Reduction of L-phenylalanine in protein hydrolysates using L-phenylalanine ammonia-lyase from Rhodosporidium toruloides.

PubMed

Castañeda, María Teresita; Adachi, Osao; Hours, Roque Alberto

2015-10-01

L-Phenylalanine ammonia-lyase (PAL, EC 4.3.1.25) from Rhodosporidium toruloides was utilized to remove L-phenylalanine (L-Phe) from different commercial protein hydrolysates. A casein acid hydrolysate (CAH, L-Phe ~2.28 %) was employed as a model substrate. t-Cinnamic acid resulting from deamination of L-Phe was extracted, analyzed at λ = 290 nm, and used for PAL activity determination. Optimum reaction conditions, optimized using successive Doehlert design, were 35 mg mL(-1) of CAH and 800 mU mL(-1) of PAL, while temperature and pH were 42 °C and 8.7, respectively. Reaction kinetics of PAL with CAH was determined under optimized conditions. Then, removal of L-Phe from CAH was tested. Results showed that more than 92 % of initial L-Phe was eliminated. Similar results were obtained with other protein hydrolysates. These findings demonstrate that PAL is a useful biocatalyst for L-Phe removal from protein hydrolysates, which can be evaluated as potential ingredients in foodstuffs for PKU patients.

Efficient preparation of enantiopure D-phenylalanine through asymmetric resolution using immobilized phenylalanine ammonia-lyase from Rhodotorula glutinis JN-1 in a recirculating packed-bed reactor.

PubMed

Zhu, Longbao; Zhou, Li; Huang, Nan; Cui, Wenjing; Liu, Zhongmei; Xiao, Ke; Zhou, Zhemin

2014-01-01

An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL) from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA). The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR) was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h⁻¹ and 0.32 g L⁻¹ h⁻¹, respectively. The optical purity (eeD) of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (eeD>99%) in the scaled-up reactor reached 7.2 g L⁻¹ h⁻¹. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine.

Efficient Preparation of Enantiopure D-Phenylalanine through Asymmetric Resolution Using Immobilized Phenylalanine Ammonia-Lyase from Rhodotorula glutinis JN-1 in a Recirculating Packed-Bed Reactor

PubMed Central

Huang, Nan; Cui, Wenjing; Liu, Zhongmei; Xiao, Ke; Zhou, Zhemin

2014-01-01

An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL) from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA). The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR) was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h−1 and 0.32 g L−1 h−1, respectively. The optical purity (ee D) of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (ee D>99%) in the scaled-up reactor reached 7.2 g L−1 h−1. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine. PMID:25268937

Microbial L-phenylalanine ammonia-lyase. Purification, subunit structure and kinetic properties of the enzyme from Rhizoctonia solani.

PubMed Central

Kalghatgi, K K; Subba Rao, P V

1975-01-01

1. Phenylalanine ammonia-lyase (EC 4.3.1.5) was purified to homogeneity from the acetone-dried powders of the mycelial felts of the plant pathogenic fungus Rhizoctonia solani. 2. A useful modification in protamine sulphate treatment to get substantial purification of the enzyme in a single-step is described. 3. The purified enzyme shows bisubstrate activity towards L-phenylalanine and L-tyrosine. 4. It is sensitive to carbonyl reagents and the inhibition is not reversed by gel filtration. 5. The molecular weight of the enzyme as determined by Sephadex G-200 chromatography and sucrose-density-gradient centrifugation is around 330000. 6. The enzyme is made up of two pairs of unidentical subunits, with a molecular weight of 70000 (alpha) and 90000 (beta) respectively. 7. Studies on initial velocity versus substrate concentration have shown significant deviations from Michaelis-Menten kinetics. 8. The double-reciprocal plots are biphasic (concave downwards) and Hofstee plots show a curvilinear pattern. 9. The apparent Km value increases from 0.18 mM to as high as 5.0 mM with the increase in the concentration of the substrate and during this process the Vmax, increases by 2-2.5-fold. 10. The value of Hill coefficient is 0.5. 11. Steady-state rates of phenylalanine ammonia-lyase reaction in the presence of inhibitors like D-phenylalanine, cinnamic, p-coumaric, caffeic, dihydrocaffeic and phenylpyruvic acid have shown that only one molecule of each type of inhibitor binds to a molecule of the enzyme. These observations suggest the involvement of negative homotropic interactions in phenylalanine ammonia-lyase. 12. The enzyme could not be desensitized by treatment with HgCl2, p-chloromercuribenzoic acid or by repeated freezing and thawing. PMID:1191266

Expression and Properties of the Highly Alkalophilic Phenylalanine Ammonia-Lyase of Thermophilic Rubrobacter xylanophilus

PubMed Central

Kovács, Klaudia; Bánóczi, Gergely; Varga, Andrea; Szabó, Izabella; Holczinger, András; Hornyánszky, Gábor; Zagyva, Imre

2014-01-01

The sequence of a phenylalanine ammonia-lyase (PAL; EC: 4.3.1.24) of the thermophilic and radiotolerant bacterium Rubrobacter xylanophilus (RxPAL) was identified by screening the genomes of bacteria for members of the phenylalanine ammonia-lyase family. A synthetic gene encoding the RxPAL protein was cloned and overexpressed in Escherichia coli TOP 10 in a soluble form with an N-terminal His6-tag and the recombinant RxPAL protein was purified by Ni-NTA affinity chromatography. The activity assay of RxPAL with l-phenylalanine at various pH values exhibited a local maximum at pH 8.5 and a global maximum at pH 11.5. Circular dichroism (CD) studies showed that RxPAL is associated with an extensive α-helical character (far UV CD) and two distinctive near-UV CD peaks. These structural characteristics were well preserved up to pH 11.0. The extremely high pH optimum of RxPAL can be rationalized by a three-dimensional homology model indicating possible disulfide bridges, extensive salt-bridge formation and an excess of negative electrostatic potential on the surface. Due to these properties, RxPAL may be a candidate as biocatalyst in synthetic biotransformations leading to unnatural l- or d-amino acids or as therapeutic enzyme in treatment of phenylketonuria or leukemia. PMID:24475062

Cinnamaldehyde inhibits phenylalanine ammonia-lyase and enzymatic browning of cut lettuce.

PubMed

Fujita, Narumi; Tanaka, Eriko; Murata, Masatsune

2006-03-01

Stored cut lettuce gradually turns brown on the cut section after several days of storage, because cutting induces phenylalanine ammonia-lyase (PAL) activity, the biosynthesis of polyphenol is promoted, and the polyphenols are oxidized by polyphenol oxidase. In this study, we screened for inhibitors of PAL derived from fermented broths of microbes and from foods and found that a cinnamon extract definitely inhibited PLA of cut lettuce. An active component was isolated by chromatographic procedures and was identified as trans-cinnamaldehyde. Browning of cut lettuce immersed in a solution containing trans-cinnamaldehyde was definitely repressed.

Molecular Characterization of a Recombinant Zea mays Phenylalanine Ammonia-Lyase (ZmPAL2) and Its Application in trans-Cinnamic Acid Production from L-Phenylalanine.

PubMed

Zang, Ying; Jiang, Ting; Cong, Ying; Zheng, Zhaojuan; Ouyang, Jia

2015-06-01

Phenylalanine ammonia-lyase (PAL) is one of the most extensively studied enzymes with its crucial role in secondary phenylpropanoid metabolism of plants. Recently, its demand has been increased for aromatic chemical production, but its applications in trans-cinnamic acid production were not much explored. In the present study, a putative PAL gene from Zea mays designated as ZmPAL2 was expressed and characterized in Escherichia coli BL21 (DE3). The recombinant ZmPAL2 exhibited a high PAL activity (7.14 U/mg) and a weak tyrosine ammonia-lyase activity. The optimal temperature of ZmPAL2 was 55 °C, and the thermal stability results showed that about 50 % of enzyme activity remained after a treatment at 60 °C for 6 h. The recombinant ZmPAL2 is a good candidate for the production of trans-cinnamic acid. The vitro conversion indicated that the recombinant ZmPAL2 could effectively catalyze the L-phenylalanine to trans-cinnamic acid, and the trans-cinnamic acid concentration can reach up to 5 g/l.

Cooperative functioning between phenylalanine ammonia lyase and isochorishmate synthase activities contributes to salicylic acid biosynthesis in soybean

USDA-ARS?s Scientific Manuscript database

Salicylic acid (SA), an essential regulator of plant defense, is derived from chorismate via either the phenylalanine ammonia lyase (PAL), or the isochorishmate synthase (ICS) catalyzed steps. The ICS pathway is thought to be the primary contributor of defense-related SA, at least in Arabidopsis. We...

Mechanism-based site-directed mutagenesis to shift the optimum pH of the phenylalanine ammonia-lyase from Rhodotorula glutinis JN-1.

PubMed

Zhu, Longbao; Zhou, Li; Cui, Wenjing; Liu, Zhongmei; Zhou, Zhemin

2014-09-01

Phenylalanine ammonia-lyase ( Rg PAL) from Rhodotorula glutinis JN-1 stereoselectively catalyzes the conversion of the l-phenylalanine into trans -cinnamic acid and ammonia, and was used in chiral resolution of dl-phenylalanine to produce the d-phenylalanine under acidic condition. However, the optimum pH of Rg PAL is 9 and the Rg PAL exhibits low catalytic efficiency at acidic side. Therefore, a mutant Rg PAL with a lower optimum pH is expected. Based on catalytic mechanism and structure analysis, we constructed a mutant Rg PAL-Q137E by site-directed mutagenesis, and found that this mutant had an extended optimum pH 7-9 with activity of 1.8-fold higher than that of the wild type at pH 7. As revealed by Friedel-Crafts-type mechanism of Rg PAL, the improvement of the Rg PAL-Q137E might be due to the negative charge of Glu137 which could stabilize the intermediate transition states through electrostatic interaction. The Rg PAL-Q137E mutant was used to resolve the racemic dl-phenylalanine, and the conversion rate and the ee D value of d-phenylalanine using Rg PAL-Q137E at pH 7 were increased by 29% and 48%, and achieved 93% and 86%, respectively. This work provides an effective strategy to shift the optimum pH which is favorable to further applications of Rg PAL.

The influence of cyclomaltooligosaccharides (cyclodextrins) on the enzymatic decomposition of l-phenylalanine catalyzed by phenylalanine ammonia-lyase.

PubMed

Gubica, Tomasz; Pełka, Agnieszka; Pałka, Katarzyna; Temeriusz, Andrzej; Kańska, Marianna

2011-09-27

Cyclomaltohexaose (α-cyclodextrin) and cyclomaltoheptaose (β-cyclodextrin) as well as their four methyl ether derivatives, that is, hexakis(2,3-di-O-methyl)cyclomaltohexaose, hexakis(2,3,6-tri-O-methyl)cyclomaltohexaose, heptakis(2,3-di-O-methyl)cyclomaltoheptaose, and heptakis(2,3,6-tri-O-methyl)cyclomaltoheptaose were investigated as the additives in the course of enzymatic decomposition of l-phenylalanine catalyzed by phenylalanine ammonia-lyase. Only a few of those additives behaved like classical inhibitors of the enzymatic reaction under investigation because the values of the Michaelis constants that were obtained, as well as the maximum velocity values depended mostly atypically on the concentrations of those additives. In most cases cyclodextrins caused mixed inhibition, both competitive and noncompetitive, but they also acted as activators for selected concentrations. This atypical behaviour of cyclodextrins is caused by three different and independent effects. The inhibitory effect of cyclodextrins is connected with the decrease of substrate concentration and unfavourable influence on the flexibility of the enzyme molecules. On the other hand, the activating effect is connected with the decrease of product concentration (the product is an inhibitor of the enzymatic reaction under investigation). All these effects are caused by the ability of the cyclodextrins to form inclusion complexes. Copyright © 2011 Elsevier Ltd. All rights reserved.

Substituted Phosphonic Analogues of Phenylglycine as Inhibitors of Phenylalanine Ammonia Lyase from Potatoes.

PubMed

Wanat, Weronika; Talma, Michał; Hurek, Józef; Pawełczak, Małgorzata; Kafarski, Paweł

2018-06-08

A series of phosphonic acid analogues of phenylglycine variously substituted in phenyl ring have been synthesized and evaluated for their inhibitory activity towards potato L-phenylalanine ammonia lyase. Most of the compounds appeared to act as moderate (micromolar) inhibitors of the enzyme. Analysis of their binding performed using molecular modeling have shown that they might be bound either in active site of the enzyme or in the non-physiologic site. The latter one is located in adjoining deep site nearby the to the entrance channel for substrate into active site. Copyright © 2018. Published by Elsevier B.V.

Effects of phenylalanine ammonia lyase (PAL) knockdown on cell wall composition, biomass digestibility, and biotic and abiotic stress responses in Brachypodium

USDA-ARS?s Scientific Manuscript database

Phenylalanine Ammonia Lyase (PAL) catalyzes the first step in the phenylpropanoid pathway in plants, controlling biosynthesis of a variety of structural and defense compounds including monolignols that polymerize into lignin. Gaps remain in our understanding of how genetic alterations to this pathwa...

Reduced phenylalanine ammonia-lyase and tyrosine ammonia-lyase activities and lignin synthesis in wheat grown under low pressure sodium lamps

NASA Technical Reports Server (NTRS)

Guerra, D.; Anderson, A. J.; Salisbury, F. B.

1985-01-01

Wheat (Triticum aestivum L. cv Fremont) grown in hydroponic culture under 24-hour continuous irradiation at 560 to 580 micromoles per square meter per second from either metalhalide (MH), high pressure sodium (HPS), or low pressure sodium (LPS) lamps reached maturity in 70 days. Grain yields were similar under all three lamps, although LPS-grown plants lodged at maturity. Phenylalanine ammonia-lyase (PAL) and a tyrosine ammonia lyase (TAL) with lesser activity were detected in all extracts of leaf, inflorescence, and stem. Ammonia-lyase activities increased with age of the plant, and plants grown under the LPS lamp displayed PAL and TAL activities lower than wheat cultured under MH and HPS radiation. Greenhouse solar-grown wheat had the highest PAL and TAL activities. Lignin content of LPS-grown wheat was also significantly reduced from that of plants grown under MH or HPS lamps or in the greenhouse, showing a correlation with the reduced PAL and TAL activities. Ratios of far red-absorbing phytochrome to total phytochrome were similar for all three lamps, but the data do not yet warrant a conclusion about specific wavelengths missing from the LPS lamps that might have induced PAL and TAL activities in plants under the other lamps.

Molecular characterization of plant growth promoting rhizobacteria that enhance peroxidase and phenylalanine ammonia-lyase activities in chile (Capsicum annuum L.) and tomato (Lycopersicon esculentum Mill.).

PubMed

Sharma, Alok; Pathak, Ashutosh; Sahgal, Manvika; Meyer, Jean-Marie; Wray, Victor; Johri, Bhavdish N

2007-11-01

Pythium and Phytophthora species are associated with damping-off diseases in vegetable nurseries and reduce seedling stand and yield. In this study, bacterial isolates were selected on the basis of in vitro antagonism potential to inhibit mycelial growth of damping-off pathogens along with plant growth properties for field assessment in wet and winter seasons. We demonstrate efficacy of bacterial isolates to protect chile and tomato plants under natural vegetable nursery and artificially created pathogen-infested (Pythium and Phytophthora spp.) nursery conditions. After 21 days of sowing, chile and tomato plants were harvested and analysed for peroxidase and phenylalanine ammonia-lyase activities. Pseudomonas sp. strains FQP PB-3, FQA PB-3 and GRP(3 )were most effective in increasing shoot length (P > 0.05%) in both artificial and natural field sites. For example, Pseudomonas sp. FQA PB-3 treatment increased shoot length by 40% in the artificial Pythium 4746 infested nursery site in chile plants in the wet season. The bacterial treatments significantly increased the activity of peroxidase and phenylalanine ammonia-lyase in chile and tomato plant tissues, which are well known as indicators of an active lignification process. Thus, we conclude that treatment with potential bacterial plant growth promoting agents help plants against pathogen invasion by modulating plant peroxidase and phenylalanine ammonia-lyase activities.

Cloning, expression and characterization of phenylalanine ammonia-lyase from Rhodotorula glutinis.

PubMed

Zhu, Longbao; Cui, Wenjing; Fang, Yueqin; Liu, Yi; Gao, Xinxing; Zhou, Zhemin

2013-05-01

The industrial-scale production of phenylalanine ammonia-lyase (PAL) mainly uses strains of Rhodotorula. However, the PAL gene from Rhodotorula has not been cloned. Here, the full-length gene of PAL from Rhodotorula glutinis was isolated. It was 2,121 bp, encoding a polypeptide with 706 amino acids and a calculated MW of 75.5 kDa. Though R. glutinis is an anamorph of Rhodosporium toruloides, the amino acid sequences of PALs them are not the same (about 74 % identity). PAL was expressed in E. coli and characterized. Its specific activity was 4.2 U mg(-1) and the k cat/K m was 1.9 × 10(4) mM(-1) s(-1), exhibiting the highest catalytic ability among the reported PALs. The genetic and biochemical information reported here should facilitate future application in industry.

Alterations in Taxol production in plant cell culture via manipulation of the phenylalanine ammonia lyase pathway.

PubMed

Brincat, Michelle C; Gibson, Donna M; Shuler, Michael L

2002-01-01

One approach to increasing secondary metabolite production in plant cell culture is to manipulate metabolic pathways to utilize more resources toward production of one desired compound or class of compounds, such as diverting carbon flux from competing secondary pathways. Since phenylalanine provides both the phenylisoserine side chain and the benzoyl moiety at C-2 of Taxol, we speculated that blockage of the phenylpropanoid pathway might divert phenylalanine into Taxol biosynthesis. We used specific enzyme inhibitors to target the first enzyme in the phenylpropanoid pathway, phenylalanine ammonia lyase (PAL), the critical control point for conversion of L-phenylalanine to trans-cinnamic acid. Cinnamic acid acted quickly in reducing PAL activity by 40-50%, without affecting total protein levels, but it generally inhibited the taxane pathway, reducing Taxol by 90% of control levels. Of the taxanes produced, 13-acetyl-9-dihydro-baccatin III and 9-dihydrobaccatin III doubled as a percentage of total taxanes in C93AD and CO93P cells treated with 0.20 and 0.25 mM cinnamic acid, when all other taxanes were lowered. The PAL inhibitor alpha-aminooxyacetic acid (AOA) almost entirely shut down Taxol production at both 0.5 and 1.5 mM, whereas L-alpha-aminooxy-beta-phenylpropionic acid (AOPP) had the opposite effect, slightly enhancing Taxol production at 1 microM but having no effect at 10 microM. The discrepancy in the effectiveness of AOA and AOPP and the lack of effect with addition of phenylalanine or benzoic acid derivatives further indicates that the impact of cinnamic acid on Taxol is related not to its effect on PAL but rather to a specific effect on the taxane pathway. On the basis of these results, a less direct route for inhibiting the phenylpropanoid pathway may be required to avoid unwanted side effects and potentially enhance Taxol production.

Multifaceted regulations of gateway enzyme phenylalanine ammonia-lyase in the biosynthesis of phenylpropanoids

DOE PAGES

Zhang, Xuebin; Liu, Chang-Jun

2014-12-11

Phenylpropanoid biosynthesis in plants engenders a vast variety of aromatic metabolites critically important for their growth, development, and environmental adaptation. Some of these aromatic compounds have high economic value. Phenylalanine ammonia-lyase (PAL) is the first committed enzyme in the pathway; it diverts the central flux of carbon from primary metabolism to the synthesis of myriad phenolics. Over the decades, many studies have shown that exquisite regulatory mechanisms at multiple levels control the transcription and the enzymatic activity of PALs. In this review, we present a current overview on our understanding of the complicated regulatory mechanisms governing PAL's activity; we particularlymore » highlight recent progresses in unraveling its post-translational modifications, its metabolite feedback regulation, and its enzyme organization.« less

Multifaceted regulations of gateway enzyme phenylalanine ammonia-lyase in the biosynthesis of phenylpropanoids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xuebin; Liu, Chang-Jun

Phenylpropanoid biosynthesis in plants engenders a vast variety of aromatic metabolites critically important for their growth, development, and environmental adaptation. Some of these aromatic compounds have high economic value. Phenylalanine ammonia-lyase (PAL) is the first committed enzyme in the pathway; it diverts the central flux of carbon from primary metabolism to the synthesis of myriad phenolics. Over the decades, many studies have shown that exquisite regulatory mechanisms at multiple levels control the transcription and the enzymatic activity of PALs. In this review, we present a current overview on our understanding of the complicated regulatory mechanisms governing PAL's activity; we particularlymore » highlight recent progresses in unraveling its post-translational modifications, its metabolite feedback regulation, and its enzyme organization.« less

Regulation of a phenylalanine ammonia lyase (BbPAL) by calmodulin in response to environmental changes in the entomopathogenic fungus Beauveria bassiana.

PubMed

Kim, Jiyoung; Park, Hyesung; Han, Jae-Gu; Oh, Junsang; Choi, Hyung-Kyoon; Kim, Seong Hwan; Sung, Gi-Ho

2015-11-01

Phenylalanine ammonia lyase (PAL, E.C. 4.3.1.5) catalyses the deamination of L -phenylalanine to trans-cinnamic acid and ammonia, facilitating a critical step in the phenylpropanoid pathway that produces a variety of secondary metabolites. In this study, we isolated BbPAL gene in the entomopathogenic fungus Beauveria bassiana. According to multiple sequence alignment, homology modelling and in vitro PAL activity, we demonstrated that BbPAL acts as a typical PAL enzyme in B. bassiana. BbPAL interacted with calmodulin (CaM) in vitro and in vivo, indicating that BbPAL is a novel CaM-binding protein. The functional role of CaM in BbPAL action was to negatively regulate the BbPAL activity in B. bassiana. High-performance liquid chromatography analysis revealed that L -phenylalanine was reduced and trans-cinnamic acid was increased in response to the CaM inhibitor W-7. Dark conditions suppressed BbPAL activity in B. bassiana, compared with light. In addition, heat and cold stresses inhibited BbPAL activity in B. bassiana. Interestingly, these negative effects of BbPAL activity by dark, heat and cold conditions were recovered by W-7 treatment, suggesting that the inhibitory mechanism is mediated through stimulation of CaM activity. Therefore, this work suggests that BbPAL plays a role in the phenylpropanoid pathway mediated by environmental stimuli via the CaM signalling pathway. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Biochemical Evaluation of Phenylalanine Ammonia Lyase from Endemic Plant Cyathobasis fruticulosa (Bunge) Aellen. for the Dietary Treatment of Phenylketonuria

PubMed Central

Aydaş, Selcen Babaoğlu; Aslım, Belma

2016-01-01

Summary Enzyme substitution therapy with the phenylalanine ammonia lyase (PAL) is a new approach to the treatment of patients with phenylketonuria (PKU). This enzyme is responsible for the conversion of phenylalanine to trans-cinnamic acid. We assessed the PAL enzyme of the endemic plant Cyathobasis fruticulosa (Bunge) Aellen. for its possible role in the dietary treatment of PKU. The enzyme was found to have a high activity of (64.9±0.1) U/mg, with the optimum pH, temperature and buffer (Tris–HCl and l-phenylalanine) concentration levels of pH=8.8, 37 °C and 100 mM, respectively. Optimum enzyme activity was achieved at pH=4.0 and 7.5, corresponding to pH levels of gastric and intestinal juice, and NaCl concentration of 200 mM. The purification of the enzyme by 1.87-fold yielded an activity of 98.6 U/mg. PAL activities determined by HPLC analyses before and after purification were similar. Two protein bands, one at 70 and the other at 23 kDa, were determined by Western blot analysis of the enzyme. This enzyme is a potential candidate for serial production of dietary food and biotechnological products. PMID:27956861

Genomic Characterization of Phenylalanine Ammonia Lyase Gene in Buckwheat

PubMed Central

Thiyagarajan, Karthikeyan; Vitali, Fabio; Tolaini, Valentina; Galeffi, Patrizia; Cantale, Cristina; Vikram, Prashant; Singh, Sukhwinder; De Rossi, Patrizia; Nobili, Chiara; Procacci, Silvia; Del Fiore, Antonella; Antonini, Alessandro; Presenti, Ombretta; Brunori, Andrea

2016-01-01

Phenylalanine Ammonia Lyase (PAL) gene which plays a key role in bio-synthesis of medicinally important compounds, Rutin/quercetin was sequence characterized for its efficient genomics application. These compounds possessing anti-diabetic and anti-cancer properties and are predominantly produced by Fagopyrum spp. In the present study, PAL gene was sequenced from three Fagopyrum spp. (F. tataricum, F. esculentum and F. dibotrys) and showed the presence of three SNPs and four insertion/deletions at intra and inter specific level. Among them, the potential SNP (position 949th bp G>C) with Parsimony Informative Site was selected and successfully utilised to individuate the zygosity/allelic variation of 16 F. tataricum varieties. Insertion mutations were identified in coding region, which resulted the change of a stretch of 39 amino acids on the putative protein. Our Study revealed that autogamous species (F. tataricum) has lower frequency of observed SNPs as compared to allogamous species (F. dibotrys and F. esculentum). The identified SNPs in F. tataricum didn’t result to amino acid change, while in other two species it caused both conservative and non-conservative variations. Consistent pattern of SNPs across the species revealed their phylogenetic importance. We found two groups of F. tataricum and one of them was closely related with F. dibotrys. Sequence characterization information of PAL gene reported in present investigation can be utilized in genetic improvement of buckwheat in reference to its medicinal value. PMID:26990297

Expanding the substrate scope of phenylalanine ammonia-lyase from Petroselinum crispum towards styrylalanines.

PubMed

Bencze, László Csaba; Filip, Alina; Bánóczi, Gergely; Toşa, Monica Ioana; Irimie, Florin Dan; Gellért, Ákos; Poppe, László; Paizs, Csaba

2017-05-03

This study focuses on the expansion of the substrate scope of phenylalanine ammonia-lyase from Petroselinum crispum (PcPAL) towards the l-enantiomers of racemic styrylalanines rac-1a-d - which are less studied and synthetically challenging unnatural amino acids - by reshaping the aromatic binding pocket of the active site of PcPAL by point mutations. Ammonia elimination from l-styrylalanine (l-1a) catalyzed by non-mutated PcPAL (wt-PcPAL) took place with a 777-fold lower k cat /K M value than the deamination of the natural substrate, l-Phe. Computer modeling of the reactions catalyzed by wt-PcPAL indicated an unproductive and two major catalytically active conformations and detrimental interactions between the aromatic moiety of l-styrylalanine, l-1a, and the phenyl ring of the residue F137 in the aromatic binding region of the active site. Replacing the residue F137 by smaller hydrophobic residues resulted in a small mutant library (F137X-PcPAL, X being V, A, and G), from which F137V-PcPAL could transform l-styrylalanine with comparable activity to that of the wt-PcPAL with l-Phe. Furthermore, F137V-PcPAL showed superior catalytic efficiency in the ammonia elimination reaction of several racemic styrylalanine derivatives (rac-1a-d) providing access to d-1a-d by kinetic resolution, even though the d-enantiomers proved to be reversible inhibitors. The enhanced catalytic efficiency of F137V-PcPAL towards racemic styrylalanines rac-1a-d could be rationalized by molecular modeling, indicating the more relaxed enzyme-substrate complexes and the promotion of conformations with higher catalytic activities as the main reasons. Unfortunately, ammonia addition onto the corresponding styrylacrylates 2a-d failed with both wt-PcPAL and F137V-PcPAL. The low equilibrium constant of the ammonia addition, the poor ligand binding affinities of 2a-d, and the non-productive binding states of the unsaturated ligands 2a-d within the active sites of either wt-PcPAL or F137V-PcPAL - as

Optimization of oligomeric enzyme activity in ionic liquids using Rhodotorula glutinis yeast phenylalanine ammonia lyase.

PubMed

Barron, Christiaan C; Sponagle, Brandon J D; Arivalagan, Pugazhendhi; D'Cunha, Godwin B

2017-01-01

Phenylalanine ammonia lyase (E.C.4.3.1.24, PAL) activity of Rhodotorula glutinis yeast has been demonstrated in four commonly used ionic liquids. PAL forward reaction was carried out in 1-butyl-3-methylimidazolium methyl sulfate ([BMIM][MeSO 4 ]), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF 4 ]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF 6 ]) and 1-butyl-3-methylimidazolium lactate ([BMIM][lactate]). Our experiments have revealed that PAL is catalytically active in ionic liquids and the enzyme activity in ([BMIM][PF 6 ]) is comparable to that obtained in aqueous buffer medium. Different conditions were optimized for maximal PAL forward activity including time of incubation (30.0min) L -phenylalanine substrate concentration (30.0mM), nature of buffer (50.0mM Tris-HCl), pH (9.0), temperature (37°C), and speed of agitation (100 rev min -1 ). Under these optimized conditions, about 83% conversion of substrate to product was obtained for the PAL forward reaction that was determined using UV spectroscopy at 290nm. PAL reverse reaction in ([BMIM][PF 6 ]) was determined spectrophotometrically at 520nm; and about 59% substrate conversion was obtained. This data provides further knowledge in enzyme biocatalysis in non-aqueous media, and may be of importance when studying the function of other oligomeric/multimeric proteins and enzymes in ionic liquids. Copyright © 2016 Elsevier Inc. All rights reserved.

Characterisation of the willow phenylalanine ammonia-lyase (PAL) gene family reveals expression differences compared with poplar

PubMed Central

de Jong, Femke; Hanley, Steven J.; Beale, Michael H.; Karp, Angela

2015-01-01

Willow is an important biomass crop for the bioenergy industry, and therefore optimal growth with minimal effects of biotic and abiotic stress is essential. The phenylpropanoid pathway is responsible for the biosynthesis of not only lignin but also of flavonoids, condensed tannins, benzenoids and phenolic glycosides which all have a role in protecting the plant against biotic and abiotic stress. All products of the phenylpropanoid pathway are important for the healthy growth of short rotation cropping species such as willow. However, the phenylpropanoid pathway in willow remains largely uncharacterised. In the current study we identified and characterised five willow phenylalanine ammonia-lyase (PAL) genes, which encode enzymes that catalyse the deamination of l-phenylalanine to form trans-cinnamic acid, the entry point into the phenylpropanoid pathway. Willow PAL1, PAL2, PAL3 and PAL4 genes were orthologous to the poplar genes. However no orthologue of PAL5 appears to be present in willow. Moreover, two tandemly repeated PAL2 orthologues were identified in a single contig. Willow PALs show similar sub-cellular localisation to the poplar genes. However, the enzyme kinetics and gene expression of the willow PAL genes differed slightly, with willow PAL2 being more widely expressed than its poplar orthologues implying a wider role for PALs in the production of flavonoids, condensed tannins, benzenoids, and phenolic glycosides, in willow. PMID:26070140

Molecular Cloning and Sequence Analysis of a Phenylalanine Ammonia-Lyase Gene from Dendrobium

PubMed Central

Cai, Yongping; Lin, Yi

2013-01-01

In this study, a phenylalanine ammonia-lyase (PAL) gene was cloned from Dendrobium candidum using homology cloning and RACE. The full-length sequence and catalytic active sites that appear in PAL proteins of Arabidopsis thaliana and Nicotiana tabacum are also found: PAL cDNA of D. candidum (designated Dc-PAL1, GenBank No. JQ765748) has 2,458 bps and contains a complete open reading frame (ORF) of 2,142 bps, which encodes 713 amino acid residues. The amino acid sequence of DcPAL1 has more than 80% sequence identity with the PAL genes of other plants, as indicated by multiple alignments. The dominant sites and catalytic active sites, which are similar to that showing in PAL proteins of Arabidopsis thaliana and Nicotiana tabacum, are also found in DcPAL1. Phylogenetic tree analysis revealed that DcPAL is more closely related to PALs from orchidaceae plants than to those of other plants. The differential expression patterns of PAL in protocorm-like body, leaf, stem, and root, suggest that the PAL gene performs multiple physiological functions in Dendrobium candidum. PMID:23638048

Suppressed phenylalanine ammonia-lyase activity after heat shock in transgenic Nicotiana plumbaginifolia containing an Arabidopsis HSP18.2-parsley PAL2 chimera gene.

PubMed

Moriwaki, M; Yamakawa, T; Washino, T; Kodama, T; Igarashi, Y

1999-01-01

The activity of phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) after heat shock (HS) in leaves and buds of transgenic Nicotiana plumbaginifolia containing an Arabidopsis HSP18.2 promoter-parsley phenylalanine ammonia-lyase 2 (HSP18.2-PAL2) chimera gene was examined. Immediately after HS treatment at 44 degrees C for 5 h, the PAL activity in both transgenic and normal (untransformed) plants was 35-38% lower than that before HS. At normal temperature (25-26 degrees C), the PAL activity recovered within 5 h of ending the HS treatment in normal plants, but not until 12-24 h in transgenic plants containing the HSP18.2-PAL2 gene. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed the presence of parsley PAL2 mRNA in transgenic plants, which remained for 8-12 h following 5-h HS at 44 degrees C; the mRNA was not observed before HS. The content of chlorogenic acid (CGA; 3-caffeoylquinic acid) decreased drastically 8-12 h after HS in transgenic plants, but only slightly in normal plants. Thus, the decrease in PAL activity accompanied by expression of the parsley PAL2 gene after HS treatment corresponded to the decrease in CGA synthesis. These results might be attributed to post-transcriptional degradation of endogenous PAL mRNA triggered by transcription of the transgene.

Stabilization of Phenylalanine Ammonia Lyase from Rhodotorula glutinis by Encapsulation in Polyethyleneimine-Mediated Biomimetic Silica.

PubMed

Cui, Jiandong; Liang, Longhao; Han, Cong; Lin Liu, Rong

2015-06-01

Phenylalanine ammonia lyase (PAL) from Rhodotorula glutinis was encapsulated within polyethyleneimine-mediated biomimetic silica. The main factors in the preparation of biomimetic silica were optimized by response surface methodology (RSM). Compared to free PAL (about 2 U), the encapsulated PAL retained more than 43 % of their initial activity after 1 h of incubation time at 60 °C, whereas free PAL lost most of activity in the same conditions. It was clearly indicated that the thermal stability of PAL was improved by encapsulation. Moreover, the encapsulated PAL exhibited the excellent stability of the enzyme against denaturants and storage stability, and pH stability was improved by encapsulation. Operational stability of 7 reaction cycles showed that the encapsulated PAL was stable. Nevertheless, the K m value of encapsulated PAL in biomimetic silica was higher than that of the free PAL due to lower total surface area and increased mass transfer resistance.

