only beginning to be examined. Here we present the 2.35-Å-resolution X-ray crystal structure of the ferulic acid decarboxylase (FDC1; UbiD) from Saccharomyces cerevisiae. FDC1 shares structural similarity with the UbiD family of enzymes that are involved in ubiquinone biosynthesis. The position of 4-vinylphenol, the product of p-coumaric acid decarboxylation, in the structure identifies a large hydrophobic cavity as the active site. Differences in the β2e-α5 loop of chains in the crystal structure suggest that the conformational flexibility of this loop allows access to the active site. The structure also implicates Glu285 as the general base in the nonoxidative decarboxylation reaction catalyzed by FDC1. Biochemical analysis showed a loss of enzymatic activity in the E285A mutant. Modeling of 3-methoxy-4-hydroxy-5-decaprenylbenzoate, a partial structure of the physiological UbiD substrate, in the binding site suggests that an ∼30-Å-long pocket adjacent to the catalytic site may accommodate the isoprenoid tail of the substrate needed for ubiquinone biosynthesis in yeast. The three-dimensional structure of yeast FDC1 provides a template for guiding protein engineering studies aimed at optimizing the efficiency of aromatic acid decarboxylation reactions in bioindustrial applications. PMID:25862228

  6. Fast response neutron emission monitor for fusion reactor using stilbene scintillator and Flash-ADC.

    PubMed

    Itoga, T; Ishikawa, M; Baba, M; Okuji, T; Oishi, T; Nakhostin, M; Nishitani, T

    2007-01-01

    The stilbene neutron detector which has been used for neutron emission profile monitoring in JT-60U has been improved, to respond to the requirement to observe the high-frequency phenomena in megahertz region such as toroidicity-induced Alfvén Eigen mode in burning plasma as well as the spatial profile and the energy spectrum. This high-frequency phenomenon is of great interest and one of the key issues in plasma physics in recent years. To achieve a fast response in the stilbene detector, a Flash-ADC is applied and the wave form of the anode signal stored directly, and neutron/gamma discrimination was carried out via software with a new scheme for data acquisition mode to extend the count rate limit to MHz region from 1.3 x 10(5) neutron/s in the past, and confirmed the adequacy of the method. PMID:17517674

  7. Cryocooled wideband digital channelizing radio-frequency receiver based on low-pass ADC

    NASA Astrophysics Data System (ADS)

    Vernik, Igor V.; Kirichenko, Dmitri E.; Dotsenko, Vladimir V.; Miller, Robert; Webber, Robert J.; Shevchenko, Pavel; Talalaevskii, Andrei; Gupta, Deepnarayan; Mukhanov, Oleg A.

    2007-11-01

    We have demonstrated a digital receiver performing direct digitization of radio-frequency signals over a wide frequency range from kilohertz to gigahertz. The complete system, consisting of a cryopackaged superconductor all-digital receiver (ADR) chip followed by room-temperature interface electronics and a field programmable gate array (FPGA) based post-processing module, has been developed. The ADR chip comprises a low-pass analog-to-digital converter (ADC) delta modulator with phase modulation-demodulation architecture together with digital in-phase and quadrature mixer and a pair of digital decimation filters. The chip is fabricated using a 4.5 kA cm-2 process and is cryopackaged using a commercial-off-the-shelf cryocooler. Experimental results in HF, VHF, UHF and L bands and their analysis, proving consistent operation of the cryopackaged ADR chip up to 24.32 GHz clock frequency, are presented and discussed.

  8. Broadband X-ray Spectroscopy of the ADC Source 4U 1822-37 with Suzaku

    NASA Technical Reports Server (NTRS)

    Cottam, J.; White, N.

    2006-01-01

    We will present the broadband spectra of the low mass x-ray binary 4U 1822-37, recently observed with Suzaku. 4U 1822-37 is the canonical accretion disk corona (ADC) source where the compact object is obscured by an extended corona that intercepts and scatters the central continuum emission, some of which is then reprocessed in the outer regions of the accretion disk. 4U 1822-37 therefore serves as an important link between x-ray binaries and AGN. The broadband x-ray spectra from the Suzaku XIS and HXD provide a unique opportunity to probe the physical conditions in the corona and the accretion disk for this important accretion geometry.

  9. Ultra-low power ADC on chip for high-performance IR detector

    NASA Astrophysics Data System (ADS)

    Decaens, Gilbert; Zecri, Michel; Maillart, Patrick; Advent, Frédéric; Baud, Laurent; Parola, Stephen; Billon-Lanfrey, David; Pistone, Frédéric; Martin, Sébastien

    2009-05-01

    The InfraRed staring arrays developed by SOFRADIR are more and more compact and offer system solutions for wide range of IR wavebands. IR detectors have been taken to an even more advanced level of sophistication to achieve staring arrays high performances. Latest developments have also been focused on the silicon readout circuit. Digital conversion on chip is one of the recent progresses in this field of activity. In order to match each system requirements, on chip high performance ultra low power ADCs have been developed. Beyond the performance aspects, digital focal plane arrays can be considered as the first step towards low cost Dewar family, since they allow for a more simple electrical interface on Dewar designs and on chip image processing. Recent results concerning these new readout circuit architectures are presented in this paper.

  10. A 512×512 CMOS Monolithic Active Pixel Sensor with integrated ADCs for space science

    NASA Astrophysics Data System (ADS)

    Prydderch, M. L.; Waltham, N. J.; Turchetta, R.; French, M. J.; Holt, R.; Marshall, A.; Burt, D.; Bell, R.; Pool, P.; Eyles, C.; Mapson-Menard, H.

    2003-10-01

    In the last few years, CMOS sensors have become widely used for consumer applications, but little has been done for scientific instruments. In this paper we present the design and experimental characterisation of a Monolithic Active Pixel Sensor (MAPS) intended for a space science application. The sensor incorporates a 525×525 array of pixels on a 25 μm pitch. Each pixel contains a detector together with three transistors that are used for pixel reset, pixel selection and charge-to-voltage conversion. The detector consists of four n-well/p-substrate diodes combining optimum charge collection and low noise performance. The array readout is column-parallel with adjustable gain column amplifiers and a 10-bit single slope ADC. Data conversion takes place simultaneously for all the 525 pixels in one row. The ADC slope can be adjusted in order to give the best dynamic range for a given brightness of a scene. The digitised data are output on a 10-bit bus at 3 MHz. An on-chip state machine generates all of the control signals needed for the readout. All of the bias currents and voltages are generated on chip by a DAC that is programmable through an I 2C compatible interface. The sensor was designed and fabricated on a standard 0.5 μm CMOS technology. The overall die size is 16.7 mm×19.9 mm including the associated readout electronics and bond pads. Preliminary test results show that the full-scale design works well, meeting the Star Tracker requirements with less than 1-bit noise, good linearity and good optical performance.

  11. ADF/ADC Web Tools for Browsing and Visualizing Astronomical Catalogs and NASA Astrophysics Mission Metadata

    NASA Astrophysics Data System (ADS)

    Shaya, E.; Kargatis, V.; Blackwell, J.; Borne, K.; White, R. A.; Cheung, C.

    1998-05-01

    Several new web based services have been introduced this year by the Astrophysics Data Facility (ADF) at the NASA Goddard Space Flight Center. IMPReSS is a graphical interface to astrophysics databases that presents the user with the footprints of observations of space-based missions. It also aids astronomers in retrieving these data by sending requests to distributed data archives. The VIEWER is a reader of ADC astronomical catalogs and journal tables that allows subsetting of catalogs by column choices and range selection and provides database-like search capability within each table. With it, the user can easily find the table data most appropriate for their purposes and then download either the subset table or the original table. CATSEYE is a tool that plots output tables from the VIEWER (and soon AMASE), making exploring the datasets fast and easy. Having completed the basic functionality of these systems, we are enhancing the site to provide advanced functionality. These will include: market basket storage of tables and records of VIEWER output for IMPReSS and AstroBrowse queries, non-HTML table responses to AstroBrowse type queries, general column arithmetic, modularity to allow entrance into the sequence of web pages at any point, histogram plots, navigable maps, and overplotting of catalog objects on mission footprint maps. When completed, the ADF/ADC web facilities will provide astronomical tabled data and mission retrieval information in several hyperlinked environments geared for users at any level, from the school student to the typical astronomer to the expert datamining tools at state-of-the-art data centers.

  12. A 10 MS/s 8-bit charge-redistribution ADC for hybrid pixel applications in 65 m CMOS

    NASA Astrophysics Data System (ADS)

    Kishishita, Tetsuichi; Hemperek, Tomasz; Krüger, Hans; Koch, Manuel; Germic, Leonard; Wermes, Norbert

    2013-12-01

    The design and measurement results of an 8-bit SAR ADC, based on a charge-redistribution DAC, are presented. This ADC is characterized by superior power efficiency and small area, realized by employing a lateral metal-metal capacitor array and a dynamic two-stage comparator. To avoid the need for a high-speed clock and its associated power consumption, an asynchronous logic was implemented in a logic control cell. A test chip has been developed in a 65 nm CMOS technology, including eight ADC channels with different layout flavors of the capacitor array, a transimpedance amplifier as a signal input structure, a serializer, and a custom-made LVDS driver for data transmission. The integral (INL) and differential (DNL) nonlinearities are measured below 0.5 LSB and 0.8 LSB, respectively, for the best channel operating at a sampling frequency of 10 MS/s. The area occupies 40 μm×70 μm for one ADC channel. The power consumption is estimated as 4 μW at 1 MS/s and 38 μW at 10 MS/s with a supply rail of 1.2 V. These excellent performance features and the natural radiation hardness of the design, due to the thin gate oxide thickness of transistors, are very interesting for front-end electronics ICs of future hybrid-pixel detector systems.

  13. Weekly multimodal MRI follow-up of two multiple sclerosis active lesions presenting a transient decrease in ADC

    PubMed Central

    Hannoun, Salem; Roch, Jean-Amédée; Durand-Dubief, Francoise; Vukusic, Sandra; Sappey-Marinier, Dominique; Guttmann, Charles RG; Cotton, Francois

    2015-01-01

    Background and purpose Blood-brain barrier disruption during the earliest phases of lesion formation in multiple sclerosis (MS) patients is commonly ascribed to perivenular inflammatory activity and is usually accompanied by increased diffusivity. Reduced diffusivity has also been shown in active lesions, albeit less frequently. This study aimed to characterize the development and natural history of contrast-enhanced lesions by weekly following five relapsing remitting (RR) MS patients. Materials and methods Diffusion tensor imaging (DTI), perfusion imaging, FLAIR and contrast-enhanced 3D T1-weighted MR, were weekly performed on five untreated patients recently diagnosed with RR MS. Results All five patients showed significant increases of the apparent diffusion coefficient (ADC) in the lesions compared to the first time point. One of the five patients presented 98 active lesions on ADC maps among which 36 had a volume larger than 10 mm3. In two of these lesions, a 1 week transient decrease in ADC was detected at the time of the first gadolinium enhancement. Also, the perfusion analysis showed a concomitant increase in the relative cerebral blood volume. Conclusions The infrequency detection of such ADC decrease in a new lesion is probably due to its very short duration. This observation may be consistent with a hyper-acute inflammatory stage concomitant with an increased reactional perfusion. PMID:25642392

  14. Low-Power CMOS Laser Doppler Imaging Using Non-CDS Pixel Readout and 13.6-bit SAR ADC.

    PubMed

    Chen, Denis Guangyin; Law, Man-Kay; Lian, Yong; Bermak, Amine

    2016-02-01

    Laser Doppler imaging (LDI) measures particle flows such as blood perfusion by sensing their Doppler shift. This paper is the first of its kind in analyzing the effect of circuit noise on LDI precision which is distinctively different from conventional imaging. Based on this result, it presents a non-correlated-double-sampling (non-CDS) pixel readout scheme along with a high-resolution successive-approximation-register (SAR) analog-to-digital-converter (ADC) with 13.6b effective resolution (ER). Measurement results from the prototype chip in 0.18 μm technology confirm the theoretical analysis and show that the two techniques improve LDI sensing precision by 6.9 dB and 4.4 dB (compared to a 10b ADC) respectively without analog pre-amplification. The sensor's ADC occupies 518 μm×84 μm and is suitable for fast column parallel readout. Its differential non-linearity (DNL), integral non-linearity (INL), and input referred noise are +3.0/-2.8 LSB, +24/-17 LSB, and 110 μVrms respectively, leading to a Figure-of-Merit (FoM) of 23 fJ/state which makes it one of the most energy efficient image sensor ADCs and an order of magnitude better than the best reported LDI system using commercial high-speed image sensors. PMID:25532189

  15. A SHA-less 14-bit, 100-MS/s pipelined ADC with comparator offset cancellation in background

    NASA Astrophysics Data System (ADS)

    Xiaofei, Wang; Hong, Zhang; Jie, Zhang; Xin, Du; Yue, Hao

    2016-03-01

    A 14-bit 100-MS/s pipelined analog-to-digital converter (ADC) without dedicated front-end sample-and-hold amplifier (SHA) is presented. In addition to elaborate matching of the sampling network in the first stage, a background offset cancellation circuit is proposed in this paper to suppress the offset of the comparators in the first-stage sub-ADC, which ensures the overall offset does not exceed the correction range of the built-in redundant structure. Fabricated in a 0.18-μm CMOS technology, the presented ADC occupies a chip area of 12 mm2, and consumes 237 mW from a 1.8-V power supply. Measurement results with a 30.1-MHz input sine wave under a sampling rate of 100 MS/s show that the ADC achieves a 71-dB signal-to-noise and distortion ratio (SNDR), an 85.4-dB spurious-free dynamic range (SFDR), a maximum differential nonlinearity (DNL) of 0.22 LSB and a maximum integral nonlinearity (INL) of 1.4 LSB. Project supported by the National Natural Science Foundation of China (No. 61474092).

  16. Design of a low power 10 bit 300 ksps multi-channel SAR ADC for wireless sensor network applications

    NASA Astrophysics Data System (ADS)

    Hui, Hong; Shiliang, Li; Tao, Zhou

    2015-04-01

    This paper presents a low power 10 bit 300 ksps successive approximation register analog-to-digital converter (SAR ADC) which is applied in wireless sensor network (WSN) applications. A single ended energy-saving split capacitor DAC array and a latch comparator with a rail to rail input stage are utilized to implement the ADC, which can reduce power dissipation while expanding the full scale input range and improve the signal-to-noise ratio (SNR). For power optimization the supply voltage of the SAR ADC is designed to be as low as 2 V. Four analog input channels are designed which make the ADC more suitable for WSN applications. The prototype circuit is fabricated using 3.3 V, 0.35 μm 2P4M CMOS technology and occupies an active chip area of 1.23 mm2. The test results show that the power dissipation is only 200 μW at a 2 V power supply and a sampling rate of 166 ksps. The calculated SNR is 58.25 dB, the ENOB is 9.38 bit and the FOM is 4.95 pJ/conversion-step. Project supported by the National Natural Science Foundation of China (No. 61107025) and the Key Innovation Team Project of Zhejiang Province (No. 2010R50010).

  17. Molecular Basis of Valine-Citrulline-PABC Linker Instability in Site-Specific ADCs and Its Mitigation by Linker Design.

    PubMed

    Dorywalska, Magdalena; Dushin, Russell; Moine, Ludivine; Farias, Santiago E; Zhou, Dahui; Navaratnam, Thayalan; Lui, Victor; Hasa-Moreno, Adela; Casas, Meritxell Galindo; Tran, Thomas-Toan; Delaria, Kathy; Liu, Shu-Hui; Foletti, Davide; O'Donnell, Christopher J; Pons, Jaume; Shelton, David L; Rajpal, Arvind; Strop, Pavel

    2016-05-01

    The degree of stability of antibody-drug linkers in systemic circulation, and the rate of their intracellular processing within target cancer cells are among the key factors determining the efficacy of antibody-drug conjugates (ADC) in vivo Previous studies demonstrated the susceptibility of cleavable linkers, as well as auristatin-based payloads, to enzymatic cleavage in rodent plasma. Here, we identify Carboxylesterase 1C as the enzyme responsible for the extracellular hydrolysis of valine-citrulline-p-aminocarbamate (VC-PABC)-based linkers in mouse plasma. We further show that the activity of Carboxylesterase 1C towards VC-PABC-based linkers, and consequently the stability of ADCs in mouse plasma, can be effectively modulated by small chemical modifications to the linker. While the introduced modifications can protect the VC-PABC-based linkers from extracellular cleavage, they do not significantly alter the intracellular linker processing by the lysosomal protease Cathepsin B. The distinct substrate preference of the serum Carboxylesterase 1C offers the opportunity to modulate the extracellular stability of cleavable ADCs without diminishing the intracellular payload release required for ADC efficacy. Mol Cancer Ther; 15(5); 958-70. ©2016 AACR. PMID:26944918

  18. A 100 MS/s 9 bit 0.43 mW SAR ADC with custom capacitor array

    NASA Astrophysics Data System (ADS)

    Jingjing, Wang; Zemin, Feng; Rongjin, Xu; Chixiao, Chen; Fan, Ye; Jun, Xu; Junyan, Ren

    2016-05-01

    A low power 9 bit 100 MS/s successive approximation register analog-to-digital converter (SAR ADC) with custom capacitor array is presented. A brand-new 3-D MOM unit capacitor is used as the basic capacitor cell of this capacitor array. The unit capacitor has a capacitance of 1 fF. Besides, the advanced capacitor array structure and switch mode decrease the power consumption a lot. To verify the effectiveness of this low power design, the 9 bit 100 MS/s SAR ADC is implemented in TSMC IP9M 65 nm LP CMOS technology. The measurement results demonstrate that this design achieves an effective number of bits (ENOB) of 7.4 bit, a signal-to-noise plus distortion ratio (SNDR) of 46.40 dB and a spurious-free dynamic range (SFDR) of 62.31 dB at 100 MS/s with 1 MHz input. The SAR ADC core occupies an area of 0.030 mm2 and consumes 0.43 mW under a supply voltage of 1.2 V. The figure of merit (FOM) of the SAR ADC achieves 23.75 fJ/conv. Project supported by the National High-Tech Research and Development Program of China (No. 2013AA014101).

  19. A Fast Multiple Sampling Method for Low-Noise CMOS Image Sensors With Column-Parallel 12-bit SAR ADCs

    PubMed Central

    Kim, Min-Kyu; Hong, Seong-Kwan; Kwon, Oh-Kyong

    2015-01-01

    This paper presents a fast multiple sampling method for low-noise CMOS image sensor (CIS) applications with column-parallel successive approximation register analog-to-digital converters (SAR ADCs). The 12-bit SAR ADC using the proposed multiple sampling method decreases the A/D conversion time by repeatedly converting a pixel output to 4-bit after the first 12-bit A/D conversion, reducing noise of the CIS by one over the square root of the number of samplings. The area of the 12-bit SAR ADC is reduced by using a 10-bit capacitor digital-to-analog converter (DAC) with four scaled reference voltages. In addition, a simple up/down counter-based digital processing logic is proposed to perform complex calculations for multiple sampling and digital correlated double sampling. To verify the proposed multiple sampling method, a 256 × 128 pixel array CIS with 12-bit SAR ADCs was fabricated using 0.18 μm CMOS process. The measurement results shows that the proposed multiple sampling method reduces each A/D conversion time from 1.2 μs to 0.45 μs and random noise from 848.3 μV to 270.4 μV, achieving a dynamic range of 68.1 dB and an SNR of 39.2 dB. PMID:26712765

  20. A 12-bit 1 MS/s SAR-ADC for multi-channel CdZnTe detectors

    NASA Astrophysics Data System (ADS)

    Wei, Liu; Tingcun, Wei; Bo, Li; Panjie, Guo; Yongcai, Hu

    2015-04-01

    This paper presents a low power, area-efficient and radiation-hardened 12-bit 1 MS/s successive approximation register (SAR) analog-to-digital converter (ADC) for multi-channel CdZnTe (CZT) detector applications. In order to improve the SAR-ADC's accuracy, a novel comparator is proposed in which the offset voltage is self-calibrated and also a new architecture for the unit capacitor array is proposed to reduce the capacitance mismatches in the charge-redistribution DAC. The ability to radiation-harden the SAR-ADC is enhanced through circuit and layout design technologies. The prototype chip was fabricated using a TSMC 0.35 μm 2P4M CMOS process. At a 3.3/5 V power supply and a sampling rate of 1 MS/s, the proposed SAR-ADC achieves a peak signal to noise and distortion ratio (SINAD) of 67.64 dB and consumes only 10 mW power. The core of the prototype chip occupies an active area of 1180 × 1080 μm2. Project supported by the Special-Funded Program on National Key Scientific Instruments and Equipment Development (No. 2011YQ040082).

  1. A Fast Multiple Sampling Method for Low-Noise CMOS Image Sensors With Column-Parallel 12-bit SAR ADCs.

    PubMed

    Kim, Min-Kyu; Hong, Seong-Kwan; Kwon, Oh-Kyong

    2015-01-01

    This paper presents a fast multiple sampling method for low-noise CMOS image sensor (CIS) applications with column-parallel successive approximation register analog-to-digital converters (SAR ADCs). The 12-bit SAR ADC using the proposed multiple sampling method decreases the A/D conversion time by repeatedly converting a pixel output to 4-bit after the first 12-bit A/D conversion, reducing noise of the CIS by one over the square root of the number of samplings. The area of the 12-bit SAR ADC is reduced by using a 10-bit capacitor digital-to-analog converter (DAC) with four scaled reference voltages. In addition, a simple up/down counter-based digital processing logic is proposed to perform complex calculations for multiple sampling and digital correlated double sampling. To verify the proposed multiple sampling method, a 256 × 128 pixel array CIS with 12-bit SAR ADCs was fabricated using 0.18 μm CMOS process. The measurement results shows that the proposed multiple sampling method reduces each A/D conversion time from 1.2 μs to 0.45 μs and random noise from 848.3 μV to 270.4 μV, achieving a dynamic range of 68.1 dB and an SNR of 39.2 dB. PMID:26712765

  2. Readout concept employing a novel on-chip 16-bit ADC for smart IR focal plane arrays

    NASA Astrophysics Data System (ADS)

    Ringh, Ulf; Jansson, Christer; Liddiard, Kevin C.

    1996-06-01

    This paper discusses CMOS readout for an uncooled 2D IR array of resistance bolometers. Factors influencing the architectural choice and detailed noise considerations for the pixel select switch are covered. A parallel readout concept using one ADC per column is the suggested architecture for an uncooled CMOS IR array. In order to meet the requirement on speed and resolution a new ADC principle had to be developed. The ADC is however of general interest where resolution above 10 bits at medium speed and low cost are desired. High linearity is obtained utilizing the first- order delta-sigma converter technique, while resolution and speed is enhanced by a successive approximation of the delta-sigma integrator residual voltage. An experimental 16 X 16 infrared bolometer detector array has been designed where a row-by-row readout operation of the bolometer array is supported by a column-wise 16-bit A/D conversion. The 16- column preamplifiers and ADC structure has been implemented in a standard 0.8 micrometers CMOS process with 40 micrometers column pitch. Measured results of the experimental array is presented, including both electronics and detectors.

  3. 1-METHYL-4-PHENYL-1,2,3,6-TETRAHYDROPYRIDINE (MPTP)-INDUCED ASTROGLIOSIS DOES NOT REQUIRE ACTIVATION OF ORNITHINE DECARBOXYLASE

    EPA Science Inventory

    Mechanical injury to the brain results in enhanced immunostaining for glial fibrillary acidic protein (GFAP) that is markedly inhibited by difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase. n the current study, systemic exposure of mice to the d...

  4. TROPHIC CONTROL OF THE ORNITHINE DECARBOXYLASE/POLYAMINE SYSTEM IN NEONATAL RAT CEREBELLUM: REGIONALLY-SELECTIVE EFFECTS OF NEONATAL LESIONS CAUSED BY 6-HYDROXYDOPAMINE

    EPA Science Inventory

    Norepinephrine has been hypothesized as a trophic factor influencing postnatal development of the cerebellum. n the current study, neonatal rats were given 6-hydroxydopanine (6-OHDA) to destroy noradrenergic projections and the effects on the ornithine decarboxylase (ODC)/polyami...

  5. Inactivation of 3-(3,4-dihydroxyphenyl)alanine decarboxylase by 2-(fluoromethyl)-3-(3,4-dihydroxyphenyl)alanine.

    PubMed

    Maycock, A L; Aster, S D; Patchett, A A

    1980-02-19

    2-(Fluoromethyl)-3-(3,4-dihydroxyphenyl)alanine [alpha-FM-Dopa (I)] causes rapid, time-dependent, stereospecific, and irreversible inhibition of hog kidney aromatic amino acid (Dopa) decarboxylase. The inactivation occurs with loss of both the carboxyl carbon and fluoride from I and results in the stoichimetric formation of a covalent enzyme-inhibitor adduct. The data are consistent with I being a suicide inactivator of the enzyme, and a plausible mechanism for the inactivation process is presented. The inactivation is highly efficient in that there is essentially no enzymatic turnover of I to produce the corresponding amine, 1-(fluoromethyl)-2-(3,4-dihydroxyphenyl)ethylamine [alpha-FM-dopamine (II)]. Amine II is also a potent inactivator of the enzyme. In vivo compound I is found to inactivate both brain and peripheral (liver) Dopa decarboxylase activity. The possible significance of these data with respect to the known antihypertensive effect of I is discussed. PMID:7356954

  6. Effects of down-regulating ornithine decarboxylase upon putrescine-associated metabolism and growth in Nicotiana tabacum L.

    PubMed Central

    Dalton, Heidi L.; Blomstedt, Cecilia K.; Neale, Alan D.; Gleadow, Ros; DeBoer, Kathleen D.; Hamill, John D.

    2016-01-01

    Transgenic plants of Nicotiana tabacum L. homozygous for an RNAi construct designed to silence ornithine decarboxylase (ODC) had significantly lower concentrations of nicotine and nornicotine, but significantly higher concentrations of anatabine, compared with vector-only controls. Silencing of ODC also led to significantly reduced concentrations of polyamines (putrescine, spermidine and spermine), tyramine and phenolamides (caffeoylputrescine and dicaffeoylspermidine) with concomitant increases in concentrations of amino acids ornithine, arginine, aspartate, glutamate and glutamine. Root transcript levels of S-adenosyl methionine decarboxylase, S-adenosyl methionine synthase and spermidine synthase (polyamine synthesis enzymes) were reduced compared with vector controls, whilst transcript levels of arginine decarboxylase (putrescine synthesis), putrescine methyltransferase (nicotine production) and multi-drug and toxic compound extrusion (alkaloid transport) proteins were elevated. In contrast, expression of two other key proteins required for alkaloid synthesis, quinolinic acid phosphoribosyltransferase (nicotinic acid production) and a PIP-family oxidoreductase (nicotinic acid condensation reactions), were diminished in roots of odc-RNAi plants relative to vector-only controls. Transcriptional and biochemical differences associated with polyamine and alkaloid metabolism were exacerbated in odc-RNAi plants in response to different forms of shoot damage. In general, apex removal had a greater effect than leaf wounding alone, with a combination of these injury treatments producing synergistic responses in some cases. Reduced expression of ODC appeared to have negative effects upon plant growth and vigour with some leaves of odc-RNAi lines being brittle and bleached compared with vector-only controls. Together, results of this study demonstrate that ornithine decarboxylase has important roles in facilitating both primary and secondary metabolism in Nicotiana. PMID

  7. Role of calcium in the modulation of ornithine decarboxylase activity in isolated pig granulosa cells in vitro

    PubMed Central

    Veldhuis, Johannes D.; Hammond, James M.

    1981-01-01

    We examined the role of Ca2+ in the control of basal and hormone-stimulated ornithine decarboxylase activity in isolated pig granulosa cells maintained under chemically defined conditions in vitro. Omission of Ca2+ from the incubation medium (measured Ca2+ concentration 5μm) decreased basal enzymic activity, and significantly (P<0.01) impaired the response to maximally stimulating doses of either lutropin or follitropin. No significant alteration occurred in the concentration of either gonadotropin required to elicit half-maximal effects. The addition of EGTA (1.27–2.0mm) to chelate residual extracellular Ca2+ further decreased hormone-induced rises in ornithine decarboxylase activity. Despite the presence of 1.27mm concentrations of extracellular Ca2+, the administration of presumptive Ca2+ antagonists, believed to impair trans-membrane Ca2+ influx [verapamil (10–100μm), nifedipine (1–100μm) or CoCl2 (1mm)] suppressed hormone-stimulated ornithine decarboxylase activity. The inhibitory effects of verapamil or of Ca2+ omission from the medium were not overcome by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (0.25mm), or by cholera toxin, or by an exogenously supplied cyclic AMP analogue, 8-bromo cyclic AMP. Conversely, micromolar concentrations of a putative bivalent-cation ionophore, A23187, increased significantly the stimulation of ornithine decarboxylase activity by saturating concentrations of lutropin or 8-bromo cyclic AMP. Thus the present observations implicate Ca2+ ions in the modulation of hormone action and cellular function in normal ovarian cells. PMID:6172119

  8. Enhancement of protocatechuate decarboxylase activity for the effective production of muconate from lignin-related aromatic compounds.

    PubMed

    Sonoki, Tomonori; Morooka, Miyuki; Sakamoto, Kimitoshi; Otsuka, Yuichiro; Nakamura, Masaya; Jellison, Jody; Goodell, Barry

    2014-12-20

    The decarboxylation reaction of protocatechuate has been described as a bottleneck and a rate-limiting step in cis,cis-muconate (ccMA) bioproduction from renewable feedstocks such as sugar. Because sugars are already in high demand in the development of many bio-based products, our work focuses on improving protocatechuate decarboxylase (Pdc) activity and ccMA production in particular, from lignin-related aromatic compounds. We previously had transformed an Escherichia coli strain using aroY, which had been used as a protocatechuate decarboxylase encoding gene from Klebsiella pneumoniae subsp. pneumoniae A170-40, and inserted other required genes from Pseudomonas putida KT2440, to allow the production of ccMA from vanillin. This recombinant strain produced ccMA from vanillin, however the Pdc reaction step remained a bottleneck during incubation. In the current study, we identify a way to increase protocatechuate decarboxylase activity in E. coli through enzyme production involving both aroY and kpdB; the latter which encodes for the B subunit of 4-hydroxybenzoate decarboxylase. This permits expression of Pdc activity at a level approximately 14-fold greater than the strain with aroY only. The expression level of AroY increased, apparently as a function of the co-expression of AroY and KpdB. Our results also imply that ccMA may inhibit vanillate demethylation, a reaction step that is rate limiting for efficient ccMA production from lignin-related aromatic compounds, so even though ccMA production may be enhanced, other challenges to overcome vanilate demethylation inhibition still remain. PMID:25449108

  9. Bacterial Lysine Decarboxylase Influences Human Dental Biofilm Lysine Content, Biofilm Accumulation and Sub-Clinical Gingival Inflammation

    PubMed Central

    Lohinai, Z.; Keremi, B.; Szoko, E.; Tabi, T.; Szabo, C.; Tulassay, Z.; Levine, M.

    2012-01-01

    Background Dental biofilms contain a protein that inhibits mammalian cell growth, possibly lysine decarboxylase from Eikenella corrodens. This enzyme decarboxylates lysine, an essential amino acid for dentally attached cell turnover in gingival sulci. Lysine depletion may stop this turnover, impairing the barrier to bacterial compounds. The aims of this study were to determine biofilm lysine and cadaverine contents before oral hygiene restriction (OHR), and their association with plaque index (PI) and gingival crevicular fluid (GCF) after OHR for a week. Methods Laser-induced fluorescence after capillary electrophoresis was used to determine lysine and cadaverine contents in dental biofilm, tongue biofilm and saliva before OHR and in dental biofilm after OHR. Results Before OHR, lysine and cadaverine contents of dental biofilm were similar and 10-fold greater than in saliva or tongue biofilm. After a week of OHR, the biofilm content of cadaverine increased and that of lysine decreased, consistent with greater biofilm lysine decarboxylase activity. Regression indicated that PI and GCF exudation were positively related to biofilm lysine post-OHR, unless biofilm lysine exceeded the minimal blood plasma content in which case PI was further increased but GCF exudation was reduced. Conclusions After OHR, lysine decarboxylase activity seems to determine biofilm lysine content and biofilm accumulation. When biofilm lysine exceeds minimal blood plasma content after OHR, less GCF appeared despite more biofilm. Lysine appears important for biofilm accumulation and the epithelial barrier to bacterial proinflammatory agents. Clinical Relevance Inhibiting lysine decarboxylase may retard the increased GCF exudation required for microbial development and gingivitis. PMID:22141361

  10. Effects of down-regulating ornithine decarboxylase upon putrescine-associated metabolism and growth in Nicotiana tabacum L.

    PubMed

    Dalton, Heidi L; Blomstedt, Cecilia K; Neale, Alan D; Gleadow, Ros; DeBoer, Kathleen D; Hamill, John D

    2016-05-01

    Transgenic plants of Nicotiana tabacum L. homozygous for an RNAi construct designed to silence ornithine decarboxylase (ODC) had significantly lower concentrations of nicotine and nornicotine, but significantly higher concentrations of anatabine, compared with vector-only controls. Silencing of ODC also led to significantly reduced concentrations of polyamines (putrescine, spermidine and spermine), tyramine and phenolamides (caffeoylputrescine and dicaffeoylspermidine) with concomitant increases in concentrations of amino acids ornithine, arginine, aspartate, glutamate and glutamine. Root transcript levels of S-adenosyl methionine decarboxylase, S-adenosyl methionine synthase and spermidine synthase (polyamine synthesis enzymes) were reduced compared with vector controls, whilst transcript levels of arginine decarboxylase (putrescine synthesis), putrescine methyltransferase (nicotine production) and multi-drug and toxic compound extrusion (alkaloid transport) proteins were elevated. In contrast, expression of two other key proteins required for alkaloid synthesis, quinolinic acid phosphoribosyltransferase (nicotinic acid production) and a PIP-family oxidoreductase (nicotinic acid condensation reactions), were diminished in roots of odc-RNAi plants relative to vector-only controls. Transcriptional and biochemical differences associated with polyamine and alkaloid metabolism were exacerbated in odc-RNAi plants in response to different forms of shoot damage. In general, apex removal had a greater effect than leaf wounding alone, with a combination of these injury treatments producing synergistic responses in some cases. Reduced expression of ODC appeared to have negative effects upon plant growth and vigour with some leaves of odc-RNAi lines being brittle and bleached compared with vector-only controls. Together, results of this study demonstrate that ornithine decarboxylase has important roles in facilitating both primary and secondary metabolism in Nicotiana. PMID

  11. A 1.33 μW 8.02-ENOB 100 kS/s successive approximation ADC with supply reduction technique for implantable retinal prosthesis.

    PubMed

    Tang, Howard; Sun, Zhuo Chao; Chew, Kin Wai Roy; Siek, Liter

    2014-12-01

    This paper presents a chip level 9 bits Charge Folding Successive-Approximation-Register (SAR) Analog-to-Digital Converter (ADC) to be used in a CMOS image sensor for retinal prosthesis. It has a maximum single-ended input range of 1.8 V but only uses a supply voltage of 0.9 V for the entire ADC through the Charge Folding method. Therefore, the input range is no longer limited by the supply rail as in conventional SAR ADC. Moreover, the ADC is controlled by an internal delay line based Asynchronous Clock Generator which can be programmed to adjust the resolution of the ADC from 5 to 9 bits. Therefore, resolution adaptation function can be applied to improve the energy efficiency up to 15%. The test chip is implemented in 0.18 μm CMOS process and occupies an area of 0.15 mm(2). At 0.9 V and 100 kS/s, the 9 bit s ADC consumes 1.33 μW and achieves an energy efficiency of 51.3 fJ/conversion-step . In addition, the power consumption can be further reduced by scaling the supply voltage and sampling frequency. At 100 kS/s, this ADC is capable of converting the input signal at a rate equivalent to 30 frames/s for a pixel array up to 3200 pixels. PMID:25608284

  12. Investigation of a substrate-specifying residue within Papaver somniferum and Catharanthus roseus aromatic amino acid decarboxylases.

    PubMed

    Torrens-Spence, Michael P; Lazear, Michael; von Guggenberg, Renee; Ding, Haizhen; Li, Jianyong

    2014-10-01

    Plant aromatic amino acid decarboxylases (AAADs) catalyze the decarboxylation of aromatic amino acids with either benzene or indole rings. Because the substrate selectivity of AAADs is intimately related to their physiological functions, primary sequence data and their differentiation could provide significant physiological insights. However, due to general high sequence identity, plant AAAD substrate specificities have been difficult to identify through primary sequence comparison. In this study, bioinformatic approaches were utilized to identify several active site residues within plant AAAD enzymes that may impact substrate specificity. Next a Papaver somniferum tyrosine decarboxylase (TyDC) was selected as a model to verify our putative substrate-dictating residues through mutation. Results indicated that mutagenesis of serine 372 to glycine enables the P. somniferum TyDC to use 5-hydroxytryptophan as a substrate, and reduces the enzyme activity toward 3,4-dihydroxy-L-phenylalanine (dopa). Additionally, the reverse mutation in a Catharanthus roseus tryptophan decarboxylase (TDC) enables the mutant enzyme to utilize tyrosine and dopa as substrates with a reduced affinity toward tryptophan. Molecular modeling and molecular docking of the P. somniferum TyDC and the C. roseus TDC enzymes provided a structural basis to explain alterations in substrate specificity. Identification of an active site residue that impacts substrate selectivity produces a primary sequence identifier that may help differentiate the indolic and phenolic substrate specificities of individual plant AAADs. PMID:25107664

  13. Cloning and characterization of a locus encoding an indolepyruvate decarboxylase involved in indole-3-acetic acid synthesis in Erwinia herbicola.

    PubMed Central

    Brandl, M T; Lindow, S E

    1996-01-01

    Erwinia herbicola 299R synthesizes indole-3-acetic acid (IAA) primarily by the indole-3-pyruvic acid pathway. A gene involved in the biosynthesis of IAA was cloned from strain 299R. This gene (ipdC) conferred the synthesis of indole-3-acetaldehyde and tryptophol upon Escherichia coli DH5 alpha in cultures supplemented with L-tryptophan. The deduced amino acid sequence of the gene product has high similarity to that of the indolepyruvate decarboxylase of Enterobacter cloacae. Regions within pyruvate decarboxylases of various fungal and plant species also exhibited considerable homology to portions of this gene. This gene therefore presumably encodes an indolepyruvate decarboxylase (IpdC) which catalyzes the conversion of indole-3-pyruvic acid to indole-3-acetaldehyde. Insertions of Tn3-spice within ipdC abolished the ability of strain 299R to synthesize indole-3-acetaldehyde and tryptophol and reduced its IAA production in tryptophan-supplemented minimal medium by approximately 10-fold, thus providing genetic evidence for the role of the indolepyruvate pathway in IAA synthesis in this strain. An ipdC probe hybridized strongly with the genomic DNA of all E. herbicola strains tested in Southern hybridization studies, suggesting that the indolepyruvate pathway is common in this species. Maximum parsimony analysis revealed that the ipdC gene is highly conserved within this group and that strains of diverse geographic origin were very similar with respect to ipdC. PMID:8900003

  14. CE-LIF determination of salivary cadaverine and lysine concentration ratio as an indicator of lysine decarboxylase enzyme activity.

    PubMed

    Tábi, Tamás; Lohinai, Zsolt; Pálfi, Melinda; Levine, Martin; Szöko, Eva

    2008-05-01

    Salivary bacteria produce the enzyme lysine decarboxylase which converts lysine to cadaverine. In the absence of appropriate oral hygiene, overgrowth of these bacteria depletes lysine. This may contribute to gingival inflammation, while cadaverine contributes to oral malodor. A selective and sensitive capillary electrophoresis method with laser-induced fluorescence detection has been developed for the determination of cadaverine and lysine in saliva, as an indicator of lysine decarboxylase enzyme activity. The diamino compounds were separated in acidic background electrolyte in their mono-labeled form after derivatization with 4-fluoro-7-nitrobenz-2-oxa-1,3-diazole (NBD-F). Linearity and reproducibility of the method in the range 1-50 μmol L(-1) have been demonstrated using saliva samples. The method was applied for the measurement of cadaverine and lysine in the saliva of healthy volunteers with or without proper oral hygiene. In the absence of oral hygiene, the mol fraction of cadaverine to cadaverine plus lysine in saliva increased significantly (0.65 ± 0.13 vs. 0.39 ± 0.18, P < 0.001), indicating the presence of higher amount of bacterial lysine decarboxylase, that may contribute to periodontal diseases. PMID:18389226

  15. Common Variation in the DOPA Decarboxylase (DDC) Gene and Human Striatal DDC Activity In Vivo.

    PubMed

    Eisenberg, Daniel P; Kohn, Philip D; Hegarty, Catherine E; Ianni, Angela M; Kolachana, Bhaskar; Gregory, Michael D; Masdeu, Joseph C; Berman, Karen F

    2016-08-01

    The synthesis of multiple amine neurotransmitters, such as dopamine, norepinephrine, serotonin, and trace amines, relies in part on DOPA decarboxylase (DDC, AADC), an enzyme that is required for normative neural operations. Because rare, loss-of-function mutations in the DDC gene result in severe enzymatic deficiency and devastating autonomic, motor, and cognitive impairment, DDC common genetic polymorphisms have been proposed as a source of more moderate, but clinically important, alterations in DDC function that may contribute to risk, course, or treatment response in complex, heritable neuropsychiatric illnesses. However, a direct link between common genetic variation in DDC and DDC activity in the living human brain has never been established. We therefore tested for this association by conducting extensive genotyping across the DDC gene in a large cohort of 120 healthy individuals, for whom DDC activity was then quantified with [(18)F]-FDOPA positron emission tomography (PET). The specific uptake constant, Ki, a measure of DDC activity, was estimated for striatal regions of interest and found to be predicted by one of five tested haplotypes, particularly in the ventral striatum. These data provide evidence for cis-acting, functional common polymorphisms in the DDC gene and support future work to determine whether such variation might meaningfully contribute to DDC-mediated neural processes relevant to neuropsychiatric illness and treatment. PMID:26924680

  16. Enhanced histamine production through the induction of histidine decarboxylase expression by phorbol ester in Jurkat cells.

    PubMed

    Nagashima, Yusuke; Kako, Koichiro; Kim, Jun-Dal; Fukamizu, Akiyoshi

    2012-11-01

    Histamine (HA), a mediator of inflammation, type I allergic responses and neurotransmission, is synthesized from L-histidine, the reaction of which is catalyzed by histidine decarboxylase (HDC). HDC has been reported to be induced by various stimuli, not only in mast cells and basophils, but also in T lymphocytes and macrophages. Although its mRNA has been shown to be increased in Jurkat cells when treated with phorbol 12-myristate 13-acetate (TPA), little is known concerning the induced production of HA by HDC. The present study quantified the trace amounts of intracellular HA using ultra-high liquid chromatography in combination with the 6-aminoquinoline carbamate-derivatization technique. To test whether the cellular level of HA is elevated by the induction of HDC in Jurkat cells treated with TPA, the peak corresponding to authentic HA in the cell lysate was fractioned and its molecular weight determined by matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry. The results of this study show that the HA level is increased by the induction of HDC expression by TPA in Jurkat cells. Therefore, this method is useful in elucidating the physiological significance of HA production. PMID:22940786

  17. [Enhancing glutamate decarboxylase activity by site-directed mutagenesis: an insight from Ramachandran plot].

    PubMed

    Ke, Piyu; Huang, Jun; Hu, Sheng; Zhao, Weirui; Lü, Changjiang; Yu, Kai; Lei, Yinlin; Wang, Jinbo; Mei, Lehe

    2016-01-01

    Glutamate decarboxylase (GAD) can catalyze the decarboxylation of glutamate into γ-aminobutyrate (GABA) and is the only enzyme of GABA biosynthesis. Improving GAD activity and thermostability will be helpful for the highly efficient biosynthesis of GABA. According to the Ramachandran plot information of GAD 1407 three-dimensional structure from Lactobacillus brevis CGMCC No. 1306, we identified the unstable site K413 as the mutation target, constructed the mutant GAD by site-directed mutagenesis and measured the thermostability and activity of the wide type and mutant GAD. Mutant K413A led to a remarkably slower inactivation rate, and its half-life at 50 °C reached 105 min which was 2.1-fold higher than the wild type GAD1407. Moreover, mutant K413I exhibited 1.6-fold higher activity in comparison with the wide type GAD1407, although it had little improvement in thermostability of GAD. Ramachandran plot can be considered as a potential approach to increase GAD thermostability and activity. PMID:27443004

  18. Novel protein-protein interaction between spermidine synthase and S-adenosylmethionine decarboxylase from Leishmania donovani.

    PubMed

    Mishra, Arjun K; Agnihotri, Pragati; Srivastava, Vijay Kumar; Pratap, J Venkatesh

    2015-01-01

    Polyamine biosynthesis pathway has long been considered an essential drug target for trypanosomatids including Leishmania. S-adenosylmethionine decarboxylase (AdoMetDc) and spermidine synthase (SpdSyn) are enzymes of this pathway that catalyze successive steps, with the product of the former, decarboxylated S-adenosylmethionine (dcSAM), acting as an aminopropyl donor for the latter enzyme. Here we have explored the possibility of and identified the protein-protein interaction between SpdSyn and AdoMetDc. The protein-protein interaction has been identified using GST pull down assay. Isothermal titration calorimetry reveals that the interaction is thermodynamically favorable. Fluorescence spectroscopy studies also confirms the interaction, with SpdSyn exhibiting a change in tertiary structure with increasing concentrations of AdoMetDc. Size exclusion chromatography suggests the presence of the complex as a hetero-oligomer. Taken together, these results suggest that the enzymes indeed form a heteromer. Computational analyses suggest that this complex differs significantly from the corresponding human complex, implying that this complex could be a better therapeutic target than the individual enzymes. PMID:25511700

  19. Quaternary Structure of the Oxaloacetate Decarboxylase Membrane Complex and Mechanistic Relationships to Pyruvate Carboxylases*

    PubMed Central

    Balsera, Monica; Buey, Ruben M.; Li, Xiao-Dan

    2011-01-01

    The oxaloacetate decarboxylase primary Na+ pump (OAD) is an essential membrane protein complex that functions in the citrate fermentation pathway of some pathogenic bacteria under anaerobic conditions. OAD contains three different subunits: Oad-α, a biotinylated extrinsic protein that catalyzes the α-ketodecarboxylation of oxaloacetate; Oad-γ, a structural bitopic membrane protein whose cytosolic tail (named as Oad-γ′) binds tightly to Oad-α; and Oad-β, a multispan transmembrane α-helical protein that constitutes the Na+ channel. How OAD is organized structurally at the membrane and what the molecular determinants are that lead to an efficient energy coupling mechanism remain elusive. In the present work, we elucidate the stoichiometry of the native complex as well as the low resolution structure of the peripheral components of OAD (Oad-α and Oad-γ′) by small angle x-ray scattering. Our results point to a quaternary assembly similar to the pyruvate carboxylase complex organization. Herein, we propose a model in which the association in pairs of Oad-α dimers, mediated by Oad-γ, results in the acquisition of a functional oligomeric state at the bacterial membrane. New structural insights for the conformational rearrangements associated with the carboxylbiotin transfer reaction within OAD are provided. PMID:21209096

  20. Aspartate beta-decarboxylase from Alcaligenes faecalis: carbon-13 kinetic isotope effect and deuterium exchange experiments

    SciTech Connect

    Rosenberg, R.M.; O'Leary, M.H.

    1985-03-26

    The authors have measured the /sup 13/C kinetic isotope effect at pH 4.0, 5.0, 6.0, and 6.5 and in D/sub 2/O at pH 5.0 and the rate of D-H exchange of the alpha and beta protons of aspartic acid in D/sub 2/O at pH 5.0 for the reaction catalyzed by the enzyme aspartate beta-decarboxylase from Alcaligenes faecalis. The /sup 13/C kinetic isotope effect, with a value of 1.0099 +/- 0.0002 at pH 5.0, is less than the intrinsic isotope effect for the decarboxylation step, indicating that the decarboxylation step is not entirely rate limiting. The authors have been able to estimate probable values of the relative free energies of the transition states of the enzymatic reaction up to and including the decarboxylation step from the /sup 13/C kinetic isotope effect and the rate of D-H exchange of alpha-H. The pH dependence of the kinetic isotope effect reflects the pKa of the pyridine nitrogen of the coenzyme pyridoxal 5'-phosphate but not that of the imine nitrogen. A mechanism is proposed for the exchange of aspartate beta-H that is consistent with the stereochemistry suggested earlier.

  1. Cloning and primary structure of a human islet isoform of glutamic acid decarboxylase from chromosome 10

    SciTech Connect

    Karlsen, A.E.; Hagopian, W.A.; Grubin, C.E.; Dube, S.; Disteche, C.M.; Adler, D.A.; Baermeier, H.; Lernmark, A. ); Mathewes, S.; Grant, F.J.; Foster, D. )

    1991-10-01

    Glutamic acid decarboxylase which catalyzes formation of {gamma}-aminobutyric acid from L-glutamic acid, is detectable in different isoforms with distinct electrophoretic and kinetic characteristics. GAD has also been implicated as an autoantigen in the vastly differing autoimmune disease stiff-man syndrome and insulin-dependent diabetes mellitus. Despite the differing GAD isoforms, only one type of GAD cDNA (GAD-1), localized to a syntenic region of chromosome 2, has been isolated from rat, mouse, and cat. Using sequence information from GAD-1 to screen a human pancreatic islet cDNA library, the authors describe the isolation of an additional GAD cDNA (GAD-2), which was mapped to the short arm of human chromosome 10. Genomic Southern blotting with GAD-2 demonstrated a hybridization pattern different form that detected by GAD-1. GAD-2 recognizes a 5.6-kilobase transcript in both islets and brain, in contrast to GAD-1, which detects a 3.7-kilobase transcript in brain only. The deduced 585-amino acid sequence coded for by GAD-2 shows < 65% identify to previously published, highly conserved GAD-1 brain sequences, which show > 96% deduced amino acid sequence homology among the three species.

  2. Functional and conformational transitions of mevalonate diphosphate decarboxylase from Bacopa monniera.

    PubMed

    Abbassi, Shakeel; Patel, Krunal; Khan, Bashir; Bhosale, Siddharth; Gaikwad, Sushama

    2016-02-01

    Functional and conformational transitions of mevalonate diphosphate decarboxylase (MDD), a key enzyme of mevalonate pathway in isoprenoid biosynthesis, from Bacopa monniera (BmMDD), cloned and overexpressed in Escherichia coli were studied under thermal, chemical and pH-mediated denaturation conditions using fluorescence and Circular dichroism spectroscopy. Native BmMDD is a helix dominant structure with 45% helix and 11% sheets and possesses seven tryptophan residues with two residues exposed on surface, three residues partially exposed and two situated in the interior of the protein. Thermal denaturation of BmMDD causes rapid structural transitions at and above 40°C and transient exposure of hydrophobic residues at 50°C, leading to aggregation of the protein. An acid induced molten globule like structure was observed at pH 4, exhibiting altered but compact secondary structure, distorted tertiary structure and exposed hydrophobic residues. The molten globule displayed different response at higher temperature and similar response to chemical denaturation as compared to the native protein. The surface tryptophans have predominantly positively charged amino acids around them, as indicated by higher KSV for KI as compared to that for CsCl. The native enzyme displayed two different lifetimes, τ1 (1.203±0.036 ns) and τ2 (3.473±0.12 ns) indicating two populations of tryptophan. PMID:26657583

  3. Non-convulsive status epilepticus associated with glutamic acid decarboxylase antibody.

    PubMed

    Cikrikçili, Ugur; Ulusoy, Canan; Turan, Selin; Yildiz, Senay; Bilgiç, Basar; Hanagasi, Hasmet; Baykan, Betül; Tüzün, Erdem; Gürvit, Hakan

    2013-07-01

    Autoimmune encephalitis associated with glutamic acid decarboxylase antibodies (GAD-Ab) often presents with treatment-resistant partial seizures, as well as other central nervous system symptoms. In contrast to several other well-characterized autoantibodies, GAD-Ab has very rarely been associated with status epilepticus. We report a 63-year-old woman initially admitted with somnolence and psychiatric findings. The EEG findings, of generalized and rhythmical slow spike-wave activity over the posterior regions of both hemispheres, together with the clinical deterioration in responsiveness, led to the diagnosis of non-convulsive status epilepticus. Investigation of a broad panel of autoantibodies, revealed only increased serum GAD-Ab levels. Following methylprednisolone and intravenous immunoglobulin treatments, the patient's neurological symptoms improved, EEG findings disappeared and GAD-Ab levels significantly decreased. GAD-Ab should be added to the list of anti-neuronal antibodies associated with non-convulsive status epilepticus. Disappearance of clinical findings and seroreversion after immunotherapy suggest that GAD-Ab might be involved in seizure pathogenesis.  PMID:23820312

  4. Highly active and stable oxaloacetate decarboxylase Na⁺ pump complex for structural analysis.

    PubMed

    Inoue, Michio; Li, Xiaodan

    2015-11-01

    The oxaloacetate decarboxylase primary Na(+) pump (Oad) produces energy for the surviving of some pathogenic bacteria under anaerobic conditions. Oad composes of three subunits: Oad-α, a biotinylated soluble subunit and catalyzes the decarboxylation of oxaloacetate; Oad-β, a transmembrane subunit and functions as a Na(+) pump; and Oad-γ, a single transmembrane α-helical anchor subunit and assembles Oad-α/β/γ complex. The molecular mechanism of Oad complex coupling the exothermic decarboxylation to generate the Na(+) electrochemical gradient remains unsolved. Our biophysical and biochemical studies suggested that the stoichiometry of Oad complex from Vibrio cholerae composed of α, β, γ in 4:2:2 stoichiometry not that of 4:4:4. The high-resolution structure determination of the Oad complex would reveal the energetic transformation mechanism from the catalytical soluble α subunit to membrane β subunit. Sufficient amount stable, conformational homogenous and active Oad complex with the right stoichiometry is the prerequisite for structural analysis. Here we report an easy and reproducible protocol to obtain high quantity and quality Oad complex protein for structural analysis. PMID:25986323

  5. Isolation and characterization of Saccharomyces cerevisiae mutants deficient in S-adenosylmethionine decarboxylase, spermidine, and spermine.

    PubMed Central

    Cohn, M S; Tabor, C W; Tabor, H

    1978-01-01

    Four mutants were isolated from Saccharomyces cerevisiae that are deficient in S-adenosylmethionine decarboxylase (spe2). All four mutants are chromosomal and fall into a single complementation group tightly linked to arg1. Since one of the mutants contained a temperature-sensitive activity, this complementation group defines the structural gene. Mutants totally lacking enzymic activity did not contain spermidine or spermine and had a greatly increased doubling time when grown in the absence of these two polyamines. Addition of 10(-6) M spermidine or 10(-5) M spermine, but not putrescine or cadaverine, restored the doubling time to that of the wild type. Diploids formed from a cross of two mutants completely deficient in spermidine and spermine were unable to sporulate in the absence of added spermidine or spermine. We obtained evidence that arg1 was not located on any of the 17 known chromosomes, and therefore we postulate that arg1 and spe2 are located on a new 18th chromosome. PMID:348678

  6. Complexes of Thermotoga maritima S-adenosylmethionine decarboxylase provide insights into substrate specificity

    SciTech Connect

    Bale, Shridhar; Baba, Kavita; McCloskey, Diane E.; Pegg, Anthony E.; Ealick, Steven E.

    2010-06-25

    The polyamines putrescine, spermidine and spermine are ubiquitous aliphatic cations and are essential for cellular growth and differentiation. S-Adenosylmethionine decarboxylase (AdoMetDC) is a critical pyruvoyl-dependent enzyme in the polyamine-biosynthetic pathway. The crystal structures of AdoMetDC from humans and plants and of the AdoMetDC proenzyme from Thermotoga maritima have been obtained previously. Here, the crystal structures of activated T. maritima AdoMetDC (TmAdoMetDC) and of its complexes with S-adenosylmethionine methyl ester and 5{prime}-deoxy-5{prime}-dimethylthioadenosine are reported. The results demonstrate for the first time that TmAdoMetDC autoprocesses without the need for additional factors and that the enzyme contains two complete active sites, both of which use residues from both chains of the homodimer. The complexes provide insights into the substrate specificity and ligand binding of AdoMetDC in prokaryotes. The conservation of the ligand-binding mode and the active-site residues between human and T. maritima AdoMetDC provides insight into the evolution of AdoMetDC.

  7. Rapid glutamic acid decarboxylase test for identification of Bacteroides and Clostridium spp.

    PubMed Central

    Jilly, B J; Schreckenberger, P C; LeBeau, L J

    1984-01-01

    A rapid 4-h test for glutamic acid decarboxylase is described for the identification of certain anaerobic bacteria. The test substrate consisted of 1.0 g of L-glutamic acid, 0.3 ml of Triton X-155, and 0.05 g of bromcresol green sodium salt in 1 liter of water. The substrate was dispensed in 0.5-ml amounts into test tubes, and a turbid suspension was made with the test organism. The test was then incubated aerobically at 35 degrees C for 4 h. The development of a blue color was considered positive. A total of 345 strains of clinically isolated anaerobic bacteria were tested. All isolates of Bacteroides fragilis, Bacteroides thetaiotaomicron, Bacteroides uniformis. Clostridium perfringens, and Clostridium sordellii gave a positive reaction. Some isolates of Bacteroides distasonis and Bacteroides vulgatus were also positive. The use of this rapid test in conjunction with other rapid methods, such as the spot indol test, will enable laboratory workers to report these pathogens on the same day on which an inoculum of pure culture growth on agar is available. PMID:6376535

  8. Tryptamine-induced resistance in tryptophan decarboxylase transgenic poplar and tobacco plants against their specific herbivores.

    PubMed

    Gill, Rishi I S; Ellis, Brian E; Isman, Murray B

    2003-04-01

    The presence of amines and their derivatives in plant tissues is known to influence insect feeding and reproduction. The enzyme tryptophan decarboxylase (TDC) catalyzes the decarboxylation of tryptophan to tryptamine, which is both a bioactive amine and a precursor of other indole derivatives. Transgenic poplar and tobacco plants ectopically expressing TDC1 accumulated elevated levels of tryptamine without affecting plant growth and development. This accumulation was consistently associated with adverse effects on feeding behavior and physiology of Malacosoma disstria Hub. (forest tent caterpillar, FTC) and Manduca sexta L. (tobacco hornworm, THW). Behavior studies with FTC and THW larvae showed that acceptability of the leaf tissue to larvae was inversely related to foliar tryptamine levels. Physiological studies with FTC and THW larvae showed that consumption of leaf tissue from the transgenic lines is deleterious to larvae growth, apparently due to a postingestive mechanism. Thus, ectopic expression of TDC1 can allow sufficient tryptamine to accumulate in poplar and tobacco leaf tissue to suppress significantly the growth of insect pests that normally feed on these plants. PMID:12775143

  9. Induction of histidine decarboxylase in macrophages inhibited by the novel NF-{kappa}B inhibitor (-)-DHMEQ

    SciTech Connect

    Suzuki, Eriko Ninomiya, Yoko; Umezawa, Kazuo

    2009-02-06

    Histamine often causes inflammation, and this amine is produced by histidine decarboxylase (HDC). We found that (-)-DHMEQ, an NF-{kappa}B inhibitor, inhibited lipopolysaccharide (LPS)-induced histamine production and HDC induction in mouse macrophage cell line RAW264.7. However, as there is no {kappa}B site in the HDC promoter, we studied the mechanism of inhibition. Knockdown of the transcription factor C/EBP{beta} reduced the HDC expression in LPS-treated cells. (-)-DHMEQ inhibited the C/EBP{beta} transcriptional activity in a reporter assay and in an electrophoresis mobility shift assay. But it did not inhibit the in vitro binding of C/EBP{beta} to DNA. It also did not lower the nuclear amount of C/EBP{beta}. On the other hand, the addition of recombinant p65, a component of NF-{kappa}B, enhanced the activity of C/EBP{beta} acting as a cofactor in vitro. Then, we found that (-)-DHMEQ lowered the nuclear amount of p65. Thus, inhibition of the C/EBP{beta} activity by (-)-DHMEQ would be due to a reduction in the amount of nuclear p65, which has a co-activator activity for C/EBP{beta} that is essential for the HDC induction. (-)-DHMEQ may be useful as an anti-inflammatory agent by lowering the histamine production in the body.

  10. Gastric protection by meciadanol. A new synthetic flavonoid inhibiting histidine decarboxylase.

    PubMed

    Konturek, S J; Kitler, M E; Brzozowski, T; Radecki, T

    1986-08-01

    Flavonoids reportedly inhibit histidine decarboxylase and reduce gastric mucosal histamine content. We studied the effects of acute and chronic intragastric administration to rats of meciadanol, a new synthetic flavonoid (Zyma S.A., Nyon, Switzerland). The action of meciadanol was compared to that of 16,16-dimethyl PGE2. Meciadanol did not affect acid or pepsin output at any dose used. High doses of 16,16-dimethyl PGE2 reduced both acid and pepsin output. Meciadanol partially prevented aspirin-induced lesions but the prevention required chronic administration of meciadanol. In contrast, a single dose of meciadanol completely prevented ethanol-induced lesions. Chronic administration of meciadanol also completely prevented ethanol-induced lesions. 16,16-Dimethyl PGE2 prevented both aspirin-induced and ethanol-induced lesions in doses that did not affect acid or pepsin output. Meciadanol did not influence the effect that either aspirin or ethanol had on endogenous mucosal PGI2. Thus, the dose range of meciadanol that protected against ulcerogens did not affect either gastric acid secretion or pepsin output. Therefore, we conclude that meciadanol's action represents true cytoprotection, which was previously attributed only to prostaglandins. PMID:3525045

  11. Structural basis of Ornithine Decarboxylase inactivation and accelerated degradation by polyamine sensor Antizyme1

    PubMed Central

    Wu, Donghui; Kaan, Hung Yi Kristal; Zheng, Xiaoxia; Tang, Xuhua; He, Yang; Vanessa Tan, Qianmin; Zhang, Neng; Song, Haiwei

    2015-01-01

    Ornithine decarboxylase (ODC) catalyzes the first and rate-limiting step of polyamine biosynthesis in humans. Polyamines are essential for cell proliferation and are implicated in cellular processes, ranging from DNA replication to apoptosis. Excessive accumulation of polyamines has a cytotoxic effect on cells and elevated level of ODC activity is associated with cancer development. To maintain normal cellular proliferation, regulation of polyamine synthesis is imposed by Antizyme1 (AZ1). The expression of AZ1 is induced by a ribosomal frameshifting mechanism in response to increased intracellular polyamines. AZ1 regulates polyamine homeostasis by inactivating ODC activity and enhancing its degradation. Here, we report the structure of human ODC in complex with N-terminally truncated AZ1 (cAZ1). The structure shows cAZ1 binding to ODC, which occludes the binding of a second molecule of ODC to form the active homodimer. Consequently, the substrate binding site is disrupted and ODC is inactivated. Structural comparison shows that the binding of cAZ1 to ODC causes a global conformational change of ODC and renders its C-terminal region flexible, therefore exposing this region for degradation by the 26S proteasome. Our structure provides the molecular basis for the inactivation of ODC by AZ1 and sheds light on how AZ1 promotes its degradation. PMID:26443277

  12. Structural analysis of Bacillus pumilus phenolic acid decarboxylase, a lipocalin-fold enzyme.

    PubMed

    Matte, Allan; Grosse, Stephan; Bergeron, Hélène; Abokitse, Kofi; Lau, Peter C K

    2010-11-01

    The decarboxylation of phenolic acids, including ferulic and p-coumaric acids, to their corresponding vinyl derivatives is of importance in the flavouring and polymer industries. Here, the crystal structure of phenolic acid decarboxylase (PAD) from Bacillus pumilus strain UI-670 is reported. The enzyme is a 161-residue polypeptide that forms dimers both in the crystal and in solution. The structure of PAD as determined by X-ray crystallography revealed a β-barrel structure and two α-helices, with a cleft formed at one edge of the barrel. The PAD structure resembles those of the lipocalin-fold proteins, which often bind hydrophobic ligands. Superposition of structurally related proteins bound to their cognate ligands shows that they and PAD bind their ligands in a conserved location within the β-barrel. Analysis of the residue-conservation pattern for PAD-related sequences mapped onto the PAD structure reveals that the conservation mainly includes residues found within the hydrophobic core of the protein, defining a common lipocalin-like fold for this enzyme family. A narrow cleft containing several conserved amino acids was observed as a structural feature and a potential ligand-binding site. PMID:21045284

  13. Structural analysis of Bacillus pumilus phenolic acid decarboxylase, a lipocalin-fold enzyme

    SciTech Connect

    Matte, Allan; Grosse, Stephan; Bergeron, Hélène; Abokitse, Kofi; Lau, Peter C.K.

    2012-04-30

    The decarboxylation of phenolic acids, including ferulic and p-coumaric acids, to their corresponding vinyl derivatives is of importance in the flavoring and polymer industries. Here, the crystal structure of phenolic acid decarboxylase (PAD) from Bacillus pumilus strain UI-670 is reported. The enzyme is a 161-residue polypeptide that forms dimers both in the crystal and in solution. The structure of PAD as determined by X-ray crystallography revealed a -barrel structure and two -helices, with a cleft formed at one edge of the barrel. The PAD structure resembles those of the lipocalin-fold proteins, which often bind hydrophobic ligands. Superposition of structurally related proteins bound to their cognate ligands shows that they and PAD bind their ligands in a conserved location within the -barrel. Analysis of the residue-conservation pattern for PAD-related sequences mapped onto the PAD structure reveals that the conservation mainly includes residues found within the hydrophobic core of the protein, defining a common lipocalin-like fold for this enzyme family. A narrow cleft containing several conserved amino acids was observed as a structural feature and a potential ligand-binding site.

  14. Overexpression of Tyrosine hydroxylase and Dopa decarboxylase associated with pupal melanization in Spodoptera exigua

    PubMed Central

    Liu, Sisi; Wang, Mo; Li, Xianchun

    2015-01-01

    Melanism has been found in a wide range of species, but the molecular mechanisms involved remain largely elusive. In this study, we studied the molecular mechanisms of the pupal melanism in Spodoptera exigua. The full length cDNA sequences of tyrosine hydroxylase (TH) and dopa decarboxylase (DDC), two key enzymes in the biosynthesis pathway of melanin, were cloned, and their temporal expression patterns in the integument were compared during the larval-pupal metamorphosis process of the S. exigua wild type (SEW) and melanic mutant (SEM) strains. No amino acid change in the protein sequence of TH and DDC was found between the two strains. Both DDC and TH were significantly over-expressed in the integument of the SEM strain at late-prepupa and 0 h pupa, respectively, compared with those of the SEW strain. Feeding 5th instar larvae of SEM with diets incorporated with 1 mg/g of the DDC inhibitor L-α-Methyl-DOPA and 0.75 mg/g of the TH inhibitor 3-iodo-tyrosine (3-IT) resulted in 20% pupae with partially-rescued phenotype and 68.2% of pupae with partially- or fully-rescued phenotype, respectively. These results indicate that overexpressions of TH and DDC are involved in the pupal melanization of S. exigua. PMID:26084938

  15. Auxins Induce Tryptophan Decarboxylase Activity in Radicles of Catharanthus Seedlings 1

    PubMed Central

    Aerts, Rob J.; Alarco, Anne-Marie; De Luca, Vincenzo

    1992-01-01

    Germinating seedlings of Catharanthus roseus produce monoterpenoid indole alkaloids as a result of a transient increase of tryptophan decarboxylase (TDC) activity. The influence of auxins on this transient rise of TDC activity was studied. External application of indolebutyric acid or 2,4-dichlorophenoxyacetic acid at a concentration of 20 to 40 μm enhanced and prolonged the rise in TDC activity in developing seedlings. Auxin treatment also influenced the morphology of the seedlings; it induced a shortening and thickening of the hypocotyl and the radicle and promoted the initiation of lateral roots in the radicle. During development, the radicles of auxin-treated seedlings displayed a gradual increase in TDC activity that was absent in the radicles of untreated controls. Examination of immunoblots revealed anti-TDC reactive proteins in extracts from radicles of auxin-treated seedlings, but none in extracts from radicles of control seedlings. In contrast, TDC activity and immunoreactive protein levels in the aerial parts of controls and auxin-treated seedlings were comparable. Our results indicate that externally applied auxins induce both abnormal development and TDC activity in the radicles of Catharanthus seedlings. Although auxins slightly delayed the light-mediated induction of the cotyledon-specific last step in vindoline biosynthesis (i.e. acetylcoenzyme A: deacetylvindolin-O-acetyltransferase activity), seedlings still synthesized vindoline, one of the major alkaloid end products. Images Figure 2 PMID:16653009

  16. Transcriptional regulation of glutamic acid decarboxylase in the male mouse amygdala by dietary phyto-oestrogens.

    PubMed

    Sandhu, K V; Yanagawa, Y; Stork, O

    2015-04-01

    Phyto-oestrogens are biologically active components of many human and laboratory animal diets. In the present study, we investigated, in adult male mice with C57BL/6 genetic background, the effects of a reduced phyto-oestrogens intake on anxiety-related behaviour and associated gene expression in the amygdala. After 6 weeks on a low-phyto-oestrogen diet (< 20 μg/g cumulative phyto-oestrogen content), animals showed reduced centre exploration in an open-field task compared to their littermates on a soybean-based standard diet (300 μg/g). Freezing behaviour in an auditory fear memory task, in contrast, was not affected. We hypothesised that this mildly increased anxiety may involve changes in the function of GABAergic local circuit neurones in the amygdala. Using GAD67(+/GFP) mice, we could demonstrate reduced transcription of the GAD67 gene in the lateral and basolateral amygdala under the low-phyto-oestrogen diet. Analysis of mRNA levels in microdissected samples confirmed this regulation and demonstrated concomitant changes in expression of the second glutamic acid decarboxylase (GAD) isoform, GAD65, as well as the anxiolytic neuropeptide Y. These molecular and behavioural alterations occurred without apparent changes in circulating oestrogens or testosterone levels. Our data suggest that expression regulation of interneurone-specific gene products in the amygdala may provide a mechanism for the control of anxiety-related behaviour through dietary phyto-oestrogens. PMID:25650988

  17. Change in the protein level of mevalonate pyrophosphate decarboxylase in tissues of mouse by pravastatin.

    PubMed

    Michihara, Akihiro; Akasaki, Kenji; Yamori, Yukio; Tsuji, Hiroshi

    2003-08-01

    We previously reported that treatment of rats with a diet containing 0.1% pravastatin and 5% cholestyramine markedly increased mevalonate pyrophosphate decarboxylase (MPD) activity in liver crude extracts compared with nontreated rats. In this study, we examined the change in the protein level of MPD in the tissues of mice administered pravastatin. When MPD content in the tissues of nontreated mice was analyzed by quantitative immunoblotting, a single protein band with an apparent molecular weight of 46 kDa was detected in all tissues and the specific protein content of MPD in liver and kidney was markedly higher than that in other tissues. When MPD content in the tissues of pravastatin-treated mice was analyzed by immunoblotting, MPD was markedly increased (9-fold) only in the liver compared with nontreated mice. Next, when MPD activity was measured in the liver between nontreated and pravastatin-treated mice, MPD activity as well as protein levels were markedly increased (11-fold) in the liver of pravastatin-treated mice compared with nontreated mice. These data suggest that a marked induction of MPD in the liver by pravastatin is responsible for the tissue-specific effect of pravastatin. PMID:12913254

  18. Histidine Decarboxylases and Their Role in Accumulation of Histamine in Tuna and Dried Saury▿

    PubMed Central

    Kanki, Masashi; Yoda, Tomoko; Tsukamoto, Teizo; Baba, Eiichiroh

    2007-01-01

    Histamine-producing bacteria (HPB) such as Photobacterium phosphoreum and Raoultella planticola possess histidine decarboxylase (HDC), which converts histidine into histamine. Histamine fish poisoning (HFP) is attributable to the ingestion of fish containing high levels of histamine produced by HPB. Because freezing greatly decreases the histamine-producing ability of HPB, especially of P. phosphoreum, it has been speculated that HFP is caused by HDC itself from HPB cells autolyzing during frozen storage, even when HPB survive frozen storage. Here we constructed recombinant HDCs of P. phosphoreum, Photobacterium damselae, R. planticola, and Morganella morganii and investigated the ability of HDCs to produce sufficient histamine to cause HFP. To elucidate the character of these HDCs, we examined the specific activity of each recombinant HDC at various temperatures, pH levels, and NaCl concentrations. Further, we also investigated the stability of each HDC under different conditions (in reaction buffer, tuna, and dried saury) at various temperatures. P. damselae HDC readily produced sufficient histamine to cause HFP in fish samples. We consider that if HDC is implicated as an independent cause of HFP in frozen-thawed fish, the most likely causative agent is HDC of P. damselae. PMID:17220267

  19. Enhanced production of butanol and acetoin by heterologous expression of an acetolactate decarboxylase in Clostridium acetobutylicum.