Structure and characterization of a cDNA clone for phenylalanine ammonia-lyase from cut-injured roots of sweet potato

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, Yoshiyuki; Matsuoka, Makoto; Yamanoto, Naoki

A cDNA clone for phenylalanine ammonia-lyase (PAL) induced in wounded sweet potato (Ipomoea batatas Lam.) root was obtained by immunoscreening a cDNA library. The protein produced in Escherichia coli cells containing the plasmid pPAL02 was indistinguishable from sweet potato PAL as judged by Ouchterlony double diffusion assays. The M{sub r} of its subunit was 77,000. The cells converted ({sup 14}C)-L-phenylalanine into ({sup 14}C)-t-cinnamic acid and PAL activity was detected in the homogenate of the cells. The activity was dependent on the presence of the pPAL02 plasmid DNA. The nucleotide sequence of the cDNA contained a 2,121-base pair (bp) open-reading framemore » capable of coding for a polypeptide with 707 amino acids (M{sub r} 77,137), a 22-bp 5{prime}-noncoding region and a 207-bp 3{prime}-noncoding region. The results suggest that the insert DNA fully encoded the amino acid sequence for sweet potato PAL that is induced by wounding. Comparison of the deduced amino acid sequence with that of a PAL cDNA fragment from Phaseolus vulgaris revealed 78.9% homology. The sequence from amino acid residues 258 to 494 was highly conserved, showing 90.7% homology.« less

Stress enhances the gene expression and enzyme activity of phenylalanine ammonia-lyase and the endogenous content of salicylic acid to induce flowering in pharbitis.

PubMed

Wada, Kaede C; Mizuuchi, Kaori; Koshio, Aya; Kaneko, Kentaro; Mitsui, Toshiaki; Takeno, Kiyotoshi

2014-07-01

The involvement of salicylic acid (SA) in the regulation of stress-induced flowering in the short-day plant pharbitis (also called Japanese morning glory) Ipomoea nil (formerly Pharbitis nil) was studied. Pharbitis cv. Violet was induced to flower when grown in 1/100-strength mineral nutrient solution under non-inductive long-day conditions. All fully expanded true leaves were removed from seedlings, leaving only the cotyledons, and flowering was induced under poor-nutrition stress conditions. This indicates that cotyledons can play a role in the regulation of poor-nutrition stress-induced flowering. The expression of the pharbitis homolog of PHENYLALANINE AMMONIA-LYASE, the enzyme activity of phenylalanine ammonia-lyase (PAL; E.C. 4.3.1.5) and the content of SA in the cotyledons were all up-regulated by the stress treatment. The Violet was also induced to flower by low-temperature stress, DNA demethylation and short-day treatment. Low-temperature stress enhanced PAL activity, whereas non-stress factors such as DNA demethylation and short-day treatment decreased the activity. The PAL enzyme activity was also examined in another cultivar, Tendan, obtaining similar results to Violet. The exogenously applied SA did not induce flowering under non-stress conditions but did promote flowering under weak stress conditions in both cultivars. These results suggest that stress-induced flowering in pharbitis is induced, at least partly, by SA, and the synthesis of SA is promoted by PAL. Copyright © 2014 Elsevier GmbH. All rights reserved.

Cloning and characterization of phenylalanine ammonia-lyase and cinnamate 4-hydroxylase and pyranocoumarin biosynthesis in Angelica gigas.

PubMed

Park, Jee Hee; Park, Nam Il; Xu, Hui; Park, Sang Un

2010-08-27

Phenylalanine ammonia-lyase (PAL) and cinnamate 4-hydroxylase (C4H) are important enzymes in the phenylpropanoid pathway and also in the accumulation of decursin (1) and decursinol angelate (2), which are major secondary metabolites in Angelica gigas. Using PCR with degenerate primers targeted to conserved regions of available orthologous PAL and C4H sequences, cDNAs encoding PAL and C4H from A. gigas were isolated. Both genes were used to show the comparative developmental and inducible accumulation of mRNAs in different organs and in suspension cells of A. gigas. PAL and C4H were induced most strongly in response to 300 microM methyl jasmonate treatment at 6 and 12 h, respectively, and were highly expressed in the fine roots of A. gigas. Similarly, the production of 1 and 2 was most prolific in the fine roots of the plant.

[Aboveground architecture and biomass distribution of Quercus variabilis].

PubMed

Yu, Bi-yun; Zhang, Wen-hui; Hu, Xiao-jing; Shen, Jia-peng; Zhen, Xue-yuan; Yang, Xiao-zhou

2015-08-01

The aboveground architecture, biomass and its allocation, and the relationship between architecture and biomass of Quercus variabilis of different diameter classes in Shangluo, south slope of Qinling Mountains were researched. The results showed that differences existed in the aboveground architecture and biomass allocation of Q. variabilis of different diameter classes. With the increase of diameter class, tree height, DBH, and crown width increased gradually. The average decline rate of each diameter class increased firstly then decreased. Q. variabilis overall bifurcation ratio and stepwise bifurcation ratio increased then declined. The specific leaf areas of Q. variabilis of all different diameter classes at vertical direction were 0.02-0.03, and the larger values of leaf mass ratio, LAI and leaf area ratio at vertical direction in diameter level I , II, III appeared in the middle and upper trunk, while in diameter level IV, V, VI, they appeared in the central trunk, with the increase of diameter class, there appeared two peaks in vertical direction, which located in the lower and upper trunk. The trunk biomass accounted for 71.8%-88.4% of Q. variabilis aboveground biomass, while the branch biomass accounted for 5.8%-19.6%, and the leaf biomass accounted for 4.2%-8.6%. With the increase of diameter class, stem biomass proportion of Q. variabilis decreased firstly then increased, while the branch and leaf biomass proportion showed a trend that increased at first then decreased, and then increased again. The aboveground biomass of Q. variabilis was significantly positively correlated to tree height, DBH, crown width and stepwise bifurcation ratio (R2:1), and positively related to the overall bifurcation ratio and stepwise bifurcation ratio (R3:2), but there was no significant correlation. Trunk biomass and total biomass aboveground were negatively related to the trunk decline rate, while branch biomass and leaf biomass were positively related to trunk decline

The Phenylalanine Ammonia-Lyase Gene Family in Raspberry. Structure, Expression, and Evolution1

PubMed Central

Kumar, Amrita; Ellis, Brian E.

2001-01-01

In raspberry (Rubus idaeus), development of fruit color and flavor are critically dependent on products of the phenylpropanoid pathway. To determine how these metabolic functions are integrated with the fruit ripening program, we are examining the properties and expression of key genes in the pathway. Here, we report that l- phenylalanine ammonia-lyase (PAL) is encoded in raspberry by a family of two genes (RiPAL1 and RiPAL2). RiPAL1 shares 88% amino acid sequence similarity to RiPAL2, but phylogenetic analysis places RiPAL1 and RiPAL2 in different clusters within the plant PAL gene family. The spatial and temporal expression patterns of the two genes were investigated in various vegetative and floral tissues using the reverse transcriptase competitor polymerase chain reaction assay. Although expression of both genes was detected in all tissues examined, RiPAL1 was associated with early fruit ripening events, whereas expression of RiPAL2 correlated more with later stages of flower and fruit development. Determination of the absolute levels of the two transcripts in various tissues showed that RiPAL1 transcripts were 3- to 10-fold more abundant than those of RiPAL2 in leaves, shoots, roots, young fruits, and ripe fruits. The two RiPAL genes therefore appear to be controlled by different regulatory mechanisms. PMID:11553751

Novel Scheme for Biosynthesis of Aryl Metabolites from l-Phenylalanine in the Fungus Bjerkandera adusta

PubMed Central

Lapadatescu, Carmen; Giniès, Christian; Le Quéré, Jean-Luc; Bonnarme, Pascal

2000-01-01

Aryl metabolite biosynthesis was studied in the white rot fungus Bjerkandera adusta cultivated in a liquid medium supplemented with l-phenylalanine. Aromatic compounds were analyzed by gas chromatography-mass spectrometry following addition of labelled precursors (14C- and 13C-labelled l-phenylalanine), which did not interfere with fungal metabolism. The major aromatic compounds identified were benzyl alcohol, benzaldehyde (bitter almond aroma), and benzoic acid. Hydroxy- and methoxybenzylic compounds (alcohols, aldehydes, and acids) were also found in fungal cultures. Intracellular enzymatic activities (phenylalanine ammonia lyase, aryl-alcohol oxidase, aryl-alcohol dehydrogenase, aryl-aldehyde dehydrogenase, lignin peroxidase) and extracellular enzymatic activities (aryl-alcohol oxidase, lignin peroxidase), as well as aromatic compounds, were detected in B. adusta cultures. Metabolite formation required de novo protein biosynthesis. Our results show that l-phenylalanine was deaminated to trans-cinnamic acid by a phenylalanine ammonia lyase and trans-cinnamic acid was in turn converted to aromatic acids (phenylpyruvic, phenylacetic, mandelic, and benzoylformic acids); benzaldehyde was a metabolic intermediate. These acids were transformed into benzaldehyde, benzyl alcohol, and benzoic acid. Our findings support the hypothesis that all of these compounds are intermediates in the biosynthetic pathway from l-phenylalanine to aryl metabolites. Additionally, trans-cinnamic acid can also be transformed via β-oxidation to benzoic acid. This was confirmed by the presence of acetophenone as a β-oxidation degradation intermediate. To our knowledge, this is the first time that a β-oxidation sequence leading to benzoic acid synthesis has been found in a white rot fungus. A novel metabolic scheme for biosynthesis of aryl metabolites from l-phenylalanine is proposed. PMID:10742235

Cinnamaldehyde inhibits enzymatic browning of cut lettuce by repressing the induction of phenylalanine ammonia-lyase without promotion of microbial growth.

PubMed

Tanaka, Eriko; Okumura, Saya; Takamiya, Rikako; Hosaka, Hitomi; Shimamura, Yuko; Murata, Masatsune

2011-06-22

Cinnamaldehyde treatment inhibited the browning of cut lettuce during cold storage. In this study, to clarify the mechanism of inhibitory action of cinnamaldehyde against the browning and to show its microbiological merit, its effect on the browning of cut lettuce was compared to that of mild heat treatment. Both cinnamaldehyde and mild heat treatments inhibited the induction of phenylalanine ammonia-lyase (PAL) activity because of cutting. As a result, the biosynthesis of polyphenols, which are substrates of polyphenol oxidase, was inhibited. This reduction of polyphenol synthesis caused the inhibition of the browning. Cinnamaldehyde treatment repressed the induction of PAL mRNA, while mild heat treatment did not repress its induction. The increase in microbes in cut lettuce treated with cinnamaldehyde was less than that treated with mild heat after 12 days.

Cadmium-induced changes in pigments, total phenolics, and phenylalanine ammonia-lyase activity in fronds of Azolla imbricata.

PubMed

Dai, Ling-Peng; Xiong, Zhi-Ting; Huang, Yu; Li, Min-Jing

2006-10-01

This study was designed to examine the effects of cadmium on several color-related parameters (including chlorophyll, carotenoid, and anthocyanin), total phenolics, and phenylalanine ammonia-lyase (PAL) activity in an aquatic fern species Azolla imbricate (A. imbricata). Cd accumulation and effects in the fronds were closely related with Cd concentration in the growth medium. The fronds under 0.5 mg/L Cd treatment turned red on the 3rd day, and this color change also appeared under 0.05 and 0.1 mg/L Cd treatment on the 5th day. Correlated with the color change, the contents of chlorophyll and carotenoid in the fronds significantly decreased in the presence of high Cd concentrations, while the anthocyanin content increased during the experiment. Significant increase in total phenolics content and PAL activity were also detected during Cd treatment. The results suggested that the Cd-induced change in color of fronds might be due to the decrease in chlorophyll and carotenoid and the increase in anthocyanin. Anthocyanin, total phenolics and their biosynthesis-related PAL might play a role in detoxification of Cd in A. imbricata.

Genome-wide characterization of phenylalanine ammonia-lyase gene family in watermelon (Citrullus lanatus).

PubMed

Dong, Chun-Juan; Shang, Qing-Mao

2013-07-01

Phenylalanine ammonia-lyase (PAL), the first enzyme in the phenylpropanoid pathway, plays a critical role in plant growth, development, and adaptation. PAL enzymes are encoded by a gene family in plants. Here, we report a genome-wide search for PAL genes in watermelon. A total of 12 PAL genes, designated ClPAL1-12, are identified . Nine are arranged in tandem in two duplication blocks located on chromosomes 4 and 7, and the other three ClPAL genes are distributed as single copies on chromosomes 2, 3, and 8. Both the cDNA and protein sequences of ClPALs share an overall high identity with each other. A phylogenetic analysis places 11 of the ClPALs into a separate cucurbit subclade, whereas ClPAL2, which belongs to neither monocots nor dicots, may serve as an ancestral PAL in plants. In the cucurbit subclade, seven ClPALs form homologous pairs with their counterparts from cucumber. Expression profiling reveals that 11 of the ClPAL genes are expressed and show preferential expression in the stems and male and female flowers. Six of the 12 ClPALs are moderately or strongly expressed in the fruits, particularly in the pulp, suggesting the potential roles of PAL in the development of fruit color and flavor. A promoter motif analysis of the ClPAL genes implies redundant but distinctive cis-regulatory structures for stress responsiveness. Finally, duplication events during the evolution and expansion of the ClPAL gene family are discussed, and the relationships between the ClPAL genes and their cucumber orthologs are estimated.

Comparative study of thylakoid membranes in terminal heterocysts and vegetative cells from two cyanobacteria, Rivularia M-261 and Anabaena variabilis, by fluorescence and absorption spectral microscopy.

PubMed

Nozue, Shuho; Katayama, Mitsunori; Terazima, Masahide; Kumazaki, Shigeichi

2017-09-01

Heterocyst is a nitrogen-fixing cell differentiated from a cell for oxygen-evolving photosynthesis (vegetative cell) in some filamentous cyanobacteria when fixed nitrogen (e.g., ammonia and nitrate) is limited. Heterocysts appear at multiple separated positions in a single filament with an interval of 10-20 cells in some genera (including Anabaena variabilis). In other genera, a single heterocyst appears only at the basal terminal in a filament (including Rivularia M-261). Such morphological diversity may necessitate different properties of heterocysts. However, possible differences in heterocysts have largely remained unexplored due to the minority of heterocysts among major vegetative cells. Here, we have applied spectroscopic microscopy to Rivularia and A. variabilis to analyze their thylakoid membranes in individual cells. Absorption and fluorescence spectral imaging enabled us to estimate concentrations and interconnections of key photosynthetic components like photosystem I (PSI), photosystem II (PSII) and subunits of light-harvesting phycobilisome including phycocyanin (PC). The concentration of PC in heterocysts of Rivularia is far higher than that of A. variabilis. Fluorescence quantum yield of PC in Rivularia heterocysts was found to be virtually the same as those in its vegetative cells, while fluorescence quantum yield of PC in A. variabilis heterocysts was enhanced in comparison with its vegetative cells. PSI concentration in the thylakoid membranes of heterocysts seems to remain nearly the same as those of the vegetative cells in both the species. The average stoichiometric ratio between PSI monomer and PC hexamer in Rivularia heterocysts is estimated to be about 1:1. Copyright © 2017 Elsevier B.V. All rights reserved.

Relationship between the enzymatic browning and phenylalanine ammonia-lyase activity of cut lettuce, and the prevention of browning by inhibitors of polyphenol biosynthesis.

PubMed

Hisaminato, H; Murata, M; Homma, S

2001-05-01

Cut lettuce stored at 4 degrees C gradually turned brown on the cut section after several days of storage. Three factors for enzymatic browning, the polyphenol content, polyphenol oxidase activity, and phenylalanine ammonia-lyase (PAL) activity, were examined during the cold storage of cut lettuce. A relationship between the browning and PAL activity was apparent. We tried to prevent this browning by using the two enzyme inhibitors, 2-aminoindane-2-phosphonic acid (AIP), an inhibitor of the phenylpropanoid pathway, and glyphosate, an inhibitor of the shikimate pathway. AIP and glyphosate significantly inhibited the browning of cut lettuce. The polyphenol content and PAL activity were both reduced by the treatment with AIP. These results show that regulating the biosynthesis of polyphenols is essential to prevent the browning of cut lettuce.

Chronic rhino-orbital mucormycosis caused by Mucor irregularis (Rhizomucor variabilis) in India

USDA-ARS?s Scientific Manuscript database

We describe a chronic case of rhino-orbital zygomycosis caused by Mucor irregularis, formerly known as Rhizomucor variabilis var. variabilis, a rare mycotic agent in humans. The infection caused progressive destruction of the nasal septum, soft and hard palate, leading to collapse of the nose bridge...

The environmental source of emerging Apophysomyces variabilis infection in India.

PubMed

Prakash, Hariprasath; Ghosh, Anup Kumar; Rudramurthy, Shivaprakash Mandya; Paul, Raees Ahmad; Gupta, Sunita; Negi, Vishwanand; Chakrabarti, Arunaloke

2016-08-01

The rare mucoraceous fungus, Apophysomyces species complex ranks second after Rhizopus arrhizus causing mucormycosis in India. The source of this agent in the environment is not clearly known. We conducted an environmental study to find its presence in Indian soil. The soil samples from different geographical locations were analyzed for isolation of Mucorales. Rhizopus arrhizus (24.6%) was most commonly isolated from soil, followed by Lichtheimia spp. (23.2%), Cunninghamella spp. (21.7%), Rhizopus microsporus (14%) and Apophysomyces spp. (4.5%). The isolation of Apophysomyces species complex was significantly associated with low nitrogen content of the soil. Based on sequencing of internal transcribed spacer (ITS) and 28S (D1/D2) regions of ribosomal DNA, the Apophysomyces isolates were identified as Apophysomyces variabilis with 98 to 100% similarity to type strain A. variabilis (CBS658.93). The analysis of amplified fragment length polymorphism (AFLP) fingerprinting data demonstrated genomic diversity of A. variabilis isolates with multiple clades (similarity 40-90%). The minimum inhibitory concentrations (MIC), MIC50 and MIC90 for A. variabilis isolates were 1 and 4 μg/ml for amphotericin B, 0.25 and 0.5 μg/ml for itraconazole, 0.125 and 0.25 μg/ml for posaconazole, 0.06 and 0.12 μg/ml for terbinafine, respectively. The present study revealed abundant presence of A. variabilis in Indian soil with low nitrogen content, its genetic heterogeneity and relatively high MICs for amphotericin B. © The Author 2016. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Functional characterization and novel rickettsiostatic effects of a Kunitz-type serine protease inhibitor from the tick Dermacentor variabilis.

PubMed

Ceraul, Shane M; Dreher-Lesnick, Sheila M; Mulenga, Albert; Rahman, M Sayeedur; Azad, Abdu F

2008-11-01

Here we report the novel bacteriostatic function of a five-domain Kunitz-type serine protease inhibitor (KPI) from the tick Dermacentor variabilis. As ticks feed, they release anticoagulants, anti-inflammatory and immunosuppressive molecules that mediate the formation of the feeding lesion on the mammalian host. A number of KPIs have been isolated and characterized from tick salivary gland extracts. Interestingly, we observe little D. variabilis KPI gene expression in the salivary gland and abundant expression in the midgut. However, our demonstration of D. variabilis KPI's anticoagulant properties indicates that D. variabilis KPI may be important for blood meal digestion in the midgut. In addition to facilitating long-term attachment and blood meal acquisition, gene expression studies of Drosophila, legumes, and ticks suggest that KPIs play some role in the response to microbial infection. Similarly, in this study, we show that challenge of D. variabilis with the spotted fever group rickettsia, Rickettsia montanensis, results in sustained D. variabilis KPI gene expression in the midgut. Furthermore, our in vitro studies show that D. variabilis KPI limits rickettsial colonization of L929 cells (mouse fibroblasts), implicating D. variabilis KPI as a bacteriostatic protein, a property that may be related to D. variabilis KPI's trypsin inhibitory capability. This work suggests that anticoagulants play some role in the midgut during feeding and that D. variabilis KPI may be involved as part of the tick's defense response to rickettsiae.

Genetics Home Reference: erythrokeratodermia variabilis et progressiva

MedlinePlus

... P, Campanelli C, Compton JG, Bale SJ, DiGiovanna JJ, Uitto J. Genetic heterogeneity in erythrokeratodermia variabilis: novel ... Itin P, Hohl D, Epstein EH Jr, DiGiovanna JJ, Compton JG, Bale SJ. Mutations in the human ...

Effect of nitrogen starvation on the level of adenosine 3',5'-monophosphate in Anabaena variabilis.

PubMed

Hood, E E; Armour, S; Ownby, J D; Handa, A K; Bressan, R A

1979-12-03

Low levels of adenosine 3',5'-monophosphate (cyclic AMP) were detected in the cyanobacterium Anabaena variabilis using a protein binding assay and two radioisotopic labelling methods. The basal concentration of intracellular cyclic AMP ranged from 0.27 pmol/mg protein in A. variabilis Kutz grown under heterotrophic conditions to 1.0--2.7 pmol/mg protein in A. variabilis strain 377 grown autotrophically. Extracellular cyclic AMP was found to comprise as much as 90% of the total cyclic AMP in rapidly growing cultures. When A. variabilis strain 377 was starved of nitrogen, a 3--4-fold increase in intracellular cyclic AMP was observed during the 24 h period coincident with early heterocyst development.

Expression and enzymatic activity of phenylalanine ammonia-lyase and p-coumarate 3-hydroxylase in mango (Mangifera indica 'Ataulfo') during ripening.

PubMed

Palafox-Carlos, H; Contreras-Vergara, C A; Muhlia-Almazán, A; Islas-Osuna, M A; González-Aguilar, G A

2014-05-16

Phenylalanine ammonia lyase (PAL) and p-coumarate 3-hydroxylase (C3H) are key enzymes in the phenylpropanoid pathway. The relative expression of PAL and C3H was evaluated in mango fruit cultivar 'Ataulfo' in four ripening stages (RS1, RS2, RS3, and RS4) by quantitative polymerase chain reaction. In addition, enzyme activity of PAL and C3H was determined in mango fruits during ripening. The PAL levels were downregulated at the RS2 and RS3 stages, while C3H levels were upregulated in fruits only at RS3. The enzyme activity of PAL followed a pattern that was different from that of the PAL expression, thus suggesting regulation at several levels. For C3H, a regulation at the transcriptional level is suggested because a similar pattern was revealed by its activity and transcript level. In this study, the complexity of secondary metabolite biosynthesis regulation is emphasized because PAL and C3H enzymes are involved in the biosynthesis of several secondary metabolites that are active during all mango ripening stages.

Familial erythrokeratodermia variabilis with pustular lesions: a new variant?

PubMed

Zhang, Li; Huo, Wei; Gao, Xing-Hua; Ma, Lei; Xiu, Yuhong; Zheng, Song; Hong, Yuziao; Chen, Hong-Duo

2010-05-01

We report here a Chinese family with erythrokeratodermia variabilis which had 30 affected members. The patients had characteristic clinical features of stationary and migratory lesions. Some of the patients had adult onset of the disease. Five out of 30 patients noted episodes of pustule-like lesions during their disease course. Histological examination of the proband showed granular cell vacuolation and upper-epidermal neutrophil aggregates. Mitochondria vacuolation was noted in keratinocytes by electron microscopic examination. No GJB3 and GJB4 pathogenic mutation was detected. These unusual presentations suggested a new phenotypic and genetic correlation in this Chinese pedigree of erythrokeratodermia variabilis.

Apophysomyces variabilis: draft genome sequence and comparison of predictive virulence determinants with other medically important Mucorales.

PubMed

Prakash, Hariprasath; Rudramurthy, Shivaprakash Mandya; Gandham, Prasad S; Ghosh, Anup Kumar; Kumar, Milner M; Badapanda, Chandan; Chakrabarti, Arunaloke

2017-09-18

Apophysomyces species are prevalent in tropical countries and A. variabilis is the second most frequent agent causing mucormycosis in India. Among Apophysomyces species, A. elegans, A. trapeziformis and A. variabilis are commonly incriminated in human infections. The genome sequences of A. elegans and A. trapeziformis are available in public database, but not A. variabilis. We, therefore, performed the whole genome sequence of A. variabilis to explore its genomic structure and possible genes determining the virulence of the organism. The whole genome of A. variabilis NCCPF 102052 was sequenced and the genomic structure of A. variabilis was compared with already available genome structures of A. elegans, A. trapeziformis and other medically important Mucorales. The total size of genome assembly of A. variabilis was 39.38 Mb with 12,764 protein-coding genes. The transposable elements (TEs) were low in Apophysomyces genome and the retrotransposon Ty3-gypsy was the common TE. Phylogenetically, Apophysomyces species were grouped closely with Phycomyces blakesleeanus. OrthoMCL analysis revealed 3025 orthologues proteins, which were common in those three pathogenic Apophysomyces species. Expansion of multiple gene families/duplication was observed in Apophysomyces genomes. Approximately 6% of Apophysomyces genes were predicted to be associated with virulence on PHIbase analysis. The virulence determinants included the protein families of CotH proteins (invasins), proteases, iron utilisation pathways, siderophores and signal transduction pathways. Serine proteases were the major group of proteases found in all Apophysomyces genomes. The carbohydrate active enzymes (CAZymes) constitute the majority of the secretory proteins. The present study is the maiden attempt to sequence and analyze the genomic structure of A. variabilis. Together with available genome sequence of A. elegans and A. trapeziformis, the study helped to indicate the possible virulence determinants of

Structure, inheritance, and expression of hybrid poplar (Populus trichocarpa x Populus deltoides) phenylalanine ammonia-lyase genes.

PubMed Central

Subramaniam, R; Reinold, S; Molitor, E K; Douglas, C J

1993-01-01

A heterologous probe encoding phenylalanine ammonia-lyase (PAL) was used to identify PAL clones in cDNA libraries made with RNA from young leaf tissue of two Populus deltoides x P. trichocarpa F1 hybrid clones. Sequence analysis of a 2.4-kb cDNA confirmed its identity as a full-length PAl clone. The predicted amino acid sequence is conserved in comparison with that of PAL genes from several other plants. Southern blot analysis of popular genomic DNA from parental and hybrid individuals, restriction site polymorphism in PAL cDNA clones, and sequence heterogeneity in the 3' ends of several cDNA clones suggested that PAL is encoded by at least two genes that can be distinguished by HindIII restriction site polymorphisms. Clones containing each type of PAL gene were isolated from a poplar genomic library. Analysis of the segregation of PAL-specific HindIII restriction fragment-length polymorphisms demonstrated the existence of two independently segregating PAL loci, one of which was mapped to a linkage group of the poplar genetic map. Developmentally regulated PAL expression in poplar was analyzed using RNA blots. Highest expression was observed in young stems, apical buds, and young leaves. Expression was lower in older stems and undetectable in mature leaves. Cellular localization of PAL expression by in situ hybridization showed very high levels of expression in subepidermal cells of leaves early during leaf development. In stems and petioles, expression was associated with subepidermal cells and vascular tissues. PMID:8108506

[Predicting the impact of global warming on the geographical distribution pattern of Quercus variabilis in China].

PubMed

Li, Yao; Zhang, Xing-wang; Fang, Yan-ming

2014-12-01

The geographical distribution of Quercus variabilis in China with its climate characteristics was analyzed based on DIVA-GIS which was also used to estimate the response of future potential distribution to global warming by Bioclim and Domain models. Analysis results showed the geographical distribution of Q. variabilis could be divided into 7 subregions: Henduan Mountains, Yunnan-Guizhou Plateau, North China, East China, Liaodong-Shandong Peninsula, Taiwan Island, and Qinling-Daba Mountains. These subregions are across 7 temperature zones, 2 moisture regions and 17 climatic subregions, including 8 climate types. The modern abundance center of Q. variabilis is Qinling, Daba and Funiu mountains. The condition of mean annual temperature 7.5-19.8 degrees C annual precipitation 471-1511 mm, is suitable for Q. variabilis. Areas under the receiver operating characteristic curve (AUC values), of Domain and Boiclim models were 0.910, 0.779; the former predicted that the potential regions of high suitability for Q. variabilis are Qinling, Daba, Funiu, Tongbai, and Dabie mountains, eastern and western Yunnan-Guizhou Plateau, hills of southern Jiangsu and Anhui, part of the mountains in North China. Global warming might lead to the shrinking in suitable region and retreating from the south for Q. variabilis.

Quality of cut lettuce treated by heat shock: prevention of enzymatic browning, repression of phenylalanine ammonia-lyase activity, and improvement on sensory evaluation during storage.

PubMed

Murata, Masatsune; Tanaka, Eriko; Minoura, Emiko; Homma, Seiichi

2004-03-01

Stored cut lettuce gradually turns brown on the cut section after several days of storage, because cutting induces phenylalanine ammonia-lyase (PAL) activity, the biosynthesis of polyphenol is promoted, and the polyphenols are oxidized by polyphenol oxidase. Here, the effect of heat shock treatment at 50 degrees C for 90 s on the quality of cut lettuce during cold storage was examined. The heat shock treatment significantly repressed the induction of PAL activity and phenolics accumulation in cut lettuce during storage, and prevented the browning of cut lettuce. Ascorbic acid content was not affected by the heat shock treatment. The sensory analysis showed that the organoleptic quality of cut lettuce treated by heat shock was significantly better than that of the control cut lettuce. These results show that heat shock treatment is useful for prolonging the shelf life of cut lettuce.

Molecular and analysis of a phenylalanine ammonia-lyase gene (LrPAL2) from Lycoris radiata.

PubMed

Jiang, Yumei; Xia, Bing; Liang, Lijian; Li, Xiaodan; Xu, Sheng; Peng, Feng; Wang, Ren

2013-03-01

Phenylalanine ammonia-lyase (PAL), the first enzyme of phenylpropanoid biosynthesis, participates in the biosynthesis of flavonoids, lignins, stilbenes and many other compounds. In this study, we cloned a 2,326 bp full-length PAL2 gene from Lycoris radiata by using degenerate oligonucleotide primer PCR (DOP-PCR) and the rapid amplification of cDNA ends method. The cDNA contains a 2,124 bp coding region encoding 707 amino acids. The LrPAL2 shares about 77.0 % nucleic acid identity and 83 % amino acid identity with LrPAL1. Furthermore, genome sequence analysis demonstrated that LrPAL2 gene contains one intron and two exons. The 5' flanking sequence of LrPAL2 was also cloned by self-formed adaptor PCR (SEFA-PCR), and a group of putative cis-acting elements such as TATA box, CAAT box, G box, TC-rich repeats, CGTCA motif and TCA-element were identified. The LrPAL2 was detected in all tissues examined, with high abundance in bulbs at leaf sprouting stage and in petals at blooming stage. Besides, LrPAL2 drastically responded to MJ, SNP and UV, moderately responded to GA and SA, and a little increased under wounding. Comparison of LrPAL2 expression and LrPAL1 expression demonstrated that LrPAL2 can be more significantly induced than LrPAL1 under the above treatments, and LrPAL2 transcripts accumulated prominently at blooming stage, especially in petals, while LrPAL1 transcripts did not accumulated significantly at blooming stage. All these results suggested that LrPAL2 might play distinct roles in different branches of the phenylpropanoid pathway.

Identification of the Allosteric Site for Phenylalanine in Rat Phenylalanine Hydroxylase*

PubMed Central

Zhang, Shengnan; Fitzpatrick, Paul F.

2016-01-01

Liver phenylalanine hydroxylase (PheH) is an allosteric enzyme that requires activation by phenylalanine for full activity. The location of the allosteric site for phenylalanine has not been established. NMR spectroscopy of the isolated regulatory domain (RDPheH(25–117) is the regulatory domain of PheH lacking residues 1–24) of the rat enzyme in the presence of phenylalanine is consistent with formation of a side-by-side ACT dimer. Six residues in RDPheH(25–117) were identified as being in the phenylalanine-binding site on the basis of intermolecular NOEs between unlabeled phenylalanine and isotopically labeled protein. The location of these residues is consistent with two allosteric sites per dimer, with each site containing residues from both monomers. Site-specific variants of five of the residues (E44Q, A47G, L48V, L62V, and H64N) decreased the affinity of RDPheH(25–117) for phenylalanine based on the ability to stabilize the dimer. Incorporation of the A47G, L48V, and H64N mutations into the intact protein increased the concentration of phenylalanine required for activation. The results identify the location of the allosteric site as the interface of the regulatory domain dimer formed in activated PheH. PMID:26823465

Identification of a plastidial phenylalanine exporter that influences flux distribution through the phenylalanine biosynthetic network

PubMed Central

Widhalm, Joshua R.; Gutensohn, Michael; Yoo, Heejin; Adebesin, Funmilayo; Qian, Yichun; Guo, Longyun; Jaini, Rohit; Lynch, Joseph H.; McCoy, Rachel M.; Shreve, Jacob T.; Thimmapuram, Jyothi; Rhodes, David; Morgan, John A.; Dudareva, Natalia

2015-01-01

In addition to proteins, L-phenylalanine is a versatile precursor for thousands of plant metabolites. Production of phenylalanine-derived compounds is a complex multi-compartmental process using phenylalanine synthesized predominantly in plastids as precursor. The transporter(s) exporting phenylalanine from plastids, however, remains unknown. Here, a gene encoding a Petunia hybrida plastidial cationic amino-acid transporter (PhpCAT) functioning in plastidial phenylalanine export is identified based on homology to an Escherichia coli phenylalanine transporter and co-expression with phenylalanine metabolic genes. Radiolabel transport assays show that PhpCAT exports all three aromatic amino acids. PhpCAT downregulation and overexpression result in decreased and increased levels, respectively, of phenylalanine-derived volatiles, as well as phenylalanine, tyrosine and their biosynthetic intermediates. Metabolic flux analysis reveals that flux through the plastidial phenylalanine biosynthetic pathway is reduced in PhpCAT RNAi lines, suggesting that the rate of phenylalanine export from plastids contributes to regulating flux through the aromatic amino-acid network. PMID:26356302

Identification of a plastidial phenylalanine exporter that influences flux distribution through the phenylalanine biosynthetic network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Widhalm, Joshua R.; Gutensohn, Michael; Yoo, Heejin

In addition to proteins, L-phenylalanine is a versatile precursor for thousands of plant metabolites. Production of phenylalanine-derived compounds is a complex multi-compartmental process using phenylalanine synthesized predominantly in plastids as precursor. The transporter(s) exporting phenylalanine from plastids, however, remains unknown. Here, a gene encoding a Petunia hybrida plastidial cationic amino-acid transporter (PhpCAT) functioning in plastidial phenylalanine export is identified based on homology to an Escherichia coli phenylalanine transporter and co-expression with phenylalanine metabolic genes. Radiolabel transport assays show that PhpCAT exports all three aromatic amino acids. PhpCAT downregulation and overexpression result in decreased and increased levels, respectively, of phenylalanine-derived volatiles,more » as well as phenylalanine, tyrosine and their biosynthetic intermediates. Metabolic flux analysis reveals that flux through the plastidial phenylalanine biosynthetic pathway is reduced in PhpCAT RNAi lines, suggesting that the rate of phenylalanine export from plastids contributes to regulating flux through the aromatic amino-acid network.« less

Identification of a plastidial phenylalanine exporter that influences flux distribution through the phenylalanine biosynthetic network

DOE PAGES

Widhalm, Joshua R.; Gutensohn, Michael; Yoo, Heejin; ...