    PubMed

    Shen, Xiaoning; Liu, Dong; Liu, Jun; Wang, Yanyan; Xu, Jiahui; Yang, Zhengjiao; Guo, Ting; Niu, Huanqing; Ying, Hanjie

    2016-09-01

    Butanol is an important industrial chemical and an attractive transportation fuel. However, the deficiency of reducing equivalents NAD(P)H in butanol fermentation results in a large quantity of oxidation products, which is a major problem limiting the atom economy and economic viability of bio-butanol processes. Here, we integrated the butanol fermentation process with a NADH-generating, acetoin biosynthesis process to improve the butanol production. By overexpressing the α-acetolactate decarboxylase gene alsD from Bacillus subtilis in Clostridium acetobutylicum, acetoin yield was significantly increased at the cost of acetone. After optimization of fermentation conditions, butanol (12.9g/L), acetoin (6.5g/L), and ethanol (1.9g/L) were generated by the recombinant strain, with acetone no more than 1.8g/L. Thus, both mass yield and product value were greatly improved. This study demonstrates that reducing power compensation is effective to improve the atom economy of butanol fermentation, and provides a novel approach to improve the economic viability of bio-butanol production. PMID:27285575

  20. Effect of retinoic acid on transglutaminase and ornithine decarboxylase activities during liver regeneration.

    PubMed

    Ohtake, Yosuke; Maruko, Akiko; Ohishi, Nao; Kawaguchi, Masasumi; Satoh, Tetsuharu; Ohkubo, Yasuhito

    2008-04-01

    Liver regeneration is regulated by several factors, including growth factors, cytokines, and post-translational modifications of several proteins. It is suggested that transglutaminase 2 (TG2) and ornithine decarboxylase (ODC) are involved in liver regeneration. To investigate the role of TG2 and ODC activities in regenerating liver, we used retinoic acid (RA), an inducer of TG2 and a suppressor of ODC. Regenerating rat liver was prepared by 70% partial hepatectomy (PH). Rats were sacrificed at 1, 2, 3, 4, and 6 days after surgery. RA was intraperitoneally injected immediately after PH. TG2 and ODC activities and products (epsilon-(gamma-glutamyl) lysine isopeptide (Gln-Lys) and polyamines, respectively) were examined at the indicated times. In RA-treated rat, DNA synthesis and ODC activity declined and the peak shifted to 2 days after PH, whereas TG2 activity increased at 1 day after PH. At that time, protein-polyamine, especially the protein-spermidine (SPD) bond, transiently decreased, whereas the formation of the Gln-Lys bond increased after PH. These results suggested that in regenerating liver, enhanced the formation of Gln-Lys bonds catalyzed by TG2 led to reduced DNA synthesis, whereas when ODC produced newly synthesized SPD, the inhibition of Gln-Lys bond production by the preferential formation of protein-SPD bonds led to an increase in DNA synthesis. PMID:18008394

  1. Ornithine decarboxylase regulates the activity and localization of rhoA via polyamination.

    PubMed

    Mäkitie, Laura T; Kanerva, Kristiina; Andersson, Leif C

    2009-04-01

    Ornithine decarboxylase (ODC) is the rate-limiting enzyme of polyamine synthesis. Polyamines and ODC are connected to cell proliferation and transformation. Resting cells display a low ODC activity while normal, proliferating cells display fluctuations in ODC activity that coincide with changes in the actin cytoskeleton during the cell cycle. Cancerous cells display constitutively elevated ODC activity. Overexpression of ODC in NIH 3T3 fibroblasts induces a transformed phenotype. The cytoskeletal rearrangements during cytokinesis and cell transformation are intimately coupled to the ODC activity but the molecular mechanisms have remained elusive. In this study we investigated how ODC and polyamines influence the organization of the cytoskeleton. Given that the small G-proteins of the rho family are key modulators of the actin cytoskeleton, we investigated the molecular interactions of rhoA with ODC and polyamines. Our results show that transglutaminase-catalyzed polyamination of rhoA regulates its activity. The polyamination status of rhoA crucially influences the progress of the cell cycle as well as the rate of transformation of rat fibroblasts infected with temperature-sensitive v-src. We also show that ODC influences the intracellular distribution of rhoA. These findings provide novel insights into the mechanisms by which ODC and polyamines regulate the dynamics of the cytoskeleton during cell proliferation and transformation. PMID:19331812

  2. Structural requirements for novel coenzyme-substrate derivatives to inhibit intracellular ornithine decarboxylase and cell proliferation.

    PubMed

    Wu, Fang; Gehring, Heinz

    2009-02-01

    Creating transition-state mimics has proven to be a powerful strategy in developing inhibitors to treat malignant diseases in several cases. In the present study, structurally diverse coenzyme-substrate derivatives mimicking this type for pyridoxal 5'-phosphate-dependent human ornithine decarboxylase (hODC), a potential anticancer target, were designed, synthesized, and tested to elucidate the structural requirements for optimal inhibition of intracellular ODC as well as of tumor cell proliferation. Of 23 conjugates, phosphopyridoxyl- and pyridoxyl-L-tryptophan methyl ester (pPTME, PTME) proved significantly more potent in suppression proliferation (IC(50) up to 25 microM) of glioma cells (LN229) than alpha-DL-difluoromethylornithine (DFMO), a medically used irreversible inhibitor of ODC. In agreement with molecular modeling predictions, the inhibitory action of pPTME and PTME toward intracellular ODC of LN229 cells exceeded that of the previous designed lead compound POB. The inhibitory active compounds feature hydrophobic side chain fragments and a kind of polyamine motif (-NH-(CH(X))(4)-NH-). In addition, they induce, as polyamine analogs often do, the activity of the polyamine catabolic enzymes polyamine oxidase and spermine/spermidine N(1)-acetyltransferase up to 250 and 780%, respectively. The dual-action mode of these compounds in LN229 cells affects the intracellular polyamine metabolism and might underlie the more favorable cell proliferation inhibition in comparison with DFMO. PMID:18922879

  3. Characterization of an avian histidine decarboxylase and localization of histaminergic neurons in the chicken brain.

    PubMed

    Bessho, Yuki; Iwakoshi-Ukena, Eiko; Tachibana, Tetsuya; Maejima, Sho; Taniuchi, Shusuke; Masuda, Keiko; Shikano, Kenshiro; Kondo, Kunihiro; Furumitsu, Megumi; Ukena, Kazuyoshi

    2014-08-22

    In mammals, it is established that histamine is a neurotransmitter and/or neuromodulator in the central nervous system. It is produced by the enzyme histidine decarboxylase (HDC) in the tuberomammillary nucleus of the posterior hypothalamus. However, HDC as well as histaminergic neurons have not yet been characterized in the avian brain. We have cloned the cDNA for HDC from the chicken hypothalamus and demonstrated that the chicken HDC sequence is highly homologous to the mammalian counterpart, and that the expressed protein shows high enzymatic activity. The expression of HDC mRNA at various sites in the brain was investigated using quantitative RT-PCR. The results showed that the HDC mRNA was highly expressed in the hypothalamic infundibulum. In situ hybridization analyses revealed that the cells containing HDC mRNA were localized in the medial mammillary nucleus of the hypothalamic infundibulum. Intracerebroventricular injection of histamine in chicks resulted in inhibition of feeding behavior. This is the first report of the characterization of histaminergic neurons in the avian brain, and our findings indicate that neuronal histamine exerts anorexigenic effects in chicks. PMID:24993302

  4. Glycine decarboxylase deficiency causes neural tube defects and features of non-ketotic hyperglycinemia in mice

    PubMed Central

    Pai, Yun Jin; Leung, Kit-Yi; Savery, Dawn; Hutchin, Tim; Prunty, Helen; Heales, Simon; Brosnan, Margaret E.; Brosnan, John T.; Copp, Andrew J.; Greene, Nicholas D.E.

    2015-01-01

    Glycine decarboxylase (GLDC) acts in the glycine cleavage system to decarboxylate glycine and transfer a one-carbon unit into folate one-carbon metabolism. GLDC mutations cause a rare recessive disease non-ketotic hyperglycinemia (NKH). Mutations have also been identified in patients with neural tube defects (NTDs); however, the relationship between NKH and NTDs is unclear. We show that reduced expression of Gldc in mice suppresses glycine cleavage system activity and causes two distinct disease phenotypes. Mutant embryos develop partially penetrant NTDs while surviving mice exhibit post-natal features of NKH including glycine accumulation, early lethality and hydrocephalus. In addition to elevated glycine, Gldc disruption also results in abnormal tissue folate profiles, with depletion of one-carbon-carrying folates, as well as growth retardation and reduced cellular proliferation. Formate treatment normalizes the folate profile, restores embryonic growth and prevents NTDs, suggesting that Gldc deficiency causes NTDs through limiting supply of one-carbon units from mitochondrial folate metabolism. PMID:25736695

  5. Extracellular expression of glutamate decarboxylase B in Escherichia coli to improve gamma-aminobutyric acid production.

    PubMed

    Zhao, Anqi; Hu, Xiaoqing; Li, Ye; Chen, Cheng; Wang, Xiaoyuan

    2016-12-01

    Escherichia coli overexpressing glutamate decarboxylase GadB can produce gamma-aminobutyric acid with addition of monosodium glutamate. The yield and productivity of gamma-aminobutyric acid might be significantly improved if the overexpressed GadB in E. coli cells can be excreted outside, where it can directly transforms monosodium glutamate to gamma-aminobutyric acid. In this study, GadB was fused to signal peptides TorA or PelB, respectively, and overexpressed in E. coli BL21(DE3). It was found that TorA could facilitate GadB secretion much better than PelB. Conditions for GadB secretion and gamma-aminobutyric acid production were optimized in E. coli BL21(DE3)/pET20b-torA-gadB, leading the secretion of more than half of the overexpressed GadB. Fed-batch fermentation for GadB expression and gamma-aminobutyric acid production of BL21(DE3)/pET20b-torA-gadB was sequentially performed in one fermenter; 264.4 and 313.1 g/L gamma-aminobutyric acid were obtained with addition of monosodium glutamate after 36 and 72 h, respectively. PMID:27549808

  6. Overexpression of Tyrosine hydroxylase and Dopa decarboxylase associated with pupal melanization in Spodoptera exigua.

    PubMed

    Liu, Sisi; Wang, Mo; Li, Xianchun

    2015-01-01

    Melanism has been found in a wide range of species, but the molecular mechanisms involved remain largely elusive. In this study, we studied the molecular mechanisms of the pupal melanism in Spodoptera exigua. The full length cDNA sequences of tyrosine hydroxylase (TH) and dopa decarboxylase (DDC), two key enzymes in the biosynthesis pathway of melanin, were cloned, and their temporal expression patterns in the integument were compared during the larval-pupal metamorphosis process of the S. exigua wild type (SEW) and melanic mutant (SEM) strains. No amino acid change in the protein sequence of TH and DDC was found between the two strains. Both DDC and TH were significantly over-expressed in the integument of the SEM strain at late-prepupa and 0 h pupa, respectively, compared with those of the SEW strain. Feeding 5(th) instar larvae of SEM with diets incorporated with 1 mg/g of the DDC inhibitor L-α-Methyl-DOPA and 0.75 mg/g of the TH inhibitor 3-iodo-tyrosine (3-IT) resulted in 20% pupae with partially-rescued phenotype and 68.2% of pupae with partially- or fully-rescued phenotype, respectively. These results indicate that overexpressions of TH and DDC are involved in the pupal melanization of S. exigua. PMID:26084938

  7. Induction of histidine decarboxylase in mouse tissues by mitogens in vivo.

    PubMed

    Endo, Y

    1983-12-15

    Various types of mitogenic substances, such as a Escherichia coli lipopolysaccharide (LPS), concanavalin A (Con A), pokeweed mitogen, polyI:polyC (a synthetic double-stranded RNA) and 12-O-tetradecanoylphorbol-13-acetate (a component of croton oil), induced histidine decarboxylase (HDC) in the liver, spleen and lung of mice at 4.5 hr after injection. Other inflammatory agents without mitogenic activity, such as zymosan, carrageenan, glycogen, D-galactosamine and N-acetyl-muramyl-L-alanyl-D-isoglutamine, did not induce the enzyme. Both LPS (a B-cell mitogen) and Con A (a T-cell mitogen) induced HDC also in nude mice that lack T-cells, indicating that T-cells are not required for HDC induction by mitogens. C3H/HeJ mice, which are LPS-low responder mice in various immunological tests, were quite a bit less responsive to LPS also in the HDC induction. These results show that mitogens with different properties can induce HDC as a common characteristic. On the basis of these results, the possible participation of macrophages in the process of HDC induction by mitogens was discussed. PMID:6661256

  8. The Genetic and Molecular Organization of the Dopa Decarboxylase Gene Cluster of Drosophila Melanogaster

    PubMed Central

    Stathakis, D. G.; Pentz, E. S.; Freeman, M. E.; Kullman, J.; Hankins, G. R.; Pearlson, N. J.; Wright, TRF.

    1995-01-01

    We report the complete molecular organization of the Dopa decarboxylase gene cluster. Mutagenesis screens recovered 77 new Df(2L)TW130 recessive lethal mutations. These new alleles combined with 263 previously isolated mutations in the cluster to define 18 essential genes. In addition, seven new deficiencies were isolated and characterized. Deficiency mapping, restriction fragment length polymorphism (RFLP) analysis and P-element-mediated germline transformation experiments determined the gene order for all 18 loci. Genomic and cDNA restriction endonuclease mapping, Northern blot analysis and DNA sequencing provided information on exact gene location, mRNA size and transcriptional direction for most of these loci. In addition, this analysis identified two transcription units that had not previously been identified by extensive mutagenesis screening. Most of the loci are contained within two dense subclusters. We discuss the effectiveness of mutagens and strategies used in our screens, the variable mutability of loci within the genome of Drosophila melanogaster, the cytological and molecular organization of the Ddc gene cluster, the validity of the one band-one gene hypothesis and a possible purpose for the clustering of genes in the Ddc region. PMID:8647399

  9. Formation of Hexacoordinate Mn(III) in Bacillus subtilis Oxalate Decarboxylase Requires Catalytic Turnover.

    PubMed

    Zhu, Wen; Wilcoxen, Jarett; Britt, R David; Richards, Nigel G J

    2016-01-26

    Oxalate decarboxylase (OxDC) catalyzes the disproportionation of oxalic acid monoanion into CO2 and formate. The enzyme has long been hypothesized to utilize dioxygen to form mononuclear Mn(III) or Mn(IV) in the catalytic site during turnover. Recombinant OxDC, however, contains only tightly bound Mn(II), and direct spectroscopic detection of the metal in higher oxidation states under optimal catalytic conditions (pH 4.2) has not yet been reported. Using parallel mode electron paramagnetic resonance spectroscopy, we now show that substantial amounts of Mn(III) are indeed formed in OxDC, but only in the presence of oxalate and dioxygen under acidic conditions. These observations provide the first direct support for proposals in which Mn(III) removes an electron from the substrate to yield a radical intermediate in which the barrier to C-C bond cleavage is significantly decreased. Thus, OxDC joins a small list of enzymes capable of stabilizing and controlling the reactivity of the powerful oxidizing species Mn(III). PMID:26744902

  10. Structural constraints on protein self-processing in l-aspartate-α-decarboxylase

    PubMed Central

    Schmitzberger, Florian; Kilkenny, Mairi L.; Lobley, Carina M.C.; Webb, Michael E.; Vinkovic, Mladen; Matak-Vinkovic, Dijana; Witty, Michael; Chirgadze, Dimitri Y.; Smith, Alison G.; Abell, Chris; Blundell, Tom L.

    2003-01-01

    Aspartate decarboxylase, which is translated as a pro-protein, undergoes intramolecular self-cleavage at Gly24–Ser25. We have determined the crystal structures of an unprocessed native precursor, in addition to Ala24 insertion, Ala26 insertion and Gly24→Ser, His11→Ala, Ser25→Ala, Ser25→Cys and Ser25→Thr mutants. Comparative analyses of the cleavage site reveal specific conformational constraints that govern self-processing and demonstrate that considerable rearrangement must occur. We suggest that Thr57 Oγ and a water molecule form an ‘oxyanion hole’ that likely stabilizes the proposed oxyoxazolidine intermediate. Thr57 and this water molecule are probable catalytic residues able to support acid–base catalysis. The conformational freedom in the loop preceding the cleavage site appears to play a determining role in the reaction. The molecular mechanism of self-processing, presented here, emphasizes the importance of stabilization of the oxyoxazolidine intermediate. Comparison of the structural features shows significant similarity to those in other self-processing systems, and suggests that models of the cleavage site of such enzymes based on Ser→Ala or Ser→Thr mutants alone may lead to erroneous interpretations of the mechanism. PMID:14633979

  11. Partial purification and characterization of arginine decarboxylase from avocado fruit, a thermostable enzyme.

    PubMed

    Winer, L; Vinkler, C; Apelbaum, A

    1984-09-01

    A partially purified preparation of arginine decarboxylase (EC 4.1.1.19), a key enzyme in polyamine metabolism in plants, was isolated from avocado (Persea americana Mill. cv Fuerte) fruit. The preparation obtained from the crude extract after ammonium sulfate precipitation, dialysis, and heat treatment, had maximal activity between pH 8.0 and 9.0 at 60 degrees C, in the presence of 1.2 millimolar MnCl(2), 2 millimolar dithiothreitol, and 0.06 millimolar pyridoxal phosphate. The K(m), of arginine for the decarboxylation reaction was determined for enzymes prepared from the seed coat of both 4-week-old avocado fruitlet and fully developed fruit, and was found to have a value of 1.85 and 2.84 millimolar, respectively. The value of V(app) (max) of these enzymes was 1613 and 68 nanomoles of CO(2) produced per milligram of protein per hour for the fruitlet and the fully developed fruit, respectively. Spermine, an end product of polyamine metabolism, caused less than 5% inhibition of the enzyme from fully developed fruit and 65% inhibition of the enzyme from the seed coat of 4-week-old fruitlets at 1 millimolar under similar conditions. The effect of different inhibitors on the enzyme and the change in the nature of the enzyme during fruit development are discussed. PMID:16663805

  12. Role of OsHAL3 protein, a putative 4'-phosphopantothenoylcysteine decarboxylase in rice.

    PubMed

    Zhang, Ning; Wang, Xuechen; Chen, Jia

    2009-01-01

    In this study, we cloned the OsHAL3 gene from rice Oryza sativa. Alignment analysis revealed that OsHAL3 has a high sequence identity to Dfp protein in Escherichia coli and AtHAL3a protein in Arabidopsis thaliana, which have 4'-phosphopantothenoylcysteine decarboxylase (PPC-DC) activity. OsHAL3 can complement mutation in the E. coli dfp gene encoding PPC-DC, so that the mutant strains with OsHAL3 can grow on rich media at 42 degrees C and on VB minimal media at 30 degrees C. Complementation tests with point mutations of OsHAL3 suggested that the conserved Cys176 residue of OsHAL3 is a key active-site residue. The mutant OsHAL3 G180A has a partly reduced activity. Related mRNA-level analysis showed that the OsHAL3 gene is induced by calcium pantothenate in rice. PMID:19232050

  13. Identification and characterization of barley mutants lacking glycine decarboxylase and carboxyl esterase activities

    SciTech Connect

    Blackwell, R.; Lewis, K.; Lea, P. )

    1990-05-01

    A barley mutant has been isolated, from a selection of fifty air-sensitive seed-lines, using a standard gel stain technique which lacks carboxyl esterase activity, but has normal levels of carbonic anhydrase. In addition, two barley mutants lacking the ability to convert glycine to serine in the mitochondria, have been characterized. Both plants accumulate glycine in air and are unable to metabolize ({sup 14}C)glycine in the short-term. When ({sup 14}C)glycine was supplied over 2h LaPr 85/55 metabolized 90%, whereas the second mutant (LaPr 87/30) metabolized 10%. Results indicate that the mutation in LaPr 85/55 is almost certainly in the glycine transporter into the mitochondrion. The mutation in LaPr 87/30 has been shown, using western blotting, to be in both the P and H proteins, two of four proteins which comprise glycine decarboxylase (P, H, T and L).

  14. Herbacetin Is a Novel Allosteric Inhibitor of Ornithine Decarboxylase with Antitumor Activity.

    PubMed

    Kim, Dong Joon; Roh, Eunmiri; Lee, Mee-Hyun; Oi, Naomi; Lim, Do Young; Kim, Myoung Ok; Cho, Yong-Yeon; Pugliese, Angelo; Shim, Jung-Hyun; Chen, Hanyong; Cho, Eun Jin; Kim, Jong-Eun; Kang, Sun Chul; Paul, Souren; Kang, Hee Eun; Jung, Ji Won; Lee, Sung-Young; Kim, Sung-Hyun; Reddy, Kanamata; Yeom, Young Il; Bode, Ann M; Dong, Zigang

    2016-03-01

    Ornithine decarboxylase (ODC) is a rate-limiting enzyme in the first step of polyamine biosynthesis that is associated with cell growth and tumor formation. Existing catalytic inhibitors of ODC have lacked efficacy in clinical testing or displayed unacceptable toxicity. In this study, we report the identification of an effective and nontoxic allosteric inhibitor of ODC. Using computer docking simulation and an in vitro ODC enzyme assay, we identified herbacetin, a natural compound found in flax and other plants, as a novel ODC inhibitor. Mechanistic investigations defined aspartate 44 in ODC as critical for binding. Herbacetin exhibited potent anticancer activity in colon cancer cell lines expressing high levels of ODC. Intraperitoneal or oral administration of herbacetin effectively suppressed HCT116 xenograft tumor growth and also reduced the number and size of polyps in a mouse model of APC-driven colon cancer (ApcMin/+). Unlike the well-established ODC inhibitor DFMO, herbacetin treatment was not associated with hearing loss. Taken together, our findings defined the natural product herbacetin as an allosteric inhibitor of ODC with chemopreventive and antitumor activity in preclinical models of colon cancer, prompting its further investigation in clinical trials. PMID:26676750

  15. Identification of the Enterobacteriaceae in Montasio cheese and assessment of their amino acid decarboxylase activity.

    PubMed

    Maifreni, Michela; Frigo, Francesca; Bartolomeoli, Ingrid; Innocente, Nadia; Biasutti, Marialuisa; Marino, Marilena

    2013-02-01

    The aim of the study was to identify the species of Enterobacteriaceae present in Montasio cheese and to assess their potential to produce biogenic amines. Plate count methods and an Enterobacterial Repetitive Intergenic Consensus Polymerase Chain Reaction (ERIC-PCR) approach, combined with 16S rDNA sequencing, were used to investigate the Enterobacteriaceae community present during the cheesemaking and ripening of 6 batches of Montasio cheese. Additionally, the potential decarboxylation abilities of selected bacterial isolates were qualitatively and quantitatively assessed against tyrosine, histidine, ornithine and lysine. The most predominant species detected during cheese manufacturing and ripening were Enterobacter cloacae, Escherichia coli and Hafnia alvei. The non-limiting physico-chemical conditions (pH, NaCl% and a(w)) during ripening were probably the cause of the presence of detectable levels of Enterobacteriaceae up to 120 d of ripening. The HPLC test showed that cadaverine and putrescine were the amines produced in higher amounts by almost all isolates, indicating that the presence of these amines in cheese can be linked to the presence of high counts of Enterobacteriaceae. 44 isolates produced low amounts of histamine (<300 ppm), and four isolates produced more than 1000 ppm of this amine. Only 9 isolates, belonging to the species Citrobacter freundii, Esch. coli and Raoultella ornithinolytica, appeared to produce tyramine. These data provided new information regarding the decarboxylase activity of some Enterobacteriaceae species, including Pantoea agglomerans, Esch. fergusonii and R. ornithinolytica. PMID:23298547

  16. Glucocorticoid hormones downregulate histidine decarboxylase mRNA and enzyme activity in rat lung.

    PubMed

    Zahnow, C A; Panula, P; Yamatodani, A; Millhorn, D E

    1998-08-01

    Histidine decarboxylase (HDC) is the primary enzyme regulating histamine biosynthesis. Histamine contributes to the pathogenesis of chronic inflammatory disorders such as asthma. Because glucocorticoids are effective in the treatment of asthma, we examined the effects of 6 h of exogenously administered dexamethasone (0.5-3,000 microg/kg ip), corticosterone (0.2-200 mg/kg ip), or endogenously elevated corticosterone (via exposure of rats to 10% oxygen) on HDC expression in the rat lung. HDC transcripts were decreased approximately 73% with dexamethasone treatment, 57% with corticosterone treatment, and 50% with exposure to 10% oxygen. Likewise, HDC enzyme activity was decreased 80% by treatment with dexamethasone and corticosterone and 60% by exposure to 10% oxygen. Adrenalectomy prevented the decreases in HDC mRNA and enzyme activity observed in rats exposed to 10% oxygen, suggesting that the adrenal gland is necessary for the mediation of hypoxic effects on HDC gene expression. These results demonstrate that corticosteroids initiate a process that leads to the decrease of HDC mRNA levels and enzyme activity in rat lung. PMID:9700103

  17. Polyamine metabolism and osmotic stress. II. Improvement of oat protoplasts by an inhibitor of arginine decarboxylase

    NASA Technical Reports Server (NTRS)

    Tiburcio, A. F.; Kaur-Sawhney, R.; Galston, A. W.

    1986-01-01

    We have attempted to improve the viability of cereal mesophyll protoplasts by pretreatment of leaves with DL-alpha-difluoromethylarginine (DFMA), a specific 'suicide' inhibitor of the enzyme (arginine decarboxylase) responsible for their osmotically induced putrescine accumulation. Leaf pretreatment with DFMA before a 6 hour osmotic shock caused a 45% decrease of putrescine and a 2-fold increase of spermine titer. After 136 hours of osmotic stress, putrescine titer in DFMA-pretreated leaves increased by only 50%, but spermidine and spermine titers increased dramatically by 3.2- and 6-fold, respectively. These increases in higher polyamines could account for the reduced chlorophyll loss and enhanced ability of pretreated leaves to incorporate tritiated thymidine, uridine, and leucine into macromolecules. Pretreatment with DFMA significantly improved the overall viability of the protoplasts isolated from these leaves. The results support the view that the osmotically induced rise in putrescine and blockage of its conversion to higher polyamines may contribute to the lack of sustained cell division in cereal mesophyll protoplasts, although other undefined factors must also play a major role.

  18. Aromatic L-amino acid decarboxylase deficiency diagnosed by clinical metabolomic profiling of plasma.

    PubMed

    Atwal, Paldeep S; Donti, Taraka R; Cardon, Aaron L; Bacino, C A; Sun, Qin; Emrick, L; Reid Sutton, V; Elsea, Sarah H

    2015-01-01

    Aromatic L-amino acid decarboxylase (AADC) deficiency is an inborn error of metabolism affecting the biosynthesis of serotonin, dopamine, and catecholamines. We report a case of AADC deficiency that was detected using the Global MAPS platform. This is a novel platform that allows for parallel clinical testing of hundreds of metabolites in a single plasma specimen. It uses a state-of-the-art mass spectrometry platform, and the resulting spectra are compared against a library of ~2500 metabolites. Our patient is now a 4 year old boy initially seen at 11 months of age for developmental delay and hypotonia. Multiple tests had not yielded a diagnosis until exome sequencing revealed compound heterozygous variants of uncertain significance (VUS), c.286G>A (p.G96R) and c.260C>T (p.P87L) in the DDC gene, causal for AADC deficiency. CSF neurotransmitter analysis confirmed the diagnosis with elevated 3-methoxytyrosine (3-O-methyldopa). Metabolomic profiling was performed on plasma and revealed marked elevation in 3-methoxytyrosine (Z-score +6.1) consistent with the diagnosis of AADC deficiency. These results demonstrate that the Global MAPS platform is able to diagnose AADC deficiency from plasma. In summary, we report a novel and less invasive approach to diagnose AADC deficiency using plasma metabolomic profiling. PMID:25956449

  19. Overexpression of Actinidia deliciosa pyruvate decarboxylase 1 gene enhances waterlogging stress in transgenic Arabidopsis thaliana.

    PubMed

    Zhang, Ji-Yu; Huang, Sheng-Nan; Wang, Gang; Xuan, Ji-Ping; Guo, Zhong-Ren

    2016-09-01

    Ethanolic fermentation is classically associated with waterlogging tolerance when plant cells switch from respiration to anaerobic fermentation. Pyruvate decarboxylase (PDC), which catalyzes the first step in this pathway, is thought to be the main regulatory enzyme. Here, we cloned a full-length PDC cDNA sequence from kiwifruit, named AdPDC1. We determined the expression of the AdPDC1 gene in kiwifruit under different environmental stresses using qRT-PCR, and the results showed that the increase of AdPDC1 expression during waterlogging stress was much higher than that during salt, cold, heat and drought stresses. Overexpression of kiwifruit AdPDC1 in transgenic Arabidopsis enhanced the resistance to waterlogging stress but could not enhance resistance to cold stress at five weeks old seedlings. Overexpression of kiwifruit AdPDC1 in transgenic Arabidopsis could not enhance resistance to NaCl and mannitol stresses at the stage of seed germination and in early seedlings. These results suggested that the kiwifruit AdPDC1 gene is required during waterlogging but might not be required during other environmental stresses. Expression of the AdPDC1 gene was down-regulated by abscisic acid (ABA) in kiwifruit, and overexpression of the AdPDC1 gene in Arabidopsis inhibited seed germination and root length under ABA treatment, indicating that ABA might negatively regulate the AdPDC1 gene under waterlogging stress. PMID:27191596

  20. Novel interactions of fluorinated nucleotide derivatives targeting orotidine-5′-monophosphate decarboxylase

    PubMed Central

    Lewis, Melissa; Avina, Maria Elena Meza; Wei, Lianhu; Crandall, Ian E.; Bello, Angelica Mara; Poduch, Ewa; Liu, Yan; Paige, Christopher J.; Kain, Kevin C.; Pai, Emil F.; Kotra, Lakshmi P.

    2011-01-01

    Fluorinated nucleosides and nucleotides are of considerable interest to medicinal chemists due to their antiviral, anticancer, and other biological activities. However, their direct interactions at target binding sites are not well understood. A new class of 2′-deoxy-2′-fluoro-C6-substituted uridine and UMP derivatives were synthesized and evaluated as inhibitors of orotidine-5′-monophosphate decarboxylase (ODCase). These compounds were synthesized from the key intermediate, fully-protected 2′-deoxy-2′-fluorouridine. Among the synthesized compounds, 2′-deoxy-2′-fluoro-6-iodo-UMP covalently inhibited human ODCase with a second-order rate constant of 0.62 ± 0.02 M−1sec−1. Interestingly, the 6-cyano-2′-fluoro derivative covalently interacted with ODCase defying the conventional thinking, where its ribosyl derivative undergoes transformation into BMP by ODCase. This confirms that the 2′-fluoro moiety influences the chemistry at the C6 position of the nucleotides, thus interactions in the active site of ODCase. Molecular interactions of the 2′-fluorinated nucleotides are compared to those with the 3′-fluorinated nucleotides bound to the corresponding target enzyme, and the carbohydrate moieties were shown to bind in different conformations. PMID:21417464

  1. Targeting ornithine decarboxylase reverses the LIN28/Let-7 axis and inhibits glycolytic metabolism in neuroblastoma

    PubMed Central

    Lozier, Ann M.; Rich, Maria E.; Grawe, Anissa Pedersen; Peck, Anderson S.; Zhao, Ping; Chang, Anthony Ting-Tung; Bond, Jeffrey P.; Sholler, Giselle Saulnier

    2015-01-01

    LIN28 has emerged as an oncogenic driver in a number of cancers, including neuroblastoma (NB). Overexpression of LIN28 correlates with poor outcome in NB, therefore drugs that impact the LIN28/Let-7 pathway could be beneficial in treating NB patients. The LIN28/Let-7 pathway affects many cellular processes including the regulation of cancer stem cells and glycolytic metabolism. Polyamines, regulated by ornithine decarboxylase (ODC) modulate eIF-5A which is a direct regulator of the LIN28/Let-7 axis. We propose that therapy inhibiting ODC will restore balance to the LIN28/Let-7 axis, suppress glycolytic metabolism, and decrease MYCN protein expression in NB. Difluoromethylornithine (DFMO) is an inhibitor of ODC in clinical trials for children with NB. In vitro experiments using NB cell lines, BE(2)-C, SMS-KCNR, and CHLA90 show that DFMO treatment reduced LIN28B and MYCN protein levels and increased Let-7 miRNA and decreased neurosphere formation. Glycolytic metabolic activity decreased with DFMO treatment in vivo. Additionally, sensitivity to DFMO treatment correlated with LIN28B overexpression (BE(2)-C>SMS-KCNR>CHLA90). This is the first study to demonstrate that DFMO treatment restores balance to the LIN28/Let-7 axis and inhibits glycolytic metabolism and neurosphere formation in NB and that PET scans may be a meaningful imaging tool to evaluate the therapeutic effects of DFMO treatment. PMID:25415050

  2. Human α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD): A structural and mechanistic unveiling

    PubMed Central

    Huo, Lu; Liu, Fange; Iwaki, Hiroaki; Li, Tingfeng; Hasegawa, Yoshie; Liu, Aimin

    2014-01-01

    Human α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase determines the fate of tryptophan metabolites in the kynurenine pathway by controlling the quinolinate levels for de novo NAD biosynthesis. The unstable nature of its substrate has made gaining insight into its reaction mechanism difficult. Our electron paramagnetic resonance (EPR) spectroscopic study on the catalytically active, Cu-substituted enzyme suggests that the native substrate does not directly ligate to the metal ion. Substrate binding did not result in a change of either the hyperfine structure or the super-hyperfine structure of the EPR spectrum. We also determined the crystal structure of the enzyme in its native state (at 1.99 Å resolution), a substrate analogue-bound form (2.50 Å resolution), and a selected active site mutant form with one of the putative substrate binding residues altered (2.32 Å resolution). These structures illustrate that each asymmetric unit contains 3 pairs of dimers. Consistent with the EPR findings, the ligand-bound complex structure shows that the substrate analogue does not directly coordinate to the metal ion but is bound to the active site by two ariginine residues through non-covalent interactions. PMID:25392945

  3. Photonic-assisted time-interleaved ADC based on optical delay line

    NASA Astrophysics Data System (ADS)

    Xu, Chen; Zheng, Shilie; Chen, Xinyi; Chi, Hao; Jin, Xiaofeng; Zhang, Xianmin

    2016-01-01

    An approach to implement photonic-assisted time-interleaved analog-to-digital conversion and its calibration method are presented. The analog modulated optical signal is divided into M channels, suffering different time delay induced by optical delay lines which provide great flexibility in producing time intervals and is then sampled by electronic analog-to-digital converters (ADCs). The channel mismatches resulting in performance degradation are estimated by a modified sine wave fitting method. The time mismatch and other mismatches are corrected by fine optical delay adjustment and digital processing, respectively. A four-channel photonic-assisted time-interleaved analog-to-digital converter (TIADC) system operating at 40 GSa s-1 was demonstrated experimentally. The photonic-assisted TIADC system was tested with a 6.31 GHz sine wave signal, exhibiting 40.3 dB signal-to-noise and distortion ratio (SINAD) and 57.6 dBc spurious-free dynamic range (SFDR). It is shown that the SINAD is dominated by the signal-to-noise ratio (SNR) of the analog optical link and the SFDR of the proposed system is limited by the linearity of the link.

  4. Measurement Of Neutron Radius In Lead By Parity Violating Scattering Flash ADC DAQ

    SciTech Connect

    Ahmed, Zafar

    2012-06-01

    This dissertation reports the experiment PREx, a parity violation experiment which is designed to measure the neutron radius in {sup 208}Pb. PREx is performed in hall A of Thomas Jefferson National Accelerator Facility from March 19th to June 21st. Longitudionally polarized electrons at energy 1 GeV scattered at and angle of {theta}{sub lab} = 5.8 {degrees} from the Lead target. Beam corrected pairty violaing counting rate asymmetry is (A{sub corr} = 594 ± 50(stat) ± 9(syst))ppb at Q{sup 2} = 0.009068GeV {sup 2}. This dissertation also presents the details of Flash ADC Data Acquisition(FADC DAQ) system for Moller polarimetry in Hall A of Thomas Jefferson National Accelerator Facility. The Moller polarimeter measures the beam polarization to high precision to meet the specification of the PREx(Lead radius experiment). The FADC DAQ is part of the upgrade of Moller polarimetery to reduce the systematic error for PREx. The hardware setup and the results of the FADC DAQ analysis are presented

  5. Flash ADC readout of the GlueX forward electromagnetic calorimeter

    NASA Astrophysics Data System (ADS)

    Kornicer, Mihajlo

    2008-10-01

    The GlueX experiment at Jefferson Lab will use a 9 GeV high-rate (10^7 -10^8/s) photon beam, incident on a liquid hydrogen target, to search for hybrid-meson production in the mass range of 1.5-2.5 GeV/c^2. Abundant photon production from neutral meson decays is expected in the decay chains of hybrid mesons, which will result in several photons in the forward region. The forward electromagnetic calorimeter (FCAL) of the GlueX detector is designed to reconstruct final state photons using an array of 2800 lead-glass blocks. The FCAL will employ flash analog-to-digital converter (FADC) technology to measure both deposited energy and photon arrival time using pulses from FEU-84-3 photomultiplier tubes. A real-time sum of the total calorimeter energy will be used as an input to the trigger. Timing information from individual crystals will be used to suppress the expected high-level of electromagnetic background from the photon beam and forward-going charged particles. We present the performance characteristics of the calorimeter readout based on simulation and data taken with a prototype 12-bit, 250 MHz flash ADC.

  6. High dynamic range CMOS image sensor with pixel level ADC and in-situ image enhancement

    NASA Astrophysics Data System (ADS)

    Harton, Austin V.; Ahmed, Mohamed I.; Beuhler, Allyson; Castro, Francisco; Dawson, Linda M.; Herold, Barry W.; Kujawa, Gregory; Lee, King F.; Mareachen, Russell D.; Scaminaci, Tony J.

    2005-03-01

    We describe a CMOS image sensor with pixel level analog to digital conversion (ADC) having high dynamic range (>100db) and the capability of performing many image processing functions at the pixel level during image capture. The sensor has a 102x98 pixel array and is implemented in a 0.18um CMOS process technology. Each pixel is 15.5um x15.5um with 15% fill factor and is comprised of a comparator, two 10 bit memory registers and control logic. A digital to analog converter and system processor are located off-chip. The photodetector produces a photocurrent yielding a photo-voltage proportional to the impinging light intensity. Once the photo-voltage is less than a predetermined global reference voltage; a global code value is latched into the pixel data buffer. This process prevents voltage saturation resulting in high dynamic range imaging. Upon completion of image capture, a digital representation of the image exists at the pixel array, thereby, allowing image data to be accessed in a parallel fashion from the focal plane array. It is demonstrated that by appropriate variation of the global reference voltage with time, it is possible to perform, during image capture, thresholding and image enhancement operations, such as, contrast stretching in a parallel manner.

  7. A reconfigurable medically cohesive biomedical front-end with ΣΔ ADC in 0.18µm CMOS.

    PubMed

    Jha, Pankaj; Patra, Pravanjan; Naik, Jairaj; Acharya, Amit; Rajalakshmi, P; Singh, Shiv Govind; Dutta, Ashudeb

    2015-08-01

    This paper presents a generic programmable analog front-end (AFE) for acquisition and digitization of various biopotential signals. This includes a lead-off detection circuit, an ultra-low current capacitively coupled signal conditioning stage with programmable gain and bandwidth, a new mixed signal automatic gain control (AGC) mechanism and a medically cohesive reconfigurable ΣΔ ADC. The full system is designed in UMC 0.18μm CMOS. The AFE achieves an overall linearity of more 10 bits with 0.47μW power consumption. The ADC provides 2(nd) order noise-shaping while using single integrator and an ENOB of ~11 bits with 5μW power consumption. The system was successfully verified for various ECG signals from PTB database. This system is intended for portable batteryless u-Healthcare devices. PMID:26736391

  8. A 128-ch Δ-Σ ADC based mixed signal IC for full digital beamforming Wireless handheld Ultrasound imaging system.

    PubMed

    Chirala, Mohan K; Phuong Huynh; Jaeyoung Ryu; Young-Hwan Kim

    2015-08-01

    This paper reports a massively integrated Δ-Σ ADC based mixed signal chipset for a handheld Wireless Ultrasound imaging system. The IC has been fabricated in a standard 0.13 μm 1.5V 7M2F CMOS process with 128 parallel channels containing Delta-Sigma (Δ-Σ) ADCs, Anti-aliasing filter, Decimation filters, Serializers and LVDS drivers. The entire chip is SPI controlled and allows group-level power control through an FPGA. The IC measures 15 × 15 mm and dissipates around ~ 4.6 W of power, with 12-bit resolution at 20 Msps sample rate. The chip was packaged in a thermally stable BGA package and demonstrated in a handheld ultrasound battery operated system with complete digital beamforming. PMID:26736516

  9. A high-speed CMOS image sensor with column-parallel single capacitor CDSs and single-slope ADCs

    NASA Astrophysics Data System (ADS)

    Li, Quanliang; Shi, Cong; Wu, Nanjian

    2011-08-01

    This paper presents a high speed CMOS image sensor (CIS) with column-parallel single capacitor correlated double samplings (CDSs), programmable gain amplifiers (PGAs) and single-slope analog-to-digital converters (ADCs). The single capacitor CDS circuit has only one capacitor so that the area CDS circuit is small. In order to attain appropriate image contrast under different light conditions, the signal range can be adjusted by PGA. Single-slope ADC has smaller chip area than others ADCs and is suitable for column-parallel CIS architectures. A prototype sensor of 256x256 pixels was realized in a 0.13μm 1P3M CIS process. Its pixel circuit is 4T active pixel sensor (APS) and pixel size is 10x10μm2. Total chip area is 4x4mm2. The prototype achieves the full frame rate in excess of 250 frames per second, the sensitivity of 10.7V/lx•s, the conversion gain of 55.6μV/e and the column-to- column fixed-pattern noise (FPN) 0.41%.

  10. Power and area efficient 4-bit column-level ADC in a CMOS pixel sensor for the ILD vertex detector

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Morel, F.; Hu-Guo, Ch; Hu, Y.

    2013-01-01

    A 48 × 64 pixels prototype CMOS pixel sensor (CPS) integrated with 4-bit column-level, self triggered ADCs for the outer layers of the ILD vertex detector (VTX) was developed and fabricated in a 0.35 μm CMOS process with a pixel pitch of 35 μm. The pixel concept combines in-pixel amplification with a correlated double sampling (CDS) operation. The ADCs accommodating the pixel read out in a rolling shutter mode complete the conversion by performing a multi-bit/step approximation. The design was optimised for power saving at sampling frequency. The prototype sensor is currently at the stage of being started testing and evaluation. So what is described is based on post simulation results rather than test data. This 4-bit ADC dissipates, at a 3-V supply and 6.25-MS/s sampling rate, 486 μW in its inactive mode, which is by far the most frequent. This value rises to 714 μW in case of the active mode. Its footprint amounts to 35 × 545 μm2.

  11. SEMICONDUCTOR INTEGRATED CIRCUITS: A low power cyclic ADC design for a wireless monitoring system for orthopedic implants

    NASA Astrophysics Data System (ADS)

    Yi, Chen; Fule, Li; Hong, Chen; Chun, Zhang; Zhihua, Wang

    2009-08-01

    This paper presents a low power cyclic analog-to-digital convertor (ADC) design for a wireless monitoring system for orthopedic implants. A two-stage cyclic structure including a single to differential converter, two multiplying DAC functional blocks (MDACs) and some comparators is adopted, which brings moderate speed and moderate resolution with low power consumption. The MDAC is implemented with the common switched capacitor method. The 1.5-bit stage greatly simplifies the design of the comparator. The operational amplifier is carefully optimized both in schematic and layout for low power and offset. The prototype chip has been fabricated in a United Microelectronics Corporation (UMC) 0.18-μm 1P6M CMOS process. The core of the ADC occupies only 0.12 mm2. With a 304.7-Hz input and 4-kHz sampling rate, the measured peak SNDR and SFDR are 47.1 dB and 57.8 dBc respectively and its DNL and INL are 0.27 LSB and 0.3 LSB, respectively. The power consumption of the ADC is only 12.5 μW in normal working mode and less than 150 nW in sleep mode.

  12. A single channel, 6-bit 410-MS/s 3bits/stage asynchronous SAR ADC based on resistive DAC

    NASA Astrophysics Data System (ADS)

    Xue, Han; Qi, Wei; Huazhong, Yang; Hui, Wang

    2015-05-01

    This paper presents a single channel, low power 6-bit 410-MS/s asynchronous successive approximation register analog-to-digital converter (SAR ADC) for ultrawide bandwidth (UWB) communication, prototyped in a SMIC 65-nm process. Based on the 3 bits/stage structure, resistive DAC, and the modified asynchronous successive approximation register control logic, the proposed ADC attains a peak spurious-free dynamic range (SFDR) of 41.95 dB, and a signal-to-noise and distortion ratio (SNDR) of 28.52 dB for 370 MS/s. At the sampling rate of 410 MS/s, this design still performs well with a 40.71-dB SFDR and 30.02-dB SNDR. A four-input dynamic comparator is designed so as to decrease the power consumption. The measurement results indicate that this SAR ADC consumes 2.03 mW, corresponding to a figure of merit of 189.17 fJ/step at 410 MS/s. Project supported by the National Science Foundation for Young Scientists of China (No. 61306029) and the National High Technology Research and Development Program of China (No. 2013AA014103).

  13. The Accuracy of ADC Measurements in Liver Is Improved by a Tailored and Computationally Efficient Local-Rigid Registration Algorithm.

    PubMed

    Ragheb, Hossein; Thacker, Neil A; Guyader, Jean-Marie; Klein, Stefan; deSouza, Nandita M; Jackson, Alan

    2015-01-01

    This study describes post-processing methodologies to reduce the effects of physiological motion in measurements of apparent diffusion coefficient (ADC) in the liver. The aims of the study are to improve the accuracy of ADC measurements in liver disease to support quantitative clinical characterisation and reduce the number of patients required for sequential studies of disease progression and therapeutic effects. Two motion correction methods are compared, one based on non-rigid registration (NRA) using freely available open source algorithms and the other a local-rigid registration (LRA) specifically designed for use with diffusion weighted magnetic resonance (DW-MR) data. Performance of these methods is evaluated using metrics computed from regional ADC histograms on abdominal image slices from healthy volunteers. While the non-rigid registration method has the advantages of being applicable on the whole volume and in a fully automatic fashion, the local-rigid registration method is faster while maintaining the integrity of the biological structures essential for analysis of tissue heterogeneity. Our findings also indicate that the averaging commonly applied to DW-MR images as part of the acquisition protocol should be avoided if possible. PMID:26204105

  14. The Accuracy of ADC Measurements in Liver Is Improved by a Tailored and Computationally Efficient Local-Rigid Registration Algorithm

    PubMed Central

    Ragheb, Hossein; Thacker, Neil A.; Guyader, Jean-Marie; Klein, Stefan; deSouza, Nandita M.; Jackson, Alan

    2015-01-01

    This study describes post-processing methodologies to reduce the effects of physiological motion in measurements of apparent diffusion coefficient (ADC) in the liver. The aims of the study are to improve the accuracy of ADC measurements in liver disease to support quantitative clinical characterisation and reduce the number of patients required for sequential studies of disease progression and therapeutic effects. Two motion correction methods are compared, one based on non-rigid registration (NRA) using freely available open source algorithms and the other a local-rigid registration (LRA) specifically designed for use with diffusion weighted magnetic resonance (DW-MR) data. Performance of these methods is evaluated using metrics computed from regional ADC histograms on abdominal image slices from healthy volunteers. While the non-rigid registration method has the advantages of being applicable on the whole volume and in a fully automatic fashion, the local-rigid registration method is faster while maintaining the integrity of the biological structures essential for analysis of tissue heterogeneity. Our findings also indicate that the averaging commonly applied to DW-MR images as part of the acquisition protocol should be avoided if possible. PMID:26204105

  15. A 12-bit, 1 MS/s SAR-ADC for a CZT-based multi-channel gamma-ray imager using a new digital calibration method

    NASA Astrophysics Data System (ADS)

    Liu, W.; Wei, T.; Yang, L.; Hu, Y.

    2016-03-01

    The successive approximation register-analog to digital converter (SAR-ADC) is widely used in the CdZnTe-based gamma-ray imager because of its outstanding characteristics of low power consumption, relatively high resolution, and small die size. This study proposes a digital bit-by-bit calibration method using an input ramp signal to further improve the conversion precision and power consumption of an SAR-ADC. The proposed method is based on the sub-radix-2 redundant architecture and the perturbation technique. The proposed calibration algorithm is simpler, more stable, and faster than traditional approaches. The prototype chip of the 12-bit, 1 MS/s radiation-hardened SAR-ADC has been designed and fabricated using the TSMC 0.35 μm 2P4M CMOS process. This SAR-ADC consumes 3 mW power and occupies a core area of 856× 802μm2. The digital bit-by-bit calibration algorithm is implemented via MATLAB for testing flexibility. The effective number of bits for this digitally calibrated SAR-ADC reaches 11.77 bits. The converter exhibits high conversion precision, low power consumption, and radiation-hardened design. Therefore, this SAR-ADC is suitable for multi-channel gamma-ray imager applications.

  16. A 12-bit high-speed column-parallel two-step single-slope analog-to-digital converter (ADC) for CMOS image sensors.

    PubMed

    Lyu, Tao; Yao, Suying; Nie, Kaiming; Xu, Jiangtao

    2014-01-01

    A 12-bit high-speed column-parallel two-step single-slope (SS) analog-to-digital converter (ADC) for CMOS image sensors is proposed. The proposed ADC employs a single ramp voltage and multiple reference voltages, and the conversion is divided into coarse phase and fine phase to improve the conversion rate. An error calibration scheme is proposed to correct errors caused by offsets among the reference voltages. The digital-to-analog converter (DAC) used for the ramp generator is based on the split-capacitor array with an attenuation capacitor. Analysis of the DAC's linearity performance versus capacitor mismatch and parasitic capacitance is presented. A prototype 1024 × 32 Time Delay Integration (TDI) CMOS image sensor with the proposed ADC architecture has been fabricated in a standard 0.18 μm CMOS process. The proposed ADC has average power consumption of 128 μW and a conventional rate 6 times higher than the conventional SS ADC. A high-quality image, captured at the line rate of 15.5 k lines/s, shows that the proposed ADC is suitable for high-speed CMOS image sensors. PMID:25407903

  17. PETA4: a multi-channel TDC/ADC ASIC for SiPM readout

    NASA Astrophysics Data System (ADS)

    Sacco, I.; Fischer, P.; Ritzert, M.

    2013-12-01

    The PETA4 ASIC is the latest member of a family of chips targeted mainly at the readout of Silicon Photomultipliers in PET, with possible use in other detector applications. PETA4 houses 36 channels on a 5 × 5mm2 die and is fabricated in the UMC 180nm technology. It uses bump bonds with a convenient pitch of ≈ 270μm to allow the construction of very compact modules at moderate substrate cost. The chip requires nearly no external components by integrating everything (PLL loop filter, bandgap reference, bias DACs,...) on chip. Power consumption is <= 40mW per channel, depending on digital speed and bias settings. Every channel has two independent frontends: an established differential amplifier which has shown to be insensitive to pickup in the target application of PET/MRI, and a single-ended frontend with very low input impedance (Zin ≈ 7Ω) for high channel count operation. A fast discriminator with tunable threshold and a noise of <= 300μV self-triggers time stamping with a bin width of 50ps as well as an integrator with programmable integration time. The amplitude signal is converted by a ≈ 9-bit SAR ADC. After conversion, events with sufficient amplitude are queued for serial readout. The previous chip version PETA3 has achieved a CRT time resolution of ≈ 200ps when reading out scintillation light from a 3 × 3×5mm3 LYSO crystal coupled at room temperature to a 3 × 3mm2 SiPM from FBK. Energy resolution for LYSO is ≈ 12.5%FWHM. LYSO crystals of 1.3mm size could be clearly identified with SiPMs of 4 × 4mm2 when using a light spreader. The architecture of PETA4 and its performance in the lab and with SiPMs will be presented.

  18. Functional Roles of the Dimer-Interface Residues in Human Ornithine Decarboxylase

    PubMed Central

    Lee, Chien-Yun; Liu, Yi-Liang; Lin, Chih-Li; Liu, Guang-Yaw; Hung, Hui-Chih

    2014-01-01

    Ornithine decarboxylase (ODC) catalyzes the decarboxylation of ornithine to putrescine and is the rate-limiting enzyme in the polyamine biosynthesis pathway. ODC is a dimeric enzyme, and the active sites of this enzyme reside at the dimer interface. Once the enzyme dissociates, the enzyme activity is lost. In this paper, we investigated the roles of amino acid residues at the dimer interface regarding the dimerization, protein stability and/or enzyme activity of ODC. A multiple sequence alignment of ODC and its homologous protein antizyme inhibitor revealed that 5 of 9 residues (residues 165, 277, 331, 332 and 389) are divergent, whereas 4 (134, 169, 294 and 322) are conserved. Analytical ultracentrifugation analysis suggested that some dimer-interface amino acid residues contribute to formation of the dimer of ODC and that this dimerization results from the cooperativity of these interface residues. The quaternary structure of the sextuple mutant Y331S/Y389D/R277S/D332E/V322D/D134A was changed to a monomer rather than a dimer, and the Kd value of the mutant was 52.8 µM, which is over 500-fold greater than that of the wild-type ODC (ODC_WT). In addition, most interface mutants showed low but detectable or negligible enzyme activity. Therefore, the protein stability of these interface mutants was measured by differential scanning calorimetry. These results indicate that these dimer-interface residues are important for dimer formation and, as a consequence, are critical for enzyme catalysis. PMID:25140796

  19. Genetic and functional analysis of the soluble oxaloacetate decarboxylase from Corynebacterium glutamicum.

    PubMed

    Klaffl, Simon; Eikmanns, Bernhard J

    2010-05-01

    Soluble, divalent cation-dependent oxaloacetate decarboxylases (ODx) catalyze the irreversible decarboxylation of oxaloacetate to pyruvate and CO(2). Although these enzymes have been characterized in different microorganisms, the genes that encode them have not been identified, and their functions have been only poorly analyzed so far. In this study, we purified a soluble ODx from wild-type C. glutamicum about 65-fold and used matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) analysis and peptide mass fingerprinting for identification of the corresponding odx gene. Inactivation and overexpression of odx led to an absence of ODx activity and to a 30-fold increase in ODx specific activity, respectively; these findings unequivocally confirmed that this gene encodes a soluble ODx. Transcriptional analysis of odx indicated that there is a leaderless transcript that is organized in an operon together with a putative S-adenosylmethionine-dependent methyltransferase gene. Biochemical analysis of ODx revealed that the molecular mass of the native enzyme is about 62 +/- 1 kDa and that the enzyme is composed of two approximately 29-kDa homodimeric subunits and has a K(m) for oxaloacetate of 1.4 mM and a V(max) of 201 micromol of oxaloacetate converted per min per mg of protein, resulting in a k(cat) of 104 s(-1). Introduction of plasmid-borne odx into a pyruvate kinase-deficient C. glutamicum strain restored growth of this mutant on acetate, indicating that a high level of ODx activity redirects the carbon flux from oxaloacetate to pyruvate in vivo. Consistently, overexpression of the odx gene in an L-lysine-producing strain of C. glutamicum led to accumulation of less L-lysine. However, inactivation of the odx gene did not improve L-lysine production under the conditions tested. PMID:20233922

  20. Inhibition of histidine decarboxylase ablates the autocrine tumorigenic effects of histamine in human cholangiocarcinoma

    PubMed Central

    Francis, Heather; DeMorrow, Sharon; Venter, Julie; Onori, Paolo; White, Mellanie; Gaudio, Eugenio; Francis, Taylor; Greene, John F; Tran, Steve; Meininger, Cynthia J; Alpini, Gianfranco

    2011-01-01

    Background In several tumours the endogenous activity of histidine decarboxylase (HDC), the enzyme stimulating histamine synthesis, sustains the autocrine trophic effect of histamine on cancer progression. Cholangiocarcinoma is a biliary cancer with limited treatment options. Histamine interacts with four G-protein coupled receptors, H1–H4 histamine receptors (HRs). Objective To determine the effects of histamine stimulation and inhibition of histamine synthesis (by modulation of HDC) on cholangiocarcinoma growth. Methods In vitro studies were performed using multiple human cholangiocarcinoma lines. The expression levels of the histamine synthetic machinery and HRs were evaluated along with the effects of histamine stimulation and inhibition on cholangiocarcinoma proliferation. A xenograft tumour model was used to measure tumour volume after treatment with histamine or inhibition of histamine synthesis by manipulation of HDC. Vascular endothelial growth factor (VEGF) expression was measured in cholangiocarcinoma cells concomitant with the evaluation of the expression of CD31 in endothelial cells in the tumour microenvironment. Results Cholangiocarcinoma cells display (1) enhanced HDC and decreased monoamine oxidase B expression resulting in increased histamine secretion; and (2) increased expression of H1–H4 HRs. Inhibition of HDC and antagonising H1HR decreased histamine secretion in Mz-ChA-1 cells. Long-term treatment with histamine increased proliferation and VEGF expression in cholangiocarcinoma that was blocked by HDC inhibitor and the H1HR antagonist. In nude mice, histamine increased tumour growth (up to 25%) and VEGF expression whereas inhibition of histamine synthesis (by reduction of HDC) ablated the autocrine stimulation of histamine on tumour growth (~80%) and VEGF expression. No changes in angiogenesis (evaluated by changes in CD31 immunoreactivity) were detected in the in vivo treatment groups. Conclusion The novel concept that an autocrine loop

  1. Diversity of plasmids encoding histidine decarboxylase gene in Tetragenococcus spp. isolated from Japanese fish sauce.

    PubMed

    Satomi, Masataka; Furushita, Manabu; Oikawa, Hiroshi; Yano, Yutaka

    2011-07-15

    Nineteen isolates of histamine producing halophilic bacteria were isolated from four fish sauce mashes, each mash accumulating over 1000 ppm of histamine. The complete sequences of the plasmids encoding the pyruvoyl dependent histidine decarboxylase gene (hdcA), which is harbored in histamine producing bacteria, were determined. In conjunction, the sequence regions adjacent to hdcA were analyzed to provide information regarding its genetic origin. As reference strains, Tetragenococcus halophilus H and T. muriaticus JCM10006(T) were also studied. Phenotypic and 16S rRNA gene sequence analyses identified all isolates as T. halophilus, a predominant histamine producing bacteria present during fish sauce fermentation. Genetic analyses (PCR, Southern blot, and complete plasmid sequencing) of the histamine producing isolates confirmed that all the isolates harbored approximately 21-37 kbp plasmids encoding a single copy of the hdc cluster consisting of four genes related to histamine production. Analysis of hdc clusters, including spacer regions, indicated >99% sequence similarity among the isolates. All of the plasmids sequenced encoded traA, however genes related to plasmid conjugation, namely mob genes and oriT, were not identified. Two putative mobile genetic elements, ISLP1-like and IS200-like, respectively, were identified in the up- and downstream region of the hdc cluster of all plasmids. Most of the sequences, except hdc cluster and two adjacent IS elements, were diverse among plasmids, suggesting that each histamine producers harbored a different histamine-related plasmid. These results suggested that the hdc cluster was not spread by clonal dissemination depending on the specific plasmid and that the hdc cluster in tetragenococcal plasmid was likely encoded on transformable elements. PMID:21616548

  2. Elevated Ornithine Decarboxylase Levels Activate ATM - DNA Damage Signaling in Normal Keratinocytes

    PubMed Central

    Wei, Gang; DeFeo, Karen; Hayes, Candace S.; Woster, Patrick M.; Mandik-Nayak, Laura; Gilmour, Susan K.

    2008-01-01

    We examined the effect of increased expression of ornithine decarboxylase (ODC), a key rate-limiting enzyme in polyamine biosynthesis, on cell survival in primary cultures of keratinocytes isolated from the skin of K6/ODC transgenic mice (Ker/ODC) and their normal littermates (Ker/Norm). Although elevated levels of ODC and polyamines stimulate proliferation of keratinocytes, Ker/ODC undergo apoptotic cell death within days of primary culture unlike Ker/Norm that continue to proliferate. Phosphorylation of ATM and its substrate p53 are significantly induced both in Ker/ODC and in K6/ODC transgenic skin. ChIP analyses show that the increased level of p53 in Ker/ODC is accompanied by increased recruitment of p53 to the Bax proximal promoter. ATM activation is polyamine-dependent since DFMO, a specific inhibitor of ODC activity, blocks its phosphorylation. Ker/ODC also display increased generation of H2O2, acrolein-lysine conjugates, and protein oxidation products as well as polyamine-dependent DNA damage, as measured by the comet assay and the expression of the phosphorylated form of the histone variant γH2AX. Both ROS generation and apoptotic cell death of Ker/ODC may, at least in part, be due to induction of a polyamine catabolic pathway that generates both H2O2 and cytotoxic aldehydes, since spermine oxidase (SMO) levels are induced in Ker/ODC. In addition, treatment with MDL 72,527, an inhibitor of SMO, blocks the production of H2O2 and increases the survival of Ker/ODC. These results demonstrate a novel activation of the ATM/DNA damage signaling pathway in response to increased ODC activity in nontumorigenic keratinocytes. PMID:18381427

  3. Enhanced expression of glutamate decarboxylase 65 improves symptoms of rat parkinsonian models.

    PubMed

    Lee, B; Lee, H; Nam, Y R; Oh, J H; Cho, Y H; Chang, J W

    2005-08-01

    In this study, we report the amelioration of parkinsonian symptoms in rat Parkinson's disease (PD) models, as a result of the expression of glutamate decarboxylase (GAD) 65 with a modified cytomegalovirus (CMV) promoter. The transfer of the gene for gamma-amino butryic acid (GAD), the rate-limiting enzyme in gama-amino butrylic acid (GABA) production, has been investigated as a means to increase inhibitory synaptic activity. Electrophysiological evidence suggests that the transfer of the GAD65 gene to the subthalamic nucleus (STN) can change the excitatory output of this nucleus to inhibitory output. Our in vitro results also demonstrated higher GAD65 expression in cells transfected with the JDK promoter, as compared to cells transfected with the CMV promoter. Also, a rat PD model in which recombinant adeno-associated virus-2 (rAAV2)-JDK-GAD65 was delivered into the STN exhibited significant behavioral improvements, as compared to the saline-injected group. Interestingly, we observed that these behavioral improvements were more obvious in rat PD models in which rAAV2-JDK-GAD65 was injected into the STN than in rat PD models in which rAAV2-CMV-GAD65 was injected into the STN. Moreover, according to electrophysiological data, the rAAV2-JDK-GAD65-injected group exhibited more constant improvements in firing rates than did the rAAV2-CMV-GAD65-injected group. These data indicate that the JDK promoter, when coupled with GAD65 expression, is more effective with regard to parkinsonian symptoms than is the CMV promoter. PMID:15829994

  4. Cysteine Sulfinic Acid Decarboxylase Regulation: A Role for FXR and SHP in Murine Hepatic Taurine Metabolism

    PubMed Central

    Kerr, Thomas A.; Matsumoto, Yuri; Matsumoto, Hitoshi; Xie, Yan; Hirschberger, Lawrence L.; Stipanuk, Martha H.; Anakk, Sayeepriyadarshini; Moore, David D.; Watanabe, Mitsuhiro; Kennedy, Susan

    2014-01-01

    Background Bile acid synthesis is regulated by nuclear receptors including farnesoid X receptor (FXR) and small heterodimer partner (SHP), and by fibroblast growth factor15/19 (FGF15/19). Because bile acid synthesis involves amino acid conjugation, we hypothesized that hepatic cysteine sulfinic acid decarboxylase (CSAD) (a key enzyme in taurine synthesis) is regulated by bile acids. Aims To investigate CSAD regulation by bile acids and CSAD regulatory mechanisms. Methods Mice were fed a control diet or a diet supplemented with either 0.5% cholate or 2% cholestyramine. To gain mechanistic insight into CSAD regulation, we utilized GW4064 (FXR agonist), FGF19, or T-0901317 (LXR agonist) and Shp−/− mice. Tissue mRNA expression was determined by qRT-PCR. Amino acids were measured by HPLC. Results Mice supplemented with dietary cholate exhibited reduced hepatic CSAD mRNA expression while those receiving cholestyramine exhibited increased hepatic CSAD mRNA expression. Activation of FXR suppressed CSAD mRNA expression whereas hepatic CSAD mRNA expression was increased in Shp−/− mice. Hepatic hypotaurine concentration (the product of CSAD) was higher in Shp−/− mice with a corresponding increase in serum (but not hepatic) taurine-conjugated bile acids. FGF19 administration suppressed hepatic CYP7A1 mRNA but did not change CSAD mRNA expression. LXR activation induced CYP7A1 mRNA yet failed to induce CSAD mRNA expression. Conclusion CSAD mRNA expression is physiologically regulated by bile acids in a feedback fashion via mechanisms involving SHP and FXR but not FGF15/19 or LXR. These novel findings implicate bile acids as regulators of CSAD mRNA via mechanisms shared in part with CYP7A1. PMID:24033844

  5. Support for involvement of glutamate decarboxylase 1 and neuropeptide Y in anxiety susceptibility.

    PubMed

    Donner, Jonas; Sipilä, Tessa; Ripatti, Samuli; Kananen, Laura; Chen, Xiangning; Kendler, Kenneth S; Lönnqvist, Jouko; Pirkola, Sami; Hettema, John M; Hovatta, Iiris

    2012-04-01

    Genetic mapping efforts have identified putative susceptibility genes for human anxiety disorders. The most intensively studied genes are involved in neurotransmitter metabolism and signaling or stress response. In addition, neuropeptides and targets of anxiolytics have been examined. It has become apparent that gene × environment interactions may explain individual variation in stress resilience and predisposition to mental disorders. We aimed to replicate previous genetic findings in 16 putative anxiety susceptibility genes and further test whether they modulate the risk for developing an anxiety disorder in adulthood after childhood stress exposure. We tested 93 single-nucleotide polymorphisms (SNPs) for genetic association to anxiety disorders in the Finnish population-based Health 2000 sample (282 cases and 575 matched controls). In addition, we examined by logistic regression modeling whether the SNP genotypes modified the effect of the number of self-reported childhood adversities on anxiety disorder risk. The most significant evidence for association was observed in glutamate decarboxylase 1 (GAD1) with phobias (P = 0.0005). A subsequent meta-analysis (N = 1985) incorporating previously published findings supported involvement of a single GAD1 risk haplotype in determining susceptibility to a broad range of internalizing disorders (P = 0.0009). We additionally found that SNPs and haplotypes in neuropeptide Y (NPY) modified the effect of childhood adversities on anxiety susceptibility (P = 0.003). In conclusion, we provide further support for involvement of mainly GAD1, but also NPY in determining predisposition to anxiety disorders. PMID:22328461

  6. Insect ornithine decarboxylase (ODC) complements SPE1 knock-out of yeast Saccharomyces cerevisiae.

    PubMed

    Choi, Soon-Yong; Park, Hee Yun; Paek, Aron; Kim, Gil Seob; Jeong, Seong Eun

    2009-12-31

    Ornithine decarboxylase (ODC) is a rate-limiting enzyme in the biosynthesis of polyamines, which are essential for cell growth, differentiation, and proliferation. This report presents the characterization of an ODC-encoding cDNA (SlitODC) isolated from a moth species, the tobacco cutworm, Spodoptera litura (Lepidoptera); its expression in a polyamine-deficient strain of yeast, S. cerevisiae; and the recovery in polyamine levels and proliferation rate with the introduction of the insect enzyme. SlitODC encodes 448 amino acid residues, 4 amino acids longer than B. Mori ODC that has 71% identity, and has a longer C-terminus, consistent with B. mori ODC, than the reported dipteran enzymes. The null mutant yeast strain in the ODC gene, SPE1, showed remarkably depleted polyamine levels; in putrescine, spermidine, and spermine, the levels were > 7, > 1, and > 4%, respectively, of the levels in the wild-type strain. This consequently caused a significant arrest in cell proliferation of > 4% of the wild-type strain in polyaminefree media. The transformed strain, with the substituted SlitODC for the deleted endogenous ODC, grew and proliferated rapidly at even a higher rate than the wild-type strain. Furthermore, its polyamine content was significantly higher than even that in the wild-type strain as well as the spe1-null mutant, particularly with a very continuously enhanced putrescine level, reflecting no inhibition mechanism operating in the putrescine synthesis step by any corresponding insect ODC antizymes to SlitODC in this yeast system. PMID:19937472

  7. Epilepsy and hippocampal neurodegeneration induced by glutamate decarboxylase inhibitors in awake rats.

    PubMed

    Salazar, Patricia; Tapia, Ricardo

    2015-10-01

    Glutamic acid decarboxylase (GAD), the enzyme responsible for GABA synthesis, requires pyridoxal phosphate (PLP) as a cofactor. Thiosemicarbazide (TSC) and γ-glutamyl-hydrazone (PLPGH) inhibit the free PLP-dependent isoform (GAD65) activity after systemic administration, leading to epilepsy in mice and in young, but not in adult rats. However, the competitive GAD inhibitor 3-mercaptopropionic acid (MPA) induces convulsions in both immature and adult rats. In the present study we tested comparatively the epileptogenic and neurotoxic effects of PLPGH, TSC and MPA, administered by microdialysis in the hippocampus of adult awake rats. Cortical EEG and motor behavior were analyzed during the next 2h, and aspartate, glutamate and GABA were measured by HPLC in the microdialysis-collected fractions. Twenty-four hours after drug administration rats were fixed for histological analysis of the hippocampus. PLPGH or TSC did not affect the motor behavior, EEG or cellular morphology, although the extracellular concentration of GABA was decreased. In contrast, MPA produced intense wet-dog shakes, EEG epileptiform discharges, a >75% reduction of extracellular GABA levels and remarkable neurodegeneration of the CA1 region, with >80% neuronal loss. The systemic administration of the NMDA glutamate receptor antagonist MK-801 30 min before MPA did not prevent the MPA-induced epilepsy but significantly protected against its neurotoxic effect, reducing neuronal loss to <30%. We conclude that in adult awake rats, drugs acting on PLP availability have only a weak effect on GABA neurotransmission, whereas direct GAD inhibition produced by MPA induces hyperexcitation leading to epilepsy and hippocampal neurodegeneration. Because this degeneration was prevented by the blockade of NMDA receptors, we conclude that it is due to glutamate-mediated excitotoxicity consequent to disinhibition of the hippocampal excitatory circuits. PMID:26354164

  8. Multiple mechanisms are responsible for altered expression of ornithine decarboxylase in overproducing variant cells.

    PubMed Central

    McConlogue, L; Dana, S L; Coffino, P

    1986-01-01

    We selected and characterized a series of mouse S49 cell variants that overproduce ornithine decarboxylase (ODC). Previously, we described variants that have an amplified ODC gene and produce about 500-fold more ODC than the wild-type cells of origin (L. McConlogue and P. Coffino, J. Biol. Chem. 258:12083-12086, 1983). We examined a series of independent variants that overproduce ODC to a lesser degree and found that a number of mechanisms other than gene amplification are responsible for the increased ODC activity. Variants were selected for resistance to 0.1 mM difluoromethylornithine, an inhibitor of ODC, by either a single or a multistep process. All showed increased ODC activity and increased ODC mRNA steady-state levels. The half-life of the enzyme was not increased in any of the variants. In one class of variant the increase of ODC mRNA was sufficient to account for ODC overproduction. In a second class, the rate of synthesis of ODC polypeptide per ODC mRNA was at least four- to eightfold higher than that in wild-type cells. Therefore, these variants were altered in the translatability of ODC mRNA. Southern analysis showed that gene amplification does not account for the increased ODC mRNA levels in any of the variants. In both variant and wild-type cells, ODC activity was responsive to changes in polyamine pools; activity was reduced following augmentation of pool size. This change in activity was associated with modification of the rate of synthesis and degradation of ODC but no change in the level of ODC mRNA. Images PMID:3023951

  9. Carbidopa abrogates L-dopa decarboxylase coactivation of the androgen receptor and delays prostate tumor progression.

    PubMed

    Wafa, Latif A; Cheng, Helen; Plaa, Nathan; Ghaidi, Fariba; Fukumoto, Takahiro; Fazli, Ladan; Gleave, Martin E; Cox, Michael E; Rennie, Paul S

    2012-06-15

    The androgen receptor (AR) plays a central role in prostate cancer progression to the castration-resistant (CR) lethal state. L-Dopa decarboxylase (DDC) is an AR coactivator that increases in expression with disease progression and is coexpressed with the receptor in prostate adenocarcinoma cells, where it may enhance AR activity. Here, we hypothesize that the DDC enzymatic inhibitor, carbidopa, can suppress DDC-coactivation of AR and retard prostate tumor growth. Treating LNCaP prostate cancer cells with carbidopa in transcriptional assays suppressed the enhanced AR transactivation seen with DDC overexpression and decreased prostate-specific antigen (PSA) mRNA levels. Carbidopa dose-dependently inhibited cell growth and decreased survival in LNCaP cell proliferation and apoptosis assays. The inhibitory effect of carbidopa on DDC-coactivation of AR and cell growth/survival was also observed in PC3 prostate cancer cells (stably expressing AR). In vivo studies demonstrated that serum PSA velocity and tumor growth rates elevated ∼2-fold in LNCaP xenografts, inducibly overexpressing DDC, were reverted to control levels with carbidopa administration. In castrated mice, treating LNCaP tumors, expressing endogenous DDC, with carbidopa delayed progression to the CR state from 6 to 10 weeks, while serum PSA and tumor growth decreased 4.3-fold and 5.4-fold, respectively. Our study is a first time demonstration that carbidopa can abrogate DDC-coactivation of AR in prostate cancer cells and tumors, decrease serum PSA, reduce tumor growth and delay CR progression. Since carbidopa is clinically approved, it may be readily used as a novel therapeutic strategy to suppress aberrant AR activity and delay prostate cancer progression. PMID:21780103

  10. Expression of the neurotransmitter-synthesizing enzyme glutamic acid decarboxylase in male germ cells.

    PubMed Central

    Persson, H; Pelto-Huikko, M; Metsis, M; Söder, O; Brene, S; Skog, S; Hökfelt, T; Ritzén, E M

    1990-01-01

    The gene encoding glutamic acid decarboxylase (GAD), the key enzyme in the synthesis of the inhibitory neurotransmitter gamma-aminobutyric acid, is shown to be expressed in the testis of several different species. Nucleotide sequence analysis of a cDNA clone isolated from the human testis confirmed the presence of GAD mRNA in the testis. The major GAD mRNA in the testis was 2.5 kilobases. Smaller amounts of a 3.7-kilobase mRNA with the same size as GAD mRNA in the brain was also detected in the testis. In situ hybridization using a GAD-specific probe revealed GAD mRNA expressing spermatocytes and spermatids located in the middle part of rat seminiferous tubules. Studies on the ontogeny of GAD mRNA expression showed low levels of GAD mRNA in testes of prepubertal rats, with increasing levels as sexual maturation is reached, compatible with GAD mRNA expression in germ cells. In agreement with this, fractionation of cells from the rat seminiferous epithelium followed by Northern (RNA) blot analysis showed the highest levels of GAD mRNA associated with spermatocytes and spermatids. Evidence for the presence of GAD protein in the rat testis was obtained from the demonstration of GAD-like immunoreactivity in seminiferous tubules, predominantly at a position where spermatids and spermatozoa are found. Furthermore, GAD-like immunoreactivity was seen in the midpiece of ejaculated human spermatozoa, the part that is responsible for generating energy for spermatozoan motility. Images PMID:1697032

  11. The Arginine Decarboxylase Pathways of Host and Pathogen Interact to Impact Inflammatory Pathways in the Lung

    PubMed Central

    Dalluge, Joseph J.; Welchlin, Cole W.; Hughes, John; Han, Wei; Blackwell, Timothy S.; Laguna, Theresa A.; Williams, Bryan J.