2015-09-10

In addition to proteins, L-phenylalanine is a versatile precursor for thousands of plant metabolites. Production of phenylalanine-derived compounds is a complex multi-compartmental process using phenylalanine synthesized predominantly in plastids as precursor. The transporter(s) exporting phenylalanine from plastids, however, remains unknown. Here, a gene encoding a Petunia hybrida plastidial cationic amino-acid transporter (PhpCAT) functioning in plastidial phenylalanine export is identified based on homology to an Escherichia coli phenylalanine transporter and co-expression with phenylalanine metabolic genes. Radiolabel transport assays show that PhpCAT exports all three aromatic amino acids. PhpCAT downregulation and overexpression result in decreased and increased levels, respectively, of phenylalanine-derived volatiles,more » as well as phenylalanine, tyrosine and their biosynthetic intermediates. Metabolic flux analysis reveals that flux through the plastidial phenylalanine biosynthetic pathway is reduced in PhpCAT RNAi lines, suggesting that the rate of phenylalanine export from plastids contributes to regulating flux through the aromatic amino-acid network.« less

Therapeutic implication of L-phenylalanine aggregation mechanism and its modulation by D-phenylalanine in phenylketonuria.

PubMed

Singh, Virender; Rai, Ratan Kumar; Arora, Ashish; Sinha, Neeraj; Thakur, Ashwani Kumar

2014-01-27

Self-assembly of phenylalanine is linked to amyloid formation toxicity in phenylketonuria disease. We are demonstrating that L-phenylalanine self-assembles to amyloid fibrils at varying experimental conditions and transforms to a gel state at saturated concentration. Biophysical methods including nuclear magnetic resonance, resistance by alpha-phenylglycine to fibril formation and preference of protected phenylalanine to self-assemble show that this behaviour of L-phenylalanine is governed mainly by hydrophobic interactions. Interestingly, D-phenylalanine arrests the fibre formation by L-phenylalanine and gives rise to flakes. These flakes do not propagate further and prevent fibre formation by L-phenylalanine. This suggests the use of D-phenylalanine as modulator of L-phenylalanine amyloid formation and may qualify as a therapeutic molecule in phenylketonuria.

Therapeutic implication of L-phenylalanine aggregation mechanism and its modulation by D-phenylalanine in phenylketonuria

PubMed Central

Singh, Virender; Rai, Ratan Kumar; Arora, Ashish; Sinha, Neeraj; Thakur, Ashwani Kumar

2014-01-01

Self-assembly of phenylalanine is linked to amyloid formation toxicity in phenylketonuria disease. We are demonstrating that L-phenylalanine self-assembles to amyloid fibrils at varying experimental conditions and transforms to a gel state at saturated concentration. Biophysical methods including nuclear magnetic resonance, resistance by alpha-phenylglycine to fibril formation and preference of protected phenylalanine to self-assemble show that this behaviour of L-phenylalanine is governed mainly by hydrophobic interactions. Interestingly, D-phenylalanine arrests the fibre formation by L-phenylalanine and gives rise to flakes. These flakes do not propagate further and prevent fibre formation by L-phenylalanine. This suggests the use of D-phenylalanine as modulator of L-phenylalanine amyloid formation and may qualify as a therapeutic molecule in phenylketonuria. PMID:24464217

Cloning and Expression Analysis of Phenylalanine Ammonia-Lyase Gene in the Mycelium and Fruit Body of the Edible Mushroom Flammulina velutipes

PubMed Central

Yun, Yeo Hong; Koo, Ja Sun

2015-01-01

Phenylalanine ammonia-lyase (PAL) gene is known to be expressed in plants, and is involved in the differentiation, growth and synthesis of secondary metabolites. However, its expression in fungi remains to be explored. To understand its expression in mushroom fungi, the PAL gene of the edible mushroom Flammulina velutipes (Fvpal) was cloned and characterized. The cloned Fvpal consists of 2,175 bp, coding for a polypeptide containing 724 amino acids and having 11 introns. The translated amino acid sequence of Fvpal shares a high identity (66%) with that of ectomycorrhizal fungus Tricholoma matsutake. Distinctively, the Fvpal expression in the mycelium was higher in minimal medium supplemented with L-tyrosine than with other aromatic amino acids. During cultivation of the mushroom on sawdust medium, Fvpal expression in the fruit body correspondingly increased as the mushroom grew. In the fruiting body, Fvpal was expressed more in the stipe than in the pileus. These results suggest that F. velutipes PAL activity differs in the different organs of the mushroom. Overall, this is first report to show that the PAL gene expression is associated with mushroom growth in fungi. PMID:26539050

Structural Basis for the Entrance into the Phenylpropanoid Metabolism Catalyzed by Phenylalanine Ammonia-Lyase

PubMed Central

Ritter, Holger; Schulz, Georg E.

2004-01-01

Because of its key role in secondary phenylpropanoid metabolism, Phe ammonia-lyase is one of the most extensively studied plant enzymes. To provide a basis for detailed structure–function studies, the enzyme from parsley (Petroselinum crispum) was crystallized, and the structure was elucidated at 1.7-Å resolution. It contains the unusual electrophilic 4-methylidene-imidazole-5-one group, which is derived from a tripeptide segment in two autocatalytic dehydration reactions. The enzyme resembles His ammonia-lyase from the general His degradation pathway but contains 207 additional residues, mainly in an N-terminal extension rigidifying a domain interface and in an inserted α-helical domain restricting the access to the active center. Presumably, Phe ammonia-lyase developed from His ammonia-lyase when fungi and plants diverged from the other kingdoms. A pathway of the catalyzed reaction is proposed in agreement with established biochemical data. The inactivation of the enzyme by a nucleophile is described in detail. PMID:15548745

Activation of phenylalanine hydroxylase by phenylalanine does not require binding in the active site.

PubMed

Roberts, Kenneth M; Khan, Crystal A; Hinck, Cynthia S; Fitzpatrick, Paul F

2014-12-16

Phenylalanine hydroxylase (PheH), a liver enzyme that catalyzes the hydroxylation of excess phenylalanine in the diet to tyrosine, is activated by phenylalanine. The lack of activity at low levels of phenylalanine has been attributed to the N-terminus of the protein's regulatory domain acting as an inhibitory peptide by blocking substrate access to the active site. The location of the site at which phenylalanine binds to activate the enzyme is unknown, and both the active site in the catalytic domain and a separate site in the N-terminal regulatory domain have been proposed. Binding of catecholamines to the active-site iron was used to probe the accessibility of the active site. Removal of the regulatory domain increases the rate constants for association of several catecholamines with the wild-type enzyme by ∼2-fold. Binding of phenylalanine in the active site is effectively abolished by mutating the active-site residue Arg270 to lysine. The k(cat)/K(phe) value is down 10⁴ for the mutant enzyme, and the K(m) value for phenylalanine for the mutant enzyme is >0.5 M. Incubation of the R270K enzyme with phenylalanine also results in a 2-fold increase in the rate constants for catecholamine binding. The change in the tryptophan fluorescence emission spectrum seen in the wild-type enzyme upon activation by phenylalanine is also seen with the R270K mutant enzyme in the presence of phenylalanine. Both results establish that activation of PheH by phenylalanine does not require binding of the amino acid in the active site. This is consistent with a separate allosteric site, likely in the regulatory domain.

Activation of Phenylalanine Hydroxylase by Phenylalanine Does Not Require Binding in the Active Site

PubMed Central

2015-01-01

Phenylalanine hydroxylase (PheH), a liver enzyme that catalyzes the hydroxylation of excess phenylalanine in the diet to tyrosine, is activated by phenylalanine. The lack of activity at low levels of phenylalanine has been attributed to the N-terminus of the protein’s regulatory domain acting as an inhibitory peptide by blocking substrate access to the active site. The location of the site at which phenylalanine binds to activate the enzyme is unknown, and both the active site in the catalytic domain and a separate site in the N-terminal regulatory domain have been proposed. Binding of catecholamines to the active-site iron was used to probe the accessibility of the active site. Removal of the regulatory domain increases the rate constants for association of several catecholamines with the wild-type enzyme by ∼2-fold. Binding of phenylalanine in the active site is effectively abolished by mutating the active-site residue Arg270 to lysine. The kcat/Kphe value is down 104 for the mutant enzyme, and the Km value for phenylalanine for the mutant enzyme is >0.5 M. Incubation of the R270K enzyme with phenylalanine also results in a 2-fold increase in the rate constants for catecholamine binding. The change in the tryptophan fluorescence emission spectrum seen in the wild-type enzyme upon activation by phenylalanine is also seen with the R270K mutant enzyme in the presence of phenylalanine. Both results establish that activation of PheH by phenylalanine does not require binding of the amino acid in the active site. This is consistent with a separate allosteric site, likely in the regulatory domain. PMID:25453233

Glycomacropeptide in children with phenylketonuria: does its phenylalanine content affect blood phenylalanine control?

PubMed

Daly, A; Evans, S; Chahal, S; Santra, S; MacDonald, A

2017-08-01

In phenylketonuria (PKU), there are no data available for children with respect to evaluating casein glycomacropeptide (CGMP) as an alternative to phenylalanine-free protein substitutes [Phe-free L-amino acid (AA)]. CGMP contains a residual amount of phenylalanine, which may alter blood phenylalanine control. In a prospective 6-month pilot study, we investigated the effect on blood phenylalanine control of CGMP-amino acid (CGMP-AA) protein substitute in 22 PKU subjects (13 boys, nine girls), median age (range) 11 years (6-16 years). Twelve received CGMP-AA and nine received Phe-free L-AA, (1 CGMP-AA withdrawal). Subjects partially or wholly replaced Phe-free L-AA with CGMP-AA. If blood phenylalanine exceeded the target range, the CGMP-AA dose was reduced and replaced with Phe-free L-amino acids. The control group remained on Phe-free L-AAs. Phenylalanine, tyrosine and Phe : Tyr ratio concentrations were compared with the results for the previous year. In the CGMP-AA group, there was a significant increase in blood phenylalanine concentrations (pre-study, 275 μmol L -1 ; CGMP-AA, 317 μmol L -1 ; P = 0.02), a decrease in tyrosine concentrations (pre-study, 50 μmol L -1 ; CGMP-AA, 40 μmol L -1 ; P = 0.03) and an increase in Phe : Tyr ratios (pre-study, Phe : Tyr 4.9:1; CGMP-AA, Phe : Tyr 8:1; P = 0.02). In the control group there was a non-significant fall in phenylalanine concentrations (pre-study 325μmol/L: study 280μmol/L [p = 0.9], and no significant changes for tyrosine or phe/tyr ratios [p = 0.9]. Children taking the CGMP-AA found it more acceptable to L-AA. Blood phenylalanine control declined with CGMP-AA but, by titrating the dose of CGMP-AA, blood phenylalanine control remained within target range. The additional intake of phenylalanine may have contributed to the change in blood phenylalanine concentration. CGMP-AA use requires careful monitoring in children. © 2017 The British Dietetic Association Ltd.

Serum phenylalanine screening

MedlinePlus

... phenylalanine. If PKU is not detected early, increasing phenylalanine levels in the baby will cause intellectual disability. When discovered early, changes in the diet can help prevent the severe side effects of PKU.

Prevalence of Rickettsia Species (Rickettsiales: Rickettsiaceae) in Dermacentor variabilis Ticks (Acari: Ixodidae) in North Carolina.

PubMed

Kakumanu, Madhavi L; Ponnusamy, Loganathan; Sutton, Haley; Meshnick, Steven R; Nicholson, William L; Apperson, Charles S

2018-05-16

The American dog tick, Dermacentor variabilis (Say), is a vector of spotted fever group (SFG) rickettsiae, including Rickettsia rickettsii the causative organism of Rocky Mountain spotted fever (RMSF). In North Carolina, SFG rickettsioses (including RMSF) are a leading cause of tick-borne illness. Knowledge of the infection rate and geographic distribution of D. variabilis ticks infected with Rickettsia spp. provides information on the spatial distribution of public health risk. Accordingly, we extracted genomic DNA from adult D. variabilis collected from field habitats in 32 North Carolina counties from 2009 to 2013. A nested PCR assay of the 23S-5S intergenic spacer (IGS) region of Rickettsia coupled with reverse line blot hybridization (RLBH) with species-specific probes was used to detect and identify rickettsiae to species. Approximately half of the 532 tick DNA samples exhibited a band of the expected size on agarose gels, indicating infection with Rickettsia spp. RLBH analyses showed R. amblyommatis (formerly 'Candidatus R. amblyommii'), R. parkeri, and R. montanensis were predominant, while other Rickettsia species detected included R. conorii-like, R. massiliae, R. rhipicephali, R. canadensis, R. bellii, and some unknown Rickettsia spp. Some ticks were infected with more than one Rickettsia species. Notably, several Rickettsia-positive ticks harbored R. rickettsii. DNA sequencing was performed on a portion of the 23S-5S IGS amplicons and the results were concordant with RLB assay results. We conclude that Rickettsia spp. are common in D. variabilis in North Carolina. Geographic patterns in the occurrence of Rickettsia-infected D. variabilis ticks across the counties sampled are discussed.

Evaluation of possible reasons for the low phenylalanine ammonia lyase activity in cellulose nitrate membrane microcapsules.

PubMed

Habibi-Moini, S; D'mello, A P

2001-03-14

Microencapsulated phenylalanine ammonia lyase (PAL) exhibits a marked reduction in activity compared to the activity of the free enzyme in pH 8.5 Tris buffer. The purpose of this investigation was to evaluate the contribution of incomplete entrapment, the internal environment of cellulose nitrate membrane microcapsules, the diffusional barrier of the membrane and the microcapsulation process to the low activity of encapsulated PAL. A solution of PAL and 10% w/v hemoglobin was incorporated into cellulose nitrate membrane microcapsules. Hemoglobin incorporation was used as a surrogate marker of PAL entrapment. Using 14C hemoglobin, the encapsulation efficiency was determined to be 70% and suggested that incomplete entrapment might partially account for the low activity of encapsulated PAL. The effect of the internal environment of the microcapsule (10% hemoglobin solution) on PAL activity was evaluated by comparing enzyme activity in 10% w/v hemoglobin solution and pH 8.5 Tris buffer. Similar K(M) and V(max) values of PAL in the two media indicated that the internal environment of the microcapsule did not contribute to the reduction in activity of the encapsulated enzyme. The contribution of a membrane diffusional barrier was determined by breaking the putative barrier and measuring PAL activity in intact and broken microcapsules. Similar activity of PAL in these two conditions is evidence for the lack of a diffusional barrier. The effect of the microencapsulation process on PAL activity was evaluated by comparing K(M) and V(max) of free and encapsulated PAL. Similar K(M) values in these two media suggested that the process did not affect the conformation of PAL. However, encapsulated PAL had a 50% lower V(max) value compared to free PAL, which showed that the microencapsulation process deactivated a substantial proportion of the enzyme.

Amino Acid Isomerization in the Production of l-Phenylalanine from d-Phenylalanine by Bacteria1

PubMed Central

Chibata, Ichiro; Tosa, Tetsuya; Sano, Ryujiro

1965-01-01

To establish an advantageous method for the production of l-amino acids, microbial isomerization of d- and dl-amino acids to l-amino acids was studied. Screening experiments on a number of microorganisms showed that cell suspensions of Pseudomonas fluorescens and P. miyamizu were capable of isomerizing d- and dl-phenylalanines to l-phenylalanine. Various conditions suitable for isomerization by these organisms were investigated. Cells grown in a medium containing d-phenylalanine showed highest isomerization activity, and almost completely converted d- or dl-phenylalanine into l-phenylalanine within 24 to 48 hr of incubation. Enzymatic studies on this isomerizing system suggested that the isomerization of d- or dl-phenylalanine is not catalyzed by a single enzyme, “amino acid isomerase,” but the conversion proceeds by a two step system as follows: d-pheylalanine is oxidized to phenylpyruvic acid by d-amino acid oxidase, and the acid is converted to l-phenylalanine by transamination or reductive amination. PMID:14339270

Isolation and genetic mapping of a Coffea canephora phenylalanine ammonia-lyase gene (CcPAL1) and its involvement in the accumulation of caffeoyl quinic acids.

PubMed

Mahesh, Venkataramaiah; Rakotomalala, Jean Jacques; Le Gal, Lénaïg; Vigne, Hélène; de Kochko, Alexandre; Hamon, Serge; Noirot, Michel; Campa, Claudine

2006-09-01

Biosynthesis of caffeoylquinic acids occurs via the phenylpropanoid pathway in which the phenylalanine ammonia-lyase (PAL) acts as a key-control enzyme. A full-length cDNA (pF6), corresponding to a PAL gene (CcPAL1), was isolated by screening a Coffea canephora fruit cDNA library and its corresponding genomic sequence was characterized. Amplification of total DNA from seven Coffea species revealed differences in intronic length. This interspecific polymorphism was used to locate the gene on a genetic map established for a backcross progeny between Coffea pseudozanguebariae and C. dewevrei. The CcPAL1 gene was found on the same linkage group, but genetically independent, as a caffeoyl-coenzyme A-O-methyltransferase gene, another gene intervening in the phenylpropanoid pathway. In the same backcross, a lower caffeoylquinic acid content was observed in seeds harvested from plants harbouring the C. pseudozanguebariae CcPAL1 allele. Involvement of the CcPAL1 allelic form in the differential accumulation of caffeoylquinic acids in coffee green beans is then discussed.

Prevalence of Rickettsia species in Dermacentor variabilis ticks from Ontario, Canada.

PubMed

Wood, Heidi; Dillon, Liz; Patel, Samir N; Ralevski, Filip

2016-07-01

Relatively little is known about the prevalence of rickettsial species in Dermacentor ticks in eastern Canada. In this study, Dermacentor ticks from the province of Ontario, Canada, were tested for the presence of spotted fever group rickettsial (SFGR) species, Coxiella burnetii and Francisella tularensis. Rickettsia rickettsii was not detected in any ticks tested, but R. montanensis was detected at a prevalence of 2.2% in D. variabilis (17/778). Two other SFGR species, R. parkeri and Candidatus R. andeanae, were detected individually in 2 Amblyomma maculatum ticks. Rickettsia peacockii, a non-pathogenic endosymbiont, was detected in two D. andersonii ticks. Given the highly abundant nature of D. variabilis, surveillance for human pathogens in this species of tick has important public health implications, but the lack of detection of known human pathogens indicates a low risk of infection via this tick species in Ontario. However, the detection of R. parkeri in an adventive A. maculatum tick indicates that health care providers should be aware of the possibility of spotted fever rickettsioses in individuals with a history of travel outside of Ontario and symptoms compatible with a spotted fever rickettsiosis. Coxiella burnetii and Francisella tularensis, human pathogens also potentially transmitted by D. variabilis, were not detected in a subset of the ticks. Copyright © 2016 Elsevier GmbH. All rights reserved.

Manoalide-related Sesterterpene from the Marine Sponge Luffariella variabilis.

PubMed

Hamada, Toshiyuki; Harada, Daisuke; Hirata, Mitsunobu; Yamashita, Keisuke; Palaniveloo, Kishneth; Okamura, Hiroaki; Iwagawa, Tetsuo; Arima, Naomichi; Iriguchi, Toshiyuki; de Voogd, Nicole J; Vairappan, Charles S

2015-06-01

A new manoalide-related sesterterpene, (4E,6E)-dehydro-25-O-methylmanoalide (1), was isolated from the organic extracts of the Bornean marine sponge Luffariella variabilis, together with the known compound (4E,6E)-dehydromanoalide (2). The structure of compound 1 was elucidated by interpretation of its spectroscopic data.

Low Temperature Induces the Accumulation of Phenylalanine Ammonia-Lyase and Chalcone Synthase mRNAs of Arabidopsis thaliana in a Light-Dependent Manner.

PubMed Central

Leyva, A.; Jarillo, J. A.; Salinas, J.; Martinez-Zapater, J. M.

1995-01-01

Anthocyanins, which accumulate in leaves and stems in response to low temperature and changes in light intensity, are synthesized through the phenylpropanoid pathway that is controlled by key enzymes that include phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS). In this work we demonstrate that PAL and CHS mRNAs accumulate in leaves of Arabidopsis thaliana (L.) Heynh. upon exposure to low temperature in a light-dependent manner. The regulation of the PAL1 gene expression by low temperature and light was examined by analyzing the expression of the [beta]-glucuronidase (uidA) reporter gene in transgenic Arabidopsis plants containing the uidA gene of Escherichia coli under the control of the PAL1 promoter. The results indicate that the accumulation of PAL1 mRNA is transcriptionally regulated. Histochemical staining for [beta]-glucuronidase activity showed that the PAL1 promoter is preferentially activated in photosynthetically active cells, paralleling anthocyanin accumulation. Moreover, we show that light may also be implicated in the regulation of the CHS gene in response to bacterial infiltration. Finally, using two transparent testa Arabidopsis mutants that are unable to accumulate anthocyanins, we demonstrate that these pigments are not required for successful development of freezing tolerance in this species. PMID:12228452

Allocation of the S-genome chromosomes of Aegilops variabilis Eig. carrying powdery mildew resistance in triticale (× Triticosecale Wittmack).

PubMed

Kwiatek, M; Belter, J; Majka, M; Wiśniewska, H

2016-03-01

It has been hypothesized that the powdery mildew adult plant resistance (APR) controlled by the Pm13 gene in Aegilops longissima Schweinf. & Muschl. (S(l)S(l)) has been evolutionary transferred to Aegilops variabilis Eig. (UUSS). The molecular marker analysis and the visual evaluation of powdery mildew symptoms in Ae. variabilis and the Ae. variabilis × Secale cereale amphiploid forms (2n = 6x = 42, UUSSRR) showed the presence of product that corresponded to Pm13 marker and the lower infection level compared to susceptible model, respectively. This study also describes the transfer of Ae. variabilis Eig. (2n = 4x = 28, U(v)U(v)S(v)S(v)) chromosomes, carrying powdery mildew resistance, into triticale (× Triticosecale Wittm., 2n = 6x = 42, AABBRR) using Ae. variabilis × S. cereale amphiploid forms. The individual chromosomes of Ae. variabilis, triticale 'Lamberto' and hybrids were characterized by genomic and fluorescence in situ hybridization (GISH/FISH). The chromosome configurations of obtained hybrid forms were studied at first metaphase of meiosis of pollen mother cells (PMCs) using GISH. The statistical analysis showed that the way of S-genome chromosome pairing and transmission to subsequent hybrid generations was diploid-like and had no influence on chromosome pairing of triticale chromosomes. The cytogenetic study of hybrid forms were supported by the marker-assisted selection using Pm13 marker and visual evaluation of natural infection by Blumeria graminis, that allowed to select the addition or substitution lines of hybrids carrying chromosome 3S(v) which were tolerant to the powdery mildew infection.

Diverse Microhabitats Experienced by Halomonas variabilis on Salt-Secreting Leaves

PubMed Central

Burch, Adrien Y.; Finkel, Omri M.; Cho, Juliana K.; Belkin, Shimshon

2013-01-01

The leaf surfaces of the salt-excreting tree Tamarix aphylla harbor a wide diversity of halophilic microorganisms, including Halomonas sp., but little is known of the factors that shape community composition in this extreme habitat. We isolated a strain of Halomonas variabilis from the leaf surface of T. aphylla and used it to determine the heterogeneity of salt concentrations experienced by bacteria in this environment. This halophilic strain was transformed with a proU::gfp reporter gene fusion, the fluorescence of which was responsive to NaCl concentrations up to 200 g liter−1. These bioreporting cells were applied to T. aphylla leaves and were subsequently recovered from dew droplets adhering to the leaf surface. Although cells from within a given dew droplet exhibited similar green fluorescent protein fluorescence, the fluorescence intensity varied between droplets and was correlated with the salt concentration measured in each drop. Growth of H. variabilis was observed in all droplets, regardless of the salt concentration. However, cells found in desiccated microniches between dew drops were low in abundance and generally dead. Other bacteria recovered from T. aphylla displayed higher desiccation tolerance than H. variabilis, both in culture and on inoculated plants, despite having lower osmotic tolerance. Thus, the Tamarix leaf surface can be described as a salty desert with occasional oases where water droplets form under humid conditions. While halotolerant bacteria such as Halomonas grow in high concentrations of salt in such wet microniches, other organisms are better suited to survive desiccation in sites that are not wetted. PMID:23160133

Regulation of Phenylalanine Hydroxylase: Conformational Changes Upon Phenylalanine Binding Detected by H/D Exchange and Mass Spectrometry†

PubMed Central

Li, Jun; Dangott, Lawrence J.; Fitzpatrick, Paul F.

2010-01-01

Phenylalanine acts as an allosteric activator of the tetrahydropterin-dependent enzyme phenylalanine hydroxylase. Hydrogen/deuterium exchange monitored by mass spectrometry has been used to gain insight into local conformational changes accompanying activation of rat phenylalanine hydroxylase by phenylalanine. Peptides in the regulatory and catalytic domains that lie in the interface between these two domains show large increases in the extent of deuterium incorporation from solvent in the presence of phenylalanine. In contrast, the effects of phenylalanine on the exchange kinetics of a mutant enzyme lacking the regulatory domain are limited to peptides surrounding the binding site for the amino acid substrate. These results support a model in which the N-terminus of the protein acts as an inhibitory peptide, with phenylalanine binding causing a conformational change in the regulatory domain that alters the interaction between the catalytic and regulatory domains. PMID:20307070

DNA Methylation Influences Chlorogenic Acid Biosynthesis in Lonicera japonica by Mediating LjbZIP8 to Regulate Phenylalanine Ammonia-Lyase 2 Expression.

PubMed

Zha, Liangping; Liu, Shuang; Liu, Juan; Jiang, Chao; Yu, Shulin; Yuan, Yuan; Yang, Jian; Wang, Yaolong; Huang, Luqi

2017-01-01

The content of active compounds differ in buds and flowers of Lonicera japonica (FLJ) and L. japonica var. chinensis (rFLJ). Chlorogenic acid (CGAs) were major active compounds of L. japonica and regarded as measurements for quality evaluation. However, little is known concerning the formation of active compounds at the molecular level. We quantified the major CGAs in FLJ and rFLJ, and found the concentrations of CGAs were higher in the buds of rFLJ than those of FLJ. Further analysis of CpG methylation of CGAs biosynthesis genes showed differences between FLJ and rFLJ in the 5'-UTR of phenylalanine ammonia-lyase 2 ( PAL2 ). We identified 11 LjbZIP proteins and 24 rLjbZIP proteins with conserved basic leucine zipper domains, subcellular localization, and electrophoretic mobility shift assay showed that the transcription factor LjbZIP8 is a nuclear-localized protein that specifically binds to the G-box element of the LjPAL2 5'-UTR. Additionally, a transactivation assay and LjbZIP8 overexpression in transgenic tobacco indicated that LjbZIP8 could function as a repressor of transcription. Finally, treatment with 5-azacytidine decreased the transcription level of LjPAL2 and CGAs content in FLJ leaves. These results raise the possibility that DNA methylation might influence the recruitment of LjbZIP8, regulating PAL2 expression level and CGAs content in L. japonica .

Responses triggered in chloroplast of Chlorella variabilis NC64A by long-term association with Paramecium bursaria.

PubMed

Minaeva, Ekaterina; Ermilova, Elena

2017-07-01

The unicellular green alga Chlorella variabilis NC64A is an endosymbiont of the ciliate Paramecium bursaria. The host's control, including the transfer of biochemical substrates from P. bursaria to C. variabilis, is involved in symbiotic relationships. C. variabilis NC64A that had been re-infected to P. bursaria for more than 1 year and isolated from the host showed higher chlorophyll levels compared to those in free-living cells. Unlike the host, the expression of C. variabilis NC64A heat shock 70 kDa protein was independent of establishment of endosymbiosis. In symbiotic cells, the levels of PII signal transduction protein (CvPII) that coordinate the central C/N anabolic metabolism were slightly higher than those in free-living cells. Furthermore, the environmental cues (light and host food bacteria availability) affected the abundance of CvPII, suggesting that synthesis of the protein was influenced by the host. Moreover, arginine concentrations in the symbiotic algae of P. bursaria were also controlled by the host's nutritional conditions. Together, our results imply that signal substrates and/or products of metabolism in host cells might act as messengers mediating the regulation of key events in symbiont cells.

Gill damage and neurotoxicity of ammonia nitrogen on the clam Ruditapes philippinarum.

PubMed

Cong, Ming; Wu, Huifeng; Yang, Haiping; Zhao, Jianmin; Lv, Jiasen

2017-04-01

Ammonia nitrogen has been a potential menace to aquatic animals along the coastline of China. Presently, the toxicological effects of ammonia nitrogen were mainly concentrated on fishes, while little attention has been paid to molluscs. In this study, the clam Ruditapes philippinarum was used as the target animal to investigate the toxic effects of ammonia nitrogen. Our results showed that ammonia exposure could significantly reduce the integrity of lysosomes in a dose-dependent manner. Metabolite analysis revealed that exposure doses and duration time of ammonia nitrogen could affect the variation profiles of gill metabolites. In detail, branched chain amino acids, glutamate, choline and phosphocholine were significantly decreased after a one-day exposure. Inosine and phenylalanine were found significantly increased and ATP was decreased after a three-day exposure. The changes of metabolites implied that metabolisms of muscle element, neurotransmission and cell apoptosis of gill tissues would be affected by ammonia exposure. Such inferences were supported by the diminished muscle element, decreased concentrations of catecholamines and increased apoptosis rates, respectively. Therefore, we take advantage of metabolomics integrated with conventional biological assays to find out that ammonia exposure could cause lysosome instability, metabolic disturbance, aberrant gill structures and changes to neurotransmitters, and would result in mollusk gill dysfunction in feeding, respiration and immunity.

Rhizomucor variabilis var. regularior and Hormographiella aspergillata infections in a leukemic bone marrow transplant recipient with refractory neutropenia.

PubMed

Abuali, Mayssa M; Posada, Roberto; Del Toro, Gustavo; Roman, Elizabeth; Ramani, Rama; Chaturvedi, Sudha; Chaturvedi, Vishnu; LaBombardi, Vincent J

2009-12-01

Rhizomucor variabilis and Hormographiella aspergillata rarely cause human infections. This report details a fatal case of a 14-year-old female with leukemia posthematopoietic cell transplant and relapse with refractory pancytopenia. The patient first developed an R. variabilis var. regularior palate infection and later developed a cutaneous H. aspergillata infection while on posaconazole and caspofungin therapy.

Rhizomucor variabilis var. regularior and Hormographiella aspergillata Infections in a Leukemic Bone Marrow Transplant Recipient with Refractory Neutropenia ▿

PubMed Central

Abuali, Mayssa M.; Posada, Roberto; Del Toro, Gustavo; Roman, Elizabeth; Ramani, Rama; Chaturvedi, Sudha; Chaturvedi, Vishnu; LaBombardi, Vincent J.

2009-01-01

Rhizomucor variabilis and Hormographiella aspergillata rarely cause human infections. This report details a fatal case of a 14-year-old female with leukemia posthematopoietic cell transplant and relapse with refractory pancytopenia. The patient first developed an R. variabilis var. regularior palate infection and later developed a cutaneous H. aspergillata infection while on posaconazole and caspofungin therapy. PMID:19846651

DNA Methylation Influences Chlorogenic Acid Biosynthesis in Lonicera japonica by Mediating LjbZIP8 to Regulate Phenylalanine Ammonia-Lyase 2 Expression

PubMed Central

Zha, Liangping; Liu, Shuang; Liu, Juan; Jiang, Chao; Yu, Shulin; Yuan, Yuan; Yang, Jian; Wang, Yaolong; Huang, Luqi

2017-01-01

The content of active compounds differ in buds and flowers of Lonicera japonica (FLJ) and L. japonica var. chinensis (rFLJ). Chlorogenic acid (CGAs) were major active compounds of L. japonica and regarded as measurements for quality evaluation. However, little is known concerning the formation of active compounds at the molecular level. We quantified the major CGAs in FLJ and rFLJ, and found the concentrations of CGAs were higher in the buds of rFLJ than those of FLJ. Further analysis of CpG methylation of CGAs biosynthesis genes showed differences between FLJ and rFLJ in the 5′-UTR of phenylalanine ammonia-lyase 2 (PAL2). We identified 11 LjbZIP proteins and 24 rLjbZIP proteins with conserved basic leucine zipper domains, subcellular localization, and electrophoretic mobility shift assay showed that the transcription factor LjbZIP8 is a nuclear-localized protein that specifically binds to the G-box element of the LjPAL2 5′-UTR. Additionally, a transactivation assay and LjbZIP8 overexpression in transgenic tobacco indicated that LjbZIP8 could function as a repressor of transcription. Finally, treatment with 5-azacytidine decreased the transcription level of LjPAL2 and CGAs content in FLJ leaves. These results raise the possibility that DNA methylation might influence the recruitment of LjbZIP8, regulating PAL2 expression level and CGAs content in L. japonica. PMID:28740500

Prevalence, Distribution, and Development of an Ecological Niche Model of Dermacentor variabilis Ticks Positive for Rickettsia montanensis.

PubMed

St John, Heidi K; Adams, Melissa L; Masuoka, Penny M; Flyer-Adams, Johanna G; Jiang, Ju; Rozmajzl, Patrick J; Stromdahl, Ellen Y; Richards, Allen L

2016-04-01

Rickettsia montanensis has long been considered a nonpathogenic member of the spotted fever group rickettsiae. However, the infection potential of R. montanensis is being revisited in light of its recent association with a case of human infection in the United States and the possibility that additional cases may have been misdiagnosed as Rocky Mountain spotted fever. To this end, DNA was extracted from American dog ticks (Dermacentor variabilis) removed from Department of Defense (DoD) personnel and their dependents at DoD medical treatment facilities (MTFs) during 2002-2012 (n = 4792). These 4792 samples were analyzed for the presence of R. montanensis (n =  36; 2.84%) and all vector DNA was confirmed to be of D. variabilis origin using a novel Dermacentor genus-specific quantitative real-time polymerase chain reaction procedure, Derm, and a novel Dermacentor species multilocus sequence typing assay. To assess the risk of R. montanensis infection, the positive and negative samples were geographically mapped utilizing MTF site locations. Tick localities were imported into a geographical information systems (GIS) program, ArcGIS, for mapping and analysis. The ecological niche modeling (ENM) program, Maxent, was used to estimate the probability of tick presence in eastern United States using locations of both R. montanensis-positive and -negative ticks, climate, and elevation data. The ENM for R. montanensis-positive D. variabilis estimated high probabilities of the positive ticks occurring in two main areas, including the northern Midwest and mid-Atlantic portions of the northeastern regions of United States, whereas the R. montanensis-negative D. variabilis tick model showed a wider estimated range. The results suggest that R. montanensis-positive and -negative D. variabilis have different ranges where humans may be at risk and are influenced by similar and different factors.

Polysaccharides from the envelopes of heterocysts and spores of the blue-green algae Anabaena variabilis and Cylindrospermum licheniforme

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cardemil, L.; Wolk, C.P.