    2014-01-01

    The arginine decarboxylase pathway, which converts arginine to agmatine, is present in both humans and most bacterial pathogens. In humans agmatine is a neurotransmitter with affinities towards α2-adrenoreceptors, serotonin receptors, and may inhibit nitric oxide synthase. In bacteria agmatine serves as a precursor to polyamine synthesis and was recently shown to enhance biofilm development in some strains of the respiratory pathogen Pseudomonas aeruginosa. We determined agmatine is at the center of a competing metabolism in the human lung during airways infections and is influenced by the metabolic phenotypes of the infecting pathogens. Ultra performance liquid chromatography with mass spectrometry detection was used to measure agmatine in human sputum samples from patients with cystic fibrosis, spent supernatant from clinical sputum isolates, and from bronchoalvelolar lavage fluid from mice infected with P. aeruginosa agmatine mutants. Agmatine in human sputum peaks during illness, decreased with treatment and is positively correlated with inflammatory cytokines. Analysis of the agmatine metabolic phenotype in clinical sputum isolates revealed most deplete agmatine when grown in its presence; however a minority appeared to generate large amounts of agmatine presumably driving sputum agmatine to high levels. Agmatine exposure to inflammatory cells and in mice demonstrated its role as a direct immune activator with effects on TNF-α production, likely through NF-κB activation. P. aeruginosa mutants for agmatine detection and metabolism were constructed and show the real-time evolution of host-derived agmatine in the airways during acute lung infection. These experiments also demonstrated pathogen agmatine production can upregulate the inflammatory response. As some clinical isolates have adapted to hypersecrete agmatine, these combined data would suggest agmatine is a novel target for immune modulation in the host-pathogen dynamic. PMID:25350753

  12. Microinjection of purified ornithine decarboxylase into Xenopus oocytes selectively stimulates ribosomal RNA synthesis.

    PubMed Central

    Russell, D H

    1983-01-01

    This study has utilized stage VI oocytes of Xenopus laevis which have amplified the rDNA gene 1,000-fold to assess whether the microinjection of ornithine decarboxylase (OrnDCase) would stimulate [alpha-32P]guanosine incorporation into 45S and 18S/28S RNA selectively. The injection of purified OrnDCase into individual oocytes resulted in a greater than 2-fold increase in the incorporation of [32P]guanosine into 45S RNA and 18S/28S RNA with no increased incorporation into low molecular weight RNA. Further, an irreversible inhibitor of OrnDCase, alpha-difluoromethylornithine (CHF2-Orn), rapidly inhibited the endogenous activity of OrnDCase when added to the buffered Hepes solution bathing the oocytes and also inhibited the incorporation of [32P]guanosine into rRNA. The inhibitory effect of CHF2-Orn could not be reversed totally by addition of 10 microM putrescine to the oocytes. OrnDCase injected into oocytes in the presence of CHF2-Orn in the media did not stimulate incorporation of [32P]guanosine label into rRNA. However, when CHF2-Orn was removed from the buffered medium at the time of the injection of label and enzyme, a 3-fold increase of 32P incorporation into 18S/28S RNA occurred. Therefore, in an in vivo model in which amplified extrachromosomal rDNA gene copies are present, the microinjection of OrnDCase was capable of specifically stimulating rRNA synthesis. CHF2-Orn, a suicide enzyme inactivator of OrnDCase, was able to inhibit rRNA synthesis and, after washout, there was a more marked stimulation of rRNA synthesis than occurred after only the injection of OrnDCase alone. These data suggest further that OrnDCase is the labile protein that regulates the initiation of RNA synthesis. PMID:6402779

  13. Phosphorylation of ornithine decarboxylase by a polyamine-dependent protein kinase.

    PubMed Central

    Atmar, V J; Kuehn, G D

    1981-01-01

    This paper presents evidence that a polyamine-dependent protein kinase (EC 2.7.1.37) purified from nuclei of the slime mold Physarum polycephalum catalyzes phosphorylation of ornithine decarboxylase (OrnDCase; L-ornithine carboxy-lyase, EC 4.1.1.17). The protein kinase had properties similar to OrnDCase antizyme. Phosphocellulose chromatography of nuclear preparations from P. polycephalum yielded the polyamine-dependent protein kinase of subunit Mr 26,000 that was resolved from a second fraction in which the protein kinase copurified with a phosphate-acceptor protein of subunit Mr 70,000. At Na+ concentrations less than approximately 150 mM, a complex formed between the protein kinase and the phosphate-acceptor protein. The complex did not demonstrate protein kinase or OrnDCase activity. The complex was dissociated by greater than 150 mM Na+ into its constituent proteins. The dissociated complex catalyzed phosphorylation of the Mr 70,000 component in the presence of spermidine and spermine, and it also demonstrated OrnDCase activity. The purified Mr 70,000 component from the complex and authentic OrnDCase, purified by procedures previously reported, were virtually identical with respect to OrnDCase activity, capacity to be phosphorylated by the polyamine-dependent protein kinase, amino acid composition, and immunological crossreactivity. Phosphorylation of OrnDCase by the polyamine-dependent protein kinase sharply inhibited OrnDCase activity. Thus, this is an example of posttranslational covalent modification of OrnDCase with concurrent alteration of its catalytic function. It is also an unusual example of control of the first enzyme in a biosynthetic pathway by a protein kinase that is, in turn, modulated by the immediate end products of the pathway. Images PMID:6946489

  14. Histidine decarboxylase and urinary methylimidazoleacetic acid in gastric neuroendocrine cells and tumours

    PubMed Central

    Tsolakis, Apostolos V; Grimelius, Lars; Granerus, Göran; Stridsberg, Mats; Falkmer, Sture E; Janson, Eva T

    2015-01-01

    AIM: To study histidine decarboxylase (HDC) expression in normal and neoplastic gastric neuroendocrine cells in relationship to the main histamine metabolite. METHODS: Control tissues from fundus (n = 3) and corpus (n = 3) mucosa of six patients undergoing operations for gastric adenocarcinoma, biopsy and/or gastric surgical specimens from 64 patients with primary gastric neuroendocrine tumours (GNETs), as well as metastases from 22 of these patients, were investigated using conventional immunohistochemistry and double immunofluorescence with commercial antibodies vs vesicular monoamine transporter 2 (VMAT-2), HDC and ghrelin. The urinary excretion of the main histamine metabolite methylimidazoleacetic acid (U-MeImAA) was determined using high-performance liquid chromatography in 27 of the 64 patients. RESULTS: In the gastric mucosa of the control tissues, co-localization studies identified neuroendocrine cells that showed immunoreactivity only to VMAT-2 and others with reactivity only to HDC. A third cell population co-expressed both antigens. There was no co-expression of HDC and ghrelin. Similar results were obtained in the foci of neuroendocrine cell hyperplasia associated with chronic atrophic gastritis type A and also in the tumours. The relative incidence of the three aforementioned markers varied in the tumours that were examined using conventional immunohistochemistry. All of these GNETs revealed both VMAT-2 and HDC immunoreactivity, and their metastases showed an immunohistochemical pattern and frequency similar to that of their primary tumours. In four patients, increased U-MeImAA excretion was detected, but only two of the patients exhibited related endocrine symptoms. CONCLUSION: Human enterochromaffin-like cells appear to partially co-express VMAT-2 and HDC. Co-expression of VMAT-2 and HDC might be required for increased histamine production in patients with GNETs. PMID:26715806

  15. Mesomere-derived glutamate decarboxylase-expressing blastocoelar mesenchyme cells of sea urchin larvae

    PubMed Central

    Katow, Hideki; Katow, Tomoko; Abe, Kouki; Ooka, Shioh; Kiyomoto, Masato; Hamanaka, Gen

    2014-01-01

    Summary The ontogenetic origin of blastocoelar glutamate decarboxylase (GAD)-expressing cells (GADCs) in larvae of the sea urchin Hemicentrotus pulcherrimus was elucidated. Whole-mount in situ hybridisation (WISH) detected transcription of the gene that encodes GAD in H. pulcherrimus (Hp-gad) in unfertilised eggs and all blastomeres in morulae. However, at and after the swimming blastula stage, the transcript accumulation was particularly prominent in clumps of ectodermal cells throughout the embryonic surface. During the gastrula stage, the transcripts also accumulated in the endomesoderm and certain blastocoelar cells. Consistent with the increasing number of Hp-gad transcribing cells, immunoblot analysis indicated that the relative abundance of Hp-Gad increased considerably from the early gastrula stage until the prism stage. The expression pattern of GADCs determined by immunohistochemistry was identical to the pattern of Hp-gad transcript accumulation determined using WISH. In early gastrulae, GADCs formed blastocoelar cell aggregates around the blastopore with primary mesenchyme cells. The increase in the number of blastocoelar GADCs was inversely proportional to the number of ectodermal GADCs ranging from a few percent of total GADCs in early gastrulae to 80% in late prism larvae; this depended on ingression of ectodermal GADCs into the blastocoel. Some of the blastocoelar GADCs were fluorescein-positive in the larvae that developed from the 16-cell stage chimeric embryos; these comprised fluorescein-labeled mesomeres and unlabelled macromeres and micromeres. Our finding indicates that some of the blastocoelar GADCs are derived from the mesomeres and thus they are the new group of mesenchyme cells, the tertiary mesenchyme cells. PMID:24357228

  16. Eflornithine (DFMO) Prevents Progression of Pancreatic Cancer by Modulating Ornithine Decarboxylase Signaling

    PubMed Central

    Mohammed, Altaf; Janakiram, Naveena B.; Madka, Venkateshwar; Ritchie, Rebekah L.; Brewer, Misty; Biddick, Laura; Patlolla, Jagan Mohan R.; Sadeghi, Michael; Lightfoot, Stan; Steele, Vernon E.; Rao, Chinthalapally V.

    2015-01-01

    Ornithine decarboxylase (ODC) is the key rate limiting enzyme in the polyamine synthesis pathway and it is overexpressed in a variety of cancers. We found that polyamine synthesis and modulation of ODC signaling occurs at early stages of pancreatic precursor lesions and increases as the tumor progresses in Kras activated p48Cre/+-LSL-KrasG12D/+ mice. Interest in use of the ODC inhibitor Eflornithine (DFMO) as a cancer chemopreventive agent has increased in recent years since ODC was shown to be transactivated by the c-myc oncogene and to cooperate with the ras oncogene in malignant transformation of epithelial tissues. We tested the effects of DFMO on pancreatic intraepithelial neoplasms (PanINs) and their progression to pancreatic ductal adenocarcinoma (PDAC) in genetically engineered Kras mice. The KrasG12D/+ mice fed DFMO at 0.1 and 0.2 % in the diet showed a significant inhibition (p<0.0001) of PDAC incidence compared with mice fed control diet. Pancreatic tumor weights were decreased by 31–43% (p<0.03–0.001) with both doses of DFMO. DFMO at 0.1 and 0.2 % caused a significant suppression (27 and 31%, P<0.02–0.004) of PanIN 3 lesions (carcinoma in situ). DFMO-treated pancreas exhibited modulated ODC pathway components along with decreased proliferation and increased expression of p21/p27 as compared with pancreatic tissues derived from mice fed control diet. In summary, our preclinical data indicate that DFMO has potential for chemoprevention of pancreatic cancer and should be evaluated in other PDAC models and in combination with other drugs in anticipation of future clinical trials. PMID:25248858

  17. Spermidine mediates degradation of ornithine decarboxylase by a non-lysosomal, ubiquitin-independent mechanism

    SciTech Connect

    Glass, J.R.; Gerner, E.W.

    1987-01-01

    The mechanism of spermidine-induced ornithine decarboxylase (OCD, E.C. 4.1.1.17) inactivation was investigated using Chinese hamster ovary (CHO) cells, maintained in serum-free medium, which display a stabilization of ODC owing to the lack of accumulation of putrescine and spermidine. Treatment of cells with 10 ..mu..M exogenous spermidine leads to rapid decay of ODC activity accompanied by a parallel decrease in enzyme protein. Analysis of the decay of (/sup 35/S)methionine-labeled ODC and separation by two-dimensional electrophoresis revealed no detectable modification in ODC structure during enhanced degradation. Spermidine-mediated inactivation of ODC occurred in a temperature-dependent manner exhibiting pseudo-first-order kinetics over a temperature range of 22-37/sup 0/C. In cultures treated continuously, an initial lag was observed after treatment with spermidine, followed by a rapid decline in activity as an apparent critical concentration of intracellular spermidine was achieved. Treating cells at 22/sup 0/C for 3 hours with 10 ..mu.. M spermidine, followed by removal of exogenous polyamine, and then shifting to varying temperatures, resulted in rates of ODC inactivation identical with that determined with a continuous treatment. Arrhenius analysis showed that polyamine mediated inactivation of ODC occurred with an activation energy of approximately 16 kcal/mol. Treatment of cells with lysosomotrophic agents had no effect of ODC degradation. ODC turnover was not dependent on ubiquitin-dependent proteolysis. These data support the hypothesis that spermidine regulates ODC degradation via a mechanism requiring new protein synthesis, and that this occurs via a non-lysosomal, ubiquitin-independent pathway.

  18. Snapshot of a Reaction Intermediate: Analysis of Benzoylformate Decarboxylase in Complex with a Benzoylphosphonate Inhibitor

    SciTech Connect

    Brandt, Gabriel S.; Kneen, Malea M.; Chakraborty, Sumit; Baykal, Ahmet T.; Nemeria, Natalia; Yep, Alejandra; Ruby, David I.; Petsko, Gregory A.; Kenyon, George L.; McLeish, Michael J.; Jordan, Frank; Ringe, Dagmar

    2009-04-22

    Benzoylformate decarboxylase (BFDC) is a thiamin diphosphate- (ThDP-) dependent enzyme acting on aromatic substrates. In addition to its metabolic role in the mandelate pathway, BFDC shows broad substrate specificity coupled with tight stereo control in the carbon-carbon bond-forming reverse reaction, making it a useful biocatalyst for the production of chiral-hydroxy ketones. The reaction of methyl benzoylphosphonate (MBP), an analogue of the natural substrate benzoylformate, with BFDC results in the formation of a stable analogue (C2{alpha}-phosphonomandelyl-ThDP) of the covalent ThDP-substrate adduct C2{alpha}-mandelyl-ThDP. Formation of the stable adduct is confirmed both by formation of a circular dichroism band characteristic of the 1',4'-iminopyrimidine tautomeric form of ThDP (commonly observed when ThDP forms tetrahedral complexes with its substrates) and by high-resolution mass spectrometry of the reaction mixture. In addition, the structure of BFDC with the MBP inhibitor was solved by X-ray crystallography to a spatial resolution of 1.37 {angstrom} (PDB ID 3FSJ). The electron density clearly shows formation of a tetrahedral adduct between the C2 atom of ThDP and the carbonyl carbon atom of the MBP. This adduct resembles the intermediate from the penultimate step of the carboligation reaction between benzaldehyde and acetaldehyde. The combination of real-time kinetic information via stopped-flow circular dichroism with steady-state data from equilibrium circular dichroism measurements and X-ray crystallography reveals details of the first step of the reaction catalyzed by BFDC. The MBP-ThDP adduct on BFDC is compared to the recently solved structure of the same adduct on benzaldehyde lyase, another ThDP-dependent enzyme capable of catalyzing aldehyde condensation with high stereospecificity.

  19. Role of UDP-Glucuronic Acid Decarboxylase in Xylan Biosynthesis in Arabidopsis.

    PubMed

    Kuang, Beiqing; Zhao, Xianhai; Zhou, Chun; Zeng, Wei; Ren, Junli; Ebert, Berit; Beahan, Cherie T; Deng, Xiaomei; Zeng, Qingyin; Zhou, Gongke; Doblin, Monika S; Heazlewood, Joshua L; Bacic, Antony; Chen, Xiaoyang; Wu, Ai-Min

    2016-08-01

    UDP-xylose (UDP-Xyl) is the Xyl donor used in the synthesis of major plant cell-wall polysaccharides such as xylan (as a backbone-chain monosaccharide) and xyloglucan (as a branching monosaccharide). The biosynthesis of UDP-Xyl from UDP-glucuronic acid (UDP-GlcA) is irreversibly catalyzed by UDP-glucuronic acid decarboxylase (UXS). Until now, little has been known about the physiological roles of UXS in plants. Here, we report that AtUXS1, AtUXS2, and AtUXS4 are located in the Golgi apparatus whereas AtUXS3, AtUXS5, and AtUXS6 are located in the cytosol. Although all six single AtUXS T-DNA mutants and the uxs1 usx2 uxs4 triple mutant show no obvious phenotype, the uxs3 uxs5 uxs6 triple mutant has an irregular xylem phenotype. Monosaccharide analysis showed that Xyl levels decreased in uxs3 uxs5 uxs6 and linkage analysis confirmed that the xylan content in uxs3 xus5 uxs6 declined, indicating that UDP-Xyl from cytosol AtUXS participates in xylan synthesis. Gel-permeation chromatography showed that the molecular weight of non-cellulosic polysaccharides in the triple mutants, mainly composed of xylans, is lower than that in the wild type, suggesting an effect on the elongation of the xylan backbone. Upon saccharification treatment stems of the uxs3 uxs5 uxs6 triple mutants released monosaccharides with a higher efficiency than those of the wild type. Taken together, our results indicate that the cytosol UXS plays a more important role than the Golgi-localized UXS in xylan biosynthesis. PMID:27179920

  20. Refractory status epilepticus and glutamic acid decarboxylase antibodies in adults: presentation, treatment and outcomes.

    PubMed

    Khawaja, Ayaz M; Vines, Brannon L; Miller, David W; Szaflarski, Jerzy P; Amara, Amy W

    2016-03-01

    Glutamic acid decarboxylase antibodies (GAD-Abs) have been implicated in refractory epilepsy. The association with refractory status epilepticus in adults has been rarely described. We discuss our experience in managing three adult patients who presented with refractory status epilepticus associated with GAD-Abs. Case series with retrospective chart and literature review. Three patients without pre-existing epilepsy who presented to our institution with generalized seizures between 2013 and 2014 were identified. Seizures proved refractory to first and second-line therapies and persisted beyond 24 hours. Patient 1 was a 22-year-old female who had elevated serum GAD-Ab titres at 0.49 mmol/l (normal: <0.02) and was treated with multiple immuno- and chemotherapies, with eventual partial seizure control. Patient 2 was a 61-year-old black female whose serum GAD-Ab titre was 0.08 mmol/l. EEG showed persistent generalized periodic discharges despite maximized therapy with anticonvulsants but no immunotherapy, resulting in withdrawal of care and discharge to nursing home. Patient 3 was a 50-year-old black female whose serum GAD-Ab titre was 0.08 mmol/l, and was discovered to have pulmonary sarcoidosis. Treatment with steroids and intravenous immunoglobulin resulted in seizure resolution. Due to the responsiveness to immunotherapy, there may be an association between GAD-Abs and refractory seizures, including refractory status epilepticus. Causation cannot be established since GAD-Abs may be elevated secondary to concurrent autoimmune diseases or formed de novo in response to GAD antigen exposure by neuronal injury. Based on this report and available literature, there may be a role for immuno- and chemotherapy in the management of refractory status epilepticus associated with GAD-Abs. PMID:26878120

  1. Leishmania donovani Ornithine Decarboxylase Is Indispensable for Parasite Survival in the Mammalian Host▿

    PubMed Central

    Boitz, Jan M.; Yates, Phillip A.; Kline, Chelsey; Gaur, Upasna; Wilson, Mary E.; Ullman, Buddy; Roberts, Sigrid C.

    2009-01-01

    Mutations within the polyamine biosynthetic pathway of Leishmania donovani, the etiological agent of visceral leishmaniasis, confer polyamine auxotrophy to the insect vector or promastigote form of the parasite. However, whether the infectious or amastigote form of the parasite requires an intact polyamine pathway has remained an open question. To address this issue, conditionally lethal Δodc mutants lacking ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis, were created by double targeted gene replacement within a virulent strain of L. donovani. ODC-deficient promastigotes and axenic amastigotes were auxotrophic for polyamines and capable of robust growth only when exogenous putrescine was supplied in the culture medium, confirming that polyamine biosynthesis is an essential nutritional pathway for L. donovani promastigotes. To assess whether the Δodc lesion also affected the ability of amastigotes to sustain a robust infection, macrophage and mouse infectivity experiments were performed. Parasite loads in murine macrophages infected with each of two independent Δodc knockout lines were decreased ∼80% compared to their wild-type counterpart. Furthermore, α-difluoromethylornithine, a suicide inhibitor of ODC, inhibited growth of wild-type L. donovani amastigotes and effectively cured macrophages of parasites, thereby preventing host cell destruction. Strikingly, however, parasitemias of both Δodc null mutants were reduced by 6 and 3 orders of magnitude, respectively, in livers and spleens of BALB/c mice. The compromised infectivity phenotypes of the Δodc knockouts in both macrophages and mice were rescued by episomal complementation of the genetic lesion. These genetic and pharmacological studies strongly implicate ODC as an essential cellular determinant that is necessary for the viability and growth of both L. donovani promastigotes and amastigotes and intimate that pharmacological inhibition of ODC is a promising

  2. Evaluation of ornithine decarboxylase activity as a marker for tumor growth rate in malignant tumors.

    PubMed

    Westin, T; Edström, S; Lundholm, K; Gustafsson, B

    1991-10-01

    Ornithine decarboxylase (ODC) is a rate-limiting enzyme in the synthesis of polyamines. Polyamines regulate DNA synthesis by a mechanism that is not fully understood. High levels of polyamines and ODC activity are associated with rapid cell growth, particularly in tumor tissues. The aim of this study was to determine whether ODC activity as a marker for rapid alterations in tumor growth could be used to investigate whether nutritional support in cancer patients stimulates tumor cell proliferation. Weight-losing head and neck cancer patients and tumor-bearing mice (MCG 101, C57/BL) were studied during different feeding regimens. The ODC activity in tumor tissue was investigated in relation to the following variables: (1) histopathologic differentiation; (2) DNA content; and (3) bromodeoxyuridine (BrdUrd) incorporation into DNA. After the animals were starved for 24 hours, a significant reduction of tumor growth was demonstrated in the experimental tumor along with a reduction of ODC activity, an accumulation of cells in the G0G1 phase, and a reduction of cells incorporating BrdUrd into DNA. Refeeding after 24 hours generated a response by all variables. Tumor biopsy specimens from patients with head and neck cancer malignancies demonstrated aneuploidy in the cells of 70% of the patients. High ODC activity in tumor tissue was demonstrated mainly among poorly differentiated tumors, and ODC activity was correlated with the compartment size of aneuploidic cells in the tumor. High ODC activity indicated a poor short-term survival (1 year). It was concluded that experimental tumor growth is highly dependent on host feeding. However, there was no evidence supporting the claim that nutritional support to cancer patients stimulates tumor cell proliferation. Determination of ODC activity may be used to monitor rapid changes in DNA synthesis and may have prognostic significance for survival. PMID:1951878

  3. Structural Basis for Nucleotide Binding and Reaction Catalysis in Mevalonate Diphosphate Decarboxylase

    SciTech Connect

    Barta, Michael L.; McWhorter, William J.; Miziorko, Henry M.; Geisbrecht, Brian V.

    2012-09-17

    Mevalonate diphosphate decarboxylase (MDD) catalyzes the final step of the mevalonate pathway, the Mg{sup 2+}-ATP dependent decarboxylation of mevalonate 5-diphosphate (MVAPP), producing isopentenyl diphosphate (IPP). Synthesis of IPP, an isoprenoid precursor molecule that is a critical intermediate in peptidoglycan and polyisoprenoid biosynthesis, is essential in Gram-positive bacteria (e.g., Staphylococcus, Streptococcus, and Enterococcus spp.), and thus the enzymes of the mevalonate pathway are ideal antimicrobial targets. MDD belongs to the GHMP superfamily of metabolite kinases that have been extensively studied for the past 50 years, yet the crystallization of GHMP kinase ternary complexes has proven to be difficult. To further our understanding of the catalytic mechanism of GHMP kinases with the purpose of developing broad spectrum antimicrobial agents that target the substrate and nucleotide binding sites, we report the crystal structures of wild-type and mutant (S192A and D283A) ternary complexes of Staphylococcus epidermidis MDD. Comparison of apo, MVAPP-bound, and ternary complex wild-type MDD provides structural information about the mode of substrate binding and the catalytic mechanism. Structural characterization of ternary complexes of catalytically deficient MDD S192A and D283A (k{sub cat} decreased 10{sup 3}- and 10{sup 5}-fold, respectively) provides insight into MDD function. The carboxylate side chain of invariant Asp{sup 283} functions as a catalytic base and is essential for the proper orientation of the MVAPP C3-hydroxyl group within the active site funnel. Several MDD amino acids within the conserved phosphate binding loop ('P-loop') provide key interactions, stabilizing the nucleotide triphosphoryl moiety. The crystal structures presented here provide a useful foundation for structure-based drug design.

  4. Production of Dopamine by Aromatic l-Amino Acid Decarboxylase Cells after Spinal Cord Injury.

    PubMed

    Ren, Li-Qun; Wienecke, Jacob; Hultborn, Hans; Zhang, Mengliang

    2016-06-15

    Aromatic l-amino acid decarboxylase (AADC) cells are widely distributed in the spinal cord, and their functions are largely unknown. We have previously found that AADC cells in the spinal cord could increase their ability to produce serotonin (5-hydroxytryptamine) from 5-hydroxytryptophan after spinal cord injury (SCI). Because AADC is a common enzyme catalyzing 5-hydroxytryptophan to serotonin and l-3,4-dihydroxyphenylalanine (l-dopa) to dopamine (DA), it seems likely that the ability of AADC cells using l-dopa to synthesize DA is also increased. To prove whether or not this is the case, a similar rat sacral SCI model and a similar experimental paradigm were adopted as that which we had used previously. In the chronic SCI rats (> 45 days), no AADC cells expressed DA if there was no exogenous l-dopa application. However, following administration of a peripheral AADC inhibitor (carbidopa) with or without a monoamine oxidase inhibitor (pargyline) co-application, systemic administration of l-dopa resulted in ∼94% of AADC cells becoming DA-immunopositive in the spinal cord below the lesion, whereas in normal or sham-operated rats none or very few of AADC cells became DA-immunopositive with the same treatment. Using tail electromyography, spontaneous tail muscle activity was increased nearly fivefold over the baseline level. When pretreated with a central AADC inhibitor (NSD-1015), further application of l-dopa failed to increase the motoneuron activity although the expression of DA in the AADC cells was not completely inhibited. These findings demonstrate that AADC cells in the spinal cord below the lesion gain the ability to produce DA from its precursor in response to SCI. This ability also enables the AADC cells to produce 5-HT and trace amines, and likely contributes to the development of hyperexcitability. These results might also be implicated for revealing the pathological mechanisms underlying l-dopa-induced dyskinesia in Parkinson's disease. PMID:26830512

  5. Human Monoclonal Islet Cell Antibodies From a Patient with Insulin- Dependent Diabetes Mellitus Reveal Glutamate Decarboxylase as the Target Antigen

    NASA Astrophysics Data System (ADS)

    Richter, Wiltrud; Endl, Josef; Eiermann, Thomas H.; Brandt, Michael; Kientsch-Engel, Rosemarie; Thivolet, Charles; Jungfer, Herbert; Scherbaum, Werner A.

    1992-09-01

    The autoimmune phenomena associated with destruction of the β cell in pancreatic islets and development of type 1 (insulin-dependent) diabetes mellitus (IDDM) include circulating islet cell antibodies. We have immortalized peripheral blood lymphocytes from prediabetic individuals and patients with newly diagnosed IDDM by Epstein-Barr virus transformation. IgG-positive cells were selected by anti-human IgG-coupled magnetic beads and expanded in cell culture. Supernatants were screened for cytoplasmic islet cell antibodies using the conventional indirect immunofluorescence test on cryostat sections of human pancreas. Six islet cell-specific B-cell lines, originating from a patient with newly diagnosed IDDM, could be stabilized on a monoclonal level. All six monoclonal islet cell antibodies (MICA 1-6) were of the IgG class. None of the MICA reacted with human thyroid, adrenal gland, anterior pituitary, liver, lung, stomach, and intestine tissues but all six reacted with pancreatic islets of different mammalian species and, in addition, with neurons of rat cerebellar cortex. MICA 1-6 were shown to recognize four distinct antigenic epitopes in islets. Islet cell antibody-positive diabetic sera but not normal human sera blocked the binding of the monoclonal antibodies to their target epitopes. Immunoprecipitation of 35S-labeled human islet cell extracts revealed that a protein of identical size to the enzyme glutamate decarboxylase (EC 4.1.1.15) was a target of all MICA. Furthermore, antigen immunotrapped by the MICA from brain homogenates showed glutamate decarboxylase enzyme activity. MICA 1-6 therefore reveal glutamate decarboxylase as the predominant target antigen of cytoplasmic islet cell autoantibodies in a patient with newly diagnosed IDDM.

  6. A mutualistic fungal symbiont of perennial ryegrass contains two different pyr4 genes, both expressing orotidine-5'-monophosphate decarboxylase.

    PubMed

    Collett, M A; Bradshaw, R E; Scott, D B

    1995-05-26

    A fragment of the Claviceps purpurea pyr4 gene, encoding orotidine-5'-monophosphate decarboxylase (OMP decarboxylase), was used to screen a genomic library from an isolate of a fungus, Acremonium sp. (designated Lp1), which grows as an endophyte in perennial ryegrass (Lolium perenne). Three positive clones, lambda MC11, lambda MC12 and lambda MC14, were isolated. Two of these clones, lambda MC12 and lambda MC14, were overlapping clones from the same locus, while lambda MC11 was from a different locus. Fragments of these clones which hybridised with C. purpurea pyr4 were sequenced and found to have similarity with pyr4 from other Pyrenomycete fungi. The pyr4 gene from lambda MC12 and lambda MC14 was designated pyr4-1 and that from lambda MC11 was designated pyr4-2. The predicted ORFs of the two genes were highly conserved, with 97.5% identity at the nucleotide level, the 5' non-coding sequences were the least conserved with 88.5% identity and the 3' non-coding sequences had 93.0% identity. RT-PCR analysis of total RNA from Lp1 demonstrated that transcripts from the two genes were present at similar levels, and hybridisation of pyr4-1 to Northern blots of total RNA from Lp1 showed that full-length transcripts were being produced. Genomic fragments containing pyr4 were transformed into a strain of Aspergillus nidulans which has a mutation in pyrG (encoding OMP decarboxylase). Both pyr4-1 and pyr4-2 complemented the pyrG mutation in A. nidulans, indicating that both encode functional OMP decarboxylases. It has been proposed [Schardl et al., Genetics 136 (1994) 1307-1317] that the two pyr4 in Lp1 arose by interspecific hybridisation, most likely between the ryegrass choke pathogen, Epichloë typhina, and another endophyte from perennial ryegrass, Acremonium lolii. Analysis by PCR amplification and direct sequencing of the variable 5' non-coding regions of pyr4, from possible ancestors to Lp1 supports this hypothesis. Comparisons of these sequences to the 5' non

  7. A known and a novel mutation in the glycine decarboxylase gene in a newborn with classic nonketotic hyperglycinemia.

    PubMed

    Beijer, P; Lichtenbelt, K D; Hofstede, F C; Nikkels, P G J; Lemmers, P; de Vries, L S

    2012-06-01

    A term neonate displayed typical features of nonketotic hyperglycinemia (NKH). Conventional magnetic resonance imaging showed corpus callosum hypoplasia and increased signal intensity of the white matter. Magnetic resonance proton spectroscopy revealed high cerebral glycine levels. The liquor/plasma glycine ratio was increased. Genetic testing detected a known and a novel mutation in the glycine decarboxylase gene, leading to the classic form of glycine encephalopathy. Prenatal genetic testing in the subsequent pregnancy showed that this fetus was not affected. As features of neonatal NKH may not be very specific, recognition of the disease may be difficult. An overview of clinical, electroencephalography, and neuroimaging findings is given in this article. PMID:22610665

  8. A Second 5-Carboxyvanillate Decarboxylase Gene, ligW2, Is Important for Lignin-Related Biphenyl Catabolism in Sphingomonas paucimobilis SYK-6

    PubMed Central

    Peng, Xue; Masai, Eiji; Kasai, Daisuke; Miyauchi, Keisuke; Katayama, Yoshihiro; Fukuda, Masao

    2005-01-01

    A lignin-related biphenyl compound, 5,5′-dehydrodivanillate (DDVA), is degraded to 5-carboxyvanillate (5CVA) by the enzyme reactions catalyzed by DDVA O-demethylase (LigX), meta-cleavage oxygenase (LigZ), and meta-cleavage compound hydrolase (LigY) in Sphingomonas paucimobilis SYK-6. 5CVA is then transformed to vanillate by a nonoxidative 5CVA decarboxylase and is further degraded through the protocatechuate 4,5-cleavage pathway. A 5CVA decarboxylase gene, ligW, was isolated from SYK-6 (X. Peng, E. Masai, H. Kitayama, K. Harada, Y, Katayama, and M. Fukuda, Appl. Environ. Microbiol. 68:4407-4415, 2002). However, disruption of ligW slightly affected the 5CVA decarboxylase activity and the growth rate on DDVA of the mutant, suggesting the presence of an alternative 5CVA decarboxylase gene. Here we isolated a second 5CVA decarboxylase gene, ligW2, which consists of a 1,050-bp open reading frame encoding a polypeptide with a molecular mass of 39,379 Da. The deduced amino acid sequence encoded by ligW2 exhibits 37% identity with the sequence encoded by ligW. Based on a gas chromatography-mass spectrometry analysis of the reaction product from 5CVA catalyzed by LigW2 in the presence of deuterium oxide, LigW2 was indicated to be a nonoxidative decarboxylase of 5CVA, like LigW. After disruption of ligW2, both the growth rate on DDVA and the 5CVA decarboxylase activity of the mutant were decreased to approximately 30% of the wild-type levels. The ligW ligW2 double mutant lost both the ability to grow on DDVA and the 5CVA decarboxylase activity. These results indicate that both ligW and ligW2 contribute to 5CVA degradation, although ligW2 plays the more important role in the growth of SYK-6 cells on DDVA. PMID:16151081

  9. MR assessment of lumbar disk herniation treated with oxygen-ozone diskolysis: the role of DWI and related ADC versus intervertebral disk volumetric analysis for detecting treatment response.