The polysaccharides from the envelopes of heterocysts of Cylindrospermum licheniforme Kutz., and of heterocysts and spores of Anabaena variabilis Kutz., like those from the differentiated cells of Anabaena cylindrica Lemm., have a 1,3-linked backbone consisting of glucosyl and mannosyl residues in a molar ratio of approximately 3:1. As is the case with A. cylindrica the polysaccharides from A. variabilis and from the heterocysts of C. licheniforme have terminal xylosyl and galactosyl residues as side branches. In addition, the polysaccharide from C. licheniforme resembles that from A. cylindrica in having terminal mannosyl residues as side branches (absent from A. variabilis). Themore » polysaccharides from A. variabilis resemble that from A. cylindrica in having glucose-containing side branches (absent from the heterocyst polysaccharide from C. licheniforme), but in contrast to the polysaccharides from the other two species they also have terminal arabinosyl residues as side branches. All of the polysaccharides mentioned appear to be structurally related; we present tentative structures for those not previously investigated. In contrast, the envelope of spores of C. licheniforme contains only a largely 4-linked galactan. The bulk of this envelope is not polysaccharide in nature, and contains aromatic groups.« less

Chapiniella variabilis (Nematoda) parasitizing Chelonoidis carbonarius and C. denticulatus (Testudinidae) in the state of Piauí.

PubMed

Freire, Simone Mousinho; Leal, Anangela Ravena da Silva; Knoff, Marcelo; Gomes, Delir Corrêa; Santos, Jeannie Nascimento Dos; Giese, Elane Guerreiro; Silva, Reinaldo José da; Mendonça, Ivete Lopes

2017-01-01

Chapiniella variabilis (Chapin, 1924), a strongylid nematode, was collected parasitizing the large intestine of the tortoises Chelonoidis carbonarius (Spix, 1824) (Cc) and C. denticulatus (Linnaeus, 1766) (Cd) in the Zoobotanical Park of the municipality of Teresina, state of Piauí, Brazil. The taxonomic identification was based on morphological and morphometric features, using bright-field and scanning electron microscopy. The present study adds new observations on the morphology, mainly relating to the mouth papillae, external and internal leaf-crown elements, excretory pore, deirids and male and female posterior end. The parasitic indices of prevalence (P), mean intensity (MI), mean abundance (MA) and range of infection (RI) of C. variabilis in these two tortoise species were: P = 100%, MI = 833.3, MA = 833.3, RI = 500-1,500 (Cc); P = 100%, MI = 472.2, MA = 472.2, RI = 333-500 (Cd). This record expands occurrences of C. variabilis to a new host, C. carbonarius, and to another state in Brazil, in the Neotropical region of South America. Adjustment to host management with the aim of improving hygiene and health conditions is suggested.

Synthesis and analysis of 2-[211At]-L-phenylalanine and 4-[211At]-L-phenylalanine and their uptake in human glioma cell cultures in-vitro.

PubMed

Meyer, Geerd J; Walte, Almut; Sriyapureddy, Siva R; Grote, Michaela; Krull, Doris; Korkmaz, Zekiye; Knapp, Wolfram H

2010-06-01

2-[211At]-L-phenylalanine and 4-[211At]-L-phenylalanine were prepared from the corresponding iodo and bromo derivatives using the Cu(+)-assisted nucleophilic exchange. 4-[211At]-L-phenylalanine was additionally prepared by destannylation of the BOC-derivatized 4-tributylstannyl-L-phenylalanine. Radiochemical yields of 2-[211At]-L-phenylalanine and 4-[211At]-L-phenylalanine by nucleophilic exchange were 52-74% and 65-85%. Radiochemical yield of 4-[211At]-L-phenylalanine by electrophilic destannylation was 35-50%. HPLC sequence analysis showed that 2-[211At]-L-phenylalanine followed the halogen sequence (Fphenylalanine eluted between 4-Br-L-phenylalanine and 4-I-L-phenylalanine (Fphenylalanine and 4-[131I]-L-phenylalanine in DBTRG-05MG glioma cells was inhibited by l-phenylalanine 7-fold and 6-fold, respectively. Copyright 2010 Elsevier Ltd. All rights reserved.

Developmental role of phenylalanine-ammonia-lyase (PAL) and cinnamate 4-hydroxylase (C4H) genes during adventitious rooting of Juglans regia L. microshoots.

PubMed

Cheniany, Monireh; Ganjeali, Ali

2016-12-01

Phenylalanine-ammonia-lyase and cinnamate-4-hydroxylase play important role in the phenylpropanoid pathway, which produces many biologically important secondary metabolites participating in normal plant development. Flavonol quercetin is the main representant of these compounds that has been identified in numerous Juglans spp. In this survey, the developmental expression patterns of PAL and C4H genes during in vitro rooting of two walnut cultivars 'Sunland' and 'Howard' was examined by RT-PCR. To understand the potential role in rooting, the changing pattern of endogenous content of quercetin was also analyzed by HPLC. The 'Sunland' with better capacity to root had more quercetin content during the "inductive phase" of rooting than 'Howard'. In each cultivar, the level of PAL transcripts showed the same behavior with the changing patterns of quercetin during root formation of microshoots. The positive correlation between the changes of quercetin and PAL-mRNA indicated that PAL gene may have an immediate effect on flavonoid pathway metabolites including quercetin. Although the behavioral change of C4H expression was similar in both cultivars during root formation (with significantly more level for 'Howard'), it was not coincide with the changes of quercerin concentrations. Our results showed that C4H function is important for the normal development, but its transcriptional regulation does not correlate with quercetin as an efficient phenolic compound for walnut rhizogenesis.

Energy transfer in Anabaena variabilis filaments adapted to nitrogen-depleted and nitrogen-enriched conditions studied by time-resolved fluorescence.

PubMed

Onishi, Aya; Aikawa, Shimpei; Kondo, Akihiko; Akimoto, Seiji

2017-09-01

Nitrogen is among the most important nutritious elements for photosynthetic organisms such as plants, algae, and cyanobacteria. Therefore, nitrogen depletion severely compromises the growth, development, and photosynthesis of these organisms. To preserve their integrity under nitrogen-depleted conditions, filamentous nitrogen-fixing cyanobacteria reduce atmospheric nitrogen to ammonia, and self-adapt by regulating their light-harvesting and excitation energy-transfer processes. To investigate the changes in the primary processes of photosynthesis, we measured the steady-state absorption and fluorescence spectra and time-resolved fluorescence spectra (TRFS) of whole filaments of the nitrogen-fixing cyanobacterium Anabaena variabilis at 77 K. The filaments were grown in standard and nitrogen-free media for 6 months. The TRFS were measured with a picosecond time-correlated single photon counting system. Despite the phycobilisome degradation, the energy-transfer paths within phycobilisome and from phycobilisome to both photosystems were maintained. However, the energy transfer from photosystem II to photosystem I was suppressed and a specific red chlorophyll band appeared under the nitrogen-depleted condition.

The effects of plant growth regulators and L-phenylalanine on phenolic compounds of sweet basil.

PubMed

Koca, Nülüfer; Karaman, Şengül

2015-01-01

The effects of methyl jasmonate (MeJA), spermine (Spm), epibrassinolide (EBL) and l-phenylalanine on sweet basil (Ocimum basilicum L.) were studied to determine the amount of phenolic compounds and enzymatic activity of phenylalanine ammonia-lyase (PAL). Total phenolic and total flavonoid contents of sweet basils were determined by a spectrophotometer, and individual phenolic compounds and activity of PAL were analysed by HPLC/UV. The highest total phenolic (6.72 mg GAE/g) and total flavonoid contents (0.92 mg QE/g) obtained from 1.0 mM Spm+MeJA application. Rosmarinic acid (RA) and caffeic acid contents significantly enhanced after the applications but no such differences observed in chicoric acid content or PAL activity. RA was the main phenolic acid in all samples and its concentration varied from 1.04 to 2.70 mg/gFW. As a result the combinations of Spm+MeJA and EBL+MeJA can induce secondary metabolites effectively and those interactions play important role in the production of phytochemicals in plants. Copyright © 2014 Elsevier Ltd. All rights reserved.

21 CFR 862.1555 - Phenylalanine test system.

Code of Federal Regulations, 2011 CFR

2011-04-01

... measure free phenylalanine (an amino acid) in serum, plasma, and urine. Measurements of phenylalanine are... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Phenylalanine test system. 862.1555 Section 862.1555 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED...

21 CFR 862.1555 - Phenylalanine test system.

Code of Federal Regulations, 2010 CFR

2010-04-01

... measure free phenylalanine (an amino acid) in serum, plasma, and urine. Measurements of phenylalanine are... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Phenylalanine test system. 862.1555 Section 862.1555 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED...

[Dynamics of Quercus variabilis seed rain and soil seed bank in different habitats on the north slope of Qinling Mountains].

PubMed

Wu, Min; Zhang, Wen-Hui; Zhou, Jian-Yun; Ma, Chuang; Ma, Li-Wei

2011-11-01

In order to explore the dynamics of Quercus variabilis seed rain and soil seed bank in different habitats on the north slope of Qinling Mountains, three kinds of micro-habitats (understory, forest gap, and forest edge) were selected, with the seed rain quantity and quality of Q. variabilis, seed amount and viability in soil seed bank, as well as the seedling development of Q. variabilis studied. The seed rain of Q. variabilis started from mid August, reached the peak in mid September-early October, and ended at the beginning of November, and there existed differences in the dissemination process, occurrence time, and composition of the seed rain among the three micro-habitats. The seed rain had the maximum intensity (39.55 +/- 5.56 seeds x m(-2)) in understory, the seeds had the earliest landing time, the longest lasting duration, and the highest viability in forest gap, and the mature seeds had the largest proportion in forest edge, accounting for 58.7% of the total. From the ending time of seed rain to next August, the total reserve of soil seed bank was the largest in understory and the smallest in forest edge. In the three habitats, the amount of mature and immature seeds, that of seeds eaten by animals, and the seed viability in soil seed bank all decreased with time. In contrast, the number of moldy seeds increased. The seeds were mainly concentrated in litter layer, a few of them were in 0-2 cm soil layer, and few were in 2-5 cm soil layer. The density of the seedlings varied with habitats, being the largest in forest gap, followed by in forest edge, and the least in understory, which suggested that forest gap was more suitable for the seed germination and seedling growth of Q. variabilis, and thus, appropriate thinning should be taken to increase forest gap to provide favorable conditions for the natural regeneration of Q. variabilis forest.

Zur Biosynthese von Phenylalanin und Tyrosin

NASA Astrophysics Data System (ADS)

Lingens, F.; Keller, E.

1983-03-01

With the discovery of arogenic acid two new pathways for the biosynthesis of phenylalanine and tyrosine have been revealed. The occurrence of two, three, or four pathways for the biosynthesis of phenylalanine and tyrosine in microorganisms and plants may be a useful tool for taxonomic classifications. Investigations on enterobacteriaceae, pseudomonads, flavobacteria, streptomycetes, archaebacteria, and on Sphaerotilus, Trichococcus and Leptothrix species from bulking sludge are described. The possible role of arogenate in the evolution of the pathways for tyrosine and phenylalanine biosynthesis is discussed.

Molecular evolution and functional characterisation of an ancient phenylalanine ammonia-lyase gene (NnPAL1) from Nelumbo nucifera: novel insight into the evolution of the PAL family in angiosperms

PubMed Central

2014-01-01

Background Phenylalanine ammonia-lyase (PAL; E.C.4.3.1.5) is a key enzyme of the phenylpropanoid pathway in plant development, and it catalyses the deamination of phenylalanine to trans-cinnamic acid, leading to the production of secondary metabolites. This enzyme has been identified in many organisms, ranging from prokaryotes to higher plants. Because Nelumbo nucifera is a basal dicot rich in many secondary metabolites, it is a suitable candidate for research on the phenylpropanoid pathway. Results Three PAL members, NnPAL1, NnPAL2 and NnPAL3, have been identified in N. nucifera using genome-wide analysis. NnPAL1 contains two introns; however, both NnPAL2 and NnPAL3 have only one intron. Molecular and evolutionary analysis of NnPAL1 confirms that it is an ancient PAL member of the angiosperms and may have a different origin. However, PAL clusters, except NnPAL1, are monophyletic after the split between dicots and monocots. These observations suggest that duplication events remain an important occurrence in the evolution of the PAL gene family. Molecular assays demonstrate that the mRNA of the NnPAL1 gene is 2343 bp in size and encodes a 717 amino acid polypeptide. The optimal pH and temperature of the recombinant NnPAL1 protein are 9.0 and 55°C, respectively. The NnPAL1 protein retains both PAL and weak TAL catalytic activities with Km values of 1.07 mM for L-phenylalanine and 3.43 mM for L-tyrosine, respectively. Cis-elements response to environmental stress are identified and confirmed using real-time PCR for treatments with abscisic acid (ABA), indoleacetic acid (IAA), ultraviolet light, Neurospora crassa (fungi) and drought. Conclusions We conclude that the angiosperm PAL genes are not derived from a single gene in an ancestral angiosperm genome; therefore, there may be another ancestral duplication and vertical inheritance from the gymnosperms. The different evolutionary histories for PAL genes in angiosperms suggest different mechanisms of functional

Stereospecificity of phenylalanine plasma kinetics and hydroxylation in man following oral application of a stable isotope-labelled pseudo-racemic mixture of L- and D-phenylalanine.

PubMed

Lehmann, W D; Theobald, N; Fischer, R; Heinrich, H C

1983-03-14

L-[15N]Phenylalanine and D-[2H5]phenylalanine have been administered orally to two healthy adult volunteers as a pseudo-racemic mixture at a dose of 25 mg/kg each. After oral application, the plasma kinetics of phenylalanine and tyrosine have been followed by the combined use of high pressure liquid chromatography and field desorption mass spectrometry. Additional incubation with D-amino acid oxidase was used to determine the enantiomeric composition of the differently labelled species of phenylalanine and tyrosine. D-Phenylalanine plasma levels show a faster rise to higher maximum values compared to L-phenylalanine (D/L ratio at maximum 3.19, 3.26). L-Phenylalanine is efficiently hydroxylated to L-tyrosine. In contrast, conversion of D-phenylalanine to the L-form with subsequent hydroxylation to L-tyrosine was observed. From the plasma kinetics it is estimated that about 1/3 of the applied dose of 25 mg/kg of D-phenylalanine is converted to the L-isomer. Of the administered dose of L-phenylalanine only very small amounts are excreted into urine as such (0.25%, 0.8%), whereas a substantial amount of the D-phenylalanine dose is found in urine (27.4%, 38.0%).

Differential inductions of phenylalanine ammonia-lyase and chalcone synthase during wounding, salicylic acid treatment, and salinity stress in safflower, Carthamus tinctorius

PubMed Central

Dehghan, Sara; Sadeghi, Mahnaz; Pöppel, Anne; Fischer, Rainer; Lakes-Harlan, Reinhard; Kavousi, Hamid Reza; Vilcinskas, Andreas; Rahnamaeian, Mohammad

2014-01-01

Safflower (Carthamus tinctorius L.) serves as a reference dicot for investigation of defence mechanisms in Asteraceae due to abundant secondary metabolites and high resistance/tolerance to environmental stresses. In plants, phenylpropanoid and flavonoid pathways are considered as two central defence signalling cascades in stress conditions. Here, we describe the isolation of two major genes in these pathways, CtPAL (phenylalanine ammonia-lyase) and CtCHS (chalcone synthase) in safflower along with monitoring their expression profiles in different stress circumstances. The aa (amino acid) sequence of isolated region of CtPAL possesses the maximum identity up to 96% to its orthologue in Cynara scolymus, while that of CtCHS retains the highest identity to its orthologue in Callistephus chinensis up to 96%. Experiments for gene expression profiling of CtPAL and CtCHS were performed after the treatment of seedlings with 0.1 and 1 mM SA (salicylic acid), wounding and salinity stress. The results of semi-quantitative RT–PCR revealed that both CtPAL and CtCHS genes are further responsive to higher concentration of SA with dissimilar patterns. Regarding wounding stress, CtPAL gets slightly induced upon injury at 3 hat (hours after treatment) (hat), whereas CtCHS gets greatly induced at 3 hat and levels off gradually afterward. Upon salinity stress, CtPAL displays a similar expression pattern by getting slightly induced at 3 hat, but CtCHS exhibits a biphasic expression profile with two prominent peaks at 3 and 24 hat. These results substantiate the involvement of phenylpropanoid and particularly flavonoid pathways in safflower during wounding and especially salinity stress. PMID:24865400

Effects of PHENYLALANINE AMMONIA LYASE ( PAL) knockdown on cell wall composition, biomass digestibility, and biotic and abiotic stress responses in Brachypodium

DOE PAGES

Cass, Cynthia L.; Peraldi, Antoine; Dowd, Patrick F.; ...

2015-06-19

The phenylpropanoid pathway in plants synthesizes a variety of structural and defence compounds, and is an important target in efforts to reduce cell wall lignin for improved biomass conversion to biofuels. Little is known concerning the trade-offs in grasses when perturbing the function of the first gene family in the pathway, PHENYLALANINE AMMONIA LYASE ( PAL). Therefore, PAL isoforms in the model grass Brachypodium distachyon were targeted, by RNA interference (RNAi), and large reductions (up to 85%) in stem tissue transcript abundance for two of the eight putative BdPAL genes were identified. The cell walls of stems of BdPAL-knockdown plantsmore » had reductions of 43% in lignin and 57% in cell wall-bound ferulate, and a nearly 2-fold increase in the amounts of polysaccharide-derived carbohydrates released by thermochemical and hydrolytic enzymic partial digestion. PAL-knockdown plants exhibited delayed development and reduced root growth, along with increased susceptibilities to the fungal pathogens Fusarium culmorum and Magnaporthe oryzae. Surprisingly, these plants generally had wild-type (WT) resistances to caterpillar herbivory, drought, and ultraviolet light. RNA sequencing analyses revealed that the expression of genes associated with stress responses including ethylene biosynthesis and signalling were significantly altered in PAL knocked-down plants under non-challenging conditions. These data reveal that, although an attenuation of the phenylpropanoid pathway increases carbohydrate availability for biofuel, it can adversely affect plant growth and disease resistance to fungal pathogens. Lastly, the data identify notable differences between the stress responses of these monocot pal mutants versus Arabidopsis (a dicot) pal mutants and provide insights into the challenges that may arise when deploying phenylpropanoid pathway-altered bioenergy crops.« less

Effects of PHENYLALANINE AMMONIA LYASE ( PAL) knockdown on cell wall composition, biomass digestibility, and biotic and abiotic stress responses in Brachypodium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cass, Cynthia L.; Peraldi, Antoine; Dowd, Patrick F.

The phenylpropanoid pathway in plants synthesizes a variety of structural and defence compounds, and is an important target in efforts to reduce cell wall lignin for improved biomass conversion to biofuels. Little is known concerning the trade-offs in grasses when perturbing the function of the first gene family in the pathway, PHENYLALANINE AMMONIA LYASE ( PAL). Therefore, PAL isoforms in the model grass Brachypodium distachyon were targeted, by RNA interference (RNAi), and large reductions (up to 85%) in stem tissue transcript abundance for two of the eight putative BdPAL genes were identified. The cell walls of stems of BdPAL-knockdown plantsmore » had reductions of 43% in lignin and 57% in cell wall-bound ferulate, and a nearly 2-fold increase in the amounts of polysaccharide-derived carbohydrates released by thermochemical and hydrolytic enzymic partial digestion. PAL-knockdown plants exhibited delayed development and reduced root growth, along with increased susceptibilities to the fungal pathogens Fusarium culmorum and Magnaporthe oryzae. Surprisingly, these plants generally had wild-type (WT) resistances to caterpillar herbivory, drought, and ultraviolet light. RNA sequencing analyses revealed that the expression of genes associated with stress responses including ethylene biosynthesis and signalling were significantly altered in PAL knocked-down plants under non-challenging conditions. These data reveal that, although an attenuation of the phenylpropanoid pathway increases carbohydrate availability for biofuel, it can adversely affect plant growth and disease resistance to fungal pathogens. Lastly, the data identify notable differences between the stress responses of these monocot pal mutants versus Arabidopsis (a dicot) pal mutants and provide insights into the challenges that may arise when deploying phenylpropanoid pathway-altered bioenergy crops.« less

Phylogeography of Quercus variabilis Based on Chloroplast DNA Sequence in East Asia: Multiple Glacial Refugia and Mainland-Migrated Island Populations

PubMed Central

Kang, Hongzhang; Sun, Xiao; Yin, Shan; Du, Hongmei; Yamanaka, Norikazu; Gapare, Washington; Wu, Harry X.; Liu, Chunjiang

2012-01-01

The biogeographical relationships between far-separated populations, in particular, those in the mainland and islands, remain unclear for widespread species in eastern Asia where the current distribution of plants was greatly influenced by the Quaternary climate. Deciduous Oriental oak (Quercus variabilis) is one of the most widely distributed species in eastern Asia. In this study, leaf material of 528 Q. variabilis trees from 50 populations across the whole distribution (Mainland China, Korea Peninsular as well as Japan, Zhoushan and Taiwan Islands) was collected, and three cpDNA intergenic spacer fragments were sequenced using universal primers. A total of 26 haplotypes were detected, and it showed a weak phylogeographical structure in eastern Asia populations at species level, however, in the central-eastern region of Mainland China, the populations had more haplotypes than those in other regions, with a significant phylogeographical structure (N ST = 0.751> G ST = 0.690, P<0.05). Q. variabilis displayed high interpopulation and low intrapopulation genetic diversity across the distribution range. Both unimodal mismatch distribution and significant negative Fu’s FS indicated a demographic expansion of Q. variabilis populations in East Asia. A fossil calibrated phylogenetic tree showed a rapid speciation during Pleistocene, with a population augment occurred in Middle Pleistocene. Both diversity patterns and ecological niche modelling indicated there could be multiple glacial refugia and possible bottleneck or founder effects occurred in the southern Japan. We dated major spatial expansion of Q. variabilis population in eastern Asia to the last glacial cycle(s), a period with sea-level fluctuations and land bridges in East China Sea as possible dispersal corridors. This study showed that geographical heterogeneity combined with climate and sea-level changes have shaped the genetic structure of this wide-ranging tree species in East Asia. PMID:23115642

Missense Mutations in the N-Terminal Domain of Human Phenylalanine Hydroxylase Interfere with Binding of Regulatory Phenylalanine

PubMed Central

Gjetting, Torben; Petersen, Marie; Guldberg, Per; Güttler, Flemming

2001-01-01

Hyperphenylalaninemia due to a deficiency of phenylalanine hydroxylase (PAH) is an autosomal recessive disorder caused by >400 mutations in the PAH gene. Recent work has suggested that the majority of PAH missense mutations impair enzyme activity by causing increased protein instability and aggregation. In this study, we describe an alternative mechanism by which some PAH mutations may render PAH defective. Database searches were used to identify regions in the N-terminal domain of PAH with homology to the regulatory domain of prephenate dehydratase (PDH), the rate-limiting enzyme in the bacterial phenylalanine biosynthesis pathway. Naturally occurring N-terminal PAH mutations are distributed in a nonrandom pattern and cluster within residues 46–48 (GAL) and 65–69 (IESRP), two motifs highly conserved in PDH. To examine whether N-terminal PAH mutations affect the ability of PAH to bind phenylalanine at the regulatory domain, wild-type and five mutant (G46S, A47V, T63P/H64N, I65T, and R68S) forms of the N-terminal domain (residues 2–120) of human PAH were expressed as fusion proteins in Escherichia coli. Binding studies showed that the wild-type form of this domain specifically binds phenylalanine, whereas all mutations abolished or significantly reduced this phenylalanine-binding capacity. Our data suggest that impairment of phenylalanine-mediated activation of PAH may be an important disease-causing mechanism of some N-terminal PAH mutations, which may explain some well-documented genotype-phenotype discrepancies in PAH deficiency. PMID:11326337

Metabolism of DL-(+/-)-phenylalanine by Aspergillus niger.

PubMed

Kishore, G; Sugumaran, M; Vaidyanathan, C S

1976-10-01

A fungus capable of degrading DL-phenylalanine was isolated from the soil and identified as Aspergillus niger. It was found to metabolize DL-phenylalanine by a new pathway involving 4-hydroxymandelic acid. D-Amino acid oxidase and L-phenylalanine: 2-oxoglutaric acid aminotransferase initiated the degradation of D- and L-phenylalanine, respectively. Both phenylpyruvate oxidase and phenylpyruvate decarboxylase activities could be demonstrated in the cell-free system. Phenylacetate hydroxylase, which required reduced nicotinamide adenine dinucleotide phosphate, converted phenylacetic acid to 2- and 4-hydroxyphenylacetic acid. Although 4-hydroxyphenylacetate was converted to 4-hydroxymandelate, 2-hydroxyphenylacetate was not utilized until the onset of sporulation. During sporulation, it was converted rapidly into homogentisate and oxidized to ring-cleaved products. 4-Hydroxymandelate was degraded to protocatechuate via 4-hydroxybenzoylformate, 4-hydroxybenzaldehyde, and 4-hydroxybenzoate.

Metabolism of DL-(+/-)-phenylalanine by Aspergillus niger.

PubMed Central

Kishore, G; Sugumaran, M; Vaidyanathan, C S

1976-01-01

A fungus capable of degrading DL-phenylalanine was isolated from the soil and identified as Aspergillus niger. It was found to metabolize DL-phenylalanine by a new pathway involving 4-hydroxymandelic acid. D-Amino acid oxidase and L-phenylalanine: 2-oxoglutaric acid aminotransferase initiated the degradation of D- and L-phenylalanine, respectively. Both phenylpyruvate oxidase and phenylpyruvate decarboxylase activities could be demonstrated in the cell-free system. Phenylacetate hydroxylase, which required reduced nicotinamide adenine dinucleotide phosphate, converted phenylacetic acid to 2- and 4-hydroxyphenylacetic acid. Although 4-hydroxyphenylacetate was converted to 4-hydroxymandelate, 2-hydroxyphenylacetate was not utilized until the onset of sporulation. During sporulation, it was converted rapidly into homogentisate and oxidized to ring-cleaved products. 4-Hydroxymandelate was degraded to protocatechuate via 4-hydroxybenzoylformate, 4-hydroxybenzaldehyde, and 4-hydroxybenzoate. PMID:10273

Genome scale metabolic reconstruction of Chlorella variabilis for exploring its metabolic potential for biofuels.

PubMed

Juneja, Ankita; Chaplen, Frank W R; Murthy, Ganti S

2016-08-01

A compartmentalized genome scale metabolic network was reconstructed for Chlorella variabilis to offer insight into various metabolic potentials from this alga. The model, iAJ526, was reconstructed with 1455 reactions, 1236 metabolites and 526 genes. 21% of the reactions were transport reactions and about 81% of the total reactions were associated with enzymes. Along with gap filling reactions, 2 major sub-pathways were added to the model, chitosan synthesis and rhamnose metabolism. The reconstructed model had reaction participation of 4.3 metabolites per reaction and average lethality fraction of 0.21. The model was effective in capturing the growth of C. variabilis under three light conditions (white, red and red+blue light) with fair agreement. This reconstructed metabolic network will serve an important role in systems biology for further exploration of metabolism for specific target metabolites and enable improved characteristics in the strain through metabolic engineering. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and Explosion Hazards of 4-Azido-l-phenylalanine.

PubMed

Richardson, Mark B; Brown, Derek B; Vasquez, Carlos A; Ziller, Joseph W; Johnston, Kevin M; Weiss, Gregory A

2018-04-20

A reliable, scalable, cost-effective, and chromatography-free synthesis of 4-azido-l-phenylalanine beginning from l-phenylalanine is described. Investigations into the safety of the synthesis reveal that the Ullman-like Cu(I)-catalyzed azidation step does not represent a significant risk. The isolated 4-azido-l-phenylalanine product, however, exhibits previously undocumented explosive characteristics.

123/125I-labelled 2-iodo-L: -phenylalanine and 2-iodo-D: -phenylalanine: comparative uptake in various tumour types and biodistribution in mice.

PubMed

Kersemans, Veerle; Cornelissen, Bart; Kersemans, Ken; Bauwens, Matthias; Dierckx, Rudi A; De Spiegeleer, Bart; Mertens, John; Slegers, Guido

2006-08-01

In vitro in the R1M cell model and in vivo in the R1M tumour-bearing athymic model, both [(123)I]-2-iodo-L: -phenylalanine and [(123)I]-2-iodo-D: -phenylalanine have shown promising results as tumour diagnostic agents for SPECT. In order to compare these two amino acid analogues and to examine whether the observed characteristics could be generalised, both isomers were evaluated in various tumour models. Transport type characterisation in vitro in A549, A2058, C6, C32, Capan2, EF43fgf4, HT29 and R1M cells with [(123)I]-2-iodo-L: -phenylalanine was performed using the method described by Shotwell et al. Subsequently, [(123)I]-2-iodo-L: -phenylalanine and [(123)I]-2-iodo-D: -phenylalanine tumour uptake and biodistribution were evaluated using dynamic planar imaging and/or dissection in A549, A2058, C6, C32, Capan2, EF43fgf4, HT29 and R1M inoculated athymic mice. Two-compartment blood modelling of the imaging results was performed. In vitro testing demonstrated that [(123)I]-2-iodo-L: -phenylalanine was transported in all tumour cell lines by LAT1. In all tumour models, the two amino acid analogues showed the same general biodistribution characteristics: high and specific tumour uptake and renal tracer clearance. Two-compartment modelling revealed that the D: -isomer showed a faster blood clearance together with a faster distribution to the peripheral compartment in comparison with [(123)I]-2-iodo-L: -phenylalanine. [(123)I]-2-iodo-L: -phenylalanine and its D: -isomer are promising tumour diagnostic agents for dynamic planar imaging. They showed a high and similar uptake in all tested tumours. [(123)I]-2-iodo-D: -phenylalanine showed better tracer characteristics concerning radiation dose to other organs.

Comparative vertical transmission of Rickettsia by Dermacentor variabilis and Amblyomma maculatum

PubMed Central

Harris, Emma K.; Verhoeve, Victoria I.; Banajee, Kaikhushroo H.; Macaluso, Jacqueline A.; Azad, Abdu F.

2017-01-01

The geographical overlap of multiple Rickettsia and tick species coincides with the molecular detection of a variety of rickettsial agents in what may be novel tick hosts. However, little is known concerning transmissibility of rickettsial species by various tick hosts. To examine the vertical transmission potential between select tick and rickettsial species, two sympatric species of ticks, Dermacentor variabilis and Amblyomma maculatum, were exposed to five different rickettsial species, including Rickettsia rickettsii, Rickettsia parkeri, Rickettsia montanensis, Rickettsia amblyommatis, or flea-borne Rickettsia felis. Fitness-related metrics including engorgement weight, egg production index, nutrient index, and egg hatch percentage were then assessed. Subsamples of egg clutches and unfed larvae, nymphs, and adults for each cohort were assessed for transovarial and transstadial transmission of rickettsiae by qPCR. Rickettsial exposure had a minimal fitness effect in D. variabilis and transovarial transmission was observed for all groups except R. rickettsii. In contrast, rickettsial exposure negatively influenced A. maculatum fitness and transovarial transmission of rickettsiae was demonstrated only for R. amblyommatis- and R. parkeri-exposed ticks. Sustained maintenance of rickettsiae via transstadial transmission was diminished from F1 larvae to F1 adults in both tick species. The findings of this study suggest transovarial transmission specificity may not be tick species dependent, and sustained vertical transmission is not common. PMID:28433729

Comparative vertical transmission of Rickettsia by Dermacentor variabilis and Amblyomma maculatum.

PubMed

Harris, Emma K; Verhoeve, Victoria I; Banajee, Kaikhushroo H; Macaluso, Jacqueline A; Azad, Abdu F; Macaluso, Kevin R

2017-06-01

The geographical overlap of multiple Rickettsia and tick species coincides with the molecular detection of a variety of rickettsial agents in what may be novel tick hosts. However, little is known concerning transmissibility of rickettsial species by various tick hosts. To examine the vertical transmission potential between select tick and rickettsial species, two sympatric species of ticks, Dermacentor variabilis and Amblyomma maculatum, were exposed to five different rickettsial species, including Rickettsia rickettsii, Rickettsia parkeri, Rickettsia montanensis, Rickettsia amblyommatis, or flea-borne Rickettsia felis. Fitness-related metrics including engorgement weight, egg production index, nutrient index, and egg hatch percentage were then assessed. Subsamples of egg clutches and unfed larvae, nymphs, and adults for each cohort were assessed for transovarial and transstadial transmission of rickettsiae by qPCR. Rickettsial exposure had a minimal fitness effect in D. variabilis and transovarial transmission was observed for all groups except R. rickettsii. In contrast, rickettsial exposure negatively influenced A. maculatum fitness and transovarial transmission of rickettsiae was demonstrated only for R. amblyommatis- and R. parkeri-exposed ticks. Sustained maintenance of rickettsiae via transstadial transmission was diminished from F 1 larvae to F 1 adults in both tick species. The findings of this study suggest transovarial transmission specificity may not be tick species dependent, and sustained vertical transmission is not common. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

Treatment of attention deficit disorder with DL-phenylalanine.

PubMed

Wood, D R; Reimherr, F W; Wender, P H

1985-09-01

Nineteen patients meeting the criteria for attention deficit disorder, residual type (adult hyperactivity), were given a 2-week double-blind crossover of DL-phenylalanine versus placebo. Thirteen subjects completed the study; the mean global rating of improvement approached significance as compared with placebo. A significant improvement was noted on mood and mood lability. The phenylalanine responders were then continued on open drug, but lost all positive benefits within 3 months. A later open trial of L-phenylalanine produced no clinical effect.

High-Affinity Vanadate Transport System in the Cyanobacterium Anabaena variabilis ATCC 29413

PubMed Central

Pratte, Brenda S.; Thiel, Teresa

2006-01-01

High-affinity vanadate transport systems have not heretofore been identified in any organism. Anabaena variabilis, which can fix nitrogen by using an alternative V-dependent nitrogenase, transported vanadate well. The concentration of vanadate giving half-maximum V-nitrogenase activity when added to V-starved cells was about 3 × 10−9 M. The genes for an ABC-type vanadate transport system, vupABC, were found in A. variabilis about 5 kb from the major cluster of genes encoding the V-nitrogenase, and like those genes, the vupABC genes were repressed by molybdate; however, unlike the V-nitrogenase genes the vanadate transport genes were expressed in vegetative cells. A vupB mutant failed to grow by using V-nitrogenase unless high levels of vanadate were provided, suggesting that there was also a low-affinity vanadate transport system that functioned in the vupB mutant. The vupABC genes belong to a family of putative metal transport genes that include only one other characterized transport system, the tungstate transport genes of Eubacterium acidaminophilum. Similar genes are not present in the complete genomes of other bacterial strains that have a V-nitrogenase, including Azotobacter vinelandii, Rhodopseudomonas palustris, and Methanosarcina barkeri. PMID:16385036

Metabolism of D-phenylalanine and its effects on concentrations of brain monoamines and amino acids in rats--a basic study on possibility of clinical use of D-phenylalanine as an antidepressant.

PubMed

Hashimoto, H; Nakajima, T; Nishimura, T; Kudo, Y; Takeda, Y; Nakao, M; Kanaya, H; Horiguchi, Y

1983-01-01

The effect of D-phenylalanine on the concentrations of brain catecholamines, serotonin, beta-phenylethylamine and amino acids was examined using rats injected intraperitoneally with 200 mg/kg of D-phenylalanine. The contents of these monoamines in the rat brain were not affected by the administration of D-phenylalanine. No spectacular change was observed in the concentrations of brain amino acids except phenylalanine, which increased about four times during 30-60 minutes after the injection. This increase was attributed to the administered D-phenylalanine. To confirm the finding that D-phenylalanine did not affect the content of beta-phenylethylamine, the metabolism of D-phenylalanine was examined using D-[14C]-phenylalanine. It was proven that D-phenylalanine did not convert to beta-phenylethylamine. On the basis of these findings the antidepressant effect of D-phenylalanine was critically discussed.

Complete genome sequence of Anabaena variabilis ATCC 29413

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thiel, Teresa; Pratte, Brenda S.; Zhong, Jinshun

2013-01-01

Anabaena variabilis ATCC 29413 is a filamentous, heterocyst-forming cyanobacterium that has served as a model organism, with an extensive literature extending over 40 years. The strain has three distinct nitrogenases that function under different environmental conditions and is capable of photoautotrophic growth in the light and true heterotrophic growth in the dark using fructose as both carbon and energy source. While this strain was first isolated in 1964 in Mississippi and named Ana-baena flos-aquae MSU A-37, it clusters phylogenetically with cyanobacteria of the genus Nostoc. The strain is a moderate thermophile, growing well at approximately 40 C. Here we providemore » some additional characteristics of the strain, and an analysis of the complete genome sequence.« less

Species Boundaries Between Three Sympatric Oak Species: Quercus aliena, Q. dentata, and Q. variabilis at the Northern Edge of Their Distribution in China.

PubMed

Lyu, Jia; Song, Jia; Liu, Yuan; Wang, Yuyao; Li, Junqing; Du, Fang K

2018-01-01

Oaks are important timber trees with wide distributions in China, but few genetic studies have been conducted on a fine scale. In this study, we seek to investigate the genetic diversity and differentiation of three sympatric oak species ( Quercus aliena Blume, Quercus dentata Thunb. ex Murray, and Quercus variabilis Blume) in their northern distribution in China using 17 bi-parentally inherited nSSRs markers and five maternally inherited chloroplast DNA (cpDNA) fragments. Both the cpDNA and the nSSRs show a high level of genetic differentiation between different oak sections. The chloroplast haplotypes are clustered into two lineages. Clear species boundaries are detected between Q. variabilis and either Q. aliena or Q. dentata . The sharing of chloroplast haplotype H1 between Q. aliena and Q. dentata suggests very recent speciation and incomplete lineage sorting or introgression of H1 from one species to another. The nSSRs data indicate a complete fixation of variation within sites for all three oak species, and that extensive gene flow occurs within species whereas only limited gene flow is detected between Q. aliena and Q. dentata and nearly no gene flow can be detected between Q. aliena and Q. variabilis and between Q. dentata and Q. variabilis . Prezygotic isolation may have contributed to the species boundaries of these three sympatric oak species.

Species Boundaries Between Three Sympatric Oak Species: Quercus aliena, Q. dentata, and Q. variabilis at the Northern Edge of Their Distribution in China

PubMed Central

Lyu, Jia; Song, Jia; Liu, Yuan; Wang, Yuyao; Li, Junqing; Du, Fang K.

2018-01-01

Oaks are important timber trees with wide distributions in China, but few genetic studies have been conducted on a fine scale. In this study, we seek to investigate the genetic diversity and differentiation of three sympatric oak species (Quercus aliena Blume, Quercus dentata Thunb. ex Murray, and Quercus variabilis Blume) in their northern distribution in China using 17 bi-parentally inherited nSSRs markers and five maternally inherited chloroplast DNA (cpDNA) fragments. Both the cpDNA and the nSSRs show a high level of genetic differentiation between different oak sections. The chloroplast haplotypes are clustered into two lineages. Clear species boundaries are detected between Q. variabilis and either Q. aliena or Q. dentata. The sharing of chloroplast haplotype H1 between Q. aliena and Q. dentata suggests very recent speciation and incomplete lineage sorting or introgression of H1 from one species to another. The nSSRs data indicate a complete fixation of variation within sites for all three oak species, and that extensive gene flow occurs within species whereas only limited gene flow is detected between Q. aliena and Q. dentata and nearly no gene flow can be detected between Q. aliena and Q. variabilis and between Q. dentata and Q. variabilis. Prezygotic isolation may have contributed to the species boundaries of these three sympatric oak species. PMID:29662501

Modulation of deprivation-induced food intake by D-phenylalanine.

PubMed

Bodnar, R J; Butler, P D

1983-09-01

D-phenylalanine has been shown to possess opiate-like effects upon pain perception. The present study examined whether it would have similar opiate-like effects upon food intake in deprived rats. The first experiment demonstrated that food intake of rats deprived for 24 h prior to injection was significantly reduced for 2 h following a 250 mg/kg dose of D-phenylalanine. However, intake over a 24 h period following injection was significantly increased following a 125 mg/kg dose of D-phenylalanine. The second experiment revealed that 0.3, 1.0, 3.0 and 10.0 mg/kg doses of naloxone dose-dependently reduced intake for 2 h in deprived rats when paired with a vehicle injection. However, the inhibitory actions of the two lower naloxone doses were significantly attenuated when paired with an injection of a 250 mg/kg dose of D-phenylalanine. These results are discussed in terms of whether D-phenylalanine possesses direct or indirect opiate-like effects upon ingestion.

Bacterial conversion of phenylalanine and aromatic carboxylic acids into dihydrodiols.

PubMed Central

Wegst, W; Tittmann, U; Eberspächer, J; Lingens, F

1981-01-01

Strain E of chloridazon-degrading bacteria, when grown on L-phenylalanine accumulates cis-2,3-dihydro-2,3-dihydroxyphenylalanine. In experiments with resting cells and during growth the bacterium converts the aromatic carboxylic acids phenylacetate, phenylpropionate, phenylbutyrate and phenyl-lactate into the corresponding cis-2,3-dihydrodiol compounds. The amino acids L-phenylalanine, N-acetyl-L-phenylalanine and t-butyloxycarbonyl-L-phenylalanine were also transformed into dihydrodiols. All seven dihydrodiols, thus obtained, were characterized both by conventional analytical techniques and by the ability to serve as substrates for a cis-dihydrodiol dehydrogenase. PMID:7306016

First Report of Rickettsia Identical to R. slovaca in Colony-Originated D. variabilis in the United States: Detection, Laboratory Animal Model, and Vector Competence of Ticks.

PubMed

Zemtsova, Galina E; Killmaster, Lindsay F; Montgomery, Merrill; Schumacher, Lauren; Burrows, Matt; Levin, Michael L

2016-02-01

Ticks of the genus Dermacentor are known vectors of rickettsial pathogens in both the Old World and New World. In North America, Dermacentor variabilis and D. andersoni are vectors of Rickettsia rickettsii, while in Europe, D. marginatus and D. reticulatus transmit R. slovaca and R. raoultii, respectively. Neither the presence of R. slovaca in the Americas nor the ability of American tick species to maintain this pathogen have been reported. Here we describe detection of Rickettsia genetically identical to R. slovaca in D. variabilis, its molecular characterization, assessment of pathogenicity to guinea pigs, and vector competence of D. variabilis ticks. Ticks from a laboratory colony of D. variabilis, established from wild ticks and maintained on naïve NZW rabbits, tested positive for spotted fever group (SFG) Rickettsia by PCR. Analysis of 17 kDa gltA, rpoB, ompA, ompB, and sca4 genes revealed 100% identity to R. slovaca sequences available in the GenBank. New Zealand white rabbits fed upon by infected ticks seroconverted to SFG Rickettsia. Guinea pigs inoculated with the Rickettsia culture or infested by the infected ticks developed antibodies to SFG Rickettsia. The intensity of clinical signs and immune response were dependent on dose and route of infection. The identified Rickettsia was detected in all life stages of D. variabilis ticks, confirming transstadial and transovarial transmission. Thirty-six percent of uninfected larvae co-fed with infected nymphs on guinea pigs were PCR-positive and able to pass rickettsia to at least 11.7% of molted nymphs. To our knowledge, this is a first report of identification of a European pathogen R. slovaca or a highly similar agent in the American dog tick, D. variabilis. Considering pathogenicity of R. slovaca in humans, further laboratory and field studies are warranted to assess the relevance of the above findings to the public health and epidemiology of SFG rickettsioses in the United States.

Reactions of aqueous L-methionine, L-phenylalanine, L-methionyl-L-phenylalanine, L-phenylalanyl-L-methionine and their mixtures with H atoms during steady radiolysis at pH 6. 5. [Gamma radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mee, L.K.; Adelstein, S.J.; Steinhart, C.M.

Phenylalanine, methionine, and their mixtures, methionyl phenylalanine, phenylalnyl methionine, and mixtures of each dipeptide with phenylalanine were reacted with radiolytically generated H atoms in aqueous solution at pH 6.5. When methionine is irradiated alone, G(-methionine) = 2.0; the principal amino acid product is ..cap alpha..-amino-n-butyric acid. The initial destruction of phenylalanine, irradiated alone, is very low, G(-phenylalanine) approximately 0.15, and it decreases with dose. In mixtures of phenylalanine and methionine, radiolytic destruction of phenylalanine is potentiated, with a maximum potentiation at a phenylalanine:methionine ratio of 2 : 1. Repair reactions are postulated to account for the low initial yield ofmore » phenylalanine, its decrease with dose, and potentiation of destruction in mixtures with methionine. The destruction of the phenylalanyl and methionyl residues in the irradiated dipeptides is similar to that found for the loss of phenylalanine and methionine in 1 : 1 mixtures of the free amino acids; the destruction of residues in 1 : 1 mixtures of either dipeptide with phenylalanine is similar to that found in mixtures of phenylalanine:methionine at a ratio of 2 : 1. Thus, it is apparent already in simple mixtures of the divalent sulfur-containing methionine and the aromatic phenylalanine that kinetic interactions occur between these two kinds of amino acids which are not revealed by irradiation of these residues separately. The behavior of the dipeptides does not provide any evidence for intramolecular transfer of radical site.« less

Effects of totally synthetic, low phenylalanine diet on adolescent phenylketonuric patients

PubMed Central

McKean, Charles M.

1971-01-01

The long-term responses of 5 adolescent phenylketonuric patients to chemically-defined, synthetic diets with normal and low phenylalanine content were determined. The synthetic preparations were found capable of sustaining good health and rapid growth in this group of profoundly retarded, behaviourally disturbed patients over a 3½-year period without clinical or biochemical evidence of nutritional inadequacy. 4 of these patients who were treated for 6 months on a comparable diet, in which 80% of the phenylalanine was replaced by tyrosine, continued to show weight maintenance and height increases. There was no evidence of poor acceptability of the imbalanced diet, whether the blood phenylalanine concentrations were at phenylketonuric or treatment levels. The phenylalanine intake required to maintain blood phenylalanine concentrations of 3-5 mg/100 ml in these 4 patients was well below normal requirements, and ranged between 6·8 and 20·1 mg/kg per day. Predictably, the phenylalanine requirement varied with individual growth rates. All 4 treated patients had objective signs of improved central nervous system function during the six-month period on the phenylalanine-restricted diet. These electrophysiological and behavioural improvements were manifest after blood phenylalanine concentrations fell below 12 mg/100 ml in 3 cases and below 5 mg/100 ml in the fourth. PMID:5118048

Surface modification of hydroxyapatite nanoparticles by poly( L-phenylalanine) via ROP of L-phenylalanine N-carboxyanhydride (Pha-NCA)

NASA Astrophysics Data System (ADS)

Dai, Yanfeng; Xu, Min; Wei, Junchao; Zhang, Haobin; Chen, Yiwang

2012-01-01

The surface of hydroxyapatite nanoparticles was modified by poly(L-phenylalanine) via the ring opening polymerization (ROP) of L-phenylalanine N-carboxyanhydride. The preparation procedure was monitored by Fourier transform infrared spectroscopy (FTIR), and the modified hydroxyapatite was characterized by thermal gravimetric analysis (TGA) and X-ray diffraction (XRD). The results showed that the surface grafting amounts of poly(L-phenylalanine) on HA ranging from 20.26% to 38.92% can be achieved by tuning the reaction condition. The XRD patterns demonstrated that the crystalline structure of the modified hydroxyapatite was nearly the same with that of HA, implying that the ROP was an efficient surface modification method. The MTT assay proved that the biocompatibility of modified HA was very good, which showed the potential application of modified HA in bone tissue engineering.

Differential metabolism of L-phenylalanine in the formation of aromatic volatiles in melon (Cucumis melo L.) fruit.

PubMed

Gonda, Itay; Davidovich-Rikanati, Rachel; Bar, Einat; Lev, Shery; Jhirad, Pliaa; Meshulam, Yuval; Wissotsky, Guy; Portnoy, Vitaly; Burger, Joseph; Schaffer, Arthur A; Tadmor, Yaakov; Giovannoni, James J; Fei, Zhangjun; Fait, Aaron; Katzir, Nurit; Lewinsohn, Efraim

2018-04-01

Studies on the active pathways and the genes involved in the biosynthesis of L-phenylalanine-derived volatiles in fleshy fruits are sparse. Melon fruit rinds converted stable-isotope labeled L-phe into more than 20 volatiles. Phenylpropanes, phenylpropenes and benzenoids are apparently produced via the well-known phenylpropanoid pathway involving phenylalanine ammonia lyase (PAL) and being (E)-cinnamic acid a key intermediate. Phenethyl derivatives seemed to be derived from L-phe via a separate biosynthetic route not involving (E)-cinnamic acid and PAL. To explore for a biosynthetic route to (E)-cinnamaldehyde in melon rinds, soluble protein cell-free extracts were assayed with (E)-cinnamic acid, CoA, ATP, NADPH and MgSO 4 , producing (E)-cinnamaldehyde in vitro. In this context, we characterized CmCNL, a gene encoding for (E)-cinnamic acid:coenzyme A ligase, inferred to be involved in the biosynthesis of (E)-cinnamaldehyde. Additionally we describe CmBAMT, a SABATH gene family member encoding a benzoic acid:S-adenosyl-L-methionine carboxyl methyltransferase having a role in the accumulation of methyl benzoate. Our approach leads to a more comprehensive understanding of L-phe metabolism into aromatic volatiles in melon fruit. Copyright © 2018 Elsevier Ltd. All rights reserved.

Site-specific incorporation of 4-iodo-L-phenylalanine through opal suppression.

PubMed

Kodama, Koichiro; Nakayama, Hiroshi; Sakamoto, Kensaku; Fukuzawa, Seketsu; Kigawa, Takanori; Yabuki, Takashi; Kitabatake, Makoto; Takio, Koji; Yokoyama, Shigeyuki

2010-08-01

A variety of unique codons have been employed to expand the genetic code. The use of the opal (UGA) codon is promising, but insufficient information is available about the UGA suppression approach, which facilitates the incorporation of non-natural amino acids through suppression of the UGA codon. In this study, the UGA codon was used to incorporate 4-iodo-l-phenylalanine into position 32 of the Ras protein in an Escherichia coli cell-free translation system. The undesired incorporation of tryptophan in response to the UGA codon was completely repressed by the addition of indolmycin. The minor amount (3%) of contaminating 4-bromo-l-phenylalanine in the building block 4-iodo-l-phenylalanine led to the significant incorporation of 4-bromo-l-phenylalanine (21%), and this problem was solved by using a purified 4-iodo-l-phenylalanine sample. Optimization of the incubation time was also important, since the undesired incorporation of free phenylalanine increased during the cell-free translation reaction. The 4-iodo-l-phenylalanine residue can be used for the chemoselective modification of proteins. This method will contribute to advancements in protein engineering studies with non-natural amino acid substitutions.

The study of structure-activity relationships among substituted N-benzoyl derivatives of phenylalanine and its analogs in a microbial antitumor prescreen: II. Derivatives of m-fluoro-DL-phenylalanine.

PubMed

Otani, T T; Briley, M R

1983-05-01

The fluoro-, chloro-, methoxy- and nitro-substituted benzoyl derivatives of m-fluoro-DL-phenylalanine, substituted singly at the ortho, meta or para position of the benzoyl phenyl ring, were prepared and tested for growth-inhibitory activity in a Lactobacillus casei system used as an antitumor prescreen. The substituted benzoyl derivatives that were previously found to be the most active for o-fluoro-DL-phenylalanine were also the most active for the m-fluoro-DL-phenylalanine. The position of the fluorine substituent in the phenylalanine also appeared to be important for inhibitory activity as the derivatives of m-fluoro-phenylalanine were in general better inhibitors than those of the corresponding o-fluorophenylalanine.

Molecular and functional characterization of vacuolar-ATPase from the American dog tick Dermacentor variabilis.

PubMed

Petchampai, N; Sunyakumthorn, P; Guillotte, M L; Thepparit, C; Kearney, M T; Mulenga, A; Azad, A F; Macaluso, K R

2014-02-01

Vacuolar (V)-ATPase is a proton-translocating enzyme that acidifies cellular compartments for various functions such as receptor-mediated endocytosis, intracellular trafficking and protein degradation. Previous studies in Dermacentor variabilis chronically infected with Rickettsia montanensis have identified V-ATPase as one of the tick-derived molecules transcribed in response to rickettsial infection. To examine the role of the tick V-ATPase in tick-Rickettsia interactions, a full-length 2887-bp cDNA (2532-bp open reading frame) clone corresponding to the transcript of the V0 domain subunit a of D. variabilis V-ATPase (DvVATPaseV0a) gene encoding an 843 amino acid protein with an estimated molecular weight of ~96 kDa was isolated from D. variabilis. Amino acid sequence analysis of DvVATPaseV0a showed the highest similarity to VATPaseV0a from Ixodes scapularis. A potential N-glycosylation site and eight putative transmembrane segments were identified in the sequence. Western blot analysis of tick tissues probed with polyclonal antibody raised against recombinant DvVATPaseV0a revealed the expression of V-ATPase in the tick ovary. Transcriptional profiles of DvVATPaseV0a demonstrated a greater mRNA expression in the tick ovary, compared with the midgut and salivary glands; however, the mRNA level in each of these tick tissues remained unchanged after infection with R. montanensis for 1 h. V-ATPase inhibition bioassays resulted in a significant decrease in the ability of R. montanensis to invade tick cells in vitro, suggesting a role of V-ATPase in rickettsial infection of tick cells. Characterization of tick-derived molecules involved in rickettsial infection is essential for a thorough understanding of rickettsial transmission within tick populations and the ecology of tick-borne rickettsial diseases. © 2013 The Authors. Insect Molecular Biology published by John Wiley & Sons Ltd on behalf of The Royal Entomological Society.

Antinociceptive effect of some carboxypeptidase A inhibitors in comparison with D-phenylalanine.

PubMed

Giusti, P; Carrara, M; Cima, L; Borin, G

1985-10-22

It had previously been shown that D-phenylalanine and hydrocinnamic acid, two in vitro inhibitors of carboxypeptidase A, possess an analgesic action when injected i.p. in mice. We have studied the in vivo effects of indole-3-acetic acid, another carboxypeptidase A inhibitor, and of the following analogs of D-phenylalanine substituted in position 4: D-tyrosine, p-fluoro-D-phenylalanine and trifluoroacetyl-p-fluoro-D-phenylalanine. Whereas indole-3-acetic acid caused a higher and shorter analgesia in comparison with D-phenylalanine, p-fluoro-D-phenylalanine and its N-trifluoroacetyl derivative yielded both a greater and a much longer lasting analgesic effect. Since the latter compound showed only slight inhibitory activity on carboxypeptidase A in vitro, we suggest that inhibition of this enzyme and analgesia might not be directly correlated.

Phenylalanine ammonia lyase from Arabidopsis thaliana (AtPAL2): A potent MIO-enzyme for the synthesis of non-canonical aromatic alpha-amino acids: Part I: Comparative characterization to the enzymes from Petroselinum crispum (PcPAL1) and Rhodosporidium toruloides (RtPAL).

PubMed

Dreßen, Alana; Hilberath, Thomas; Mackfeld, Ursula; Billmeier, Arne; Rudat, Jens; Pohl, Martina

2017-09-20

Phenylalanine ammonia lyase (PAL) from Arabidopsis thaliana (AtPAL2) was comparatively characterized to the well-studied enzyme from parsley (PcPAL1) and Rhodosporidium toruloides (RtPAL) with respect to kinetic parameters for the deamination and the amination reaction, pH- and temperature optima and the substrate range of the amination reaction. Whereas both plant enzymes are specific for phenylalanine, the bifunctional enzyme from Rhodosporidium toruloides shows K M -values for L-Phe and L-Tyr in the same order of magnitude and, compared to both plant enzymes, a 10-15-fold higher activity. At 30°C all enzymes were sufficiently stable with half-lives of 3.4days (PcPAL1), 4.6days (AtPAL2) and 9.7days (RtPAL/TAL). Very good results for the amination of various trans-cinnamic acid derivatives were obtained using E. coli cells as whole cell biocatalysts in ammonium carbonate buffer. Investigation of the substrate ranges gave interesting results for the newly tested enzymes from A. thaliana and R. toruloides. Only the latter accepts besides 4-hydroxy-CA also 3-methoxy-4-hydroxy-CA as a substrate, which is an interesting intermediate for the formation of pharmaceutically relevant L-Dopa. AtPAL2 is a very good catalyst for the formation of (S)-3-F-Phe, (S)-4-F-Phe and (S)-2-Cl-Phe. Such non-canonical amino acids are valuable building blocks for the formation of various drug molecules. Copyright © 2017 Elsevier B.V. All rights reserved.

The thermodynamic parameters of solution of L-phenylalanine in water

NASA Astrophysics Data System (ADS)

Kustov, A. V.; Korolev, V. P.

2007-02-01

The heat effects of solution of L-phenylalanine in water were measured over wide concentration and temperature ranges. The enthalpies of solution of L-phenylalanine were found to be independent of the content of the amino acid in solution over the concentration range studied. The standard enthalpies, heat capacities, and entropies of solution of the amino acid and the solubility of L-phenylalanine over the temperature range studied were calculated.

Phenylalanine transfer across the isolated perfused human placenta: an experimental and modeling investigation

PubMed Central

Lofthouse, E. M.; Perazzolo, S.; Brooks, S.; Crocker, I. P.; Glazier, J. D.; Johnstone, E. D.; Panitchob, N.; Sibley, C. P.; Widdows, K. L.; Sengers, B. G.

2015-01-01

Membrane transporters are considered essential for placental amino acid transfer, but the contribution of other factors, such as blood flow and metabolism, is poorly defined. In this study we combine experimental and modeling approaches to understand the determinants of [14C]phenylalanine transfer across the isolated perfused human placenta. Transfer of [14C]phenylalanine across the isolated perfused human placenta was determined at different maternal and fetal flow rates. Maternal flow rate was set at 10, 14, and 18 ml/min for 1 h each. At each maternal flow rate, fetal flow rates were set at 3, 6, and 9 ml/min for 20 min each. Appearance of [14C]phenylalanine was measured in the maternal and fetal venous exudates. Computational modeling of phenylalanine transfer was undertaken to allow comparison of the experimental data with predicted phenylalanine uptake and transfer under different initial assumptions. Placental uptake (mol/min) of [14C]phenylalanine increased with maternal, but not fetal, flow. Delivery (mol/min) of [14C]phenylalanine to the fetal circulation was not associated with fetal or maternal flow. The absence of a relationship between placental phenylalanine uptake and net flux of phenylalanine to the fetal circulation suggests that factors other than flow or transporter-mediated uptake are important determinants of phenylalanine transfer. These observations could be explained by tight regulation of free amino acid levels within the placenta or properties of the facilitated transporters mediating phenylalanine transport. We suggest that amino acid metabolism, primarily incorporation into protein, is controlling free amino acid levels and, thus, placental transfer. PMID:26676251

Effect of mineral phosphates on growth and nitrogen fixation of diazotrophic cyanobacteria Anabaena variabilis and Westiellopsis prolifica.

PubMed

Yandigeri, Mahesh S; Yadav, Arvind K; Meena, Kamlesh Kumar; Pabbi, Sunil

2010-03-01

The nitrogen fixing cyanobacterial strains namely Anabaena variabilis (Nostocales, Nostocaceae) and Westiellopsis prolifica (Nostocales, Hapalosiphonaceae) were evaluated for their nitrogen fixation and growth potential in response to different concentrations (10, 20 and 30 mg P) of the alternate insoluble P-sources Mussorie Rock Phosphate and Tricalcium Phosphate. Distinct and significant intergeneric differences were observed with respect to nitrogen fixation measured as Acetylene Reduction Activity (ARA) and growth potential as soluble proteins, total carbohydrate content, dry weight and total chlorophyll content in response to different concentrations of Mussorie Rock Phosphate and Tricalcium Phosphate. Both the strains showed higher soluble protein content at 20 mg P (Mussorie Rock Phosphate) that increased with time of incubation in A. variabilis. Both cyanobacteria recorded maximum Acetylene Reduction Activity at 20 mg P (Tricalcium Phosphate) followed by activity in presence of soluble phosphate (K2HPO4). The mean activity at all concentrations of insoluble phosphate (Mussorie Rock Phosphate and Tricalcium Phosphate) was more than in the presence of soluble phosphate.

Characterization of proteases from Planomicrobium sp. L-2 isolated from the gastrointestinal tract of Octopus variabilis (Sasaki)

NASA Astrophysics Data System (ADS)

Jin, Yulan; Wang, Yurong; Xiao, Lin; Lin, Xiukun

2016-05-01

A crude protease produced from Planomicrobium sp. L-2 is described, and its effectiveness as an additive in liquid detergent evaluated. We isolate the protease-producing Planomicrobium sp. L-2 from the gastrointestinal tract of Octopus variabilis. At least three caseinolytic protease clear bands were observed in zymogram analysis. The crude alkaline protease was highly tolerant of a pH range from 7.0 to 9.0, and temperatures to 50°C after incubation for 1 h. Proteolytic enzymes were stable towards three surfactants (5% Tween 80, 1% Triton X-100 and 0.05% SDS) and an oxidizing agent (1% hydrogen peroxide), in addition to being highly stable and compatible with popular commercial laundry powered detergent brands available in China. Our study demonstrates the potential these proteases have for development into novel classes of detergent additive. This study also suggests that the gastrointestinal tract of Octopus variabilis may be a rich source of commercially valuable strains of enzyme.

The structurally unique photosynthetic Chlorella variabilis NC64A hydrogenase does not interact with plant-type ferredoxins.

PubMed

Engelbrecht, Vera; Rodríguez-Maciá, Patricia; Esselborn, Julian; Sawyer, Anne; Hemschemeier, Anja; Rüdiger, Olaf; Lubitz, Wolfgang; Winkler, Martin; Happe, Thomas

2017-09-01

Hydrogenases from green algae are linked to the photosynthetic electron transfer chain via the plant-type ferredoxin PetF. In this work the [FeFe]-hydrogenase from the Trebouxiophycean alga Chlorella variabilis NC64A (CvHydA1), which in contrast to other green algal hydrogenases contains additional FeS-cluster binding domains, was purified and specific enzyme activities for both hydrogen (H 2 ) production and H 2 oxidation were determined. Interestingly, although C. variabilis NC64A, like many Chlorophycean algal strains, exhibited light-dependent H 2 production activity upon sulfur deprivation, CvHydA1 did not interact in vitro with several plant-type [2Fe-2S]-ferredoxins, but only with a bacterial2[4Fe4S]-ferredoxin. In an electrochemical characterization, the enzyme exhibited features typical of bacterial [FeFe]-hydrogenases (e.g. minor anaerobic oxidative inactivation), as well as of algal enzymes (very high oxygen sensitivity). Copyright © 2017 Elsevier B.V. All rights reserved.

Chiral discrimination in cyclodextrin complexes of amino acid derivatives: beta-cyclodextrin/N-acetyl-L-phenylalanine and N-acetyl-D-phenylalanine complexes.

PubMed

Alexander, Jennifer M; Clark, Joanna L; Brett, Tom J; Stezowski, John J

2002-04-16

In a systematic study of molecular recognition of amino acid derivatives in solid-state beta-cyclodextrin (beta-CD) complexes, we have determined crystal structures for complexes of beta-cyclodextrin/N-acetyl-L-phenylalanine at 298 and 20 K and for N-acetyl-D-phenylalanine at 298 K. The crystal structures for the N-acetyl-L-phenylalanine complex present disordered inclusion complexes for which the distribution of guest molecules at room temperature is not resolvable; however, they can be located with considerable confidence at low temperature. In contrast, the complex with N-acetyl-D-phenylalanine is well ordered at room temperature. The latter complex presents an example of a complex in this series in which a water molecule is included deeply in the hydrophobic torus of the extended dimer host. In an effort to understand the mechanisms of molecular recognition giving rise to the dramatic differences in crystallographic order in these crystal structures, we have examined the intermolecular interactions in detail and have examined insertion of the enantiomer of the D-complex into the chiral beta-CD complex crystal lattice.

Ammonia and amino acid profiles in liver cirrhosis: effects of variables leading to hepatic encephalopathy.

PubMed

Holecek, Milan

2015-01-01

Hyperammonemia and severe amino acid imbalances play central role in hepatic encephalopathy (HE). In the article is demonstrated that the main source of ammonia in cirrhotic subjects is activated breakdown of glutamine (GLN) in enterocytes and the kidneys and the main source of GLN is ammonia detoxification to GLN in the brain and skeletal muscle. Branched-chain amino acids (BCAA; valine, leucine, and isoleucine) decrease due to activated GLN synthesis in muscle. Aromatic amino acids (AAA; phenylalanine, tyrosine, and tryptophan) and methionine increase due to portosystemic shunts and reduced ability of diseased liver. The effects on aminoacidemia of the following variables that may affect the course of liver disease are discussed: nutritional status, starvation, protein intake, inflammation, acute hepatocellular damage, bleeding from varices, portosystemic shunts, hepatic cancer, and renal failure. It is concluded that (1) neither ammonia nor amino acid concentrations correlate closely with the severity of liver disease; (2) BCAA/AAA ratio could be used as a good index of liver impairment and for early detection of derangements in amino acid metabolism; (3) variables potentially leading to overt encephalopathy exert substantial but uneven effects; and (4) careful monitoring of ammonia and aminoacidemia may discover important break points in the course of liver disease and indicate appropriate therapeutic approach. Of special importance might be isoleucine deficiency in bleeding from varices, arginine deficiency in sepsis, and a marked rise of GLN and ammonia levels that may appear in all events leading to HE. Copyright © 2015 Elsevier Inc. All rights reserved.

Range-wide genetic analysis of Dermacentor variabilis and its Francisella-like endosymbionts demonstrates phylogeographic concordance between both taxa

USDA-ARS?s Scientific Manuscript database

Background: The American dog tick, Dermacentor variabilis, is an important vector of pathogens to humans, wildlife, and domestic animals in North America. Although this tick is widely distributed in the US and Canada, knowledge of its range-wide phylogeographic patterns remains incomplete. Methods:...

Recommendations for the nutrition management of phenylalanine hydroxylase deficiency

PubMed Central

Singh, Rani H.; Rohr, Fran; Frazier, Dianne; Cunningham, Amy; Mofidi, Shideh; Ogata, Beth; Splett, Patricia L.; Moseley, Kathryn; Huntington, Kathleen; Acosta, Phyllis B.; Vockley, Jerry; Van Calcar, Sandra C.

2014-01-01

The effectiveness of a phenylalanine-restricted diet to improve the outcome of individuals with phenylalanine hydroxylase deficiency (OMIM no. 261600) has been recognized since the first patients were treated 60 years ago. However, the treatment regime is complex, costly, and often difficult to maintain for the long term. Improvements and refinements in the diet for phenylalanine hydroxylase deficiency have been made over the years, and adjunctive therapies have proven to be successful for certain patients. Yet evidence-based guidelines for managing phenylalanine hydroxylase deficiency, optimizing outcomes, and addressing all available therapies are lacking. Thus, recommendations for nutrition management were developed using evidence from peer-reviewed publications, gray literature, and consensus surveys. The areas investigated included choice of appropriate medical foods, integration of adjunctive therapies, treatment during pregnancy, monitoring of nutritional and clinical markers, prevention of nutrient deficiencies, providing of access to care, and compliance strategies. This process has not only provided assessment and refinement of current nutrition management and monitoring recommendations but also charted a direction for future studies. This document serves as a companion to the concurrently published American College of Medical Genetics and Genomics guideline for the medical treatment of phenylalanine hydroxylase deficiency. Genet Med 16 2, 121–131. PMID:24385075

Differential expression of two glutathione S-transferases identified from the American dog tick, Dermacentor variabilis.

PubMed

Dreher-Lesnick, S M; Mulenga, A; Simser, J A; Azad, A F

2006-08-01

Reciprocal signalling and gene expression play a cardinal role during pathogen-host molecular interactions and are prerequisite to the maintenance of balanced homeostasis. Gene expression repertoire changes during rickettsial infection and glutathione-S-transferases (GSTs) were among the genes found up-regulated in Rickettsia-infected Dermacentor variabilis. GSTs are well known to play an important part in cellular stress responses in the host. We have cloned two full-length GSTs from D. variabilis (DvGST1 and DvGST2). Comparison of these two DvGST molecules with those of other species indicate that DvGST1 is related to the mammalian class theta and insect class delta GSTs, while DvGST2 does not seem to fall in the same family. Northern blotting analyses revealed differential expression patterns, where DvGST1 and DvGST2 transcripts are found in the tick gut, with DvGST2 transcripts also present in the ovaries. Both DvGST transcripts are up-regulated upon tick feeding. Challenge of fed adult ticks with Escherichia coli injection showed decreased transcript amounts compared with ticks injected with phosphate-buffered saline (sham) and naïve ticks.

Proteinase K-catalyzed synthesis of linear and star oligo(L-phenylalanine) conjugates.

PubMed

Ageitos, Jose M; Baker, Peter J; Sugahara, Michihiro; Numata, Keiji

2013-10-14

Chemoenzymatic synthesis of peptides is a green and clean chemical reaction that offers high yields without using organic synthesis and serves as an alternative to traditional peptide synthesis methods. This report describes the chemoenzymatic synthesis of oligo(L-phenylalanine) mediated by proteinase K from Tritirachium album, which is one of the most widely used proteases in molecular biological studies. The synthesized linear oligo-phenylalanine showed a unique self-assembly in aqueous solutions. To further functionalize linear oligo(L-phenylalanine) as a low-molecular-weight gelator, it was cosynthesized with tris(2-aminoethyl)amine to obtain star-oligo(L-phenylalanine), which was bioconjugated to demonstrate its self-assembly into fluorescent fibers. The self-assembled fibers of star-oligo(L-phenylalanine) formed fibrous networks with various branching ratios, which depended on the molecular weights and molecular aspect ratios of star-oligo(L-phenylalanine). This is the first study to demonstrate that proteinase K is a suitable enzyme for chemoenzymatic cosynthesis of oligopeptides and star-shaped heteropeptides.