    PubMed

    Splendiani, A; Perri, M; Conchiglia, A; Fasano, F; Di Egidio, G; Masciocchi, C; Gallucci, M

    2013-06-01

    We prospectively assessed the diagnostic criteria of morphologic MRI study (MMS) and the accuracy of DWI and related ADC values (DWI-ADC) versus intervertebral disk volumetric analysis (IDVA) for predicting shrinkage of lumbar disk herniation treated with oxygen-ozone (O2-O3) diskolysis. Sixty-eight patients (36 men and 32 women; mean age 39) with lumbosciatica underwent O2-O3 diskolysis. The six-month MRI follow-up was performed with FSE-T2 and T2-fat, SE-T1 and DWI-weighted images. IDVA was determined using OsiriX(®). Diagnostic criteria and accuracy were evaluated with regards to DWI and related ADC in detecting response to ozone therapy. Fifty-eight of 68 patients had successful outcomes (responders), whereas ten patients showed unsatisfactory outcomes (non-responders). MMS showed that a centrally located herniated disk and grade 1 nerve root compression were more common in the responder group (p < 0.05). DWI-ADC and IDVA showed statistically significant shrinkage in the sixth month of follow-up (p < 0.05) with a mean ADC value reduction of 2.10 × 10(-3) mm(2)/s +/- 0.19 SD in the second month of follow-up (p < 0.05). DWI-ADC had an accuracy of 0.81 in detecting response to therapy around the second month of follow-up. DWI-ADC appear to be useful adjuncts to MMS in the follow-up of patients undergoing O2-O3 diskolysis. PMID:23859294

  10. Aldehyde Tag Coupled with HIPS Chemistry Enables the Production of ADCs Conjugated Site-Specifically to Different Antibody Regions with Distinct in Vivo Efficacy and PK Outcomes

    PubMed Central

    2015-01-01

    It is becoming increasingly clear that site-specific conjugation offers significant advantages over conventional conjugation chemistries used to make antibody–drug conjugates (ADCs). Site-specific payload placement allows for control over both the drug-to-antibody ratio (DAR) and the conjugation site, both of which play an important role in governing the pharmacokinetics (PK), disposition, and efficacy of the ADC. In addition to the DAR and site of conjugation, linker composition also plays an important role in the properties of an ADC. We have previously reported a novel site-specific conjugation platform comprising linker payloads designed to selectively react with site-specifically engineered aldehyde tags on an antibody backbone. This chemistry results in a stable C–C bond between the antibody and the cytotoxin payload, providing a uniquely stable connection with respect to the other linker chemistries used to generate ADCs. The flexibility and versatility of the aldehyde tag conjugation platform has enabled us to undertake a systematic evaluation of the impact of conjugation site and linker composition on ADC properties. Here, we describe the production and characterization of a panel of ADCs bearing the aldehyde tag at different locations on an IgG1 backbone conjugated using Hydrazino-iso-Pictet-Spengler (HIPS) chemistry. We demonstrate that in a panel of ADCs with aldehyde tags at different locations, the site of conjugation has a dramatic impact on in vivo efficacy and pharmacokinetic behavior in rodents; this advantage translates to an improved safety profile in rats as compared to a conventional lysine conjugate. PMID:24924618

  11. The use of DWI to assess spleen and liver quantitative ADC changes in the detection of liver fibrosis stages in chronic viral hepatitis.

    PubMed

    Cece, Hasan; Ercan, Abdulbasit; Yıldız, Sema; Karakas, Ekrem; Karakas, Omer; Boyacı, Fatıma Nurefsan; Aydogan, Timucin; Karakas, Emel Yigit; Cullu, Nesat; Ulas, Turgay

    2013-08-01

    This study aimed to evaluate the changes in spleen and liver diffusion-weighted magnetic resonance imaging (DWI) in chronic viral hepatitis patients. The study comprised 47 patients and 30 healthy volunteers. DWIs were obtained. Apparent Diffusion Coefficient (ADC) measurements were made by transferring the images to the workstation. The measurements of value b 1000 were made from a total of five points of the liver and three points of the spleen. Liver biopsy was performed on the 47 patients. The fibrosis stages of the patients were defined according to the METAVIR scoring system. Student's t-test was used in the comparison of mean ages, liver and spleen ADC values between the patient and the control group. Kruskal-Wallis followed by Mann-Whitney U Test with Bonferroni adjustment was performed in the comparison of mean ADC values of the patients at different stages and the control group. A statistically significant difference was determined between the patient and control group in respect of liver and spleen mean ADC values (P<0.05). F3 group showed a significant difference compared to control and F1 and F4 group showed a significant difference compared to control, F1, F2 and F3 group in terms of the mean liver ADC value (P<0.01). F3 and F4 group showed a significant difference compared to control and F1 group in terms of the mean spleen ADC value (P<0.01). As a result we believe that the measurement of liver and spleen ADC values may be an indicator in the determination of the level of fibrosis. PMID:23518145

  12. Brain extraction in pediatric ADC maps, toward characterizing neuro-development in multi-platform and multi-institution clinical images.

    PubMed

    Ou, Yangming; Gollub, Randy L; Retzepi, Kallirroi; Reynolds, Nathaniel; Pienaar, Rudolph; Pieper, Steve; Murphy, Shawn N; Grant, P Ellen; Zöllei, Lilla

    2015-11-15

    Apparent Diffusion Coefficient (ADC) maps can be used to characterize myelination and to detect abnormalities in the developing brain. However, given the normal variation in regional ADC with myelination, detection of abnormalities is difficult when based on visual assessment. Quantitative and automated analysis of pediatric ADC maps is thus desired but requires accurate brain extraction as the first step. Currently, most existing brain extraction methods are optimized for structural T1-weighted MR images of fully myelinated brains. Due to differences in age and image contrast, these approaches do not translate well to pediatric ADC maps. To address this problem, we present a multi-atlas brain extraction framework that has 1) specificity: designed and optimized specifically for pediatric ADC maps; 2) generality: applicable to multi-platform and multi-institution data, and to subjects at various neuro-developmental stages across the first 6 years of life; 3) accuracy: highly accurate compared to expert annotations; and 4) consistency: consistently accurate regardless of sources of data and ages of subjects. We show how we achieve these goals, via optimizing major components in a multi-atlas brain extraction framework, and via developing and evaluating new criteria for its atlas ranking component. Moreover, we demonstrate that these goals can be achieved with a fixed set of atlases and a fixed set of parameters, which opens doors for our optimized framework to be used in large-scale and multi-institution neuro-developmental and clinical studies. In a pilot study, we use this framework in a dataset containing scanner-generated ADC maps from 308 pediatric patients collected during the course of routine clinical care. Our framework leads to successful quantifications of the changes in whole-brain volumes and mean ADC values across the first 6 years of life. PMID:26260429

  13. VizieR Online Data Catalog: SAO Star Catalog J2000 (SAO Staff 1966; USNO, ADC 1990)

    NASA Astrophysics Data System (ADS)

    SAO Staff

    1995-10-01

    This machine-readable SAO catalog from the Astronomical Data Center is based on an original binary version of the Smithsonian Astrophysical Observatory Star Catalog (SAO, SAO Staff 1966). Subsequent improvements by T. A. Nagy (1979) included the addition of equatorial coordinates in radians and cross-identifications from the Table of Correspondences SAO/HD/DM/GC (Morin 1973). As a prelude to creation of the 1984 version of the SAO, a new version of the SAO-HD-GC-DM Cross Index was prepared (Roman, Warren, and Schofield 1983). The 1984 version of the SAO contained the corrected and extended cross identifications, all errata published up to January 1984 and known to the ADC, numerous errors forwarded to the ADC by colleagues, and errors discovered at the ADC during the course of this work. Clayton A. Smith of the U. S. Naval Observatory provided J2000.0 positions and proper motions for the SAO stars. Published and unpublished errors discovered in the previous version (1984) have been corrected (up to May 1991). The catalog contains SAO number; the right ascension and declination with a B1950.0 equinox and epoch; annual proper motion and its standard deviation, photographic and visual magnitudes; spectral type; references to sources; the Durchmusterung (DM) identifier if the star is listed in the Bonner DM (BD), Cordoba DM (CD), or Cape Photographic DM (CP); component identification; The Henry Draper (Extension) (HD or HDE) number; and J2000 positions and proper motions. Multiple-star component identifications have been added to stars where more than one SAO entry has the same DM number. The Henry Draper Extension (HDE) numbers have been added for stars found in both volumes of the extension. Data for duplicate SAO entries (those referring to the same star) have been flagged. J2000 positions in usual units and in radians have been added. (1 data file).

  14. A reference voltage in capacitor-resister hybrid SAR ADC for front-end readout system of CZT detector

    NASA Astrophysics Data System (ADS)

    Wei, Liu; Tingcun, Wei; Bo, Li; Lifeng, Yang; Yongcai, Hu

    2016-01-01

    An on-chip reference voltage has been designed in capacitor-resister hybrid SAR ADC for CZT detector with the TSMC 0.35 μm 2P4M CMOS process. The voltage reference has a dynamic load since using variable capacitors and resistances, which need a large driving ability to deal with the current related to the time and sampling rate. Most of the previous articles about the reference for ADC present only the bandgap part for a low temperature coefficient and high PSRR. However, it is not enough and overall, it needs to consider the output driving ability. The proposed voltage reference is realized by the band-gap reference, voltage generator and output buffer. Apart from a low temperature coefficient and high PSRR, it has the features of a large driving ability and low power consumption. What is more, for CZT detectors application in space, a radiation-hardened design has been considered. The measurement results show that the output reference voltage of the buffer is 4.096 V. When the temperature varied from 0 to 80 °C, the temperature coefficient is 12.2 ppm/°C. The PSRR was -70 dB @ 100 kHz. The drive current of the reference can reach up to 10 mA. The area of the voltage reference in the SAR ADC chip is only 449 × 614 μm2. The total power consumption is only 1.092 mW. Project supported by the National Key Scientific Instrument and Equipment Development Project (No. 2011YQ040082), the National Natural Science Foundation of China (No. 61376034), and the Shaanxi Province Science and Technology Innovation Project (No. 2015KTZDGY03-03).

  15. Improving single slope ADC and an example implemented in FPGA with 16.7 GHz equivalent counter clook frequency

    SciTech Connect

    Wu, Jinyuan; Odeghe, John; Stackley, Scott; Zha, Charles; /Rice U.

    2011-11-01

    Single slope ADC is a common building block in many ASCI or FPGA based front-end systems due to its simplicity, small silicon footprint, low noise interference and low power consumption. In single slope ADC, using a Gray code counter is a popular scheme for time digitization, in which the comparator output drives the clock (CK) port of a register to latch the bits from the Gray code counter. Unfortunately, feeding the comparator output into the CK-port causes unnecessary complexities and artificial challenges. In this case, the propagation delays of all bits from the counter to the register inputs must be matched and the counter must be a Gray code one. A simple improvement on the circuit topology, i.e., feeding the comparator output into the D-port of a register, will avoid these unnecessary challenges, eliminating the requirement of the propagation delay match of the counter bits and allowing the use of regular binary counters. This scheme not only simplifies current designs for low speeds and resolutions, but also opens possibilities for applications requiring higher speeds and resolutions. A multi-channel single slope ADC based on a low-cost FPGA device has been implemented and tested. The timing measurement bin width in this work is 60 ps, which would need a 16.7 GHz counter clock had it implemented with the conventional Gray code counter scheme. A 12-bit performance is achieved using a fully differential circuit making comparison between the input and the ramping reference, both in differential format.

  16. A 12 bit 40 MSPS SAR ADC with a redundancy algorithm and digital calibration for the ATLAS LAr calorimeter readout

    NASA Astrophysics Data System (ADS)

    Zeloufi, M.

    2016-01-01

    We present a SAR ADC with a generalized redundant search algorithm offering the flexibility to relax the requirements on the DAC settling time. The redundancy also allows a digital background calibration, based on a code density analysis, to compensate for the capacitor mismatch effects. The total number of capacitors used in this architecture is limited to one half of the one in a classical SAR design. Only 211 unit capacitors were necessary to reach 12 bit resolution, and the switching algorithm is intrinsically monotonic. The design is fully differential featuring 12 bit 40 MS/s in a CMOS 130 nm 1P8M process.

  17. Structural insights into the Escherichia coli lysine decarboxylases and molecular determinants of interaction with the AAA+ ATPase RavA

    PubMed Central

    Kandiah, Eaazhisai; Carriel, Diego; Perard, Julien; Malet, Hélène; Bacia, Maria; Liu, Kaiyin; Chan, Sze W. S.; Houry, Walid A.; Ollagnier de Choudens, Sandrine; Elsen, Sylvie; Gutsche, Irina

    2016-01-01

    The inducible lysine decarboxylase LdcI is an important enterobacterial acid stress response enzyme whereas LdcC is its close paralogue thought to play mainly a metabolic role. A unique macromolecular cage formed by two decamers of the Escherichia coli LdcI and five hexamers of the AAA+ ATPase RavA was shown to counteract acid stress under starvation. Previously, we proposed a pseudoatomic model of the LdcI-RavA cage based on its cryo-electron microscopy map and crystal structures of an inactive LdcI decamer and a RavA monomer. We now present cryo-electron microscopy 3D reconstructions of the E. coli LdcI and LdcC, and an improved map of the LdcI bound to the LARA domain of RavA, at pH optimal for their enzymatic activity. Comparison with each other and with available structures uncovers differences between LdcI and LdcC explaining why only the acid stress response enzyme is capable of binding RavA. We identify interdomain movements associated with the pH-dependent enzyme activation and with the RavA binding. Multiple sequence alignment coupled to a phylogenetic analysis reveals that certain enterobacteria exert evolutionary pressure on the lysine decarboxylase towards the cage-like assembly with RavA, implying that this complex may have an important function under particular stress conditions. PMID:27080013

  18. Specific protein binding to a conserved region of the ornithine decarboxylase mRNA 5'-untranslated region.

    PubMed

    Manzella, J M; Blackshear, P J

    1992-04-01

    An RNA gel retardation assay was used to identify one or more cellular protein(s) (ornithine decarboxylase mRNA 5'-UTR binding protein (ODCBP)) that bind specifically to a conserved region of the 5'-untranslated region (5'-UTR) of rat ornithine decarboxylase (ODC) mRNA. Ultraviolet light cross-linking demonstrated that this protein has an apparent Mr = 58,000 in mammalian cells. Treatment with the oxidizing agent diamide prevented binding of the ODCBP to ODC mRNA; addition of beta-mercaptoethanol reversed this inhibition and permitted mRNA.ODCBP complex formation. Cytoplasmic extracts from a variety of animal cells and tissues demonstrated similar binding activities; however, there was marked tissue-specific expression of the protein in the rat, with brain, heart, lung, and testis containing large amounts, and kidney, spleen, and skeletal muscle expressing negligible amounts. Binding was completely prevented by several mutations within a highly conserved heptanucleotide region (CCAU/ACUC) that was within 61 bases of the initiation codon in ODC mRNAs from mammals, Xenopus, and Caenorhabditis elegans; mutations 5' and 3' of the conserved heptanucleotide domain had no effect on binding activity. Binding was not affected by manipulation of cellular polyamine levels or by treatment of cells with agents that stimulate ODC biosynthesis. Thus, we have identified a widely distributed cellular protein that binds to a conserved domain within the 5'-UTR of ODC mRNA from many animal species; functional consequences of this binding remain to be determined. PMID:1551914

  19. The yeast Dekkera bruxellensis genome contains two orthologs of the ARO10 gene encoding for phenylpyruvate decarboxylase.

    PubMed

    de Souza Liberal, Anna Theresa; Carazzolle, Marcelo Falsarella; Pereira, Gonçalo Amarante; Simões, Diogo Ardaillon; de Morais, Marcos Antonio

    2012-07-01

    The yeast Dekkera bruxellensis possesses important physiological traits that enable it to grow in industrial environments as either spoiling yeast of wine production or a fermenting strain used for lambic beer, or fermenting yeast in the bioethanol production process. In this work, in silico analysis of the Dekkera genome database allowed the identification of two paralogous genes encoding for phenylpyruvate decarboxylase (DbARO10) that represents a unique trait among the hemiascomycetes. The molecular analysis of the theoretical protein confirmed its protein identity. Upon cultivation of the cell in medium containing phenylpyruvate, both increases in gene expression and in phenylpyruvate decarboxylase activity were observed. Both genes were differentially expressed depending on the culture condition and the type of metabolism, which indicated the difference in the biological function of their corresponding proteins. The importance of the duplicated DbARO10 genes in the D. bruxellensis genome was discussed and represents the first effort to understand the production of flavor by this yeast. PMID:22806152

  20. Two UDP-glucuronic acid decarboxylases involved in the biosynthesis of a bacterial exopolysaccharide in Paenibacillus elgii.

    PubMed

    Li, Ou; Qian, Chao-Dong; Zheng, Dao-Qiong; Wang, Pin-Mei; Liu, Yu; Jiang, Xin-Hang; Wu, Xue-Chang

    2015-04-01

    Xylose is described as a component of bacterial exopolysaccharides in only a limited number of bacterial strains. A bacterial strain, Paenibacillus elgii, B69 was shown to be efficient in producing a xylose-containing exopolysaccharide. Sequence analysis was performed to identify the genes encoding the uridine diphosphate (UDP)-glucuronic acid decarboxylase required for the synthesis of UDP-xylose, the precursor of the exopolysaccharide. Two sequences, designated as Peuxs1 and Peuxs2, were found as the candidate genes for such enzymes. The activities of the UDP-glucuronic acid decarboxylases were proven by heterologous expression and real-time nuclear magnetic resonance analysis. The intracellular activity and effect of these genes on the synthesis of exopolysaccharide were further investigated by developing a thymidylate synthase based knockout system. This system was used to substitute the conventional antibiotic resistance gene system in P. elgii, a natural multi-antibiotic resistant strain. Results of intracellular nucleotide sugar analysis showed that the intracellular UDP-xylose and UDP-glucuronic acid levels were affected in Peuxs1 or Peuxs2 knockout strains. The knockout of either Peuxs1 or Peuxs2 reduced the polysaccharide production and changed the monosaccharide ratio. No polysaccharide was found in the Peuxs1/Peuxs2 double knockout strain. Our results show that P. elgii can be efficient in forming UDP-xylose, which is then used for the synthesis of xylose-containing exopolysaccharide. PMID:25573472

  1. Surfactant-induced chronic pruritus: Role of L-histidine decarboxylase expression and histamine production in epidermis.

    PubMed

    Inami, Yoshihiro; Sasaki, Atsushi; Andoh, Tsugunobu; Kuraishi, Yasushi

    2014-11-01

    Shampoo and cleansers containing anionic surfactants including sodium dodecyl sulphate (SDS) often cause pruritus in humans. Daily application of 1-10% SDS for 4 days induced hind-paw scratching (an itch-related behaviour) in a concentration-dependent manner, and 10% SDS also caused dermatitis, skin dryness, barrier disruption, and an increase in skin surface pH in mice. SDS-induced scratching was inhibited by the opioid receptor antagonist naloxone and the H histamine receptor antagonist terfenadine. Mast-cell deficiency did not inhibit SDS-induced scratching, although it almost completely depleted histamine in the dermis. Treatment with SDS increased the histamine content of the epidermis, but not that of the dermis. SDS treatment increased the gene expression and post-translation processing of L-histidine decarboxylase in the epidermis. The present results suggest that repeated application of SDS induces itch through increased production of epidermal histamine, which results from an increase in the gene expression and post-translation processing of L-histidine decarboxylase. PMID:24603881

  2. Structural Basis of Enzymatic Activity for the Ferulic Acid Decarboxylase (FADase) from Enterobacter sp. Px6-4

    PubMed Central

    Liang, Lianming; Sun, Yuna; Huang, Jingwen; Li, Xuemei; Cao, Yi; Meng, Zhaohui; Zhang, Ke-Qin

    2011-01-01

    Microbial ferulic acid decarboxylase (FADase) catalyzes the transformation of ferulic acid to 4-hydroxy-3-methoxystyrene (4-vinylguaiacol) via non-oxidative decarboxylation. Here we report the crystal structures of the Enterobacter sp. Px6-4 FADase and the enzyme in complex with substrate analogues. Our analyses revealed that FADase possessed a half-opened bottom β-barrel with the catalytic pocket located between the middle of the core β-barrel and the helical bottom. Its structure shared a high degree of similarity with members of the phenolic acid decarboxylase (PAD) superfamily. Structural analysis revealed that FADase catalyzed reactions by an “open-closed” mechanism involving a pocket of 8×8×15 Å dimension on the surface of the enzyme. The active pocket could directly contact the solvent and allow the substrate to enter when induced by substrate analogues. Site-directed mutagenesis showed that the E134A mutation decreased the enzyme activity by more than 60%, and Y21A and Y27A mutations abolished the enzyme activity completely. The combined structural and mutagenesis results suggest that during decarboxylation of ferulic acid by FADase, Trp25 and Tyr27 are required for the entering and proper orientation of the substrate while Glu134 and Asn23 participate in proton transfer. PMID:21283705

  3. Molecular and biochemical characterisation of ornithine decarboxylases in the sheep abomasal nematode parasites Teladorsagia circumcincta and Haemonchus contortus.

    PubMed

    Umair, Saleh; Knight, Jacqueline S; Simpson, Heather V

    2013-06-01

    Full length cDNA encoding ornithine decarboxylases (ODC; EC 4.1.1.17) were cloned from the sheep abomasal nematode parasites Teladorsagia circumcincta (TcODC) and Haemonchus contortus (HcODC). The TcODC (1272 bp) and HcODC cDNA (1266 bp) encoded 424 and 422 amino acid proteins respectively. The predicted TcODC amino acid sequence showed 87% identity with HcODC and 65% and 64% with Caenorhabditis elegans and Caenorhabditis briggsae ODC respectively. All binding sites and active regions were completely conserved in both proteins. Soluble N-terminal His-tagged ODC proteins were expressed in Escherichia coli strain BL21, purified and characterised. The recombinant TcODC and HcODC had very similar kinetic properties: K(m) ornithine was 0.2-0.25 mM, optimum [PLP] was 0.3 mM and the pH optima were pH 8. No enzyme activity was detected when arginine was used as substrate. One millimolar difluoromethylornithine (DFMO) completely inhibited TcODC and HcODC activity, whereas 2 mM agmatine did not inhibit activity. The present study showed that ODC is a separate enzyme from arginine decarboxylase and strictly uses ornithine as substrate. PMID:23499950

  4. Crystallization and preliminary crystallographic analysis of orotidine 5′-monophosphate decarboxylase from the human malaria parasite Plasmodium falciparum

    SciTech Connect

    Krungkrai, Sudaratana R.; Tokuoka, Keiji; Kusakari, Yukiko; Inoue, Tsuyoshi; Adachi, Hiroaki; Matsumura, Hiroyoshi; Takano, Kazufumi; Murakami, Satoshi; Mori, Yusuke; Kai, Yasushi; Krungkrai, Jerapan; Horii, Toshihiro

    2006-06-01

    Orotidine 5′-monophosphate decarboxylase of human malaria parasite P. falciparum was crystallized by the seeding method in a hanging drop using PEG 3000 as a precipitant. A complete set of diffraction data from a native crystal was collected to 2.7 Å resolution at 100 K using synchrotron radiation. Orotidine 5′-monophosphate (OMP) decarboxylase (OMPDC; EC 4.1.1.23) catalyzes the final step in the de novo synthesis of uridine 5′-monophosphate (UMP) and defects in the enzyme are lethal in the malaria parasite Plasmodium falciparum. Active recombinant P. falciparum OMPDC (PfOMPDC) was crystallized by the seeding method in a hanging drop using PEG 3000 as a precipitant. A complete set of diffraction data from a native crystal was collected to 2.7 Å resolution at 100 K using synchrotron radiation at the Swiss Light Source. The crystal exhibits trigonal symmetry (space group R3), with hexagonal unit-cell parameters a = b = 201.81, c = 44.03 Å. With a dimer in the asymmetric unit, the solvent content is 46% (V{sub M} = 2.3 Å{sup 3} Da{sup −1})

  5. Molecular cloning and sequence analysis of the cDNA encoding rat liver cysteine sulfinate decarboxylase (CSD).

    PubMed

    Reymond, I; Sergeant, A; Tappaz, M

    1996-06-01

    The taurine biosynthesis enzyme, cysteine sulfinate decarboxylase (CSD), was purified to homogeneity from rat liver. Three CSD peptides generated by tryptic cleavage were isolated and partially sequenced. Two of them showed a marked homology with glutamate decarboxylase and their respective position on the CSD amino acid sequence was postulated accordingly. Using appropriate degenerated primers derived from these two peptides, a PCR amplified DNA fragment was generated from liver poly(A)+ mRNA, cloned and used as a probe to screen a rat liver cDNA library. Three cDNAs, length around 1800 bp, were isolated which all contained an open reading frame (ORF) encoding a 493 amino acid protein with a calculated molecular mass of 55.2 kDa close to the experimental values for CSD. The encoded protein contained the sequence of the three peptides isolated from homogenous liver CSD. Our data confirm and significantly extend those recently published (Kaisaki et al. (1995) Biochim. Biophys. Acta 1262, 79-82). Indeed, an additional base pair found 1371 bp downstream from the initiation codon led to a shift in the open reading frame which extended the carboxy-terminal end by 15 amino acid residues and altogether modified 36 amino acids. The validity of this correction is supported by the finding that the corrected reading frame encoded a peptide issued from CSD tryptic cleavage that was not encoded anywhere in the CSD sequence previously reported. PMID:8679699

  6. Fern L-methionine decarboxylase: Kinetics and mechanism of decarboxylation and abortive transamination

    SciTech Connect

    Akhtar, M.; Stevenson, D.E.; Gani, D. )

    1990-08-21

    L-Methionine decarboxylase from Dryopteris filix-mas catalyzes the decarboxylation of L-methionine and a range of straight- and branched-chain L-amino acids to give the corresponding amine products. The deuterium solvent isotope effects for the decarboxylation of (2S)-methionine are {sup D}(V/K) = 6.5 and {sup D}V = 2.3, for (2S)-valine are {sup D}(V/K) = 1.9 and {sup D}V = 2.6, and for (2S)-lecuine are {sup D}(V/K) = 2.5 and {sup D}V = 1.0 at pL 5.5. At pL 6.0 and above, where the value of k{sub cat} for all of the substrates is low, the solvent isotope effects on V{sub max} for methionine are 1.1-1.2 whereas the effects on V/K remain unchanged, indicating that the solvent-sensitive transition state occurs before the first irreversible step, carbon dioxide desorption. At very high concentration, the product amine can promote transamination of the coenzyme. However, the reaction occurs infrequently and does not influence the partitioning between decarboxylation and substrate-mediated abortive transamination under steady-state turnover conditions. The partition ratio, normal catalytic versus abortive events, can be determined from the amount of substrate consumed by a known amount of enzyme at infinite time, and the rate of inactivation can be determined by measuring the decrease in enzyme activity with respect to time. Experiments conducted in deuterium oxide allowed the solvent isotope effects for the partition ratio and the abortive reaction to be determined. {sup 1}H NMR spectroscopic analysis of 3-(methylthio)-1-aminopropane isolated from incubations conducted in 50 molar % deuterium oxide at pL 4.8 and at pL 6.5 indicated that the proton donor was monoprotic and, therefore, is probably the imidazolium side chain of a histidine residue.

  7. Mechanism of the Orotidine 5′-Monophosphate Decarboxylase-Catalyzed Reaction: Evidence for Substrate Destabilization

    SciTech Connect

    Chan, K.; Wood, M; Fedorov, A; Fedorov, E; Imker, H; Amyes, T; Richard, J; Almo, S; Gerlt, J

    2009-01-01

    The reaction catalyzed by orotidine 5'-monophosphate decarboxylase (OMPDC) involves a stabilized anionic intermediate, although the structural basis for the rate acceleration (kcat/knon, 7.1 x 1016) and proficiency (kcat/KM)/knon, 4.8 x 1022 M-1 is uncertain. That the OMPDCs from Methanothermobacter thermautotrophicus (MtOMPDC) and Saccharomyces cerevisiae (ScOMPDC) catalyze the exchange of H6 of the UMP product with solvent deuterium allows an estimate of a lower limit on the rate acceleration associated with stabilization of the intermediate and its flanking transition states (=1010). The origin of the 'missing' contribution, =107 (1017 total - =1010), is of interest. Based on structures of liganded complexes, unfavorable electrostatic interactions between the substrate carboxylate group and a proximal Asp (Asp 70 in MtOMPDC and Asp 91 in ScOMPDC) have been proposed to contribute to the catalytic efficiency. We investigated that hypothesis by structural and functional characterization of the D70N and D70G mutants of MtOMPDC and the D91N mutant of ScOMPDC. The substitutions for Asp 70 in MtOMPDC significantly decrease the value of kcat for decarboxylation of FOMP (a more reactive substrate analogue) but have little effect on the value of kex for exchange of H6 of FUMP with solvent deuterium; the structures of wild-type MtOMPDC and its mutants are superimposable when complexed with 6-azaUMP. In contrast, the D91N mutant of ScOMPDC does not catalyze exchange of H6 of FUMP; the structures of wild-type ScOMPDC and its D91N mutant are not superimposable when complexed with 6-azaUMP, with differences in both the conformation of the active site loop and the orientation of the ligand vis vis the active site residues. We propose that the differential effects of substitutions for Asp 70 of MtOMPDC on decarboxylation and exchange provide additional evidence for a carbanionic intermediate as well as the involvement of Asp 70 in substrate destabilization.

  8. Substrate Binding Mode and Molecular Basis of a Specificity Switch in Oxalate Decarboxylase

    PubMed Central

    2016-01-01

    Oxalate decarboxylase (OxDC) catalyzes the conversion of oxalate into formate and carbon dioxide in a remarkable reaction that requires manganese and dioxygen. Previous studies have shown that replacing an active-site loop segment Ser161-Glu162-Asn163-Ser164 in the N-terminal domain of OxDC with the cognate residues Asp161-Ala162-Ser-163-Asn164 of an evolutionarily related, Mn-dependent oxalate oxidase gives a chimeric variant (DASN) that exhibits significantly increased oxidase activity. The mechanistic basis for this change in activity has now been investigated using membrane inlet mass spectrometry (MIMS) and isotope effect (IE) measurements. Quantitative analysis of the reaction stoichiometry as a function of oxalate concentration, as determined by MIMS, suggests that the increased oxidase activity of the DASN OxDC variant is associated with only a small fraction of the enzyme molecules in solution. In addition, IE measurements show that C–C bond cleavage in the DASN OxDC variant proceeds via the same mechanism as in the wild-type enzyme, even though the Glu162 side chain is absent. Thus, replacement of the loop residues does not modulate the chemistry of the enzyme-bound Mn(II) ion. Taken together, these results raise the possibility that the observed oxidase activity of the DASN OxDC variant arises from an increased level of access of the solvent to the active site during catalysis, implying that the functional role of Glu162 is to control loop conformation. A 2.6 Å resolution X-ray crystal structure of a complex between oxalate and the Co(II)-substituted ΔE162 OxDC variant, in which Glu162 has been deleted from the active site loop, reveals the likely mode by which the substrate coordinates the catalytically active Mn ion prior to C–C bond cleavage. The “end-on” conformation of oxalate observed in the structure is consistent with the previously published V/K IE data and provides an empty coordination site for the dioxygen ligand that is thought to

  9. Possible role for glutamic acid decarboxylase in fibromyalgia symptoms: a conceptual model for chronic pain.

    PubMed

    Fitzgerald, Caris T; Carter, Lawrence P

    2011-09-01

    Fibromyalgia (FM) is a condition of chronic generalized musculoskeletal pain that is thought to be a disorder of central pain sensitization. A number of neurotransmitters in the ascending and descending pain pathways have been implicated in FM including glutamate and GABA. Glutamic acid decarboxylase (GAD) is the rate-limiting enzyme in the conversion of glutamate to GABA and decreased expression or activity of this enzyme could result in an imbalance of excitatory and inhibitory neurotransmission in the ascending and descending pain pathways. Specifically, the expression and activity of the predominant isoform of GAD (GAD65) is influenced by several factors that are associated with FM such as female sex, poor diet, obesity, sedentary lifestyle, and stress. We hypothesize that decreased GAD expression and/or activity plays a role in the development and exacerbation of FM leading to impairments in the three common domains of FM symptomatology: increased pain (hyperalgesia and allodynia), disrupted sleep, and disturbances in mood (anxiety and depression). There are several lines of evidence that appear to support a role of GAD in FM. First, the defining symptom of FM is pain and GAD65 knockout mice have been shown to exhibit supraspinal hyperalgesia. Second, GAD has been implicated in disorders of muscle stiffness and rigidity and morning stiffness is a common symptom of FM. Third, stress, depression, and anxiety, which are often comorbid with FM, decrease GAD activity. Fourth, FM is associated with poor sleep, specifically disrupted non-rapid eye movement (NREM) sleep, and the pharmacological induction of NREM sleep is associated with the activation of GAD-containing neurons in the preoptic hypothalamus. Fifth, FM is more commonly diagnosed in women than men and the activity of GAD is reduced by low levels of its cofactor pyroxidine, which is less well-absorbed by women and can be further lowered by diet, tobacco, and alcohol intake. Sixth, FM patients tend to be

  10. Filarial parasites possess an antizyme but lack a functional ornithine decarboxylase.

    PubMed

    Kurosinski, Marc-André; Lüersen, Kai; Ndjonka, Dieudonne; Younis, Abuelhassan Elshazly; Brattig, Norbert W; Liebau, Eva

    2013-06-01

    In eukaryotes, the key player in polyamine metabolism is the ornithine decarboxylase (ODC) that catalyses the first and rate limiting step in cellular polyamine synthesis. The half life of ODC is strictly regulated by the antizyme (AZ), which promotes its degradation. Older reports on the polyamine situation in filarial parasites indicate a lack of ornithine decarboxylation activity and an increased uptake of polyamines. Our in silico analysis of the Brugia malayi genome revealed only an ODC-like protein that lacks essential residues. Consequently, the recombinant protein had no enzymatic ODC activity. Furthermore, only ODC-like genes were found in the available draft genomes of other filarial parasites. In this ODC-free scenario, we set out to investigate the AZ of O. volvulus (OvAZ). The expression of the recombinant protein allowed us to analyse the localization of OvAZ in different O. volvulus stages as well as to identify it as target for the human humoral immune response. Strong immunostaining was observed in the outer zone of the uterine epithelium as well as in the uterus lumen around the periphery of the developing parasite, indicating a potential role of the OvAZ in the control of polyamine levels during embryonic development. By employing a novel in vivo method using Caenorhabditis elegans, we postulate that the OvAZ enters the secretory pathway. Even though the ODCs are absent in filarial parasites, OvAZ has the ability to bind to various ODCs, thereby demonstrating the functionality of the conserved AZ-binding domains. Finally, pull-down assays show an interaction between B. malayi AZ and the B. malayi ODC-like protein, indicating that the B. malayi ODC-like protein might function as an AZI. Taken together, our results suggest that filarial species do not possess the ODC while retaining the ODC-regulatory proteins AZ and AZI. It is tempting to speculate that both proteins are retained for the regulation of polyamine transport systems. PMID:23474393

  11. Cytokine regulation of glutamate decarboxylase biosynthesis in isolated rat islets of Langerhans.

    PubMed Central

    Schmidli, R S; Faulkner-Jones, B E; Harrison, L C; James, R F; DeAizpurua, H J

    1996-01-01

    Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease in which cytokines are thought to play an important role in beta-cell destruction and immune regulation. A major target of beta-cell autoimmunity in IDDM is the enzyme glutamate decarboxylase (GAD). We hypothesized that cytokines in the insulitis lesion modulate the synthesis of GAD. This may, in turn, modify the rate of beta-cell destruction. Accordingly we cultured rat islets in the presence and absence of cytokines, and measured synthesis of both isoforms of GAD, GAD65 and GAD67, by [35S]methionine incorporation and immunoprecipitation with a rabbit antiserum that recognizes both GAD65 and GAD67. Incubation of islets with interleukin (IL)-1 beta (1 ng/ml, 24 h), tumour necrosis factor alpha (TNF-alpha; 200 units/ml, 24 h) or interferon gamma (IFN-gamma; 500 units/ml, 72 h) significantly decreased the synthesis of both GAD65 and GAD67, but reduced neither total protein synthesis nor insulin accumulation in the medium or content. Incubation of islets for 24 h in IFN-alpha (1000 units/ml), TNF-beta (50 ng/ml), IL 2 (1000 units/ml), IL-4 (100 ng/ml), IL-6 (10 ng/ml), IL-10 (20 ng/ml), IL-12 (10 ng/ml) or transforming growth factor beta 2 (TGF-beta 2; 5 ng/ml) did not significantly alter GAD65 or GAD67 synthesis. Inhibition of GAD65 and GAD67 protein synthesis by IL-1 beta, TNF-alpha or IFN-gamma was reversed by co-incubation with the nitric oxide synthase inhibitor, NG-monomethyl arginine (NMMA). Expression of both GAD65 and GAD67 mRNA, measured by RNase protection assay, was also decreased by IL-1 beta and completely restored to baseline levels by NMMA. Thus the synthesis of both isoforms of islet GAD is selectively decreased in the presence of IL-1 beta, TNF-alpha or IFN-gamma by a NO-mediated mechanism, probably at the level of cytokine gene transcription. As GAD autoimmunity has been previously shown to have a pathogenic role in an animal model of IDDM, its inhibition by cytokines might limit

  12. Cholera Toxin B Subunit Linked to Glutamic Acid Decarboxylase Suppresses Dendritic Cell Maturation and Function

    PubMed Central

    Odumosu, Oludare; Nicholas, Dequina; Payne, Kimberly; Langridge, William

    2012-01-01

    Dendritic cells are the largest population of antigen presenting cells in the body. One of their main functions is to regulate the delicate balance between immunity and tolerance responsible for maintenance of immunological homeostasis. Disruption of this delicate balance often results in chronic inflammation responsible for initiation of organ specific autoimmune diseases such as rheumatoid arthritis, multiple sclerosis and type I diabetes. The cholera toxin B subunit (CTB) is a weak mucosal adjuvant known for its ability to stimulate immunity to antigenic proteins. However, conjugation of CTB to many autoantigens can induce immunological tolerance resulting in suppression of autoimmunity. In this study, we examined whether linkage of CTB to a 5 kDa C-terminal protein fragment of the major diabetes autoantigen glutamic acid decarboxylase (GAD35), can block dendritic cell (DC) functions such as biosynthesis of co-stimulatory factor proteins CD86, CD83, CD80 and CD40 and secretion of inflammatory cytokines. The results of human umbilical cord blood monocyte-derived DC - GAD35 autoantigen incubation experiments showed that inoculation of immature DCs (iDCs), with CTB-GAD35 protein dramatically suppressed levels of CD86, CD83, CD80 and CD40 co-stimulatory factor protein biosynthesis in comparison with GAD35 alone inoculated iDCs. Surprisingly, incubation of iDCs in the presence of the CTB-autoantigen and the strong immunostimulatory molecules PMA and Ionomycin revealed that CTB-GAD35 was capable of arresting PMA + Ionomycin induced DC maturation. Consistant with this finding, CTB-GAD35 mediated suppression of DC maturation was accompanied by a dramatic decrease in the secretion of the pro-inflammatory cytokines IL-12/23p40 and IL-6 and a significant increase in secretion of the immunosuppressive cytokine IL-10. Taken together, our experimental data suggest that linkage of the weak adjuvant CTB to the dominant type 1 diabetes autoantigen GAD strongly inhibits DC

  13. A 12-bit compact column-parallel SAR ADC with dynamic power control technique for high-speed CMOS image sensors

    NASA Astrophysics Data System (ADS)

    Quanliang, Li; Liyuan, Liu; Ye, Han; Zhongxiang, Cao; Nanjian, Wu

    2014-10-01

    This paper presents a 12-bit column-parallel successive approximation register analog-to-digital converter (SAR ADC) for high-speed CMOS image sensors. A segmented binary-weighted switched capacitor digital-to-analog converter (CDAC) and a staggered structure MOM unit capacitor is used to reduce the ADC area and to make its layout fit double pixel pitches. An electrical field shielding layout method is proposed to eliminate the parasitic capacitance on the top plate of the unit capacitor. A dynamic power control technique is proposed to reduce the power consumption of a single channel during readout. An off-chip foreground digital calibration is adopted to compensate for the nonlinearity due to the mismatch of unit capacitors among the CDAC. The prototype SAR ADC is fabricated in a 0.18 μm 1P5M CIS process. A single SAR ADC occupies 20 × 2020 μm2. Sampling at 833 kS/s, the measured differential nonlinearity, integral nonlinearity and effective number of bits of SAR ADC with calibration are 0.9/-1 LSB, 1/-1.1 LSB and 11.24 bits, respectively; the power consumption is only 0.26 mW under a 1.8-V supply and decreases linearly as the frame rate decreases.