Sodium sulfite pH-buffering effect for improved xylose-phenylalanine conversion to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine during an aqueous Maillard reaction.

PubMed

Cui, Heping; Duhoranimana, Emmanuel; Karangwa, Eric; Jia, Chengsheng; Zhang, Xiaoming

2018-04-25

The yield of the Maillard reaction intermediate (MRI), prepared in aqueous medium, is usually unsatisfactory. However, the addition of sodium sulfite could improve the conversion of xylose-phenylalanine (Xyl-Phe) to the MRI (N-(1-deoxy-d-xylulos-1-yl)-phenylalanine) in aqueous medium. Sodium sulfite (Na 2 SO 3 ) showed a significant pH-buffering effect during the Maillard reaction, which accounted for its facilitation of the N-(1-deoxy-d-xylulos-1-yl)-phenylalanine yield. The results revealed that the pH could be maintained at a relatively high level (above 7.0) for an optimized pH-buffering effect when Na 2 SO 3 (4.0%) was added before the reaction of Xyl-Phe. Thus, the conversion of Xyl-Phe to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine increased from 47.23% to 74.86%. Furthermore, the addition moment of Na 2 SO 3 and corresponding solution pH were crucial factors in regulating the pH-buffering effect of Na 2 SO 3 on N-(1-deoxy-d-xylulos-1-yl)-phenylalanine yield. Based on the pH-buffering effect of Na 2 SO 3 and maintaining the optimal pH 7.4 relatively stable, the conversion of Xyl-Phe to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine was successfully improved. Copyright © 2017 Elsevier Ltd. All rights reserved.

[DL-phenylalanine as an antidepressant. Open study (author's transl)].

PubMed

Beckmann, H; Ludolph, E

1978-01-01

In an open study dl-phenylalanine in doses from 75--200 mg/day was administered to 20 depressed patients for 20 days. At the end of the trial 12 patients (8 with complete, 4 with good response) could be discharged without any further treatment. 4 patients with partially untypical depressions experienced mild to moderate responses, whereas 4 patients did not respond at all to the phenylalanine administration. Depressive "core symptoms" as depressed mood, retardation and/or agitation were preferentially, anxiety and sleep disturbances moderately and hypochondriasis and compulsiveness were not influenced. It is concluded that dl-phenylalanine might have substantial antidepressant properties and that further controlled investigations are justified.

An additional substrate binding site in a bacterial phenylalanine hydroxylase

PubMed Central

Ronau, Judith A.; Paul, Lake N.; Fuchs, Julian E.; Corn, Isaac R.; Wagner, Kyle T.; Liedl, Klaus R.; Abu-Omar, Mahdi M.; Das, Chittaranjan

2014-01-01

Phenylalanine hydroxylase (PAH) is a non-heme iron enzyme that catalyzes phenylalanine oxidation to tyrosine, a reaction that must be kept under tight regulatory control. Mammalian PAH features a regulatory domain where binding of the substrate leads to allosteric activation of the enzyme. However, existence of PAH regulation in evolutionarily distant organisms, such as certain bacteria in which it occurs, has so far been underappreciated. In an attempt to crystallographically characterize substrate binding by PAH from Chromobacterium violaceum (cPAH), a single-domain monomeric enzyme, electron density for phenylalanine was observed at a distal site, 15.7Å from the active site. Isothermal titration calorimetry (ITC) experiments revealed a dissociation constant of 24 ± 1.1 µM for phenylalanine. Under the same conditions, no detectable binding was observed in ITC for alanine, tyrosine, or isoleucine, indicating the distal site may be selective for phenylalanine. Point mutations of residues in the distal site that contact phenylalanine (F258A, Y155A, T254A) lead to impaired binding, consistent with the presence of distal site binding in solution. Kinetic analysis reveals that the distal site mutants suffer a discernible loss in their catalytic activity. However, x-ray structures of Y155A and F258A, two of the mutants showing more noticeable defect in their activity, show no discernible change in their active site structure, suggesting that the effect of distal binding may transpire through protein dynamics in solution. PMID:23860686

Phenylalanine ammonia-lyase activity in suspension cultures of Ulmus pumila and U. campestris treated with spores of Ceratocystis ulmi.

PubMed

Corchete, M P; Diez, J J; Valle, T

1993-12-01

Cell suspension cultures of a Ceratocystis ulmi-resistant (Ulmus pumila) and a -susceptible elm (U.campestris) were established from leaf callus tissue. Treatment of cultures with spores of C.ulmi induced a large increase in the activity of phenylalanine ammonialyase, only in the cells of the resistant species U.pumila with a maximum after 24 h. Inoculated U.pumila cells also excreted a red unidentified chemical into the culture medium. Neither responses were induced in inoculated U.campestris cultures. The results are discussed in relation to the development of the elm cell culture system as a model for studying the differential biochemical mechanisms of disease resistance in elms.

A phenylalanine ammonia-lyase ortholog (PkPAL1) from Picrorhiza kurrooa Royle ex. Benth: molecular cloning, promoter analysis and response to biotic and abiotic elicitors.

PubMed

Bhat, Wajid Waheed; Razdan, Sumeer; Rana, Satiander; Dhar, Niha; Wani, Tariq Ahmad; Qazi, Parvaiz; Vishwakarma, Ram; Lattoo, Surrinder K

2014-09-01

Picrorhiza kurrooa Royle ex Benth. is a highly reputed medicinal herb utilised in the preparation of a number of herbal drug formulations, principally due to the presence of novel monoterpene iridoid glycosides kenned as picrosides. Phenylalanine ammonia-lyase catalyses an important rate-limiting step in phenylpropanoid pathway and supplies precursors like cinnamic acid, vanillic acid, ferulic acid, etc., to a variety of secondary metabolites including picrosides. The imperilled status of P. kurrooa coupled with lack of information regarding biogenesis of picrosides necessitates deciphering the biosynthetic pathway for picrosides. In the present study, a PAL gene, designated PkPAL1 was isolated from P. kurrooa. The cDNA is 2312 bp in length, consisting of an ORF of 2142 bp encoding for a 713 amino acid protein having a predicted molecular weight of 77.66 kDa and an isoelectric point of pH 6.82. qRT-PCR analysis of various tissues of P. kurrooa showed that PkPAL1 transcript levels were highest in the leaves, consistent with picroside accumulation pattern. Using Genome walking, a 718 bp promoter region was also isolated resulting in identification of distinct cis-regulatory elements including TGA-element, TGACG-motif, CGTCA-motif, etc. qRT-PCR indicated up-regulation of PkPAL1 by methyl jasmonate, salicylic acid, 2,4-dicholorophenoxy acetic acid and UV-B elicitations that corroborated positively with the identified cis-elements within the promoter region. Moreover, altitude was found to have a positive effect on the PkPAL1 transcript levels, driving the expression of PkPAL1 abundantly. Based on docking analysis, we identified eight residues as potentially essential for substrate binding in PkPAL1. Copyright © 2014 Elsevier B.V. All rights reserved.

Fluorescent Biphenyl Derivatives of Phenylalanine Suitable for Protein Modification

PubMed Central

Chen, Shengxi; Fahmi, Nour Eddine; Bhattacharya, Chandrabali; Wang, Lin; Jin, Yuguang; Benkovic, Stephen J.; Hecht, Sidney M.

2013-01-01

In a recent study, we demonstrated that structurally compact fluorophores incorporated into the side chains of amino acids could be introduced into dihydrofolate reductase from E. coli (ecDHFR) with minimal disruption of protein structure or function, even where the site of incorporation was within a folded region of the protein. The modified proteins could be employed for FRET measurements, providing sensitive monitors of changes in protein conformation. The very favorable results achieved in that study encouraged us to prepare additional fluorescent amino acids of potential utility for studying protein dynamics. Presently, we describe the synthesis and photophysical characterization of four positional isomers of biphenyl-phenylalanine, all of which were found to exhibit potentially useful fluorescent properties. All four phenylalanine derivatives were used to activate suppressor tRNA transcripts, and incorporated into multiple positions of ecDHFR. All phenylalanine derivatives were incorporated with good efficiency into position 16 of ecDHFR, and afforded modified proteins which consumed NADPH at rates up to about twice the rate measured for wild type. This phenomenon has been noted on a number of occasions previously and shown to be due to an increase in the off-rate of tetrahydrofolate from the enzyme, altering a step that is normally rate limiting. When introduced into sterically accessible position 49, the four phenylalanine derivatives afforded DHFRs having catalytic function comparable to wild type. The four phenylalanine derivatives were also introduced into position 115 of ecDHFR, which is known to be a folded region of the protein less tolerant of structural alteration. As anticipated, significant differences were noted in the catalytic efficiencies of the derived proteins. The ability of two of the sizeable biphenyl-phenylalanine derivatives to be accommodated at position 115 with minimal perturbation of DHFR function is attributed to rotational

Beak measurements of octopus ( Octopus variabilis) in Jiaozhou Bay and their use in size and biomass estimation

NASA Astrophysics Data System (ADS)

Xue, Ying; Ren, Yiping; Meng, Wenrong; Li, Long; Mao, Xia; Han, Dongyan; Ma, Qiuyun

2013-09-01

Cephalopods play key roles in global marine ecosystems as both predators and preys. Regressive estimation of original size and weight of cephalopod from beak measurements is a powerful tool of interrogating the feeding ecology of predators at higher trophic levels. In this study, regressive relationships among beak measurements and body length and weight were determined for an octopus species ( Octopus variabilis), an important endemic cephalopod species in the northwest Pacific Ocean. A total of 193 individuals (63 males and 130 females) were collected at a monthly interval from Jiaozhou Bay, China. Regressive relationships among 6 beak measurements (upper hood length, UHL; upper crest length, UCL; lower hood length, LHL; lower crest length, LCL; and upper and lower beak weights) and mantle length (ML), total length (TL) and body weight (W) were determined. Results showed that the relationships between beak size and TL and beak size and ML were linearly regressive, while those between beak size and W fitted a power function model. LHL and UCL were the most useful measurements for estimating the size and biomass of O. variabilis. The relationships among beak measurements and body length (either ML or TL) were not significantly different between two sexes; while those among several beak measurements (UHL, LHL and LBW) and body weight (W) were sexually different. Since male individuals of this species have a slightly greater body weight distribution than female individuals, the body weight was not an appropriate measurement for estimating size and biomass, especially when the sex of individuals in the stomachs of predators was unknown. These relationships provided essential information for future use in size and biomass estimation of O. variabilis, as well as the estimation of predator/prey size ratios in the diet of top predators.

Syntheses of halogen derivatives of L-tryptophan, L-tyrosine and L-phenylalanine labeled with hydrogen isotopes.

PubMed

Pająk, Małgorzata; Pałka, Katarzyna; Winnicka, Elżbieta; Kańska, Marianna

2016-01-01

Halogenated, labeled with tritium and doubly with deuterium and tritium, derivatives of L-tryptophan, i.e. 5'-bromo-[2-(3)H]-, 5'-bromo-[2-(2)H/(3)H]-, 5'-fluoro-[2-(3)H]-5'-fluoro-[2-(2)H/(3)H]-, 6'-fluoro-[2-(3)H]-, 6'-fluoro-[2-(2)H/(3)H]-L-tryptophan, as well as, L-tyrosine, i.e. 3'-fluoro-[2-(3)H]-, 3'-fluoro-[2-(2)H/(3)H]-, 3'-chloro-[2-(3)H]-, and 3'-chloro-[2-(2)H/(3)H]-L-tyrosine, and also L-phenylalanine, i.e. 2'-fluoro-[(3S)-(3)H]-, 2'-fluoro-[(3S)-(2)H/(3) H]-, 2'-chloro-[(3S)-(3)H]-, 2'-chloro-[(3S)-(2)H/(3)H]-, 4'-chloro-[(3S)-(3)H]-, and 4'-chloro-[(3S)-(2)H/(3)H]-L-phenylalanine were synthesized using enzymatic methods. Isotopomers of L-tryptophan were synthesized by coupling of halogenated indoles with S-methyl-L-cysteine carried out in deuteriated or tritiated incubation media. Labeled halogenated derivatives of L-tyrosine were obtained by the enzymatically supported exchange between halogenated L-tyrosine and isotopic water. Labeled halogenated isotopologues of L-Phe were synthesized by the enzymatic addition of ammonia to halogenated cinnamic acid. As a source of hydrogen tritiated water (HTO) and heavy water (D2O) with addition of HTO were used. Copyright © 2015 John Wiley & Sons, Ltd.

PKU: high plasma phenylalanine concentrations are associated with increased prevalence of mood swings.

PubMed

Anjema, Karen; van Rijn, Margreet; Verkerk, Paul H; Burgerhof, Johannes G M; Heiner-Fokkema, M Rebecca; van Spronsen, Francjan J

2011-11-01

In phenylketonuria, knowledge about the relation between behavior and plasma phenylalanine is scarce. The aim of this study was to determine whether high phenylalanine is associated with disturbed behavior noticed by the patient and or close environment (parents or partners). 48 early treated PKU patients (median age 8.5, range 0-35 years) participated (median phenylalanine concentration in total sample 277 (range 89-1171) μmol/l; and in patients <12 years 238 (range 89-521) μmol/l). After sending blood samples, patients or close environment were interviewed with a standardized questionnaire whether they noticed hyperactivity, annoying behavior, mood swings and introvert or extravert behavior. The interviewer as well as the respondents were blinded with regard to the phenylalanine concentration. Patients reported less deviant behavior compared to close environment. Mood swings were positively associated with phenylalanine concentrations in the total group (P=0.039) and patients <12 years (P=0.042). The relationships between temporary high phenylalanine concentrations and hyperactivity, annoying behavior, introvert and extravert behavior were not statistically significant. there is a positive association between phenylalanine concentrations and mood swings. Copyright © 2011 Elsevier Inc. All rights reserved.

Antagonism of stress-induced analgesia by D-phenylalanine, an anti-enkephalinase.

PubMed

Bodnar, R J; Lattner, M; Wallace, M M

1980-12-01

Methionine- and leucine-enkephalin produce mild and transient analgesic effects, presumably because of enzymatic degradation. Administration of high (250 mg/kg) doses of D-phenylalanine retards the degradation process and elicits analgesia which is reversed by naloxone and which summates with electroacupuncture analgesia. The present study evaluated D-phenylalanine's dose-dependent effects upon a non-opioid analgesic treatment, cold-water swims (CWS), and compared this with morphine. following determination of flinch-jump baselines, three groups of rats received respectively either 25, 50 or 100 mg/kg of D-phenylalanine intraperitoneally in three conditions: alone, with CWS (2 degrees C for 3.5 min), and with morphine (5 mg/kg, SC). Parallel controls with saline were also tested. Simultaneous exposure with each minimally analgesic dose of D-phenylalanine reduced significantly the analgesic, but not hypothermic effects of CWS. By contrast, morphine analgesia was unaffected by D-phenylalanine. These data provide further support that different pain-inhibitory systems mediate CWS and morphine analgesia and suggest that activation of one system is capable of exerting collateral inhibition upon the other.

Simultaneous and selective decarboxylation of L-serine and deamination of L-phenylalanine in an amino acid mixture--a means of separating amino acids for synthesizing biobased chemicals.

PubMed

Teng, Yinglai; Scott, Elinor L; Witte-van Dijk, Susan C M; Sanders, Johan P M

2016-01-25

Amino acids (AAs) obtained from the hydrolysis of biomass-derived proteins are interesting feedstocks for the chemical industry. They can be prepared from the byproduct of biofuel production and agricultural wastes. They are rich in functionalities needed in petrochemicals, providing the opportunity to save energy, reagents, and process steps. However, their separation is required before they can be applied for further applications. Electrodialysis (ED) is a promising separation method, but its efficiency needs to be improved when separating AAs with similar isoelectric points. Thus, specific conversions are required to form product with different charges. Here we studied the enzymatic conversions which can be used as a means to aid the ED separation of neutral AAs. A model mixture containing L-serine, L-phenylalanine and L-methionine was used. The reactions of L-serine decarboxylase and L-phenylalanine ammonia-lyase were employed to specifically convert serine and phenylalanine into ethanolamine and trans-cinnamic acid. At the isoelectric point of methionine (pH 5.74), the charge of ethanolamine and trans-cinnamic acid are +1 and -1, therefore facilitating potential separation into three different streams by electrodialysis. Here the enzyme kinetics, specificity, inhibition and the operational stabilities were studied, showing that both enzymes can be applied simultaneously to aid the ED separation of neutral AAs. Copyright © 2015 Elsevier B.V. All rights reserved.

Relationships between phenylalanine levels, intelligence and socioeconomic status of patients with phenylketonuria.

PubMed

Castro, Isabel Pimenta Spínola; Borges, Juliana Martins; Chagas, Heloísa Alves; Tibúrcio, Jacqueline; Starling, Ana Lúcia Pimenta; Aguiar, Marcos José Burle de

2012-07-01

To assess intelligence and its relationship with blood phenylalanine concentrations and socioeconomic status in patients with phenylketonuria after 6 to 12 years of treatment. Sixty-three children were classified according to phenylalanine levels and socioeconomic status and assessed using the Wechsler Intelligence Scale for Children. The Statistical Package for the Social Sciences (SPSS) was used to analyze phenylalanine; ANOVA was used to analyze intelligence quotients (IQ) and phenylalanine levels; and ordinal logistic regression was used to analyze the likelihood of higher IQ. The overall IQ scores of 90.5% of the children were within a range from borderline intellectual deficiency to very high intelligence; for verbal IQ this proportion was 96.8% and 92.1% had performance IQ scores within this band. The categories from low to upper-medium socioeconomic status contained 98.4% of patients' families. The likelihood of having medium to high IQ was 4.29 times greater for children with good phenylalanine control and 4.03 greater for those from higher socioeconomic strata. Treatment prevented mental retardation in 90.5% of the patients. Control of phenylalanine levels and higher socioeconomic status were associated with higher IQ scores.

Determination of Phenylalanine and Tyrosine by High Performance Liquid Chromatography-Tandem Mass Spectrometry.

PubMed

Peat, Judy; Garg, Uttam

2016-01-01

Hyperphenylalaninemia/phenylketonuria (PKU) is one of the most common inborn errors of amino acid metabolism affecting about 1:15,000 infants in the United States. PKU is an autosomal recessive disorder that if untreated results in mental retardation. The most common cause of PKU is deficiency of the enzyme phenylalanine hydroxylase that converts phenylalanine to tyrosine. Tyrosine deficiency results in impaired synthesis of catecholamines and thyroxine. Less commonly, it can result from defects in the synthesis or regeneration of tetrahydrobiopterin (BH4), an essential cofactor for the enzyme phenylalanine hydroxylase. Increased phenylalanine and decreased tyrosine in blood are used in the diagnosis and follow-up of patients with PKU. LC/MS/MS method is described for the quantification of phenylalanine and tyrosine.

On the asymmetric adsorption of phenylalanine enantiomers by kaolin.

NASA Technical Reports Server (NTRS)

Bonner, W. A.; Flores, J.

1973-01-01

The attempt is described to verify a recent report that kaolin adsorbs D- and L-phenylalanine enantiomers to different extents from aqueous solutions at both pH 5.8 and pH 2. No evidence whatsoever could be found for the differential adsorption of D- versus L-phenylalanine by kaolin from either pH 6 or pH 2 solutions.

The role of competition in the phase shift to dominance of the zoanthid Palythoa cf. variabilis on coral reefs.

PubMed

Cruz, Igor Cristino Silva; Meira, Verena Henschen; de Kikuchi, Ruy Kenji Papa; Creed, Joel Christopher

2016-04-01

Phase shift phenomena are becoming increasingly common. However, they are also opportunities to better understand how communities are structured. In Southwest Atlantic coral reefs, a shift to the zoanthid Palythoa cf. variabilis dominance has been described. To test if competition drove this process, we carried out a manipulative experiment with three coral species. To estimate the natural frequency of encounters we assess the relationship between the proportion of encounters and this zoanthids coverage. The contact causes necrosis in 78% of coral colonies (6.47 ± SD 7.92 cm(2)) in 118 days. We found a logarithmic relationship between the proportion of these encounters and the cover of P. cf. variabilis, where 5.5% coverage of this zoanthid is enough to put 50% of coral colonies in contact, increasing their partial mortality. We demonstrate that zoanthid coverage increase followed by coral mortality increase will reduce coral cover and that competition drives the phase shift process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis of CuPF6 -(S)-BINAP loaded resin and its enantioselectivity toward phenylalanine enantiomers.

PubMed

Liu, Xiong; Zhou, Wenqi; Xu, Longqi

2017-09-01

A type of resin-anchored CuPF 6 -(S)-BINAP was synthesized and identified. The PS-CuPF 6 -(S)-BINAP resin was used to adsorb the phenylalanine enantiomers. The results showed that the adsorption capacity of PS-CuPF 6 -(S)-BINAP resin toward L-phenylalanine was higher than that of resin toward D-phenylalanine. PS-CuPF 6 -(S)-BINAP resin exhibited good enantioselectivity toward L-phenylalanine and D-phenylalanine. The influence of phenylalanine concentration, pH, adsorption time, and temperature on the enantioselectivity of the resin were investigated. The results showed that the enantioselectivity of the resin increased with increasing the phenylalanine concentration, pH, and adsorption time, while it decreased with an increase in temperature. The causes for these influences are discussed. The highest enantioselectivity (α = 2.81) was obtained when the condition of phenylalanine concentration was 0.05 mmol/mL, pH was 8, adsorption time was 12 h, and temperature 5°C. The desorption test for removing D/L-phenylalanine on PS-CuPF 6 -(S)-BINAP resin was also investigated. The desorption ratios of D-phenylalanine and L-phenylalanine at pH of 1 were 95.7% and 94.3%, respectively. This result indicated that the PS-CuPF 6 -(S)-BINAP resin could be regenerated by shaking with an acidic solution. The reusability of the PS-CuPF 6 -(S)-BINAP resin was also assessed and the resin exhibited considerable reusability. © 2017 Wiley Periodicals, Inc.

Dl-phenylalanine in depressed patients: an open study.

PubMed

Beckmann, H; Strauss, M A; Ludolph, E

1977-01-01

In an open study dl-phenylalanine in doses from 75-200 mg/day was administered to 20 depressed patients for 20 days. Patients were classified according to the International Classification of Diseases (ICD). The AMP system, the Hamilton depression scale and the von Zerssen self rating questionnaire were used for documentation of psychopathological, neurologic and somatic changes. In addition a global clinical impression was agreed upon by experienced psychiatrists. At the end of the trial 12 patients (8 with complete, 4 with good response) could be discharged without any further treatment. 4 patients with partially untypical depressions experienced mild to moderate responses, whereas 4 patients did not respond at all to the phenylalanine administration. Depressive "core symptoms" as depressed mood, retardation and/or agitation were preferentially, anxiety and sleep disturbances moderately and hypochondriasis and compulsiveness were not influenced. It is concluded that dl-phenylalanine might have substantial antidepressant properties and that further more controlled investigations are warranted.

D-phenylalanine: a putative enkephalinase inhibitor studied in a primate acute pain model.

PubMed

Halpern, L M; Dong, W K

1986-02-01

D-Phenylalanine, along with morphine, acetylsalicylic acid and zomepirac sodium were evaluated for their antinociceptive actions in monkeys (M. fascicularis) trained to autoregulate nociceptive stimulation using a discrete-trials, aversive-threshold paradigm. Morphine sulfate produced dose-related increases in aversive threshold which were reversible after administration of naloxone (12.5 or 25 micrograms/kg i.m.). D-Phenylalanine (500 mg/kg p.o.) produced a small increase in aversive threshold which was not statistically significant and not naloxone reversible. Acetylsalicylic acid (200 mg/kg p.o.) but not zomepirac sodium (200 mg/kg p.o.) in combination with D-phenylalanine (500 mg/kg) produced a small statistically significant increase in aversive threshold. Our results argue against the hypothesis that D-phenylalanine is responsible for increasing aversive thresholds via opiate receptor mechanisms involving increased activity of enkephalins at synaptic loci. Previous studies by others in rats and mice showed that D-phenylalanine and acetylsalicylic acid produced increases in nociceptive thresholds which were naloxone reversible. Our failure to find opiate receptor mediated analgesia in a primate model with demonstrated opiate receptor selectivity and sensitivity is discussed in terms of previous basic and clinical research indicating an analgesic role for D-phenylalanine. Possible species difference in drug action is discussed in terms of inhibition by D-phenylalanine of carboxy-peptidase-like enkephalin processing enzymes as well as inhibition of carboxypeptidase-like enkephalin degrading enzymes.

Container volume and subirrigation schedule influence Quercus variabilis seedling growth and nutrient status in the nursery and field

Treesearch

Qiaoyu Sun; R. Kasten Dumroese; Yong Liu

2018-01-01

Container volume and irrigation management affect seedling growth in the nursery and field. We evaluated the effects of container volumes (D40, 656 ml; D60, 983 ml) and subirrigation schedules (85%, 75%, 65%, and 55% of 100% total substrate moisture content, TSMC) on seedling growth in a greenhouse and outplanting performance of Chinese cork oak (Quercus variabilis...

Ammonia blood test

MedlinePlus

Serum ammonia; Encephalopathy - ammonia; Cirrhosis - ammonia; Liver failure - ammonia ... Ammonia (NH3) is produced by cells throughout the body, especially the intestines, liver, and kidneys. Most of ...

Induction of Maltose Release by Light in the Endosymbiont Chlorella variabilis of Paramecium bursaria.

PubMed

Shibata, Aika; Takahashi, Fumio; Kasahara, Masahiro; Imamura, Nobutaka

2016-11-01

The endosymbiotic green algae of Paramecium bursaria are known to release a photosynthate to the host cells. The endosymbiont Chlorella variabilis F36-ZK isolated in Japan releases maltose under acidic conditions, and such release requires both light and low pH. However, whether photosynthate release is due to light sensing by photoreceptors or is merely a consequence of active photosynthesis is unclear. Herein, we studied the effect of light on maltose release from C. variabilis F36-ZK; we measured maltose release using a combination of 1-phenyl-3-methyl-5-pyrazolone derivative and 14 C-tracer methods. Blue (450nm) or red (around 600nm) light was most effective to stimulate maltose release. This suggests that the photosynthetic pathway probably participates in maltose release, because the effective wavelength corresponds to the absorption spectrum of chlorophyll. Furthermore, maltose release was slightly affected by addition of a photosynthetic inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, but was abolished by another inhibitor of photosynthesis, 2,5-dibromo-6-isopropyl-3-methyl-1,4-benzoquinone, suggesting that electron flow through photosystem I may be more involved in maltose release. Interestingly, starving F36-ZK cells cultured under prolonged dark conditions did not release maltose but retained their photosynthetic capacity. Our results thus show that maltose release is regulated by light and cellular conditions in endosymbiotic Chlorella. Copyright © 2016. Published by Elsevier GmbH.

Complete mitochondrial DNA sequences of the Victoria tilapia (Oreochromis variabilis) and Redbelly Tilapia (Tilapia zilli): genome characterization and phylogeny analysis.

PubMed

Kinaro, Zachary Omambia; Xue, Liangyi; Volatiana, Josies Ancella

2016-07-01

The Cichlid fishes have played an important role in evolutionary biology, population studies and aquaculture industry with East African species representing a model suited for studying adaptive radiation and speciation for cichlid genome projects in which closely related genomes are fast emerging presenting questions on phenotype-genotype relations. The complete mitochondrial genomes presented here are for two closely related but eco-morphologically distinct Lake Victoria basin cichlids, Oreochromis variabilis, an endangered native species and Tilapia zilli, an invasive species, both of which are important economic fishes in local areas. The complete mitochondrial genomes determined for O. variabilis and T. zilli are 16 626 and 16,619 bp, respectively. Both the mitogenomes contain 13 protein-coding genes, 22 tRNAs, 2 rRNAs and a non-coding control region, which are typical of vertebrate mitogenomes. Phylogenetic analyses of the two species revealed that though both lie within family Cichlidae, they are remotely related.

Polymorphism and Modulation of Para-Substituted l-Phenylalanine.

PubMed

Sögütoglu, Leyla-Cann; Lutz, Martin; Meekes, Hugo; de Gelder, René; Vlieg, Elias

2017-12-06

The crystal structure of para -methyl-l-phenylalanine at 230 K resembles that of the para-fluorinated analogue from the literature but is commensurately modulated with seven molecules in the asymmetric unit ( Z ' = 7). At 100 K, the superstructure loses its modulation, leading to a unit cell with Z ' = 1, with clear disorder in the phenyl ring orientations. The methyl-substituent in para -methyl-l-phenylalanine has, in contrast to fluorine, no polar interactions with protons of neighboring molecules, which might allow for the well-defined modulation of the crystal structure at 230 K.

Bioproduction of L-Aspartic Acid and Cinnamic Acid by L-Aspartate Ammonia Lyase from Pseudomonas aeruginosa PAO1.

PubMed

Patel, Arti T; Akhani, Rekha C; Patel, Manisha J; Dedania, Samir R; Patel, Darshan H

2017-06-01

Aspartase (L-aspartate ammonia lyase, EC 4.3.1.1) catalyses the reversible amination and deamination of L-aspartic acid to fumaric acid which can be used to produce important biochemical. In this study, we have explored the characteristics of aspartase from Pseudomonas aeruginosa PAO1 (PA-AspA). To overproduce PA-AspA, the 1425-bp gene was introduced in Escherichia coli BL21 and purified. A 51.0-kDa protein was observed as a homogenous purified protein on SDS-PAGE. The enzyme was optimally active at pH 8.0 and 35 °C. PA-AspA has retained 56% activity after 7 days of incubation at 35 °C, which displays the hyperthermostablility characteristics of the enzyme. PA-AspA is activated in the presence of metal ions and Mg2+ is found to be most effective. Among the substrates tested for specificity of PA-AspA, L-phenylalanine (38.35 ± 2.68) showed the highest specific activity followed by L-aspartic acid (31.21 ± 3.31) and fumarate (5.42 ± 2.94). K m values for L-phenylalanine, L-aspartic acid and fumarate were 1.71 mM, 0.346 μM and 2 M, respectively. The catalytic efficiency (k cat /K m ) for L-aspartic acid (14.18 s -1  mM -1 ) was higher than that for L-phenylalanine (4.65 s -1  mM -1 ). For bioconversion, from an initial concentration of 1000 mM of fumarate and 30 mM of L-phenylalanine, PA-AspA was found to convert 395.31 μM L-aspartic acid and 3.47 mM cinnamic acid, respectively.

Enantioselective binding of L, D-phenylalanine to ct DNA

NASA Astrophysics Data System (ADS)

Zhang, Lijin; Xu, Jianhua; Huang, Yan; Min, Shungeng

2009-10-01

The enantioselective binding of L, D-phenylalanine to calf thymus DNA was studied by absorption, circular dichroism, fluorescence quenching, viscosity, salt effect and emission experiments. The results obtained from absorption, circular dichroism, fluorescence quenching and viscosity experiments excluded the intercalative binding and salt effect experiments did not support electrostatic binding. So the binding of L, D-phenylalanine to ct DNA should be groove binding. Furthermore, the emission spectra revealed that the binding is enantioselective.

Enantioselective binding of L,D-phenylalanine to ct DNA.

PubMed

Zhang, Lijin; Xu, Jianhua; Huang, Yan; Min, Shungeng

2009-10-15

The enantioselective binding of L,D-phenylalanine to calf thymus DNA was studied by absorption, circular dichroism, fluorescence quenching, viscosity, salt effect and emission experiments. The results obtained from absorption, circular dichroism, fluorescence quenching and viscosity experiments excluded the intercalative binding and salt effect experiments did not support electrostatic binding. So the binding of l,d-phenylalanine to ct DNA should be groove binding. Furthermore, the emission spectra revealed that the binding is enantioselective.

21 CFR 582.5590 - Phenylalanine.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Phenylalanine. 582.5590 Section 582.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

21 CFR 582.5590 - Phenylalanine.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Phenylalanine. 582.5590 Section 582.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

21 CFR 582.5590 - Phenylalanine.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Phenylalanine. 582.5590 Section 582.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

21 CFR 582.5590 - Phenylalanine.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Phenylalanine. 582.5590 Section 582.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

21 CFR 582.5590 - Phenylalanine.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Phenylalanine. 582.5590 Section 582.5590 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

Preparation of l-phenylalanine-imprinted solid-phase extraction sorbent by Pickering emulsion polymerization and the selective enrichment of l-phenylalanine from human urine.

PubMed

Li, Ji; Hu, Xiaoling; Guan, Ping; Zhang, Xiaoyan; Qian, Liwei; Zhang, Nan; Du, Chunbao; Song, Renyuan

2016-05-01

A novel l-phenylalanine molecularly imprinted solid-phase extraction sorbent was synthesized by the combination of Pickering emulsion polymerization and ion-pair dummy template imprinting. Compared to other polymerization methods, the molecularly imprinted polymers thus prepared exhibit a high specific surface, large pore diameter, and appropriate particle size. The key parameters for solid-phase extraction were optimized, and the result indicated that the molecularly imprinted polymer thus prepared exhibits a good recovery of 98.9% for l-phenylalanine. Under the optimized conditions of the procedure, an analytical method for l-phenylalanine was well established. By comparing the performance of the molecularly imprinted polymer and a commercial reverse-phase silica gel, the obtained molecularly imprinted polymer as an solid-phase extraction sorbent is more suitable, exhibiting high precision (relative standard deviation 3.2%, n = 4) and a low limit of detection (60.0 ± 1.9 nmol·L(-1) ) for the isolation of l-phenylalanine. Based on these results, the combination of the Pickering emulsion polymerization and ion-pair dummy template imprinting is effective for preparing selective solid-phase extraction sorbents for the separation of amino acids and organic acids from complex biological samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enzymological Basis for Growth Inhibition by l-Phenylalanine in the Cyanobacterium Synechocystis sp. 29108

PubMed Central

Hall, Geraldine C.; Jensen, Roy A.

1980-01-01

The pattern of allosteric control in the biosynthetic pathway for aromatic amino acids provides a basis to explain vulnerability to growth inhibition by l-phenylalanine (0.2 mM or greater) in the unicellular cyanobacterium Synechocystis sp. 29108. We attribute growth inhibition to the hypersensitivity of 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase to feedback inhibition by l-phenylalanine. Hyperregulation of this initial enzyme of aromatic biosynthesis depletes the supply of precursors needed for biosynthesis of l-tyrosine and l-tryptophan. Consistent with this mechanism is the total reversal of phenylalanine inhibition by a combination of tyrosine and tryptophan. Inhibited cultures also contained decreased levels of phycocyanin pigments, a characteristic previously correlated with amino acid starvation in cyanobacteria. l-Phenylalanine is a potent noncompetitive inhibitor (with both substrates) of 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase, whereas l-tyrosine is a very weak inhibitor. Prephenate dehydratase also displays allosteric sensitivity to phenylalanine (inhibition) and to tyrosine (activation). Both 2-fluoro and 4-fluoro derivatives of phenylalanine were potent analog antimetabolites, and these were used in addition to l-phenylalanine as selective agents for resistant mutants. Mutants were isolated which excreted both phenylalanine and tyrosine, the consequence of an altered 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase no longer sensitive to feedback inhibition. Simultaneous insensitivity to l-tyrosine suggests that l-tyrosine acts as a weak analog mimic of l-phenylalanine at a common binding site. Prephenate dehydratase in the regulatory mutants was unaltered. Surprisingly, in view of the lack of regulation in the tyrosine branchlet of the pathway, such mutants excrete more phenylalanine than tyrosine, indicating that l-tyrosine activation dominates l-phenylalanine inhibition of prephenate dehydratase in vivo. In mutant Phe r19 the

Contact Irritancy and Toxicity of Permethrin-Treated Clothing for Ixodes scapularis, Amblyomma americanum, and Dermacentor variabilis Ticks (Acari: Ixodidae).

PubMed

Prose, Robert; Breuner, Nicole E; Johnson, Tammi L; Eisen, Rebecca J; Eisen, Lars

2018-05-24

Clothing treated with the pyrethroid permethrin is available in the United States as consumer products to prevent tick bites. We used tick bioassays to quantify contact irritancy and toxicity of permethrin-treated clothing for three important tick vectors of human pathogens: the blacklegged tick, Ixodes scapularis Say (Acari: Ixodidae); the lone star tick, Amblyomma americanum (L.) (Acari: Ixodidae); and the American dog tick, Dermacentor variabilis (Say) (Acari: Ixodidae). We first demonstrated that field-collected I. scapularis nymphs from Minnesota were as susceptible as laboratory-reared nymphs to a permethrin-treated textile. Field ticks examined in bioassays on the same day they were collected displayed contact irritancy by actively dislodging from a vertically oriented permethrin-treated textile, and a forced 1-min exposure resulted in all ticks being unable to move normally, thus posing no more than minimal risk of biting, 1 h after contact with the treated textile. Moreover, we documented lack of normal movement for laboratory-reared I. scapularis nymphs by 1 h after contact for 1 min with a wide range of permethrin-treated clothing, including garments made from cotton, synthetic materials, and blends. A comparison of the impact of a permethrin-treated textile across tick species and life stages revealed the strongest effect on I. scapularis nymphs (0% with normal movement 1 h after a 1-min exposure), followed by A. americanum nymphs (14.0%), I. scapularis females (38.0%), D. variabilis females (82.0%), and A. americanum females (98.0%). Loss of normal movement for all ticks 1 h after contact with the permethrin-treated textile required exposures of 1 min for I. scapularis nymphs, 2 min for A. americanum nymphs, and 5 min for female I. scapularis, D. variabilis, and A. americanum ticks. We conclude that use of permethrin-treated clothing shows promise to prevent bites by medically important ticks. Further research needs are discussed.

Interaction of L-Phenylalanine with a Phospholipid Monolayer at the Water-Air Interface.

PubMed

Griffith, Elizabeth C; Perkins, Russell J; Telesford, Dana-Marie; Adams, Ellen M; Cwiklik, Lukasz; Allen, Heather C; Roeselová, Martina; Vaida, Veronica

2015-07-23

The interaction of L-phenylalanine with a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayer at the air-water interface was explored using a combination of experimental techniques and molecular dynamics (MD) simulations. By means of Langmuir trough methods and Brewster angle microscopy, L-phenylalanine was shown to significantly alter the interfacial tension and the surface domain morphology of the DPPC film. In addition, confocal microscopy was used to explore the aggregation state of L-phenylalanine in the bulk aqueous phase. Finally, MD simulations were performed to gain molecular-level information on the interactions of L-phenylalanine and DPPC at the interface. Taken together, these results show that L-phenylalanine intercalates into a DPPC film at the air-water interface, thereby affecting the surface tension, phase morphology, and ordering of the DPPC film. The results are discussed in the context of biological systems and the mechanism of diseases such as phenylketonuria.

Hidden overflow pathway to L-phenylalanine in Pseudomonas aeruginosa.

PubMed Central

Fiske, M J; Whitaker, R J; Jensen, R A

1983-01-01

Pseudomonas aeruginosa is representative of a large group of pseudomonad bacteria that possess coexisting alternative pathways to L-phenylalanine (as well as to L-tyrosine). These multiple flow routes to aromatic end products apparently account for the inordinate resistance of P. aeruginosa to end product analogs. Manipulation of carbon source nutrition produced a physiological state of sensitivity to p-fluorophenylalanine and m-fluorophenylalanine, each a specific antimetabolite of L-phenylalanine. Analog-resistant mutants obtained fell into two classes. One type lacked feedback sensitivity of prephenate dehydratase and was the most dramatic excretor of L-phenylalanine. The presence of L-tyrosine curbed phenylalanine excretion to one-third, a finding explained by potent early-pathway regulation of 3-deoxy-D-arabinoheptulosonate 7-phosphate (DAHP) synthase-Tyr (a DAHP synthase subject to allosteric inhibition by L-tyrosine). The second class of regulatory mutants possessed a completely feedback-resistant DAHP synthase-Tyr, the major species (greater than 90%) of two isozymes. Deregulation of DAHP synthase-Tyr resulted in the escape of most chorismate molecules produced into an unregulated overflow route consisting of chorismate mutase (monofunctional), prephenate aminotransferase, and arogenate dehydratase. In the wild type the operation of the overflow pathway is restrained by factors that restrict early-pathway flux. These factors include the highly potent feedback control of DAHP synthase isozymes by end products as well as the strikingly variable abilities of different carbon source nutrients to supply the aromatic pathway with beginning substrates. Even in the wild type, where all allosteric regulation in intact, some phenylalanine overflow was found on glucose-based medium, but not on fructose-based medium. This carbon source-dependent difference was much more exaggerated in each class of regulatory mutants. PMID:6132913

Amino Acid Synthesis in Photosynthesizing Spinach Cells: Effects of Ammonia on Pool Sizes and Rates of Labeling from 14CO 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larsen, Peder Olesen; Cornwell, Karen L.; Gee, Sherry L.

1981-08-01

In this paper, isolated cells from leaves of Spinacia oleracea have been maintained in a state capable of high rates of photosynthetic CO 2 fixation for more than 60 hours. The incorporation of 14CO 2 under saturating CO 2 conditions into carbohydrates, carboxylic acids, and amino acids, and the effect of ammonia on this incorporation have been studied. Total incorporation, specific radioactivity, and pool size have been determined as a function of time for most of the protein amino acids and for γ-aminobutyric acid. The measurements of specific radio-activities and of the approaches to 14C “saturation” of some amino acidsmore » indicate the presence and relative sizes of metabolically active and passive pools of these amino acids. Added ammonia decreased carbon fixation into carbohydrates and increased fixation into carboxylic acids and amino acids. Different amino acids were, however, affected in different and highly specific ways. Ammonia caused large stimulatory effects in incorporation of 14C into glutamine (a factor of 21), aspartate, asparagine, valine, alanine, arginine, and histidine. No effect or slight decreases were seen in glycine, serine, phenylalanine, and tyrosine labeling. In the case of glutamate, 14C labeling decreased, but specific radioactivity increased. The production of labeled γ-aminobutyric acid was virtually stopped by ammonia. The results indicate that added ammonia stimulates the reactions mediated by pyruvate kinase and phosphoenolpyruvate carboxylase, as seen with other plant systems. Finally, the data on the effects of added ammonia on total labeling, pool sizes, and specific radioactivities of several amino acids provides a number of indications about the intracellular sites of principal synthesis from carbon skeletons of these amino acids and the selective nature of effects of increased intracellular ammonia concentration on such synthesis.« less

The genetic incorporation of p-azidomethyl-l-phenylalanine into proteins in yeast.

PubMed

Supekova, Lubica; Zambaldo, Claudio; Choi, Seihyun; Lim, Reyna; Luo, Xiaozhou; Kazane, Stephanie A; Young, Travis S; Schultz, Peter G

2018-05-15

The noncanonical amino acid p-azidomethyl-l-phenylalanine can be genetically incorporated into proteins in bacteria, and has been used both as a spectroscopic probe and for the selective modification of proteins by alkynes using click chemistry. Here we report identification of Escherichia coli tyrosyl tRNA synthetase mutants that allow incorporation of p-azidomethyl-l-phenylalanine into proteins in yeast. When expressed together with the cognate E. coli tRNA CUA Tyr , the new mutant tyrosyl tRNA synthetases directed robust incorporation of p-azidomethyl-l-phenylalanine into a model protein, human superoxide dismutase, in response to the UAG amber nonsense codon. Mass spectrometry analysis of purified superoxide dismutase proteins confirmed the efficient site-specific incorporation of p-azidomethyl-l-phenylalanine. This work provides an additional tool for the selective modification of proteins in eukaryotic cells. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electrospray ionization mass spectrometry of mixtures of triterpene glycosides with L-phenylalanine

NASA Astrophysics Data System (ADS)

Lekar, A. V.; Vetrova, E. V.; Borisenko, N. I.; Yakovishin, L. A.; Grishkovets, V. I.; Borisenko, S. N.

2011-09-01

Electrospray-ionization mass spectrometry (ESI-MS) was used to investigate for the first time the molecular complexation of L-phenylalanine with hederagenin 3-O- α- L-rhamnopyranosyl-(1 → 2)-O- α- L-arabinopyranoside ( α-hederin) and its 28-O- α- L-rhamnopyranosyl-(1 → 4)-O-β- D-glucopyranosyl-(1 → 6)-O-β- D-glucopyranosyl ester (hederasaponin C). The glycoside/ L-phenylalanine complexes with a 1:1 molar ratio turned out to be most stable. The structures of the glycosides and L-phenylalanine have been concluded to have an impact on the complexation process.

L-Phenylalanine Transport in Saccharomyces cerevisiae: Participation of GAP1, BAP2, and AGP1

PubMed Central

Sáenz, Daniel A.; Chianelli, Mónica S.; Stella, Carlos A.

2014-01-01

We focused on the participation of GAP1, BAP2, and AGP1 in L-phenylalanine transport in yeast. In order to study the physiological functions of GAP1, BAP2, and AGP1 in L-phenylalanine transport, we examined the kinetics, substrate specificity, and regulation of these systems, employing isogenic haploid strains with the respective genes disrupted individually and in combination. During the characterization of phenylalanine transport, we noted important regulatory phenomena associated with these systems. Our results show that Agp1p is the major transporter of the phenylalanine in a gap1 strain growing in synthetic media with leucine present as an inducer. In a wild type strain grown in the presence of leucine, when ammonium ion was the nitrogen source, Bap2p is the principal phenylalanine carrier. PMID:24701347

Neuropsychological assessment among children and adolescents with phenylketonuria and hyperphenylalaninemia and its relationship with plasma phenylalanine levels.

PubMed

González García, María B; Conde-Guzon, Pablo; Alcalde Martín, Carlos; Conde-Guzon, María J; Velasco Zúñiga, Roberto

2017-06-01

Although with early treatment phenylketonuria patients may have average intelligence levels, it is important to optimize the nutritional management to maintain adequate phenylalanine levels, so that patients can develop their intellectal potential free of abnormalities in their daily activities due to deficits of cognitive executive functions. This study presents a series of 26 patients, diagnosed and treated early, who underwent a psychometric evaluation together with phenylalanine determinations along their lives, and at the time of doing the tests. A trend is observed towards a reverse relationship between IQ and concurrent phenylalanine concentration, phenylalanine median and phenylalanine/tyrosine ratio. Likewise, a trend towards a negative relationship is observed between executive functions and concurrent phenylalanine values along patients' lives. Sociedad Argentina de Pediatría.

[Enhanced resistance to emotional stress through the use of D-phenylalanine].

PubMed

Iumatov, E A; Sarychev, E I; Kozlovskiĭ, I I; Mineeva, M F; Demidov, V M; Morozov, I S; Kozlovskaia, M M

1991-01-01

Stress-protective action was studied of D-phenylalanine, having an ability to decrease destruction of endogenic enkefalins. In the experiments stability of the experimental (receiving D-phenylalanine) and control groups of male rats of August line to emotional stress was compared in conditions of immobilization stress by parameters of animals survival rate, adrenal glands hypertrophy development, involution of thymus, pathologic changes in lungs (abscesses development), ulcero-dystrophic disturbances in stomach, and also the activity and kinetic properties of enzyme tyrosin-hydroxylase in the hypothalamus were determined. It was shown that by several of the mentioned physiological parameters the D-phenylalanine significantly increased the animals stability to the emotional stress and decreased tyrosinhydroxylase activity which participates in activation of katecholaminergic processes.

Immobilization of Phenylalanine Ammonia‐Lyase on Single‐Walled Carbon Nanotubes for Stereoselective Biotransformations in Batch and Continuous‐Flow Modes

PubMed Central

Bartha‐Vári, Judith H.; Toşa, Monica I.; Irimie, Florin‐Dan; Weiser, Diána; Boros, Zoltán; Vértessy, Beáta G.

2015-01-01

Abstract Carboxylated single‐walled carbon nanotubes (SwCNTCOOH) were used as a support for the covalent immobilization of phenylalanine ammonia‐lyase (PAL) from parsley by two different methods. The nanostructured biocatalysts (SwCNTCOOH‐PALI and SwCNTCOOH‐PALII) with low diffusional limitation were tested in the batch‐mode kinetic resolution of racemic 2‐amino‐3‐(thiophen‐2‐yl)propanoic acid (1) to yield a mixture of (R)‐1 and (E)‐3‐(thiophen‐2‐yl)acrylic acid (2) and in ammonia addition to 2 to yield enantiopure (S)‐1. SwCNTCOOH‐PALII was a stable biocatalyst (>90 % of the original activity remained after six cycles with 1 and after three cycles in 6 m NH3 with 2). The study of ammonia addition to 2 in a continuous‐flow microreactor filled with SwCNTCOOH‐PALII (2 m NH3, pH 10.0, 15 bar) between 30–80 °C indicated no significant loss of activity over 72 h up to 60 °C. SwCNTCOOH‐PALII in the continuous‐flow system at 30 °C was more productive (specific reaction rate, r flow=2.39 μmol min−1 g−1) than in the batch reaction (r batch=1.34 μmol min−1 g−1). PMID:26925171

Rational design of aminoacyl-tRNA synthetase specific for p-acetyl-L-phenylalanine.

PubMed

Sun, Renhua; Zheng, Heng; Fang, Zhengzhi; Yao, Wenbing

2010-01-01

The Methanococcus jannaschii tRNA(Tyr)/tyrosyl-tRNA synthetase pair has been engineered to incorporate unnatural amino acids into proteins in Escherichia coli site-specifically. In order to add other unnatural amino acids into proteins by this approach, the amino acid binding site of M. jannaschii tyrosyl-tRNA synthetase need to be mutated. The crystal structures of M. jannaschii tyrosyl-tRNA synthetase and its mutations were determined, which provided an opportunity to design aminoacyl-tRNA synthetases specific for other unnatural amino acids. In our study, we attempted to design aminoacyl-tRNA synthetases being able to deliver p-acetyl-L-phenylalanine into proteins. p-Acetyl-L-phenylalanine was superimposed on tyrosyl in M. jannaschii tyrosyl-tRNA synthetase-tyrosine complex. Tyr32 needed to be changed to non-polar amino acid with shorter side chain, Val, Leu, Ile, Gly or Ala, in order to reduce steric clash and provide hydrophobic environment to acetyl on p-acetyl-L-phenylalanine. Asp158 and Ile159 would be changed to specific amino acids for the same reason. So we designed 60 aminoacyl-tRNA synthetases. Binding of these aminoacyl-tRNA synthetases with p-acetyl-L-phenylalanine indicated that only 15 of them turned out to be able to bind p-acetyl-L-phenylalanine with reasonable poses. Binding affinity computation proved that the mutation of Tyr32Leu and Asp158Gly benefited p-acetyl-L-phenylalanine binding. And two of the designed aminoacyl-tRNA synthetases had considerable binding affinities. They seemed to be very promising to be able to incorporate p-acetyl-L-phenylalanine into proteins in E. coli. The results show that the combination of homology modeling and molecular docking is a feasible method to filter inappropriate mutations in molecular design and point out beneficial mutations. Copyright 2009 Elsevier Inc. All rights reserved.

Ammonia Monitor

NASA Technical Reports Server (NTRS)

Sauer, Richard L. (Inventor); Akse, James R. (Inventor); Thompson, John O. (Inventor); Atwater, James E. (Inventor)

1999-01-01

Ammonia monitor and method of use are disclosed. A continuous, real-time determination of the concentration of ammonia in an aqueous process stream is possible over a wide dynamic range of concentrations. No reagents are required because pH is controlled by an in-line solid-phase base. Ammonia is selectively transported across a membrane from the process stream to an analytical stream to an analytical stream under pH control. The specific electrical conductance of the analytical stream is measured and used to determine the concentration of ammonia.

Isolation and Synthetic Diversification of Jadomycin 4-Amino-l-phenylalanine.

PubMed

Martinez-Farina, Camilo F; Robertson, Andrew W; Yin, Huimin; Monro, Susan; McFarland, Sherri A; Syvitski, Raymond T; Jakeman, David L

2015-06-26

Streptomyces venezuelae ISP5230 was grown in the presence of phenylalanine analogues to observe whether they could be incorporated into novel jadomycin structures. It was found that the bacteria successfully produced jadomycins incorporating 4-aminophenylalanine enantiomers. Upon isolation and characterization of jadomycin 4-amino-l-phenylalanine (1), it was synthetically derivatized, using activated succinimidyl esters, to yield a small jadomycin amide library. These are the first examples of oxazolone-ring-containing jadomycins that have incorporated an amino functionality subsequently used for derivatization.

Photoactive ligands probing the sweet taste receptor. Design and synthesis of highly potent diazirinyl D-phenylalanine derivatives.

PubMed

Masuda, Katsuyoshi; Koizumi, Ayako; Misaka, Takumi; Hatanaka, Yasumaru; Abe, Keiko; Tanaka, Takaharu; Ishiguro, Masaji; Hashimoto, Makoto

2010-02-01

Some D-amino acids such as d-tryptophan and D-phenylalanine are well known as naturally-occurring sweeteners. Photoreactive D-phenylalanine derivatives containing trifluoromethyldiazirinyl moiety at 3- or 4-position of phenylalanine, were designed as sweeteners for functional analysis with photoaffinity labeling. The trifluoromethyldiazirinyl D-phenylalanine derivatives were prepared effectively with chemo-enzymatic methods using L-amino acid oxidase and were found to have potent activity toward the human sweet taste receptor. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

The de novo engineering of pyrrolysyl-tRNA synthetase for genetic incorporation of L-phenylalanine and its derivatives.

PubMed

Wang, Yane-Shih; Russell, William K; Wang, Zhiyong; Wan, Wei; Dodd, Lindsey E; Pai, Pei-Jing; Russell, David H; Liu, Wenshe R

2011-03-01

Using evolved pyrrolysyl-tRNA synthetase-tRNA(CUA)(Pyl) pairs, L-phenylalanine, p-iodo-L-phenylalanine and p-bromo-L-phenylalanine have been genetically incorporated into proteins at amber mutation sites in E. coli.

Phenylalanine as a nitrogen source induces root growth and nitrogen-use efficiency in Populus × canescens.

PubMed

Jiao, Yu; Chen, Yinghao; Ma, Chaofeng; Qin, Jingjing; Nguyen, Thi Hong Nhung; Liu, Di; Gan, Honghao; Ding, Shen; Luo, Zhi-Bin

2018-01-01

To investigate the physiological responses of poplars to amino acids as sole nitrogen (N) sources, Populus × canescens (Ait.) Smith plants were supplied with one of three nitrogen fertilizers (NH4NO3, phenylalanine (Phe) or the mixture of NH4NO3 and Phe) in sand culture. A larger root system, and decreased leaf size and CO2 assimilation rate was observed in Phe- versus NH4NO3-treated poplars. Consistently, a greater root biomass and a decreased shoot growth were detected in Phe-supplied poplars. Decreased enzymatic activities of nitrate reductase (NR), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) and elevated activities of nitrite reductase (NiR), phenylalanine ammonia lyase (PAL), glutamine synthetase (GS) and asparagine synthase (AS) were found in Phe-treated roots. Accordingly, reduced concentrations of NH4+, NO3- and total N, and enhanced N-use efficiencies (NUEs) were detected in Phe-supplied poplars. Moreover, the transcript levels of putative Phe transporters ANT1 and ANT3 were upregulated, and the mRNA levels of NR, glutamine synthetase 2 (GS2), NADH-dependent glutamate synthase (NADH-GOGAT), GDH and asparagine synthetase 2 (ASN2) were downexpressed in Phe-treated roots and/or leaves. The 15N-labeled Phe was mainly allocated in the roots and only a small amount of 15N-Phe was translocated to poplar aerial parts. These results indicate that poplar roots can acquire Phe as an N source to support plant growth and that Phe-induced NUEs in the poplars are probably associated with NH4+ re-utilization after Phe deamination and the carbon bonus simultaneously obtained during Phe uptake. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Pre-acclimation to low ammonia improves ammonia handling in common carp (Cyprinus carpio) when exposed subsequently to high environmental ammonia.

PubMed

Shrivastava, Jyotsna; Sinha, Amit Kumar; Datta, Surjya Narayan; Blust, Ronny; De Boeck, Gudrun

2016-11-01

We tested whether exposing fish to low ammonia concentrations induced acclimation processes and helped fish to tolerate subsequent (sub)lethal ammonia exposure by activating ammonia excretory pathways. Common carp (Cyprinus carpio) were pre-exposed to 0.27mM ammonia (∼10% 96h LC 50 ) for 3, 7 and 14days. Thereafter, each of these pre-exposed and parallel naïve groups were exposed to 1.35mM high environmental ammonia (HEA, ∼50% 96h LC 50 ) for 12h and 48h to assess the occurrence of ammonia acclimation based on sub-lethal end-points, and to lethal ammonia concentrations (2.7mM, 96h LC 50 ) in order to assess improved survival time. Results show that fish pre-exposed to ammonia for 3 and 7days had a longer survival time than the ammonia naïve fish. However, this effect disappeared after prolonged (14days) pre-exposure. Ammonia excretion rate (J amm ) was strongly inhibited (or even reversed) in the unacclimated groups during HEA. On the contrary, after 3days the pre-exposure fish maintained J amm while after 7days these pre-acclimated fish were able to increase J amm efficiently. Again, this effect disappeared after 14days of pre-acclimation. The efficient ammonia efflux in pre-acclimated fish was associated with the up-regulation of branchial mRNA expression of ammonia transporters and exchangers. Pre-exposure with ammonia for 3-7days stimulated an increment in the transcript level of gill Rhcg-a and Rhcg-b mRNA relative to the naïve control group and the up-regulation of these two Rhcg homologs was reinforced during subsequent HEA exposure. No effect of pre-exposure was noted for Rhbg. Relative to unacclimated fish, the transcript level of Na + /H + exchangers (NHE-3) was raised in 3-7days pre-acclimated fish and remained higher during the subsequent HEA exposure while gill H + -ATPase activities and mRNA levels were not affected by pre-acclimation episodes. Likewise, ammonia pre-acclimated fish with or without HEA exposure displayed pronounced up

Susceptibility of four tick species, Amblyomma americanum, Dermacentor variabilis, Ixodes scapularis, and Rhipicephalus sanguineus (Acari: Ixodidae), to nootkatone from essential oil of grapefruit.

PubMed

Flor-Weiler, Lina B; Behle, Robert W; Stafford, Kirby C

2011-03-01

Toxicity of nootkatone was determined in laboratory assays against unfed nymphs of Amblyomma americanum L., Dermacentor variabilis (Say), Ixodes scapularis Say, and Rhipicephalus sanguineus Latreille. We determined the 50% lethal concentration (LC50) and 90% lethal concentration (LC90) of nootkatone by recording tick mortality 24 h after exposure in treated glass vials. Nymphs were susceptible to nootkatone with LC50 values of 0.352, 0.233, 0.169, and 0.197 microg/cm2, and LC90 values of 1.001, 0.644, 0.549, and 0.485 microg/cm2 for A. americanum, D. variabilis, I. scapularis, and R. sanguineus, respectively. The LC50 value for R. sanquineus was not significantly different from D. variabilis or I. scapularis. Other LC50 comparisons were significantly different. The LC90 for A. americanum was higher when compared with the three other tick species, which were not significantly different. Because nootkatone is volatile, we measured the amount of nootkatone recovered from duplicate-treated vials before tick exposure and from vials after tick exposure. Nootkatone recovered from vials before exposure ranged from 82 to 112% of the expected amounts. The nootkatone recovered after the 24-h exposure period ranged from 89% from vials coated with higher concentrations of nootkatone, down to 29% from vials coated with low nootkatone concentrations. Determination of the nootkatone residue after vial coating demonstrated loss of the active compound while verifying the levels of tick exposure. Toxicity of low concentrations of nootkatone to the active questing stage of ticks reported in this study provides a reference point for future formulation research to exploit nootkatone as a safe and environment-friendly tick control.

The Amino Acid Specificity for Activation of Phenylalanine Hydroxylase Matches the Specificity for Stabilization of Regulatory Domain Dimers

PubMed Central

2016-01-01

Liver phenylalanine hydroxylase is allosterically activated by phenylalanine. The structural changes that accompany activation have not been identified, but recent studies of the effects of phenylalanine on the isolated regulatory domain of the enzyme support a model in which phenylalanine binding promotes regulatory domain dimerization. Such a model predicts that compounds that stabilize the regulatory domain dimer will also activate the enzyme. Nuclear magnetic resonance spectroscopy and analytical ultracentrifugation were used to determine the ability of different amino acids and phenylalanine analogues to stabilize the regulatory domain dimer. The abilities of these compounds to activate the enzyme were analyzed by measuring their effects on the fluorescence change that accompanies activation and on the activity directly. At concentrations of 10–50 mM, d-phenylalanine, l-methionine, l-norleucine, and (S)-2-amino-3-phenyl-1-propanol were able to activate the enzyme to the same extent as 1 mM l-phenylalanine. Lower levels of activation were seen with l-4-aminophenylalanine, l-leucine, l-isoleucine, and 3-phenylpropionate. The ability of these compounds to stabilize the regulatory domain dimer agreed with their ability to activate the enzyme. These results support a model in which allosteric activation of phenylalanine hydroxylase is linked to dimerization of regulatory domains. PMID:26252467

Comparative phylogenetic analyses of Halomonas variabilis and related organisms based on 16S rRNA, gyrB and ectBC gene sequences.

PubMed

Okamoto, Takuji; Maruyama, Akihiko; Imura, Satoshi; Takeyama, Haruko; Naganuma, Takeshi

2004-05-01

Halomonas variabilis and phylogenetically related organisms were isolated from various habitats such as Antarctic terrain and saline ponds, deep-sea sediment, deep-sea waters affected by hydrothermal plumes, and hydrothermal vent fluids. Ten strains were selected for physiological and phylogenetic characterization in detail. All of those strains were found to be piezotolerant and psychrotolerant, as well as euryhaline halophilic or halotolerant. Their stress tolerance may facilitate their wide occurrence, even in so-called extreme environments. The 16S rDNA-based phylogenetic relationship was complemented by analyses of the DNA gyrase subunit B gene (gyrB) and genes involved in the synthesis of the major compatible solute, ectoine: diaminobutyric acid aminotransferase gene (ectB) and ectoine synthase gene (ectC). The phylogenetic relationships of H. variabilis and related organisms were very similar in terms of 16S rDNA, gyrB, and ectB. The ectC-based tree was inconsistent with the other phylogenetic trees. For that reason, ectC was inferred to derive from horizontal transfer.

Phenylalanine and Phenylglycine Analogues as Arginine Mimetics in Dengue Protease Inhibitors.

PubMed

Weigel, Lena F; Nitsche, Christoph; Graf, Dominik; Bartenschlager, Ralf; Klein, Christian D

2015-10-08

Dengue virus is an increasingly global pathogen. One of the promising targets for antiviral drug discovery against dengue and related flaviviruses such as West Nile virus is the viral serine protease NS2B-NS3. We here report the synthesis and in vitro characterization of potent peptidic inhibitors of dengue virus protease that incorporate phenylalanine and phenylglycine derivatives as arginine-mimicking groups with modulated basicity. The most promising compounds were (4-amidino)-L-phenylalanine-containing inhibitors, which reached nanomolar affinities against dengue virus protease. The type and position of the substituents on the phenylglycine and phenylalanine side chains has a significant effect on the inhibitory activity against dengue virus protease and selectivity against other proteases. In addition, the non-natural, basic amino acids described here may have relevance for the development of other peptidic and peptidomimetic drugs such as inhibitors of the blood clotting cascade.

Enhancement of  l-phenylalanine production in Escherichia coli by heterologous expression of Vitreoscilla hemoglobin.

PubMed

Wu, Wei-Bin; Guo, Xiao-Lei; Zhang, Ming-Liang; Huang, Qing-Gen; Qi, Feng; Huang, Jian-Zhong

2018-05-01

l-Phenylalanine is an important amino acid that is widely used in the production of food flavors and pharmaceuticals. Generally, l-phenylalanine production by engineered Escherichia coli requires a high rate of oxygen supply. However, the coexpression of Vitreoscilla hemoglobin gene (vgb), driven bya tac promoter, with the genes encoding 3-deoxy-d-arabinoheptulosonate-7-phosphate synthetase (aroF) and feedback-resistant chorismate mutase/prephenate dehydratase (pheA fbr ), led to increased productivity and decreased demand for aeration by E. coli CICC10245. Shake-flask studies showed that vgb-expressing strains displayed higher rates of oxygen uptake, and l-phenylalanine production under standard aeration conditions was increased. In the aerobic fermentation process, cell growth, l-phenylalanine production, and glucose consumption by the recombinant E. coli strain PAPV, which harbored aroF, pheA fbr , and tac-vgb genes, were increased compared to that in the strain harboring only aroF and pheA fbr (E. coli strain PAP), especially under oxygen-limited conditions. The vgb-expressing strain PAPV produced 21.9% more biomass and 16.6% more l-phenylalanine, while consuming only approximately 5% more glucose after 48 H of fermentation. This study demonstrates a method to enhance the l-phenylalanine production by E. coli using less intensive and thus more economical aeration conditions. © 2017 International Union of Biochemistry and Molecular Biology, Inc.

Adaptation of Phenylalanine and Tyrosine Catabolic Pathway to Hibernation in Bats

PubMed Central

Cui, Jie; Liu, Yang; McAllan, Bronwyn M.; Liao, Chen-Chung; Zhang, Shuyi

2013-01-01

Some mammals hibernate in response to harsh environments. Although hibernating mammals may metabolize proteins, the nitrogen metabolic pathways commonly activated during hibernation are not fully characterized. In contrast to the hypothesis of amino acid preservation, we found evidence of amino acid metabolism as three of five key enzymes, including phenylalanine hydroxylase (PAH), homogentisate 1,2-dioxygenase (HGD), fumarylacetoacetase (FAH), involved in phenylalanine and tyrosine catabolism were co-upregulated during hibernation in two distantly related species of bats, Myotis ricketti and Rhinolophus ferrumequinum. In addition, the levels of phenylalanine in the livers of these bats were significantly decreased during hibernation. Because phenylalanine and tyrosine are both glucogenic and ketogenic, these results indicate the role of this catabolic pathway in energy supply. Since any deficiency in the catabolism of these two amino acids can cause accumulations of toxic metabolites, these results also suggest the detoxification role of these enzymes during hibernation. A higher selective constraint on PAH, HPD, and HGD in hibernators than in non-hibernators was observed, and hibernators had more conserved amino acid residues in each of these enzymes than non-hibernators. These conserved amino acid residues are mostly located in positions critical for the structure and activity of the enzymes. Taken together, results of this work provide novel insights in nitrogen metabolism and removal of harmful metabolites during bat hibernation. PMID:23620802

Organic and Inorganic Nitrogen Impact Chlorella variabilis Productivity and Host Quality for Viral Production and Cell Lysis.

PubMed

Cheng, Yu-Shen; Labavitch, John; VanderGheynst, Jean S

2015-05-01

Microalgae have been proposed as a potential feedstock for biofuel production; however, cell disruption is usually required for collection and utilization of cytoplasmic polysaccharides and lipids. Virus infection might be one approach to disrupt the cell wall. The concentration of yeast extract and presence of KNO3 in algae cultivation media were investigated to observe their effects on Chlorella variabilis NC64A physiology and composition and the subsequent effect on production of Chlorella virus and disruption of infected cells. Cytoplasmic starch accumulation increased from 5% to approximately 35% of the total dry weight when yeast extract decreased from 1 to 0.25 g L(-1). When cells were cultured with the lowest nitrogen levels, the total polysaccharide accounted for more than 50% of the cell wall, which was 1.7 times higher than the content in cells cultured with the highest nitrogen levels. The C/N ratio of the algal biomass decreased by a factor of approximately 2 when yeast extract increased from 0.25 to 1 g L(-1). After virus infection, cells with a low C/N ratio produced a 7.6 times higher burst size than cells with a high C/N ratio, suggesting that the nitrogen content in C. variabilis has a large influence on viral production and cell lysis. The results have implications on management of nitrogen for both the synthesis of products from algae and product recovery via viral lysis.

Racemization of aspartic acid and phenylalanine in the sweetener aspartame at 100 degrees C.

PubMed Central

Boehm, M F; Bada, J L

1984-01-01

The racemization half-lives (i.e., the time required to reach a D/L = 0.33) at pH 6.8 for aspartic acid and phenylalanine in the sweetener aspartame (L-aspartyl-L-phenylalanine methyl ester) were determined to be 13 and 23 hours, respectively, at 100 degrees C. Racemization at this pH does not occur in aspartame but rather in its diketopiperazine decomposition product. Our results indicate that the use of aspartame to sweeten neutral pH foods and beverages that are then heated at elevated temperature could generate D-aspartic acid and D-phenylalanine. The nutritive consequences of these D-amino acids in the human diet are not well established, and thus aspartame should probably not be used as a sweetener when the exposure of neutral pH foods and beverages to elevated temperatures is required. At pH 4, a typical pH of most foods and beverages that might be sweetened with aspartame, the half-lives are 47 hours for aspartic acid and 1200 hours for phenylalanine at 100 degrees C. Racemization at pH 4 takes place in aspartame itself. Although the racemization rates at pH 4 are slow and no appreciable racemization of aspartic acid and phenylalanine should occur during the normal use of aspartame, some food and beverage components could conceivably act as catalysts. Additional studies are required to evaluate whether the use of aspartame as a sugar substitute might not in turn result in an increased human consumption of D-aspartic acid and D-phenylalanine. PMID:6591191

Nuclear magnetic resonance studies of phenylalanine analog interactions with normal and sicklen hemoglobin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Y.H.