  14. A 0.23 pJ 11.05-bit ENOB 125-MS/s pipelined ADC in a 0.18 μm CMOS process

    NASA Astrophysics Data System (ADS)

    Yong, Wang; Jianyun, Zhang; Rui, Yin; Yuhang, Zhao; Wei, Zhang

    2015-05-01

    This paper describes a 12-bit 125-MS/s pipelined analog-to-digital converter (ADC) that is implemented in a 0.18 μm CMOS process. A gate-bootstrapping switch is used as the bottom-sampling switch in the first stage to enhance the sampling linearity. The measured differential and integral nonlinearities of the prototype are less than 0.79 least significant bit (LSB) and 0.86 LSB, respectively, at the full sampling rate. The ADC exhibits an effective number of bits (ENOB) of more than 11.05 bits at the input frequency of 10.5 MHz. The ADC also achieves a 10.5 bits ENOB with the Nyquist input frequency at the full sample rate. In addition, the ADC consumes 62 mW from a 1.9 V power supply and occupies 1.17 mm2, which includes an on-chip reference buffer. The figure-of-merit of this ADC is 0.23 pJ/step. Project supported by the Foundation of Shanghai Municipal Commission of Economy and Informatization (No. 130311).

  15. A 960-fps sub-sampling object extraction CMOS image sensor with 12-bit column parallel ADCs and ALUs

    NASA Astrophysics Data System (ADS)

    Motohashi, Yuichi; Kubo, Takashi; Kanto, Hiroaki; Tate, Tomoyasu; Sugawa, Shigetoshi

    2007-02-01

    A CMOS image sensor with highly accurate object extraction pre-processing functions by 960-fps sub-sampling operation, 12-bit column parallel successive approximation ADCs and column parallel ALUs has been developed. The pixel is composed of four transistors type pixel which shares the source follower transistor and the pixel select transistor. The each ADC is composed of the noise and signal holding capacitance, the noise reduction circuit, the comparator and the small DAC that combined both the reference voltage ratios and capacitance ratios. In the ALU, the object categorization pre-processing is performed by the each macro block of 3 × 3 pixels which has a reference pixel and its neighboring eight pixels. The three image features which are the edge of object, the direction of edge-vector and the average of light-intensity of 3 × 3 pixels corresponded to each pixel are extracted by the ALUs. The image and the results of the object extraction pre-processing are outputted by every 60-fps. The image sensor was fabricated by 0.35-μm 2P3M technology. The pixel pitch is 5.3-μm, the number of pixels is 640H × 360V and the chip size is 4.9-mm square.

  16. An ultra-low power self-timed column-level ADC for a CMOS pixel sensor based vertex detector

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Wang, M.

    2014-11-01

    The International Large Detector (ILD) is a detector concept for the future linear collider experiment. The vertex detector is the key tool to achieve high precision measurements for flavor tagging, which puts stringent requirements on the CMOS pixel sensors. Due to the cooling systems which deteriorate the material budget and increase the multiple scattering, it is important to reduce the power consumption. This paper presents an ultra-low power self-timed column-level ADC for the CMOS pixel sensors, aiming to equip the outer layers of the vertex detector. The ADC was designed to operate in two modes (active and idle) adapted to the low hit density in the outer layers. The architecture employs an enhanced sample-and-hold circuit and a self-timed technique. The total power consumption with a 3-V supply is 225μW during idle mode, which is the most frequent situation. This value rises to 425μW in the case of the active mode. It occupies an area of 35 × 590μm2.

  17. Immobilization by Polyurethane of Pseudomonas dacunhae Cells Containing l-Aspartate β-Decarboxylase Activity and Application to l-Alanine Production

    PubMed Central

    Fusee, Murray C.; Weber, Jennifer E.

    1984-01-01

    Whole cells of Pseudomonas dacunhae containing l-aspartate β-decarboxylase activity were immobilized by mixing a cell suspension with a liquid isocyanate-capped polyurethane prepolymer (Hypol; W. R. Grace & Co., Lexington, Mass.). The immobilized cell preparation was used to convert l-aspartic acid to l-alanine. Properties of the immobilized P. dacunhae cells containing aspartate β-decarboxylase activity were investigated with batch reactors. Retention of enzyme activity was observed to be as much as 100% when cell lysis was allowed to occur before immobilization. The pH and temperature optima were determined to be 5.5 and 45°C, respectively. Immobilized P. dacunhael-aspartate β-decarboxylase activity was stabilized by the addition of 0.1 mM pyridoxal-5-phosphate and 0.1 mM α-ketoglutaric acid to a 1.7 M ammonium aspartate (pH 5.5) substrate solution. Under conditions of semicontinuous use in a batch reactor, a 2.5% loss in immobilized l-aspartate β-decarboxylase activity was observed over a 31-day period. PMID:16346636

  18. Significant enhancement of methionol production by co-expression of the aminotransferase gene ARO8 and the decarboxylase gene ARO10 in Saccharomyces cerevisiae.

    PubMed

    Yin, Sheng; Lang, Tiandan; Xiao, Xiao; Liu, Li; Sun, Baoguo; Wang, Chengtao

    2015-03-01

    Methionol is an important volatile sulfur flavor compound, which can be produced via the Ehrlich pathway in Saccharomyces cerevisiae. Aminotransferase and decarboxylase are essential enzymes catalyzing methionol biosynthesis. In this work, two aminotransferase genes ARO8 and ARO9 and one decarboxylase gene ARO10 were introduced into S. cerevisiae S288c, respectively, via an expression vector. Over-expression of ARO8 resulted in higher aminotransferase activity than that of ARO9. And the cellular decarboxylase activity was remarkably increased by over-expression of ARO10. A co-expression vector carrying both ARO8 and ARO10 was further constructed to generate the recombinant strain S810. Shaking flask experiments showed that the methionol yield from S810 reached 1.27 g L(-1), which was increased by 51.8 and 68.8% compared to that from the wild-type strain and the control strain harboring the empty vector. The fed-batch fermentation by strain S810 produced 3.24 g L(-1) of methionol after 72 h of cultivation in a bioreactor. These results demonstrated that co-expression of ARO8 and ARO10 significantly boosted the methionol production. It is the first time that more than 3.0 g L(-1) of methionol produced by genetically engineered yeast strain was reported by co-expression of the aminotransferase and decarboxylase via the Ehrlich pathway. PMID:25743068

  19. Steady-state and transient-state analysis of growth and metabolite production in a Saccharomyces cerevisiae strain with reduced pyruvate-decarboxylase activity

    SciTech Connect

    Flikweert, M.T.; Kuyper, M.; Maris, A.J.A. van; Koetter, P.; Dijken, J.P. van; Pronk, J.T.

    1999-07-01

    Pyruvate decarboxylase is a key enzyme in the production of low-molecular-weight byproducts (ethanol, acetate) in biomass-directed applications of Saccharomyces cerevisiae. To investigate whether decreased expression levels of pyruvate decarboxylase can reduce byproduct formation, the PDC2 gene, which encodes a positive regulator of pyruvate-decarboxylase synthesis, was inactivated in the prototrophic strain S. cerevisiae CEN.PK113-7D. This caused a 3--4-fold reduction of pyruvate-decarboxylase activity in glucose-limited, aerobic chemostat cultures grown at a dilution rate of 0.10 h{sup {minus}1}. Upon exposure of such cultures to a 50 mM glucose pulse, ethanol and acetate were the major byproducts formed by the wild type. In the pdc2{Delta} strain, formation of ethanol and acetate was reduced by 60--70%. In contrast to the wild type, the pdc2{Delta} strain produced substantial amounts of pyruvate after a glucose pulse. Nevertheless, its overall byproduct formation was ca. 50% lower. The specific rate of glucose consumption after a glucose pulse to pdc2{Delta} cultures was about 40% lower than in wild-type cultures.

  20. A 12-bit 60-MS/s 36-mW SHA-less opamp-sharing pipeline ADC in 130 nm CMOS

    NASA Astrophysics Data System (ADS)

    Wen, X.; Chen, J.; You, Y.; Feng, Y.; Tang, Y.; Zuo, Z.; Vosooghi, B.; Fan, Q.; Xiao, L.; Gong, D.; Liu, T.; Ye, J.

    2016-01-01

    This paper presents a 12-bit 60-MS/s SHA-less opamp-sharing pipeline analog-to-digital converter (ADC) implemented in a 0.13-μ m CMOS technology. A switch-embedded dual-input current-reused operational transconductance amplifier (OTA) with an overlapping two-phase clocking scheme is proposed to achieve low power consumption and eliminate the non-resetting and memory effects observed in conventional opamp-sharing techniques. To further reduce the power consumption, the ADC also incorporates a SHA-less multi-bit structure. The ADC achieves a signal-to-noise and distortion ratio of 64.9 dB and a spurious-free dynamic range of 77.1 dB at 60 MS/s. It occupies 2.3 mm 2 of area and consumes 36 mW of power under a 1.2-V supply.

  1. A 300-mV 220-nW event-driven ADC with real-time QRS detection for wearable ECG sensors.

    PubMed

    Zhang, Xiaoyang; Lian, Yong

    2014-12-01

    This paper presents an ultra-low-power event-driven analog-to-digital converter (ADC) with real-time QRS detection for wearable electrocardiogram (ECG) sensors in wireless body sensor network (WBSN) applications. Two QRS detection algorithms, pulse-triggered (PUT) and time-assisted PUT (t-PUT), are proposed based on the level-crossing events generated from the ADC. The PUT detector achieves 97.63% sensitivity and 97.33% positive prediction in simulation on the MIT-BIH Arrhythmia Database. The t-PUT improves the sensitivity and positive prediction to 97.76% and 98.59% respectively. Fabricated in 0.13 μm CMOS technology, the ADC with QRS detector consumes only 220 nW measured under 300 mV power supply, making it the first nanoWatt compact analog-to-information (A2I) converter with embedded QRS detector. PMID:25608283

  2. Pyruvate decarboxylase catalyzes decarboxylation of branched-chain 2-oxo acids but is not essential for fusel alcohol production by Saccharomyces cerevisiae.

    PubMed

    ter Schure, E G; Flikweert, M T; van Dijken, J P; Pronk, J T; Verrips, C T

    1998-04-01

    The fusel alcohols 3-methyl-1-butanol, 2-methyl-1-butanol, and 2-methyl-propanol are important flavor compounds in yeast-derived food products and beverages. The formation of these compounds from branched-chain amino acids is generally assumed to occur via the Ehrlich pathway, which involves the concerted action of a branched-chain transaminase, a decarboxylase, and an alcohol dehydrogenase. Partially purified preparations of pyruvate decarboxylase (EC 4.1.1.1) have been reported to catalyze the decarboxylation of the branched-chain 2-oxo acids formed upon transamination of leucine, isoleucine, and valine. Indeed, in a coupled enzymatic assay with horse liver alcohol dehydrogenase, cell extracts of a wild-type Saccharomyces cerevisiae strain exhibited significant decarboxylation rates with these branched-chain 2-oxo acids. Decarboxylation of branched-chain 2-oxo acids was not detectable in cell extracts of an isogenic strain in which all three PDC genes had been disrupted. Experiments with cell extracts from S. cerevisiae mutants expressing a single PDC gene demonstrated that both PDC1- and PDC5-encoded isoenzymes can decarboxylate branched-chain 2-oxo acids. To investigate whether pyruvate decarboxylase is essential for fusel alcohol production by whole cells, wild-type S. cerevisiae and an isogenic pyruvate decarboxylase-negative strain were grown on ethanol with a mixture of leucine, isoleucine, and valine as the nitrogen source. Surprisingly, the three corresponding fusel alcohols were produced in both strains. This result proves that decarboxylation of branched-chain 2-oxo acids via pyruvate decarboxylase is not an essential step in fusel alcohol production. PMID:9546164

  3. Novel S-adenosyl-L-methionine decarboxylase inhibitors as potent antiproliferative agents against intraerythrocytic Plasmodium falciparum parasites☆

    PubMed Central

    le Roux, Dina; Burger, Pieter B.; Niemand, Jandeli; Grobler, Anne; Urbán, Patricia; Fernàndez-Busquets, Xavier; Barker, Robert H.; Serrano, Adelfa E.; I. Louw, Abraham; Birkholtz, Lyn-Marie

    2013-01-01

    S-adenosyl-l-methionine decarboxylase (AdoMetDC) in the polyamine biosynthesis pathway has been identified as a suitable drug target in Plasmodium falciparum parasites, which causes the most lethal form of malaria. Derivatives of an irreversible inhibitor of this enzyme, 5′-{[(Z)-4-amino-2-butenyl]methylamino}-5′-deoxyadenosine (MDL73811), have been developed with improved pharmacokinetic profiles and activity against related parasites, Trypanosoma brucei. Here, these derivatives were assayed for inhibition of AdoMetDC from P. falciparum parasites and the methylated derivative, 8-methyl-5′-{[(Z)-4-aminobut-2-enyl]methylamino}-5′-deoxyadenosine (Genz-644131) was shown to be the most active. The in vitro efficacy of Genz-644131 was markedly increased by nanoencapsulation in immunoliposomes, which specifically targeted intraerythrocytic P. falciparum parasites. PMID:24596666

  4. Inhibition of Morganella morganii Histidine Decarboxylase Activity and Histamine Accumulation in Mackerel Muscle Derived from Filipendula ulumaria Extracts.

    PubMed

    Nitta, Yoko; Yasukata, Fumiko; Kitamoto, Noritoshi; Ito, Mikiko; Sakaue, Motoyoshi; Kikuzaki, Hiroe; Ueno, Hiroshi

    2016-03-01

    Filipendula ulmaria, also known as meadowsweet, is an herb; its extract was examined for the prevention of histamine production, primarily that caused by contaminated fish. The efficacy of meadowsweet was assessed using two parameters: inhibition of Morganella morganii histidine decarboxylase (HDC) and inhibition of histamine accumulation in mackerel. Ellagitannins from F. ulmaria (rugosin D, rugosin A methyl ester, tellimagrandin II, and rugosin A) were previously shown to be potent inhibitors of human HDC; and in the present work, these compounds inhibited M. morganii HDC, with half maximal inhibitory concentration values of 1.5, 4.4, 6.1, and 6.8 μM, respectively. Application of the extracts (at 2 wt%) to mackerel meat yielded significantly decreased histamine accumulation compared with treatment with phosphate-buffered saline as a control. Hence, F. ulmaria exhibits inhibitory activity against bacterial HDC and might be effective for preventing food poisoning caused by histamine. PMID:26939657

  5. A rare cause of severe diarrhoea diagnosed by urine metabolic screening: aromatic L-amino acid decarboxylase deficiency.

    PubMed

    Lee, L K; Cheung, K M; Cheng, W W; Ko, C H; Lee, Hencher H C; Ching, C K; Mak, Chloe M

    2014-04-01

    A 15-year-old Chinese male with infantile-onset hypotonia, developmental delay, ptosis, and oculogyric episodes presented with a history of chronic diarrhoea since the age of 5 years. At presentation, he had an exacerbation of diarrhoeal symptoms resulting in dehydration and malnutrition with a concurrent severe chest infection. In view of his infantile-onset hypotonia, oculogyric crises, and protracted diarrhoea, an autonomic disturbance related to neurotransmitters was suspected. Urine organic acid profiling was compatible with aromatic L-amino acid decarboxylase deficiency. The diagnosis was confirmed based on cerebrospinal fluid analysis and genetic mutation analysis. The patient was treated with a combination of bromocriptine, selegiline, and pyridoxine; a satisfactory reduction in diarrhoea ensued. Our report highlights the importance of urine organic acid screening in infantile-onset hypotonia, especially when accompanied by oculogyric crises, and severe diarrhoea which could manifest as a result of autonomic disturbance. PMID:24714172

  6. Improvement of ethanol production by recombinant expression of pyruvate decarboxylase in the white-rot fungus Phanerochaete sordida YK-624.

    PubMed

    Wang, Jianqiao; Hirabayashi, Sho; Mori, Toshio; Kawagishi, Hirokazu; Hirai, Hirofumi

    2016-07-01

    To improve ethanol production by Phanerochaete sordida YK-624, the pyruvate decarboxylase (PDC) gene was cloned from and reintroduced into this hyper lignin-degrading fungus; the gene encodes a key enzyme in alcoholic fermentation. We screened 16 transformant P. sordida YK-624 strains that each expressed a second, recombinant PDC gene (pdc) and then identified the transformant strain (designated GP7) with the highest ethanol production. Direct ethanol production from hardwood was 1.41 higher with GP7 than with wild-type P. sordida YK-624. RT-PCR analysis indicated that the increased PDC activity was caused by elevated recombinant pdc expression. Taken together, these results suggested that ethanol production by P. sordida YK-624 can be improved by the stable expression of an additional, recombinant pdc. PMID:26766784

  7. Engineering Salidroside Biosynthetic Pathway in Hairy Root Cultures of Rhodiola crenulata Based on Metabolic Characterization of Tyrosine Decarboxylase

    PubMed Central

    Zeng, Lingjiang; Liu, Xiaoqiang; Qiu, Fei; Zheng, Weilie; Quan, Hong; Liao, Zhihua; Chen, Min; Huang, Wenlin; Liu, Wanhong; Wang, Qiang

    2013-01-01

    Tyrosine decarboxylase initializes salidroside biosynthesis. Metabolic characterization of tyrosine decarboxylase gene from Rhodiola crenulata (RcTYDC) revealed that it played an important role in salidroside biosynthesis. Recombinant 53 kDa RcTYDC converted tyrosine into tyramine. RcTYDC gene expression was induced coordinately with the expression of RcUDPGT (the last gene involved in salidroside biosynthesis) in SA/MeJA treatment; the expression of RcTYDC and RcUDPGT was dramatically upregulated by SA, respectively 49 folds and 36 folds compared with control. MeJA also significantly increased the expression of RcTYDC and RcUDPGT in hairy root cultures. The tissue profile of RcTYDC and RcUDPGT was highly similar: highest expression levels found in stems, higher expression levels in leaves than in flowers and roots. The gene expressing levels were consistent with the salidroside accumulation levels. This strongly suggested that RcTYDC played an important role in salidroside biosynthesis in R. crenulata. Finally, RcTYDC was used to engineering salidroside biosynthetic pathway in R. crenulata hairy roots via metabolic engineering strategy of overexpression. All the transgenic lines showed much higher expression levels of RcTYDC than non-transgenic one. The transgenic lines produced tyramine, tyrosol and salidroside at higher levels, which were respectively 3.21–6.84, 1.50–2.19 and 1.27–3.47 folds compared with the corresponding compound in non-transgenic lines. In conclusion, RcTYDC overexpression promoted tyramine biosynthesis that facilitated more metabolic flux flowing toward the downstream pathway and as a result, the intermediate tyrosol was accumulated more that led to the increased production of the end-product salidroside. PMID:24124492

  8. Analysis of a 30 kbp plasmid encoding histidine decarboxylase gene in Tetragenococcus halophilus isolated from fish sauce.

    PubMed

    Satomi, Masataka; Furushita, Manabu; Oikawa, Hiroshi; Yoshikawa-Takahashi, Miwako; Yano, Yutaka

    2008-08-15

    In order to analyze the genes related to the histamine production, a strain of histamine producing halophilic bacteria, referred to as strain H, was isolated using enrichment culture and dilution-to-extinction methods with histidine broth inoculated from the fish sauce mashes. The two Japanese fish sauce mashes used, accumulate over 1000 mg/l of histamine. Phenotypic and 16 S rRNA gene sequence analyses identified strain H as Tetragenococcus halophilus, the predominant histamine producing bacteria present during fish sauce fermentation. Genetic analyses (PCR and Southern blot) of the histamine producing strain confirmed that the strain harbored a 30 kbp plasmid (pHDC) encoding a single copy of the pyruvoyl dependent histidine decarboxylase gene (hdc). A comparison of hdcA that is a structural gene of histidine decarboxylase among strain H, Lactobacillus hilgardii 0006, L. sakei LTH2076, Oenococcus oeni 9204, T. halophilus and T. muriaticus JCM10006 (T) indicated >99% sequence similarity. The hdc gene cluster consisted of 4 ORFs, hdcP, hdcA, hdcB, and hdcRS, and were almost identical to that of L. hilgardii 0006 with 99% sequence similarity including the structural hdc spacer region. However, the approximately 500 bp regions upstream and downstream of the hdc gene were different between that of strain H and L. hilgardii 0006. The complete sequence of pHDC revealed 29,924 nucleotides including 28 ORFs, two pairs of IR (inverted repeat), similar sequence of plasmid conjugative elements, and a theta-type replicon. These results suggested that hdc could be encoded on transformable elements among lactic acid bacteria. PMID:18573560

  9. Cortical Gene Expression After a Conditional Knockout of 67 kDa Glutamic Acid Decarboxylase in Parvalbumin Neurons.

    PubMed

    Georgiev, Danko; Yoshihara, Toru; Kawabata, Rika; Matsubara, Takurou; Tsubomoto, Makoto; Minabe, Yoshio; Lewis, David A; Hashimoto, Takanori

    2016-07-01

    In the cortex of subjects with schizophrenia, expression of glutamic acid decarboxylase 67 (GAD67), the enzyme primarily responsible for cortical GABA synthesis, is reduced in the subset of GABA neurons that express parvalbumin (PV). This GAD67 deficit is accompanied by lower cortical levels of other GABA-associated transcripts, including GABA transporter-1, PV, brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B, somatostatin, GABAA receptor α1 subunit, and KCNS3 potassium channel subunit mRNAs. In contrast, messenger RNA (mRNA) levels for glutamic acid decarboxylase 65 (GAD65), another enzyme for GABA synthesis, are not altered. We tested the hypothesis that this pattern of GABA-associated transcript levels is secondary to the GAD67 deficit in PV neurons by analyzing cortical levels of these GABA-associated mRNAs in mice with a PV neuron-specific GAD67 knockout. Using in situ hybridization, we found that none of the examined GABA-associated transcripts had lower cortical expression in the knockout mice. In contrast, PV, BDNF, KCNS3, and GAD65 mRNA levels were higher in the homozygous mice. In addition, our behavioral test battery failed to detect a change in sensorimotor gating or working memory, although the homozygous mice exhibited increased spontaneous activities. These findings suggest that reduced GAD67 expression in PV neurons is not an upstream cause of the lower levels of GABA-associated transcripts, or of the characteristic behaviors, in schizophrenia. In PV neuron-specific GAD67 knockout mice, increased levels of PV, BDNF, and KCNS3 mRNAs might be the consequence of increased neuronal activity secondary to lower GABA synthesis, whereas increased GAD65 mRNA might represent a compensatory response to increase GABA synthesis. PMID:26980143

  10. Pyruvate decarboxylase from Zymomonas mobilis. Structure and re-activation of apoenzyme by the cofactors thiamin diphosphate and magnesium ion.

    PubMed Central

    Diefenbach, R J; Duggleby, R G

    1991-01-01

    To study the mechanism of re-activation of Zymomonas mobilis pyruvate decarboxylase apoenzyme by its cofactors thiamin diphosphate and Mg2+, cofactor-free enzyme was prepared by dialysis against 1 mM-dipicolinic acid at pH 8.2. This apoenzyme was then used in a series of experiments that included determination of: (a) the affinity towards one cofactor when the other was present at saturating concentrations; (b) cofactor-binding rates by measuring the quenching of tryptophan fluorescence on the apoenzyme; (c) the effect of replacement of cofactors with various analogues; (d) the stoichiometry of bound cofactors in holoenzyme; and (e) the molecular mass of apoenzyme by gel filtration. The results of these experiments form the basis for a proposed model for the re-activation of Z. mobilis pyruvate decarboxylase apoenzyme by its cofactors. In this model there exists two alterative but equivalent pathways for cofactor binding. In each pathway the first step is an independent reversible binding of either thiamin diphosphate (Kd 187 microM) or Mg2+ (Kd 1.31 mM) to free apoenzyme. When both cofactors are present, the second cofactor-binding step to form active holoenzyme is a slow quasi-irreversible step. This second binding step is a co-operative process for both thiamin diphosphate (Kd 0.353 microM) and Mg2+ (Kd 2.47 microM). Both the apo- and the holo-enzyme have a tetrameric subunit structure, with cofactors binding in a 1:1 ratio with each subunit. PMID:2049073

  11. Proceedings of the Sixth Applied Diamond Conference/Second Frontier Carbon Technology Joint Conference (ADC/FCT 2001)

    NASA Technical Reports Server (NTRS)

    Tzeng, Y. (Editor); Miyoshi, K. (Editor); Yoshikawa, M. (Editor); Murakawa, M. (Editor); Koga, Y. (Editor); Kobashi, K. (Editor); Amaratunga, G. A. J. (Editor)

    2001-01-01

    These are the Proceedings of the Sixth Applied Diamond Conference/Second Frontier Carbon Technology Joint Conference hosted by Auburn University from August 6 to 10, 2001. The diamond CVD process was first reported by Dr. Spitsyn in 1981 and Prof. S. Iijima reported his discovery of carbon nanotubes in 1991. In the past years, both diamond-related materials and novel carbon materials have attracted considerable interest by the scientific, technological, and industrial community. Many practical and commercial products of diamond materials are reported in these proceedings. A broad variety of applications of carbon nanotubes and novel carbons have also been explored and demonstrated. Having more than 200 invited and contributing papers by authors from over 20 countries for presentations at ADC/FCT 2001 clearly demonstrates that these materials, due to the combination of their superior properties, are both scientifically amazing and economically significant.

  12. X-ray spectroscopy of the ADC source X1822-371 with Chandra and XMM-Newton

    NASA Astrophysics Data System (ADS)

    Iaria, R.; Di Salvo, T.; D'Aì, A.; Burderi, L.; Mineo, T.; Riggio, A.; Papitto, A.; Robba, N. R.

    2013-01-01

    Context. The eclipsing low-mass X-ray binary X1822-371 is the prototype of the accretion disc corona (ADC) sources. Its inclination angle (≃82.5°) is high enough that flux from the neutron star is blocked by the edge-on accretion disc. Because the neutron star's direct emission is hidden, its ADC emission is visible. The physical properties of the ADC in X1822-371 have been widely studied, but are still debated in literature. In light of the recent literature and of the results reported in this work we show that the ADC is optically thin. Aims: We analyse two Chandra observations and one XMM-Newton observation to study the discrete features in this source and their variation as a function of the orbital phase, deriving constraints on the temperature, density, and location of the plasma responsible for emission lines. Methods: The HETGS and XMM/Epic-pn observed X1822-371 for 140 and 50 ks, respectively. We extracted an averaged spectrum and five spectra from five selected orbital-phase intervals that are 0.04-0.25, 0.25-0.50, 0.50-0.75, 0.75-0.95, and, finally, 0.95-1.04; the orbital phase zero corresponds to the eclipse time. All spectra cover the energy band between 0.35 and 12 keV. Results: We confirm the presence of local neutral matter that partially covers the X-ray emitting region; the equivalent hydrogen column is 5 × 1022 cm-2 and the covered fraction is about 60-65%. We identify several emission lines of He-like and H-like ions, and a prominent fluorescence iron line associated with a blending of Fe i-Fe xv resonant transitions. The transitions of He-like ions show that the intercombination dominates over the forbidden and resonance lines. The line fluxes are the highest during the orbital phases between 0.04 and 0.75. Conclusions: We discuss the presence of an extended, optically thin corona with optical depth of about 0.01 that scatters the X-ray photons from the innermost region into the line of sight. The photoionised plasma producing the O viii

  13. Bayes-Optimal Joint Channel-and-Data Estimation for Massive MIMO With Low-Precision ADCs

    NASA Astrophysics Data System (ADS)

    Wen, Chao-Kai; Wang, Chang-Jen; Jin, Shi; Wong, Kai-Kit; Ting, Pangan

    2016-05-01

    This paper considers a multiple-input multiple-output (MIMO) receiver with very low-precision analog-to-digital convertors (ADCs) with the goal of developing massive MIMO antenna systems that require minimal cost and power. Previous studies demonstrated that the training duration should be {\\em relatively long} to obtain acceptable channel state information. To address this requirement, we adopt a joint channel-and-data (JCD) estimation method based on Bayes-optimal inference. This method yields minimal mean square errors with respect to the channels and payload data. We develop a Bayes-optimal JCD estimator using a recent technique based on approximate message passing. We then present an analytical framework to study the theoretical performance of the estimator in the large-system limit. Simulation results confirm our analytical results, which allow the efficient evaluation of the performance of quantized massive MIMO systems and provide insights into effective system design.

  14. Proceedings of the Seventh Applied Diamond Conference/Third Frontier Carbon Technology Joint Conference (ADC/FCT 2003)

    NASA Technical Reports Server (NTRS)

    Murakawa, M. (Editor); Miyoshi, K. (Editor); Koga, Y. (Editor); Schaefer, L. (Editor); Tzeng, Y. (Editor)

    2003-01-01

    These are the Proceedings of the Seventh Applied Diamond Conference/Third Frontier Carbon Technology Joint Conference held at Epochal Tsukuba International Conference Center from August 18 to 21, 2003. The diamond CVD process was first reported by Dr. Spitsyn in 1981 and Prof. S. Iijima reported his discovery of carbon nanotubes in 1991. In the past years, both diamond-related materials and novel carbon materials have attracted considerable interest by the scientific, technological, and industrial community. Many practical and commercial products of diamond materials are reported in these proceedings. A broad variety of applications of carbon nanotubes and novel carbons have also been explored and demonstrated. Having more than 175 invited and contributing papers by authors from over 18 countries for presentations at ADC/FCT 2003 clearly demonstrates that these materials, due to the combination of their superior properties, are both scientifically amazing and economically significant.

  15. A low power front-end architecture for SiPM readout with integrated ADC and multiplexed readout

    NASA Astrophysics Data System (ADS)

    Sacco, I.; Fischer, P.; Ritzert, M.; Peric, I.

    2013-01-01

    Silicon Photo-Multiplier (SiPM) detectors are becoming widely used for optical photon and, in conjunction with suited scintillators, for gamma detection in both medical imaging and particle physics experiments. The spatial resolution can be improved by using smaller SiPMs with a corresponding increase in front-end channels density. The timing resolution of the whole system is a function of the detector parameters and of the characteristics of the front-end electronics. We present a low power front-end readout architecture which allows reading out several SiPMs though a single line in order to maximize the number of SiPMs. The design offers good timing performance and includes a simple charge digitizer in every channel. Four different single-ended channel designs have been designed, submitted for fabrication and characterized electronically and with SiPMs. The timing performance is obtained by using a low input impedance, precise threshold setting of a leading edge discriminator and a programmable input dc potential to set the SiPM HV bias on a channel per channel basis. Programmable low- and high-pass filters should allow reducing baseline fluctuations and noise. A simple ADC is implemented by first integrating the signal current and then discharging it at a constant rate until the baseline is reached again. The current consumption of the single channel is typically less than 10 mA. The time and energy information are sent out on a single wire. In order to keep as low as possible the output cabling the signals from different channels can be multiplexed on the same cable. The processing of these signals (extraction of time, ADC amplitude determination and channel number decoding) is performed by an external FPGA. The overall architecture, the front-end designs, and measurements with SiPMs are presented.

  16. Job Training and Fulfillment Study. An Examination of Aspirations, Needs and Solutions for ADC Mothers in the Cincinnati, Ohio Area. Final Report.

    ERIC Educational Resources Information Center

    Innovative Consultants, Inc., Cincinnati, OH.

    A study was conducted to provide much-needed, in-depth qualitative information and direction regarding the experiences, attitudes, value systems, and aspirations of various segments of the Aid to Dependent Children (ADC) recipients. Eight focus groups, each composed of 8 to 10 persons, were conducted in May 1990 in Cincinnati, Ohio. Discussion…

  17. Multispectral tissue characterization in a RIF-1 tumor model: monitoring the ADC and T2 responses to single-dose radiotherapy. Part II.

    PubMed

    Henning, Erica C; Azuma, Chieko; Sotak, Christopher H; Helmer, Karl G

    2007-03-01

    A multispectral (MS) approach that combines apparent diffusion coefficient (ADC) and T(2) parameter maps with k-means (KM) clustering was employed to distinguish multiple compartments within viable tumor tissue (V1 and V2) and necrosis (N1 and N2) following single-dose (1000 cGy) radiotherapy in a radiation-induced fibrosarcoma (RIF-1) tumor model. The contributions of cell kill and tumor growth kinetics to the radiotherapy-induced response were investigated. A larger pretreatment V1 volume was correlated with decreased tumor growth delay (TGD) (r = 0.68) and cell kill (r = 0.71). There was no correlation for the pretreatment V2 volume. These results suggest that V1 tissue is well oxygenated and radiosensitive, whereas V2 tissue is hypoxic and therefore radioresistant. The relationship between an early ADC response and vasogenic edema and formation of necrosis was investigated. A trend for increased ADC was observed prior to an increase in the necrotic fraction (NF). Because there were no changes in T(2), these observations suggest that the early increase in ADC is more likely based on a slight reduction in cell density, rather than radiation-induced vasogenic edema. Quantitative assessments of individual tissue regions, tumor growth kinetics, and cell kill should provide a more accurate means of monitoring therapy in preclinical animal models because such assessments can minimize the issue of intertumor variability. PMID:17326182

  18. Parametric Response Mapping of Apparent Diffusion Coefficient (ADC) as an Imaging Biomarker to Distinguish Pseudoprogression from True Tumor Progression In Peptide-Based Vaccine Therapy for Pediatric Diffuse Instrinsic Pontine Glioma

    PubMed Central

    Ceschin, Rafael; Kurland, Brenda F.; Abberbock, Shira R.; Ellingson, Benjamin M.; Okada, Hideho; Jakacki, Regina I.; Pollack, Ian F.; Panigrahy, Ashok

    2015-01-01

    Background and Purpose Immune response to cancer therapy may result in pseudoprogression, which can only be identified retrospectively and which may disrupt an effective therapy. This study assesses whether serial parametric response mapping (PRM, a voxel-by-voxel method of image analysis also known as functional diffusion mapping) analysis of ADC measurements following peptide-based vaccination may help prospectively distinguish progression from pseudoprogression in pediatric patients with diffuse intrinsic pontine gliomas. Materials and Methods From 2009–2012, 21 children age 4–18 with diffuse intrinsic pontine gliomas were enrolled in a serial peptide-based vaccination protocol following radiotherapy. DWI was acquired before immunotherapy and at six week intervals during vaccine treatment. Pseudoprogression was identified retrospectively based on clinical and radiographic findings, excluding DWI. Parametric response mapping was used to analyze 96 scans, comparing ADC measures at multiple time points (from first vaccine to up to 12 weeks after the vaccine was halted) to pre-vaccine baseline values. Log-transformed fractional increased ADC (fiADC), fractional decreased ADC (fdADC), and parametric response mapping ratio (fiADC/fdADC) were compared between patients with and without pseudoprogression, using generalized estimating equations with inverse weighting by cluster size. Results Median survival was 13.1 months from diagnosis (range 6.4–24.9 months). Four of 21 children (19%) were assessed as experiencing pseudoprogression. Patients with pseudoprogression had higher fitted average log-transformed parametric response mapping ratios (p=0.01) and fiADCs (p=0.0004), compared to patients without pseudoprogression. Conclusion Serial parametric response mapping of ADC, performed at multiple time points of therapy, may distinguish pseudoprogression from true progression in patients with diffuse intrinsic pontine gliomas treated with peptide-based vaccination

  19. Simultaneous [18F]FDG-PET/MRI: Correlation of Apparent Diffusion Coefficient (ADC) and Standardized Uptake Value (SUV) in Primary and Recurrent Cervical Cancer

    PubMed Central

    Bremicker, K.; Höckel, M.; Barthel, H.; Kluge, R.; Kahn, T.; Sabri, O.; Stumpp, P.

    2015-01-01

    Objectives Previous non–simultaneous PET/MR studies have shown heterogeneous results about the correlation between standardized uptake values (SUVs) and apparent diffusion coefficients (ADCs). The aim of this study was to investigate correlations in patients with primary and recurrent tumors using a simultaneous PET/MRI system which could lead to a better understanding of tumor biology and might play a role in early response assessment. Methods We included 31 patients with histologically confirmed primary (n = 14) or recurrent cervical cancer (n = 17) who underwent simultaneous whole-body 18F-FDG-PET/MRI comprising DWI. Image analysis was performed by a radiologist and a nuclear physician who identified tumor margins and quantified ADC and SUV. Pearson correlations were calculated to investigate the association between ADC and SUV. Results 92 lesions were detected. We found a significant inverse correlation between SUVmax and ADCmin (r = -0.532, p = 0.05) in primary tumors as well as in primary metastases (r = -0.362, p = 0.05) and between SUVmean and ADCmin (r = -0.403, p = 0.03). In recurrent local tumors we found correlations for SUVmax and ADCmin (r = -0.747, p = 0.002) and SUVmean and ADCmin (r = -0.773, p = 0.001). Associations for recurrent metastases were not significant (p>0.05). Conclusions Our study demonstrates the feasibility of fast and reliable measurement of SUV and ADC with simultaneous PET/MRI. In patients with cervical cancer we found significant inverse correlations for SUV and ADC which could play a major role for further tumor characterization and therapy decisions. PMID:26551527

  20. Gd-EOB-DTPA-Enhanced MR Imaging of the Liver: The Effect on T2 Relaxation Times and Apparent Diffusion Coefficient (ADC)

    PubMed Central

    Cieszanowski, Andrzej; Podgórska, Joanna; Rosiak, Grzegorz; Maj, Edyta; Grudziński, Ireneusz P.; Kaczyński, Bartosz; Szeszkowski, Wojciech; Milczarek, Krzysztof; Rowiński, Olgierd

    2016-01-01

    Summary Background To investigate the effect of gadoxetic acid disodium (Gd-EOB-DTPA) on T2 relaxation times and apparent diffusion coefficient (ADC) values of the liver and focal liver lesions on a 1.5-T system. Material/Methods Magnetic resonance (MR) studies of 50 patients with 35 liver lesions were retrospectively analyzed. All examinations were performed at 1.5T and included T2-weighted turbo spin-echo (TSE) and diffusion-weighted (DW) images acquired before and after intravenous administration of Gd-EOB-DTPA. To assess the effect of this hepatobiliary contrast agent on T2-weighted TSE images and DW images T2 relaxation times and ADC values of the liver and FLLs were calculated and compared pre- and post-injection. Results The mean T2 relaxation times of the liver and focal hepatic lesions were lower on enhanced than on unenhanced T2-weighted TSE images (decrease of 2.7% and 3.6% respectively), although these differences were not statistically significant. The mean ADC values of the liver showed statistically significant decrease (of 4.6%) on contrast-enhanced DW images, compared to unenhanced images (P>0.05). The mean ADC value of liver lesions was lower on enhanced than on unenhanced DW images, but this difference (of 2.9%) did not reach statistical significance. Conclusions The mean T2 relaxation times of the liver and focal liver lesions as well as the mean ADC values of liver lesions were not significantly different before and after administration of Gd-EOB-DTPA. Therefore, acquisition of T2-weighted and DW images between the dynamic contrast-enhanced examination and hepatobiliary phase is feasible and time-saving. PMID:27026795

  1. Modulation of ornithine decarboxylase activity in the normal and regenerating rat liver by various doses of the peptide morphogen of Hydra

    SciTech Connect

    Yarygin, K.N.; Kazimirskii, A.N.; Kositskii, G.I.; Rubina, A.Yu.; Vinogradov, V.A.; Pylaev, A.S.

    1986-11-01

    In this investigation, changes in ornithine decarboxylase (ODC) activity were studied in the normal and regenerating liver of rats receiving injections of various doses of Hydra peptide morphogen (HPM). Activity of ODC was determined by a radioisotope method based on liberation of /sup 14/CO/sub 2/ from L-(1-/sup 14/C)-ornithine. The results indicate in the author's opinion that HPM may have a role in the regulation of anabolic processes and, in particular, of regenerative processes in mammals.

  2. Chemical fragmentation by o-iodosobenzoic acid of. cap alpha. -chain of histidine decarboxylase from Micrococcus sp. n. at tryptophan residues

    SciTech Connect

    Alekseeva, E.A.; Grebenshchikova, O.G.; Prozorovskii, V.N.

    1987-02-10

    The carboxymethylated ..cap alpha..-chain of histidine decarboxylase from Micrococcus sp. n., which contains four tryptophan residues, was cleaved by o-iodosobenzoic acid. Five fragments were isolated in homogeneous form by means of gel filtration on Sephadex, rechromatography, and high-voltage paper electrophoresis. The molecular weight, amino acid composition, and N-terminal amino acid sequence were determined for all the peptides isolated.

  3. Alleviation of low temperature sweetening in potato by expressing Arabidopsis pyruvate decarboxylase gene and stress-inducible rd29A : A preliminary study.

    PubMed

    Pinhero, Reena; Pazhekattu, Rinu; Marangoni, Alejandro G; Liu, Qiang; Yada, Rickey Y

    2011-04-01

    The acceptability of potatoes for processing chips and French fries is largely dependent on the color of the finished product. Most potato cultivars and varieties stored at temperatures below 9-10 °C are subjected to low temperature sweetening (LTS) which result in the production of bitter-tasting, dark colored chips and French fries which are unacceptable to consumers. However, storing tubers at low temperatures (i.e., <10 °C) has many advantages such as lowered weight loss during storage, natural control of sprouting, and reduction/elimination of chemical sprout inhibitors. Our earlier research results on LTS suggested a role for pyruvate decarboxylase (PDC) in LTS-tolerance. In the present study, the role of PDC was examined whereby the potato variety Snowden was transformed with Arabidopsis cold-inducible pyruvate decarboxylase gene 1 (AtPDC1) under the control of promoter rd29A. Two transgenic plants were selected and storage studies were conducted on tubers harvested from one of the transgenic lines grown under green house conditions. Transgenic tubers showed higher Agtron chip color score indicating lighter chip and lower reducing sugar and sucrose concentrations compared to the untransformed tubers during the storage periods studied at 12 °C and 5 °C. These results suggest that overexpression of pyruvate decarboxylase gene resulted in low temperature sweetening tolerance in the transgenic Snowden. PMID:23573000

  4. A metabolic strategy to enhance long-term survival by Phx1 through stationary phase-specific pyruvate decarboxylases in fission yeast

    PubMed Central

    Kim, Ji-Yoon; Kim, Eun-Jung; Lopez-Maury, Luis; Bähler, Jürg; Roe, Jung-Hye

    2014-01-01

    In the fission yeast Schizosaccharomyces pombe, the stationary phase-specific transcription factor Phx1 contributes to long-term survival, stress tolerance, and meiosis. We identified Phx1-dependent genes through transcriptome analysis, and further analyzed those related with carbohydrate and thiamine metabolism, whose expression decreased in Δphx1. Consistent with mRNA changes, the level of thiamine pyrophosphate (TPP) and TPP-utilizing pyruvate decarboxylase activity that converts pyruvate to acetaldehyde were also reduced in the mutant. Therefore, Phx1 appears to shift metabolic flux by diverting pyruvate from the TCA cycle and respiration to ethanol fermentation. Among the four predicted genes for pyruvate decarboxylase, only the Phx1-dependent genes (pdc201+ and pdc202+) contributed to long-term survival as judged by mutation and overexpression studies. These findings indicate that the Phx1-mediated long-term survival is achieved primarily through increasing the synthesis and activity of pyruvate decarboxylase. Consistent with this hypothesis, we observed that Phx1 curtailed respiration when cells entered stationary phase. Introduction of Δphx1 mutation compromised the long-lived phenotypes of Δpka1 and Δsck2 mutants that are devoid of pro-aging kinases of nutrient-signalling pathways, and of the Δpyp1 mutant with constitutively activated stress-responsive kinase Sty1. Therefore, achievement of long-term viability through both nutrient limitation and anti-stress response appears to be dependent on Phx1. PMID:25102102

  5. A metabolic strategy to enhance long-term survival by Phx1 through stationary phase-specific pyruvate decarboxylases in fission yeast.

    PubMed

    Kim, Ji-Yoon; Kim, Eun-Jung; Lopez-Maury, Luis; Bähler, Jürg; Roe, Jung-Hye

    2014-07-01

    In the fission yeast Schizosaccharomyces pombe, the stationary phase-specific transcription factor Phx1 contributes to long-term survival, stress tolerance, and meiosis. We identified Phx1-dependent genes through transcriptome analysis, and further analyzed those related with carbohydrate and thiamine metabolism, whose expression decreased in ∆phx1. Consistent with mRNA changes, the level of thiamine pyrophosphate (TPP) and TPP-utilizing pyruvate decarboxylase activity that converts pyruvate to acetaldehyde were also reduced in the mutant. Therefore, Phx1 appears to shift metabolic flux by diverting pyruvate from the TCA cycle and respiration to ethanol fermentation. Among the four predicted genes for pyruvate decarboxylase, only the Phx1-dependent genes (pdc201+ and pdc202+) contributed to long-term survival as judged by mutation and overexpression studies. These findings indicate that the Phx1-mediated long-term survival is achieved primarily through increasing the synthesis and activity of pyruvate decarboxylase. Consistent with this hypothesis, we observed that Phx1 curtailed respiration when cells entered stationary phase. Introduction of Δphx1 mutation compromised the long-lived phenotypes of Δpka1 and Δsck2 mutants that are devoid of pro-aging kinases of nutrient-signalling pathways, and of the Δpyp1 mutant with constitutively activated stress-responsive kinase Sty1. Therefore, achievement of long-term viability through both nutrient limitation and anti-stress response appears to be dependent on Phx1. PMID:25102102

  6. In Vivo Formation of the Protein Disulfide Bond That Enhances the Thermostability of Diphosphomevalonate Decarboxylase, an Intracellular Enzyme from the Hyperthermophilic Archaeon Sulfolobus solfataricus

    PubMed Central

    Hattori, Ai; Unno, Hideaki; Goda, Shuichiro; Motoyama, Kento; Yoshimura, Tohru

    2015-01-01

    ABSTRACT In the present study, the crystal structure of recombinant diphosphomevalonate decarboxylase from the hyperthermophilic archaeon Sulfolobus solfataricus was solved as the first example of an archaeal and thermophile-derived diphosphomevalonate decarboxylase. The enzyme forms a homodimer, as expected for most eukaryotic and bacterial orthologs. Interestingly, the subunits of the homodimer are connected via an intersubunit disulfide bond, which presumably formed during the purification process of the recombinant enzyme expressed in Escherichia coli. When mutagenesis replaced the disulfide-forming cysteine residue with serine, however, the thermostability of the enzyme was significantly lowered. In the presence of β-mercaptoethanol at a concentration where the disulfide bond was completely reduced, the wild-type enzyme was less stable to heat. Moreover, Western blot analysis combined with nonreducing SDS-PAGE of the whole cells of S. solfataricus proved that the disulfide bond was predominantly formed in the cells. These results suggest that the disulfide bond is required for the cytosolic enzyme to acquire further thermostability and to exert activity at the growth temperature of S. solfataricus. IMPORTANCE This study is the first report to describe the crystal structures of archaeal diphosphomevalonate decarboxylase, an enzyme involved in the classical mevalonate pathway. A stability-conferring intersubunit disulfide bond is a remarkable feature that is not found in eukaryotic and bacterial orthologs. The evidence that the disulfide bond also is formed in S. solfataricus cells suggests its physiological importance. PMID:26303832

  7. Free-running ADC- and FPGA-based signal processing method for brain PET using GAPD arrays

    NASA Astrophysics Data System (ADS)

    Hu, Wei; Choi, Yong; Hong, Key Jo; Kang, Jihoon; Jung, Jin Ho; Huh, Youn Suk; Lim, Hyun Keong; Kim, Sang Su; Kim, Byung-Tae; Chung, Yonghyun

    2012-02-01

    Currently, for most photomultiplier tube (PMT)-based PET systems, constant fraction discriminators (CFD) and time to digital converters (TDC) have been employed to detect gamma ray signal arrival time, whereas anger logic circuits and peak detection analog-to-digital converters (ADCs) have been implemented to acquire position and energy information of detected events. As compared to PMT the Geiger-mode avalanche photodiodes (GAPDs) have a variety of advantages, such as compactness, low bias voltage requirement and MRI compatibility. Furthermore, the individual read-out method using a GAPD array coupled 1:1 with an array scintillator can provide better image uniformity than can be achieved using PMT and anger logic circuits. Recently, a brain PET using 72 GAPD arrays (4×4 array, pixel size: 3 mm×3 mm) coupled 1:1 with LYSO scintillators (4×4 array, pixel size: 3 mm×3 mm×20 mm) has been developed for simultaneous PET/MRI imaging in our laboratory. Eighteen 64:1 position decoder circuits (PDCs) were used to reduce GAPD channel number and three off-the-shelf free-running ADC and field programmable gate array (FPGA) combined data acquisition (DAQ) cards were used for data acquisition and processing. In this study, a free-running ADC- and FPGA-based signal processing method was developed for the detection of gamma ray signal arrival time, energy and position information all together for each GAPD channel. For the method developed herein, three DAQ cards continuously acquired 18 channels of pre-amplified analog gamma ray signals and 108-bit digital addresses from 18 PDCs. In the FPGA, the digitized gamma ray pulses and digital addresses were processed to generate data packages containing pulse arrival time, baseline value, energy value and GAPD channel ID. Finally, these data packages were saved to a 128 Mbyte on-board synchronous dynamic random access memory (SDRAM) and then transferred to a host computer for coincidence sorting and image reconstruction. In order to

  8. Diffusion-weighted images (DWI) without ADC values in assessment of small focal nodules in cirrhotic liver

    PubMed Central

    Chen, Mai-Lin; Zhang, Xiao-Yan; Qi, Li-Ping; Shi, Qing-Lei; Chen, Bin

    2014-01-01

    Objective To assess if diffusion-weighted magnetic resonance (MR) imaging without apparent diffusion coefficient (ADC) values provides added diagnostic value in combination with conventional MR imaging in the detection and characterization of small nodules in cirrhotic liver. Methods Two observers retrospectively and independently analyzed 86 nodules (≤3 cm) certified pathologically in 33 patients with liver cirrhosis, including 48 hepatocellular carcinoma (HCC) nodules, 13 high-grade dysplastic nodules (HDN), 10 low-grade dysplastic nodules (LDNs) and 15 other benign nodules. All these focal nodules were evaluated with conventional MR images (T1-weighted, T2-weighted and dynamic gadolinium-enhanced images) and breath-hold diffusion-weighted images (DWI) (b=500 s/mm2). The nodules were classified by using a scale of 1-3 (1, not seen; 3, well seen) on DWI for qualitative assessment. These small nodules were characterized by two radiologists. ADC values weren’t measured. The diagnostic performance of the combined DWI-conventional images and the conventional images alone was evaluated using receiver operating characteristic (ROC) curves. The area under the curves (Az), sensitivity and specificity values for characterizing different small nodules were also calculated. Results Among 48 HCC nodules, 33 (68.8%) were graded as 3 (well seen), 6 (12.5%) were graded as 2 (partially obscured), and 9 weren’t seen on DWI. Among 13 HDNs, there were 3 (23.1%) and 4 (30.8%) graded as 3 and 2 respectively. Five (50%) of 10 benign nodules were partially obscured and slightly hyperintense. For 86 nodules, the average diagnostic accuracy of combined DWI-conventional images was 82.56%, which was increased significantly compared with conventional MR images with 76.17%. For HCC and HDN, the diagnostic accuracy of combined DWI-conventional images increased from 78.69% to 86.07%. Conclusions Diffusion-weighted MR imaging does provide added diagnostic value in the detection and

  9. Removal kinetics of antibodies against glutamic acid decarboxylase by various plasmapheresis modalities in the treatment of neurological disorders.

    PubMed

    Ohkubo, Atsushi; Okado, Tomokazu; Kurashima, Naoki; Maeda, Takuma; Miyamoto, Satoko; Nakamura, Ayako; Seshima, Hiroshi; Iimori, Soichiro; Sohara, Eisei; Uchida, Shinichi; Rai, Tatemitsu

    2014-06-01

    Plasmapheresis is one of the acute treatment modalities for neurological disorders associated with antibodies against glutamic acid decarboxylase (anti-GAD). However, there is little information about the removal kinetics of anti-GAD by various plasmapheresis modalities. Here, we investigated the removal rate of anti-GAD and fibrinogen (Fib) by immunoadsorption (IA), plasma exchange using a conventional plasma separator (OP-PE), and plasma exchange using a high cut-off selective membrane plasma separator (EC-PE) in two cases of anti-GAD-associated neurological diseases. In case 1, IA and OP-PE were used, and the percent reductions were as follows: anti-GAD: 38.2% and 69.1% and Fib: 67.7% and 68.2%, respectively. In case 2, OP-PE and EC-PE were used, and the percent reductions were as follows: anti-GAD: 65.8% and 48.5% and Fib: 68.5% and 19.8%, respectively. OP-PE could remove anti-GAD more efficiently than IA. Further, EC-PE could maintain coagulation factors such as Fib better than IA and OP-PE. It is important to select the appropriate plasmapheresis modality on the basis of the removal kinetics. PMID:24965288

  10. Lack of Association Between Polymorphisms in Dopa Decarboxylase and Dopamine Receptor-1 Genes With Childhood Autism in Chinese Han Population.

    PubMed

    Yu, Hong; Liu, Jun; Yang, Aiping; Yang, Guohui; Yang, Wenjun; Lei, Heyue; Quan, Jianjun; Zhang, Zengyu

    2016-04-01

    Genetic factors play an important role in childhood autism. This study is to determine the association of single-nucleotide polymorphisms in dopa decarboxylase (DDC) and dopamine receptor-1 (DRD1) genes with childhood autism, in a Chinese Han population. A total of 211 autistic children and 250 age- and gender-matched healthy controls were recruited. The severity of disease was determined by Children Autism Rating Scale scores. TaqMan Probe by real-time polymerase chain reaction was used to determine genotypes and allele frequencies of single-nucleotide polymorphism rs6592961 in DDC and rs251937 in DRD1. Case-control and case-only studies were respectively performed, to determine the contribution of both single-nucleotide polymorphisms to the predisposition of disease and its severity. Our results showed that there was no significant association of the genotypes and allele frequencies of both single-nucleotide polymorphisms concerning childhood autism and its severity. More studies with larger samples are needed to corroborate their predicting roles. PMID:26337060

  11. IGF2BP2 Alternative Variants Associated with Glutamic Acid Decarboxylase Antibodies Negative Diabetes in Malaysian Subjects

    PubMed Central

    Salem, Sameer D.; Saif-Ali, Riyadh; Ismail, Ikram S.; Al-Hamodi, Zaid; Poh, Rozaida; Muniandy, Sekaran

    2012-01-01

    Background The association of Insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) common variants (rs4402960 and rs1470579) with type 2 diabetes (T2D) has been performed in different populations. The aim of this study was to evaluate the association of alternative variants of IGF2BP2; rs6777038, rs16860234 and rs7651090 with glutamic acid decarboxylase antibodies (GADA) negative diabetes in Malaysian Subjects. Methods/Principal Findings IGF2BP2; rs6777038, rs16860234 and rs7651090 single nucleotide polymorphisms (SNPs) were genotyped in 1107 GADA negative diabetic patients and 620 control subjects of Asian from Malaysia. The additive genetic model adjusted for age, race, gender and BMI showed that alternative variants; rs6777038, rs16860234 and rs7651090 of IGF2BP2 associated with GADA negative diabetes (OR = 1.21; 1.36; 1.35, P = 0.03; 0.0004; 0.0002, respectively). In addition, the CCG haplotype and diplotype CCG-TCG increased the risk of diabetes (OR = 1.51, P = 0.01; OR = 2.36, P = 0.009, respectively). Conclusions/Significance IGF2BP2 alternative variants were associated with GADA negative diabetes. The IGF2BP2 haplotypes and diplotypes increased the risk of diabetes in Malaysian subject. PMID:23029108

  12. Crystal structures of malonyl-coenzyme A decarboxylase provide insights into its catalytic mechanism and disease-causing mutations.

    PubMed

    Froese, D Sean; Forouhar, Farhad; Tran, Timothy H; Vollmar, Melanie; Kim, Yi Seul; Lew, Scott; Neely, Helen; Seetharaman, Jayaraman; Shen, Yang; Xiao, Rong; Acton, Thomas B; Everett, John K; Cannone, Giuseppe; Puranik, Sriharsha; Savitsky, Pavel; Krojer, Tobias; Pilka, Ewa S; Kiyani, Wasim; Lee, Wen Hwa; Marsden, Brian D; von Delft, Frank; Allerston, Charles K; Spagnolo, Laura; Gileadi, Opher; Montelione, Gaetano T; Oppermann, Udo; Yue, Wyatt W; Tong, Liang

    2013-07-01

    Malonyl-coenzyme A decarboxylase (MCD) is found from bacteria to humans, has important roles in regulating fatty acid metabolism and food intake, and is an attractive target for drug discovery. We report here four crystal structures of MCD from human, Rhodopseudomonas palustris, Agrobacterium vitis, and Cupriavidus metallidurans at up to 2.3 Å resolution. The MCD monomer contains an N-terminal helical domain involved in oligomerization and a C-terminal catalytic domain. The four structures exhibit substantial differences in the organization of the helical domains and, consequently, the oligomeric states and intersubunit interfaces. Unexpectedly, the MCD catalytic domain is structurally homologous to those of the GCN5-related N-acetyltransferase superfamily, especially the curacin A polyketide synthase catalytic module, with a conserved His-Ser/Thr dyad important for catalysis. Our structures, along with mutagenesis and kinetic studies, provide a molecular basis for understanding pathogenic mutations and catalysis, as well as a template for structure-based drug design. PMID:23791943

  13. Antisense expression of Gossypium hirsutum UDP-glucuronate decarboxylase in Arabidopsis leads to changes in cell wall components.

    PubMed

    Zhang, D M; Pan, Y X; Zhang, Y; Li, Z K; Wu, L Q; Liu, H W; Zhang, G Y; Wang, X F; Ma, Z Y

    2016-01-01

    UDP-glucuronate decarboxylase (UDP-xylose synthase; UXS, EC 4.1.1.35) is an essential enzyme of the non-cellulosic polysaccharide biosynthetic pathway. In the present study, using transient expression of fluorescently labeled Gossypium hirsutum UXS (GhUXS3) protein in onion epidermal cells, we observed that this protein was distributed in the cytoplasm. The GhUXS3 cDNA of cotton was expressed in an antisense orientation in Arabidopsis thaliana by Agrobacterium tumefaciens-mediated transformation. Homozygous plants showing down-regulation of UXS were analyzed with northern blots. Compared to the untransformed control, transgenic plant showed shorter roots, earlier blossom formation, and delayed senescence. Biochemical analysis indicated that levels of rhamnose, mannose, galactose, glucose, xylose, and cellulose were reduced in some of the down-regulated antisense plants. These results suggest that GhUXS3 regulates the conversion of non-cellulosic polysaccharides and modulates their composition in plant cell walls. We also discuss a possible cellular function for GhUXS in determining the quality of cotton fibers. PMID:26909959

  14. Terminal Olefin (1-Alkene) Biosynthesis by a Novel P450 Fatty Acid Decarboxylase from Jeotgalicoccus Species ▿ †

    PubMed Central

    Rude, Mathew A.; Baron, Tarah S.; Brubaker, Shane; Alibhai, Murtaza; Del Cardayre, Stephen B.; Schirmer, Andreas

    2011-01-01

    Terminal olefins (1-alkenes) are natural products that have important industrial applications as both fuels and chemicals. However, their biosynthesis has been largely unexplored. We describe a group of bacteria, Jeotgalicoccus spp., which synthesize terminal olefins, in particular 18-methyl-1-nonadecene and 17-methyl-1-nonadecene. These olefins are derived from intermediates of fatty acid biosynthesis, and the key enzyme in Jeotgalicoccus sp. ATCC 8456 is a terminal olefin-forming fatty acid decarboxylase. This enzyme, Jeotgalicoccus sp. OleT (OleTJE), was identified by purification from cell lysates, and its encoding gene was identified from a draft genome sequence of Jeotgalicoccus sp. ATCC 8456 using reverse genetics. Heterologous expression of the identified gene conferred olefin biosynthesis to Escherichia coli. OleTJE is a P450 from the cyp152 family, which includes bacterial fatty acid hydroxylases. Some cyp152 P450 enzymes have the ability to decarboxylate and to hydroxylate fatty acids (in α- and/or β-position), suggesting a common reaction intermediate in their catalytic mechanism and specific structural determinants that favor one reaction over the other. The discovery of these terminal olefin-forming P450 enzymes represents a third biosynthetic pathway (in addition to alkane and long-chain olefin biosynthesis) to convert fatty acid intermediates into hydrocarbons. Olefin-forming fatty acid decarboxylation is a novel reaction that can now be added to the catalytic repertoire of the versatile cytochrome P450 enzyme family. PMID:21216900

  15. Crystal structure of tyrosine decarboxylase and identification of key residues involved in conformational swing and substrate binding.

    PubMed

    Zhu, Haixia; Xu, Guochao; Zhang, Kai; Kong, Xudong; Han, Ruizhi; Zhou, Jiahai; Ni, Ye

    2016-01-01

    Tyrosine decarboxylase (TDC) is a pyridoxal 5-phosphate (PLP)-dependent enzyme and is mainly responsible for the synthesis of tyramine, an important biogenic amine. In this study, the crystal structures of the apo and holo forms of Lactobacillus brevis TDC (LbTDC) were determined. The LbTDC displays only 25% sequence identity with the only reported TDC structure. Site-directed mutagenesis of the conformationally flexible sites and catalytic center was performed to investigate the potential catalytic mechanism. It was found that H241 in the active site plays an important role in PLP binding because it has different conformations in the apo and holo structures of LbTDC. After binding to PLP, H241 rotated to the position adjacent to the PLP pyridine ring. Alanine scanning mutagenesis revealed several crucial regions that determine the substrate specificity and catalytic activity. Among the mutants, the S586A variant displayed increased catalytic efficiency and substrate affinity, which is attributed to decreased steric hindrance and increased hydrophobicity, as verified by the saturation mutagenesis at S586. Our results provide structural information about the residues important for the protein engineering of TDC to improve catalytic efficiency in the green manufacturing of tyramine. PMID:27292129

  16. Direct production of cadaverine from soluble starch using Corynebacterium glutamicum coexpressing alpha-amylase and lysine decarboxylase.

    PubMed

    Tateno, Toshihiro; Okada, Yusuke; Tsuchidate, Takeyuki; Tanaka, Tsutomu; Fukuda, Hideki; Kondo, Akihiko

    2009-02-01

    Here, we demonstrated the one-step production of cadaverine from starch using a Corynebacterium glutamicum strain coexpressing Streptococcus bovis 148 alpha-amylase (AmyA) and Escherichia coli K-12 lysine decarboxylase (CadA). We constructed the E. coli-C. glutamicum shuttle vector, which produces CadA under the control of the high constitutive expression (HCE) promoter, and transformed this vector into C. glutamicum CSS secreting AmyA. The engineered C. glutamicum expressed both CadA and AmyA, which retained their activity. We performed cadaverine fermentation using 50 g/l soluble starch as the sole carbon source without pyridoxal-5'-phosphate, which is the coenzyme for CadA. C. glutamicum coexpressing AmyA and CadA successfully produced cadaverine from soluble starch and the yield of cadaverine was 23.4 mM after 21 h. CadA expression levels under the control of the HCE promoter were assumed to be sufficient to convert L-lysine to cadaverine, as there was no accumulation of L-lysine in the culture medium during fermentation. Thus, we demonstrated that C. glutamicum has great potential to produce cadaverine from biomass resources. PMID:18989633

  17. Investigation of the enzymatic mechanism of yeast orotidine-5'-monophosphate decarboxylase using sup 13 C kinetic isotope effects

    SciTech Connect

    Smiley, J.A.; Bell, J.B.; Jones, M.E. ); Paneth, P.; O'Leary, M.H. )

    1991-06-25

    Orotidine-5'-monophosphate decarboxylase (ODCase) from Saccharomyces cerevisiae displays an observed {sup 13}C kinetic isotope effect of 1.0247 {plus minus} 0.0008 at 25 C, pH 6.8. The observed isotope effect is sensitive to changes in the reaction medium, such as pH, temperature, or glycerol content. The value of 1.0494 {plus minus} 0.0006 measured at pH 4.0, 25 C, is not altered significantly by temperature or glycerol, and thus the intrinsic isotope effect for the reaction is apparently being observed under these conditions and decarboxylation is almost entirely rate-determining. These data require a catalytic mechanism with freely reversible binding and one in which a very limited contribution to the overall rate is made by chemical steps preceding decarboxylation; the zwitterion mechanism of Beak and Siegel, which involves only protonation of the pyrimidine ring, is such a mechanism. With use of an intrinsic isotope effect of 1.05, a partitioning factor of less than unity is calculated for ODCase at pH 6.0, 25 C. A quantitative kinetic analysis using this result excludes the possibility of an enzymatic mechanism involving covalent attachment of an enzyme nucleophile to C-5 of the pyrimidine ring. These data fit a kinetic model in which an enzyme proton necessary for catalysis is titrated at high pH, thus providing evidence for the catalytic mechanism of Beak and Siegal.

  18. Ornithine decarboxylase is a target for chemoprevention of basal and squamous cell carcinomas in Ptch1+/- mice.

    PubMed

    Tang, Xiuwei; Kim, Arianna L; Feith, David J; Pegg, Anthony E; Russo, Justin; Zhang, Hong; Aszterbaum, Michelle; Kopelovich, Levy; Epstein, Ervin H; Bickers, David R; Athar, Mohammad

    2004-03-01

    Solar ultraviolet B (UVB) radiation induces cutaneous ornithine decarboxylase (ODC), the first enzyme in the polyamine-biosynthesis pathway, which drives continued proliferation and clonal expansion of initiated (mutated) cells, leading to tumorigenesis. Therefore ODC is a potentially important target for chemoprevention of basal cell carcinomas (BCCs), the majority of which have mutations in the tumor-suppressor gene known as patched (PTCH). To assess this possibility, we first overexpressed ODC in the skin of Ptch1+/- mice using a keratin 6 (K6) promoter that directs constitutive ODC expression in the outer root sheath of the hair follicle. UVB irradiation of these mice accelerated induction of BCCs as compared with their Ptch1+/- littermates. To further verify the role of ODC in BCC tumorigenesis, we used an antizyme (AZ) approach to inhibit ODC activity in the Ptch1+/- mice. Ptch1+/- mice with AZ overexpression driven by the K6 promoter were resistant to the induction of BCCs by UVB. Furthermore, oral administration of the suicidal ODC inhibitor alpha-difluoromethylornithine reduced UVB-induced BCCs in Ptch1+/- mice. These results demonstrate the crucial importance of ODC for the induction of BCCs and indicate that chemopreventive strategies directed at inhibiting this enzyme may be useful in reducing BCCs in human populations. PMID:15067319

  19. Improving nutritional quality and fungal tolerance in soya bean and grass pea by expressing an oxalate decarboxylase.

    PubMed

    Kumar, Vinay; Chattopadhyay, Arnab; Ghosh, Sumit; Irfan, Mohammad; Chakraborty, Niranjan; Chakraborty, Subhra; Datta, Asis

    2016-06-01

    Soya bean (Glycine max) and grass pea (Lathyrus sativus) seeds are important sources of dietary proteins; however, they also contain antinutritional metabolite oxalic acid (OA). Excess dietary intake of OA leads to nephrolithiasis due to the formation of calcium oxalate crystals in kidneys. Besides, OA is also a known precursor of β-N-oxalyl-L-α,β-diaminopropionic acid (β-ODAP), a neurotoxin found in grass pea. Here, we report the reduction in OA level in soya bean (up to 73%) and grass pea (up to 75%) seeds by constitutive and/or seed-specific expression of an oxalate-degrading enzyme, oxalate decarboxylase (FvOXDC) of Flammulina velutipes. In addition, β-ODAP level of grass pea seeds was also reduced up to 73%. Reduced OA content was interrelated with the associated increase in seeds micronutrients such as calcium, iron and zinc. Moreover, constitutive expression of FvOXDC led to improved tolerance to the fungal pathogen Sclerotinia sclerotiorum that requires OA during host colonization. Importantly, FvOXDC-expressing soya bean and grass pea plants were similar to the wild type with respect to the morphology and photosynthetic rates, and seed protein pool remained unaltered as revealed by the comparative proteomic analysis. Taken together, these results demonstrated improved seed quality and tolerance to the fungal pathogen in two important legume crops, by the expression of an oxalate-degrading enzyme. PMID:26798990

  20. Product feedback regulation implicated in translational control of the Trypanosoma brucei S-adenosylmethionine decarboxylase regulatory subunit prozyme

    PubMed Central

    Xiao, Yanjing; Nguyen, Suong; Kim, Sok Ho; Volkov, Oleg A.; Tu, Benjamin P.; Phillips, Margaret A.

    2013-01-01

    Summary Human African sleeping sickness (HAT) is caused by the parasitic protozoan Trypanosoma brucei. Polyamine biosynthesis is an important drug target in the treatment of HAT. Previously we showed that trypanosomatid S-adenosylmethionine decarboxylase (AdoMetDC), a key enzyme for biosynthesis of the polyamine spermidine, is activated by heterodimer formation with an inactive paralog termed prozyme. Furthermore, prozyme protein levels were regulated in response reduced AdoMetDC activity. Herein we show that T. brucei encodes three prozyme transcripts. The 3’UTRs of these transcripts were mapped and chloramphenicol acetyltransferase (CAT) reporter constructs were used to identify a 1.2 kb region that contained a 3’UTR prozyme regulatory element sufficient to up regulate CAT protein levels (but not RNA) upon AdoMetDC inhibition, supporting the hypothesis that prozyme expression is regulated translationally. To gain insight into trans-acting factors, genetic rescue of AdoMetDC RNAi knockdown lines with human AdoMetDC was performed leading to rescue of the cell growth block, and restoration of prozyme protein to wild-type levels. Polyamine and AdoMet metabolite analysis showed that prozyme protein levels were inversely proportional to intracellular levels of decarboxylated AdoMet (dcAdoMet). These data suggest that prozyme translation may be regulated by dcAdoMet, a metabolite not previously identified to play a regulatory role. PMID:23634831