Several phenylalanine derivatives have been found to inhibit the gelation of deoxygenated sickle hemoglobin (deoxy HbS). Proton and /sup 19/F-NMR techniques were used to monitor the interaction of selected phenylalanine derivatives with the Hb molecule by using fluorine containing phenylalanine derivatives, Hb labeled at the ..beta..93 position with N-(2,2,2-trifluoroethyl) iodoacetamide (IA-F/sub 3/), and by monitoring the relaxation rates of the C2 and C4 histidine protons. The results show that the /sup 19/F spin-spin relaxation times of L-phenylalanin-4-fluorobenzylamide (PheNBz1-F), which has a deoxy HbS antigelling activity comparable to that of the amino acid, tryptophan, are affected much more strongly by interactionmore » with Hb than are those of glycin-4-fluorobenzylamide (GlyNBz1-F). In contrast, it is shown that N-(2,2,5,5-tetramethylpyrrolidin-1-oxy-3-carboxyl)-L-phenylalanine t-butyl ester (SL-Phe) exhibits specific binding to Hb, and an antigelling activity more than two orders of magnitude greater than that of phenylalanine. These results indicate that the fluorine nuclei strongly influenced by the presence of spin label nitroxide are located in a conformation within a few angstroms of the SL-Phe binding site. Proton NMR relaxation measurements of the C2 and C4 proton resonances from the ..beta..2, 4b143 and ..beta..146 histidine residues show significant and selective effects from the binding of SL-Phe to Hb, indicating that the SL-Phe binding site must be close to the side chains of these three residues. The strong antigelation activity of SL-Phe suggests that this binding site may be one of the intermolecular contact sites of importance to the deoxy HbS aggregation process.« less

Combustion driven ammonia generation strategies for passive ammonia SCR system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toner, Joel G.; Narayanaswamy, Kushal; Szekely, Jr., Gerald A.

A method for controlling ammonia generation in an exhaust gas feedstream output from an internal combustion engine equipped with an exhaust aftertreatment system including a first aftertreatment device includes executing an ammonia generation cycle to generate ammonia on the first aftertreatment device. A desired air-fuel ratio output from the engine and entering the exhaust aftertreatment system conducive for generating ammonia on the first aftertreatment device is determined. Operation of a selected combination of a plurality of cylinders of the engine is selectively altered to achieve the desired air-fuel ratio entering the exhaust aftertreatment system.

Spectroscopic characterization of Cu(II) complex of L-phenylalanine and D, L-tryptophan

NASA Astrophysics Data System (ADS)

Altun, Özlen; Bilcen, Selin

2010-02-01

In this work, the reactions involving L-phenylalanine and D, L-tryptophan in the presence of Cu(II) ion were studied. Optimum conditions for the reactions were established as pH 7 and λ = 641 nm. When the reaction was kinetic, it was observed that the following rate formula was found as dA/ An = k dt and k = 3.2 × 10 -4 s -1, according to absorbance measurements. Using a perpetual change curve, the ratio of [Cu]/[Cu] + L-phenylalanine + [ D, L-tryptophan] was found 1:1:1. According to this result, one molecule of L-phenylalanine and one molecule of D, L-tryptophan react with one molecule Cu(II) ion.

Detection of L-phenylalanine using molecularly imprinted solid-phase extraction and flow injection electrochemiluminescence.

PubMed

Lu, Juanjuan; Ge, Shenguang; Wan, Fuwei; Yu, Jinghua

2012-01-01

A novel flow injection electrochemiluminescence method combined with molecularly imprinted solid-phase extraction was developed for the determination of L-phenylalanine, in which ${\\rm{Ru(bpy}})_3^{2 + }$ was used as the luminophor and indium tin oxide glass was modified as the working electrode. Molecularly imprinted polymers, synthesized by self-assembly with functional monomer and crossing linker, were used for the selective extraction of L-phenylalanine. In order to overcome the drawbacks of traditional electrochemiluminescence cells such as high IR drop, high over-potential and so on, a novel electrochemiluminescence cell was developed. The enhanced electrochemiluminescence intensity was linearly related with the concentration of L-phenylalanine in the range from 1.0×10(-7) to 5.0×10(-5) g/mL with a detection limit of 2.59×10(-8) g/mL. The relative standard deviation for the determination of 1.0×10(-6) g/mL L-phenylalanine was 1.2% (n=11). The method showed higher sensitivity and good repeatability, and was successfully applied for the determination of L-phenylalanine in egg white, chicken and serum samples. A possible mechanism for the enhanced electrochemiluminescence response on indium tin oxide glass is proposed. Copyright © 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

Impact of Dietary Intake on Bone Turnover in Patients with Phenylalanine Hydroxylase Deficiency.

PubMed

Coakley, Kathryn E; Felner, Eric I; Tangpricha, Vin; Wilson, Peter W F; Singh, Rani H

2017-01-01

Phenylalanine hydroxylase (PAH) deficiency is a genetic disorder characterized by deficiency of the PAH enzyme. Patients follow a phenylalanine-restricted diet low in intact protein, and must consume synthetic medical food (MF) to supply phenylalanine-free protein. We assessed relationships between dietary intake and nutrient source (food or MF) on bone mineral density (BMD) and bone turnover markers (BTM) in PAH deficiency. Blood from 44 fasted females 11-52 years of age was analyzed for plasma phenylalanine, serum BTM [CTx (resorption), P1NP (formation)], vitamin D, and parathyroid hormone (PTH). BTM ratios were calculated to assess resorption relative to formation (CTx/P1NP). Dual energy X-ray absorptiometry measured total BMD and age-matched Z-scores. Three-day food records were analyzed for total nutrient intake, nutrients by source (food, MF), and compliance with MF prescription. Spearman's partial coefficients (adjusted for age, BMI, energy intake, blood phenylalanine) assessed correlations. All had normal BMD for age (Z-score >-2). Sixty-four percent had high resorption and normal formation indicating uncoupled bone turnover. CTx/P1NP was positively associated with food phenylalanine (r 2 = 0.39; p-value = 0.017), energy (r 2 = 0.41; p-value = 0.011) and zinc (r 2 = 0.41; p-value = 0.014). CTx/P1NP was negatively associated with MF fat (r 2 = -0.44; p-value = 0.008), MF compliance (r 2 = -0.34; p-value = 0.056), and positively with food sodium (r 2 = 0.43; p-value = 0.014). CTx/P1NP decreased significantly with age (p-value = 0.002) and higher PTH (p-value = 0.0002). Phenylalanine was not correlated with any bone indicator. Females with PAH deficiency had normal BMD but elevated BTM, particularly resorption. More favorable ratios were associated with nutrients from MF and compliance. Younger females had less favorable BTM ratios. Promoting micronutrient intake through compliance with MF may impact bone metabolism in patients with PAH deficiency. Bone

The coxBAC Operon Encodes a Cytochrome c Oxidase Required for Heterotrophic Growth in the Cyanobacterium Anabaena variabilis Strain ATCC 29413

PubMed Central

Schmetterer, Georg; Valladares, Ana; Pils, Dietmar; Steinbach, Susanne; Pacher, Margit; Muro-Pastor, Alicia M.; Flores, Enrique; Herrero, Antonia

2001-01-01

Three genes, coxB, coxA, and coxC, found in a clone from a gene library of the cyanobacterium Anabaena variabilis strain ATCC 29413, were identified by hybridization with an oligonucleotide specific for aa3-type cytochrome c oxidases. Deletion of these genes from the genome of A. variabilis strain ATCC 29413 FD yielded strain CSW1, which displayed no chemoheterotrophic growth and an impaired cytochrome c oxidase activity. Photoautotrophic growth of CSW1, however, was unchanged, even with dinitrogen as the nitrogen source. A higher cytochrome c oxidase activity was detected in membrane preparations from dinitrogen-grown CSW1 than from nitrate-grown CSW1, but comparable activities of respiratory oxygen uptake were found in the wild type and in CSW1. Our data indicate that the identified cox gene cluster is essential for fructose-dependent growth in the dark, but not for growth on dinitrogen, and that other terminal respiratory oxidases are expressed in this cyanobacterium. Transcription analysis showed that coxBAC constitutes an operon which is expressed from two transcriptional start points. The use of one of them was stimulated by fructose. PMID:11591688

DL-phenylalanine versus imipramine: a double-blind controlled study.

PubMed

Beckmann, H; Athen, D; Olteanu, M; Zimmer, R

1979-07-04

In a double-blind study, DL-phenylalanine (150--200 mg/24 h) or imipramine (150--200 mg/24 h) was administered to 40 depressed patients (20 patients in each group) for 30 days. Diagnoses were established according to the International Classification of Disease (ICD). The AMP system, the Hamilton Depression Scale and the Bf-S self rating questionnaire (von Zerssen et al., 1974) were used to document psychopathological, neurologic, and somatic changes. Twenty-seven patients (14 on imipramine, 13 on phenylalanine) completed the 30-day trial. No statistical difference could be found between these two drug treatment groups (Student's t-test) using the Hamilton Depression Scale and the Bf-S self rating questionnaire. Ratings for anxiety were significantly lower in the imipramine group on days 10 and 20, but not on day 30; in addition, sleep disturbances were more influenced by imipramine on days 1, 5, and 10, but not on days 20 and 30. Separate analysis of psychopathological syndromes as somatic depressive syndrome and retarded depressive syndrome did not show a group difference (0.05 level of significance using a two-way analysis of variance). It is concluded that DL-phenylalanine might have substantial antidepresant properties. However, certain methodological considerations still warrant a careful interpretation.

21 CFR 862.1555 - Phenylalanine test system.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Phenylalanine test system. 862.1555 Section 862.1555 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862...

Comparison of salicylate and D-phenylalanine for detection of hydroxyl radicals in chemical and biological reactions.

PubMed

Bailey, S M; Fauconnet, A L; Reinke, L A

1997-02-01

Hydroxylation of salicylate and D-phenylalanine was measured to test the usefulness of these compounds for hydroxyl radical (HO(•)) detection in chemical and biological systems. When HO(•) were produced by the photolytic decomposition of hydrogen peroxide, nearly equal amounts of 2,5- and 2,3-dihydroxybenzoic acid (DHBA) were produced from salicylate, with catechol as a minor product. In the photolytic reaction, nearly equal concentrations of p-,m-, and o-tyrosine were formed from D-phenylalanine. When salicylate or D-phenylalanine was present with Fenton reagents or in iron(II) autoxidation systems, the relative proportions of hydroxylated products were similar to those observed after photolysis, although less total products were usually detected. In contrast, when similar experiments were conducted with isolated hepatic microsomes and perfused livers, 2,5-DHBA was the primary product from salicylate, and p-tyrosine was the major product from D-phenylalanine. Cytochrome P-450 enzymes can hydroxylate salicylate to produce 2,5-DHBA, and it is likely that phenylalanine hydroxylase produces most of the p-tyrosine detected in hepatic tissues. Thus, although both salicylate and D-phenylalanine are useful probes for hydroxyl radical formation in chemical systems, hydroxylated products formed from enzymatic reactions complicate interpretation of data from both compounds in vivo.

Co-expression of five genes in E coli for L-phenylalanine in Brevibacterium flavum

PubMed Central

Wu, Yong-Qing; Jiang, Pei-Hong; Fan, Chang-Sheng; Wang, Jian-Gang; Shang, Liang; Huang, Wei-Da

2003-01-01

AIM: To study the effect of co-expression of ppsA, pckA, aroG, pheA and tyrB genes on the production of L-phenylalanine, and to construct a genetic engineering strain for L-phenylalanine. METHODS: ppsA and pckA genes were amplified from genomic DNA of E. coli by polymerase chain reaction, and then introduced into shuttle vectors between E coli and Brevibacterium flavum to generate constructs pJN2 and pJN5. pJN2 was generated by inserting ppsA and pckA genes into vector pCZ; whereas pJN5 was obtained by introducing ppsA and pckA genes into pCZ-GAB, which was originally constructed for co-expression of aroG, pheA and tyrB genes. The recombinant plasmids were then introduced into B. flavum by electroporation and the transformants were used for L-phenylalanine fermentation. RESULTS: Compared with the original B. flavum cells, all the transformants were showed to have increased five enzyme activities specifically, and have enhanced L-phenylalanine biosynthesis ability variably. pJN5 transformant was observed to have the highest elevation of L-phenylalanine production by a 3.4-fold. Co-expression of ppsA and pckA increased activity of DAHP synthetase significantly. CONCLUSION: Co-expression of ppsA and pckA genes in B. flavum could remarkably increase the expression of DAHP synthetase; Co-expression of ppsA, pckA, aroG, pheA and tyrB of E. coli in B. flavum was a feasible approach to construct a strain for phenylalanine production. PMID:12532463

Intramolecular interactions of L-phenylalanine revealed by inner shell chemical shift

NASA Astrophysics Data System (ADS)

Ganesan, Aravindhan; Wang, Feng

2009-07-01

Intramolecular interactions of the functional groups, carboxylic acid, amino, and phenyl in L-phenylalanine have been revealed through inner shell chemical shift. The chemical shift and electronic structures are studied using its derivatives, 2-phenethylamine (PEA) and 3-phenylpropionic acid (PPA), through substitutions of the functional groups on the chiral carbon Cα, i.e., carboxylic acid (-COOH) and amino (-NH2) groups. Inner shell ionization spectra of L-phenylalanine are simulated using density functional theory based B3LYP/TZVP and LB94/et-pVQZ models, which achieve excellent agreement with the most recently available synchrotron sourced x-ray photoemission spectroscopy of L-phenylalanine (Elettra, Italy). The present study reveals insight into behavior of the peptide bond (CO-NH) through chemical shift of the C1-Cα-Cβ(-Cγ) chain and intramolecular interactions with phenyl. It is found that the chemical shift of the carbonyl C1(=O) site exhibits an apparently redshift (smaller energy) when interacting with the phenyl aromatic group. Removal of the amino group (-NH2) from L-phenylalanine (which forms PPA) brings this energy on C1 close to that in L-alanine (δ <0.01 eV). Chemical environment of Cα and Cβ exhibits more significant differences in L-alanine than in the aromatic species, indicating that the phenyl group indeed affects the peptide bond in the amino acid fragment. No direct evidences are found that the carbonyl acid and amino group interact with the phenyl ring through conventional hydrogen bonds.

Transcriptional Response of the Archaeal Ammonia Oxidizer Nitrosopumilus maritimus to Low and Environmentally Relevant Ammonia Concentrations

PubMed Central

Stahl, David A.

2013-01-01

The ability of chemoautotrophic ammonia-oxidizing archaea to compete for ammonia among marine microorganisms at low ambient concentrations has been in part attributed to their extremely high affinity for ammonia, but as yet there is no mechanistic understanding of supporting metabolism. We examined transcription of selected genes for anabolic functions (CO2 fixation, ammonia transport, and cell wall synthesis) and a central catabolic function (ammonia oxidation) in the thaumarchaeon Nitrosopumilus maritimus SCM1 growing at two ammonia concentrations, as measured by combined ammonia and ammonium, one well above the Km for ammonia oxidation (∼500 μM) and the other well below the Km (<10 nM). Transcript levels were generally immediately and differentially repressed when cells transitioned from ammonia-replete to ammonia-limiting conditions. Transcript levels for ammonia oxidation, CO2 fixation, and one of the ammonia transport genes were approximately the same at high and low ammonia availability. Transcripts for all analyzed genes decreased with time in the complete absence of ammonia, but with various rates of decay. The new steady-state mRNA levels established are presumably more reflective of the natural physiological state of ammonia-oxidizing archaea and offer a reference for interpreting message abundance patterns in the natural environment. PMID:23995944

Amino acid N-malonyltransferases from mung beans. Action on 1-aminocyclopropane-1-carboxylic acid and D-phenylalanine.

PubMed

Guo, L; Phillips, A T; Arteca, R N

1993-12-05

1-Aminocyclopropane-1-carboxylate (ACC) N-malonyltransferase from etiolated mung bean hypocotyls was examined for its relationship to D-phenylalanine N-malonyltransferase and other enzymes which transfer malonyl groups from malonyl-CoA to D-amino acids. Throughout a 3600-fold purification the ratio of D-phenylalanine N-malonyltransferase activity to ACC N-malonyltransferase activity was unchanged. Antibodies raised against purified ACC N-malonyltransferase 55-kDa protein were also able to precipitate all D-phenylalanine-directed activity from partially purified mung bean extracts. The irreversible inhibitors phenylglyoxal and tetranitromethane reduced malonyltransferase activity towards D-phenylalanine to the same extent as that for ACC. In addition, several other D-amino acids, particularly D-tryptophan and D-tyrosine, were able to inhibit action towards both ACC and D-phenylalanine. These lines of evidence suggest that a single enzyme is capable of promoting malonylation of both ACC and D-phenylalanine. Km values for D-phenylalanine and malonyl-CoA were found to be 48 and 43 microM, respectively; these values are 10-fold lower than the corresponding values when ACC was substrate. Coenzyme A was a noncompetitive (mixed type) product inhibitor towards malonyl-CoA at both unsaturated and saturated ACC concentrations. The enzyme was also inhibited uncompetitively at high concentrations of malonyl-CoA. We propose that the enzyme follows an Ordered Bi-Bi reaction pathway, with the amino acid substrate being bound initially.

Simultaneous effect of temperature, cyanide and ammonia-oxidizing bacteria concentrations on ammonia oxidation.

PubMed

Do, Hyojin; Lim, Juntaek; Shin, Seung Gu; Wu, Yi-Ju; Ahn, Johng-Hwa; Hwang, Seokhwan

2008-11-01

For biological nitrification, a set of experiments were carried out to approximate the response of lag period along with ammonia oxidation rate with respect to different concentrations of cyanide (CN-) and ammonia-oxidizing bacteria (AOB), and temperature variation in laboratory-scale batch reactors. The effects of simultaneous changes in these three factors on ammonia oxidation were quantitatively estimated and modeled using response surface analysis. The lag period and the ammonia oxidation rate responded differently to changes in the three factors. The lag period and the ammonia oxidation rate were significantly affected by the CN- and AOB concentrations, while temperature changes only affected the ammonia oxidation rate. The increase of AOB concentration and temperature alleviated the inhibition effect of cyanide on ammonia oxidation. The statistical method used in this study can be extended to estimate the quantitative effects of other environmental factors that can change simultaneously.

The role of aromatic phenylalanine residues in binding carotenoid to light-harvesting model and wild-type complexes.

PubMed

García-Martín, A; Pazur, A; Wilhelm, B; Silber, M; Robert, B; Braun, P

2008-09-26

The mode of carotenoid (Crt) binding to polypeptide and specifying its function is as yet largely unknown. Statistical analysis of major photosystems I and II suggests that aromatic residues make up a significant part of the Crt binding pockets. Phenylalanine residues ensure approximately 25%--at some carbon atoms even up to 40%--of the total contacts with Crts. By use of an alanine-leucine model transmembrane helix that replaces the native helix of the bacterial light-harvesting complex 2 (LH2) alpha-subunit, we study the effects of polypeptide residues on cofactor binding in a model sequence context. Here, it is shown that phenylalanine residues located in the close vicinity of the Crts' polyene backbone significantly contribute to the binding of the Crt to the model protein. The replacement of a phenylalanine with leucine in the model helix results in significant reduction in the complexes' Crt content. This effect is strongly enhanced by the removal of a second phenylalanine in close vicinity to the Crt, i.e., of the wild-type (WT) beta-subunit. Remarkably, the mutation of only two phenylalanine residues in the LH2 WT sequence, alpha-Phe at position -12 and beta-Phe at -8, results in the loss of nearly 50% of functional Crt. Resonance Raman spectra indicate that the Crt conformation is fundamentally altered by the absence of the phenylalanines' aromatic side chains, suggesting that they lock the Crt into a precise, well-defined configuration. Thus, binding and specific functionalisation of Crt in the model and WT light-harvesting complex is reliant on the aromatic residue phenylalanine. The use of the light-harvesting complex as a model system thus substantiates the notion that the aromatic residue phenylalanine is a key factor for the binding of Crt to transmembrane proteins.

Gene Expression of Tissue-Specific Molecules in Ex vivo Dermacentor variabilis (Acari: Ixodidae) During Rickettsial Exposure

PubMed Central

SUNYAKUMTHORN, PIYANATE; PETCHAMPAI, NATTHIDA; GRASPERGE, BRITTON J.; KEARNEY, MICHAEL T.; SONENSHINE, DANIEL E.; MACALUSO, KEVIN R.

2014-01-01

Ticks serve as both vectors and the reservoir hosts capable of transmitting spotted fever group Rickettsia by horizontal and vertical transmission. Persistent maintenance of Rickettsia species in tick populations is dependent on the specificity of the tick and Rickettsia relationship that limits vertical transmission of particular Rickettsia species, suggesting host-derived mechanisms of control. Tick-derived molecules are differentially expressed in a tissue-specific manner in response to rickettsial infection; however, little is known about tick response to specific rickettsial species. To test the hypothesis that tissue-specific tick-derived molecules are uniquely responsive to rickettsial infection, a bioassay to characterize the tick tissue-specific response to different rickettsial species was used. Whole organs of Dermacentor variabilis (Say) were exposed to either Rickettsia montanensis or Rickettsia amblyommii, two Rickettsia species common, or absent, in field-collected D. variabilis, respectively, for 1 and 12 h and harvested for quantitative real time-polymerase chain reaction assays of putative immune-like tick-derived factors. The results indicated that tick genes are differently expressed in a temporal and tissue-specific manner. Genes encoding glutathione S-transferase 1 (dvgst1) and Kunitz protease inhibitor (dvkpi) were highly expressed in midgut, and rickettsial exposure downregulated the expression of both genes. Two other genes encoding glutathione S-transferase 2 (dvgst2) and β-thymosin (dvβ-thy) were highly expressed in ovary, with dvβ-thy expression significantly downregulated in ovaries exposed to R. montanensis, but not R. amblyommii, at 12-h postexposure, suggesting a selective response. Deciphering the tissue-specific molecular interactions between tick and Rickettsia will enhance our understanding of the key mechanisms that mediate rickettsial infection in ticks. PMID:24180114

Mapping the functional landscape of frequent phenylalanine hydroxylase (PAH) genotypes promotes personalised medicine in phenylketonuria.

PubMed

Danecka, Marta K; Woidy, Mathias; Zschocke, Johannes; Feillet, François; Muntau, Ania C; Gersting, Søren W

2015-03-01

In phenylketonuria, genetic heterogeneity, frequent compound heterozygosity, and the lack of functional data for phenylalanine hydroxylase genotypes hamper reliable phenotype prediction and individualised treatment. A literature search revealed 690 different phenylalanine hydroxylase genotypes in 3066 phenylketonuria patients from Europe and the Middle East. We determined phenylalanine hydroxylase function of 30 frequent homozygous and compound heterozygous genotypes covering 55% of the study population, generated activity landscapes, and assessed the phenylalanine hydroxylase working range in the metabolic (phenylalanine) and therapeutic (tetrahydrobiopterin) space. Shared patterns in genotype-specific functional landscapes were linked to biochemical and pharmacological phenotypes, where (1) residual activity below 3.5% was associated with classical phenylketonuria unresponsive to pharmacological treatment; (2) lack of defined peak activity induced loss of response to tetrahydrobiopterin; (3) a higher cofactor need was linked to inconsistent clinical phenotypes and low rates of tetrahydrobiopterin response; and (4) residual activity above 5%, a defined peak of activity, and a normal cofactor need were associated with pharmacologically treatable mild phenotypes. In addition, we provide a web application for retrieving country-specific information on genotypes and genotype-specific phenylalanine hydroxylase function that warrants continuous extension, updates, and research on demand. The combination of genotype-specific functional analyses with biochemical, clinical, and therapeutic data of individual patients may serve as a powerful tool to enable phenotype prediction and to establish personalised medicine strategies for dietary regimens and pharmacological treatment in phenylketonuria. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

A comparison of the effects of morphine, enkephalin, kyotorphin and D-phenylalanine on rat central neurones.

PubMed Central

Stone, T. W.

1983-01-01

1 Morphine, Met-enkephalin, kyotorphin and D-phenylalanine have been applied by microiontophoresis to neurones in the globus pallidus and cerebral cortex of rats anaesthetized with urethane. 2 In the pallidum, most cells were inhibited by all the agonists, with a high correspondence between cells inhibited by Met-enkephalin and D-phenylalanine and by Met-enkephalin and kyotorphin. Whereas responses to Met-enkephalin were readily antagonized by naloxone, responses to kyotorphin and D-phenylalanine were not. 3 In the cerebral cortex a high proportion of cells was excited by all four agonists and antagonism by naloxone was less consistent than in pallidum. 4 It is concluded that the naloxone-reversible analgesic effects of kyotorphin and D-phenylalanine may be mediated indirectly, rather through an activation of opiate receptors. PMID:6871550

A comparison of the effects of morphine, enkephalin, kyotorphin and D-phenylalanine on rat central neurones.

PubMed

Stone, T W

1983-05-01

1 Morphine, Met-enkephalin, kyotorphin and D-phenylalanine have been applied by microiontophoresis to neurones in the globus pallidus and cerebral cortex of rats anaesthetized with urethane. 2 In the pallidum, most cells were inhibited by all the agonists, with a high correspondence between cells inhibited by Met-enkephalin and D-phenylalanine and by Met-enkephalin and kyotorphin. Whereas responses to Met-enkephalin were readily antagonized by naloxone, responses to kyotorphin and D-phenylalanine were not. 3 In the cerebral cortex a high proportion of cells was excited by all four agonists and antagonism by naloxone was less consistent than in pallidum. 4 It is concluded that the naloxone-reversible analgesic effects of kyotorphin and D-phenylalanine may be mediated indirectly, rather through an activation of opiate receptors.

Improving the Production of L-Phenylalanine by Identifying Key Enzymes Through Multi-Enzyme Reaction System in Vitro

PubMed Central

Ding, Dongqin; Liu, Yongfei; Xu, Yiran; Zheng, Ping; Li, Haixing; Zhang, Dawei; Sun, Jibin

2016-01-01

L-Phenylalanine (L-Phe) is an important amino acid used in both food and medicinal applications. We developed an in vitro system that allowed a direct, quantitative investigation of phenylalanine biosynthesis in E. coli. Here, the absolute concentrations of six enzymes (AroK, AroL, AroA, AroC, PheA and TyrB) involved in the shikimate (SHIK) pathway were determined by a quantitative proteomics approach and in vitro enzyme titration experiments. The reconstitution of an in vitro reaction system for these six enzymes was established and their effects on the phenylalanine production were tested. The results showed that the yield of phenylalanine increased 3.0 and 2.1 times when the concentrations of shikimate kinase (AroL) and 5-enolpyruvoyl shikimate 3-phosphate (EPSP) synthase (AroA) were increased 2.5 times. Consistent results were obtained from in vivo via the overexpression of AroA in a phenylalanine-producing strain, and the titer of phenylalanine reached 62.47 g/l after 48 h cultivation in a 5-liter jar fermentor. Our quantitative findings provide a practical method to detect the potential bottleneck in a specific metabolic pathway to determine which gene products should be targeted to improve the yield of the desired product. PMID:27558633

Insights into the catalytic mechanisms of phenylalanine and tryptophan hydroxylase from kinetic isotope effects on aromatic hydroxylation.

PubMed

Pavon, Jorge Alex; Fitzpatrick, Paul F

2006-09-12

Phenylalanine hydroxylase (PheH) and tryptophan hydroxylase (TrpH) catalyze the aromatic hydroxylation of phenylalanine and tryptophan, forming tyrosine and 5-hydroxytryptophan, respectively. The reactions of PheH and TrpH have been investigated with [4-(2)H]-, [3,5-(2)H(2)]-, and (2)H(5)-phenylalanine as substrates. All (D)k(cat) values are normal with Delta117PheH, the catalytic core of rat phenylalanine hydroxylase, ranging from 1.12-1.41. In contrast, for Delta117PheH V379D, a mutant protein in which the stoichiometry between tetrahydropterin oxidation and amino acid hydroxylation is altered, the (D)k(cat) value with [4-(2)H]-phenylalanine is 0.92 but is normal with [3,5-(2)H(2)]-phenylalanine. The ratio of tetrahydropterin oxidation to amino acid hydroxylation for Delta117PheH V379D shows a similar inverse isotope effect with [4-(2)H]-phenylalanine. Intramolecular isotope effects, determined from the deuterium contents of the tyrosine formed from [4-(2)H]-and [3,5(2)H(2)]-phenylalanine, are identical for Delta117PheH and Delta117PheH V379D, suggesting that steps subsequent to oxygen addition are unaffected in the mutant protein. The inverse effects are consistent with the reaction of an activated ferryl-oxo species at the para position of the side chain of the amino acid to form a cationic intermediate. The normal effects on the (D)k(cat) value for the wild-type enzyme are attributed to an isotope effect of 5.1 on the tautomerization of a dienone intermediate to tyrosine with a rate constant 6- to7-fold that for hydroxylation. In addition, there is a slight ( approximately 34%) preference for the loss of the hydrogen originally at C4 of phenylalanine. With (2)H(5)-indole-tryptophan as a substrate for Delta117PheH, the (D)k(cat) value is 0.89, consistent with hydroxylation being rate-limiting in this case. When deuterated phenylalanines are used as substrates for TrpH, the (D)k(cat) values are within error of those for Delta117PheH V379D. Overall, these results

Insights into the Catalytic Mechanisms of Phenylalanine and Tryptophan Hydroxylase from Kinetic Isotope Effects on Aromatic Hydroxylation†

PubMed Central

Pavon, Jorge Alex; Fitzpatrick, Paul F.

2006-01-01

Phenylalanine hydroxylase (PheH) and tryptophan hydroxylase (TrpH) catalyze the aromatic hydroxylation of phenylalanine and tryptophan, forming tyrosine and 5-hydroxytryptophan, respectively. The reactions of PheH and TrpH have been investigated with [4-2H]-, [3,5-2H2]-, and 2H5-phenylalanine as substrates. All Dkcat values are normal with Δ117PheH, the catalytic core of rat phenylalanine hydroxylase, ranging from 1.12–1.41. In contrast, for Δ117PheH V379D, a mutant protein in which the stoichiometry between tetrahydropterin oxidation and amino acid hydroxylation is altered, the Dkcat value with [4-2H]-phenylalanine is 0.92 but is normal with [3,5-2H2]-phenylalanine. The ratio of tetrahydropterin oxidation to amino acid hydroxylation for Δ117PheH V379D shows a similar inverse isotope effect with [4-2H]-phenylalanine. Intramolecular isotope effects, determined from the deuterium contents of the tyrosine formed from [4-2H]-and [3,52H2]-phenylalanine, are identical for Δ117PheH and Δ117PheH V379D, suggesting that steps subsequent to oxygen addition are unaffected in the mutant protein. The inverse effects are consistent with the reaction of an activated ferryl-oxo species at the para position of the side chain of the amino acid to form a cationic intermediate. The normal effects on the Dkcat value for the wild-type enzyme are attributed to an isotope effect of 5.1 on the tautomerization of a dienone intermediate to tyrosine with a rate constant 6- to7-fold that for hydroxylation. In addition, there is a slight (∼34%) preference for the loss of the hydrogen originally at C4 of phenylalanine. With 2H5-indole-tryptophan as a substrate for Δ117PheH, the Dkcat value is 0.89, consistent with hydroxylation being rate-limiting in this case. When deuterated phenylalanines are used as substrates for TrpH, the Dkcat values are within error of those for Δ117PheH V379D. Overall, these results are consistent with the aromatic amino acid hydroxylases all sharing the same

Production of α-keto acids Part I. Immobilized cells ofTrigonopsis variabilis containing D-amino acid oxidase.

PubMed

Brodelius, P; Nilsson, K; Mosbach, K

1981-12-01

Whole cells ofTrigonopsis variabilis were immobilized by entrapment in Ca(2+)-alginate and used for the production of α-keto acids from the corresponding D-amino acids. The D-amino acid oxidase within the immobilized cells has a broad substrate specificity. Hydrogen peroxide formed in the enzymatic reaction was efficiently hydrolyzed by manganese oxide co-immobilized with the cells. The amino acid oxidase activity was assayed with a new method based on reversed-phase HPLC. Oxygen requirements, bead size, concentration of cells in the beads, flow rate, and other factors were investigated in a " trickle-bed " reactor.

A new approach for quantitative analysis of L-phenylalanine using a novel semi-sandwich immunometric assay.

PubMed

Kubota, Kazuyuki; Mizukoshi, Toshimi; Miyano, Hiroshi

2013-10-01

Here, we describe a novel method for L-phenylalanine analysis using a sandwich-type immunometric assay approach for use as a new method for amino acid analysis. To overcome difficulties of the preparation of high-affinity and selectivity monoclonal antibodies against L-phenylalanine and the inability to use sandwich-type immunometric assays due to their small molecular weight, three procedures were examined. First, amino groups of L-phenylalanine were modified by "N-Fmoc-L-cysteine" (FC) residues and the derivative (FC-Phe) was used as a hapten. Immunization of mice with bovine serum albumin/FC-Phe conjugate successfully yielded specific monoclonal anti-FC-Phe antibodies. Second, a new derivatization reagent, "biotin linker conjugate of FC-Phe N-succinimidyl ester" (FC(Biotin)-NHS), was synthesized to convert L-phenylalanine to FC-(Biotin)-Phe as a hapten structure. The biotin moiety linked to the thiol group of cysteine formed a second binding site for streptavidin/horseradish peroxidase (HRP) conjugates for optical detection. Third, a new semi-sandwich-type immunometric assay was established using pre-derivatized L-phenylalanine, the monoclonal anti-FC-Phe antibody, and streptavidin/HRP conjugate (without second antibody). Using the new "semi-sandwich" immunometric assay system, a detection limit of 35 nM (60 amol per analysis) and a detection range of 0.1-20 μM were attained using a standard L-phenylalanine solution. Rat plasma samples were analyzed to test reliability. Intra-day assay precision was within 6% of the coefficient of variation; inter-day variation was 0.1%. The recovery rates were from 92.4 to 123.7%. This is the first report of the quantitative determination of L-phenylalanine using a reliable semi-sandwich immunometric assay approach and will be applicable to the quantitative determination of other amino acids.

Transfer of D-phenylalanine from gramicidin S synthetase 1 to gramicidin S synthetase 2 in gramicidin S synthesis.

PubMed

Hori, K; Kanda, M; Miura, S; Yamada, Y; Saito, Y

1983-01-01

The transfer of phenylalanine from gramicidin S synthetase 1 (GS 1) to gramicidin S synthetase 2 (GS 2) was studied by the use of combinations of wild-type GS 1 with various GS 2s from a wild strain and gramicidin S non-producing mutant strains of Bacillus brevis Nagano. The combinations of mutant GS 2s lacking 4'-phosphopantetheine (from BI-4, C-3, E-1, and E-2) did not transfer D-phenylalanine from GS 1, although they could activate all the constituent amino acids. Other mutant GS 2s containing 4'-phosphopantetheine, except GS 2 from BII-3 (proline-activation lacking) accepted D-phenylalanine from intact GS 1. To ascertain more directly whether 4'-phosphopantetheine is involved in the transfer of D-phenylalanine from GS 1 to GS 2, pepsin digests of GS 2 that accepted [14C]phenylalanine were analyzed by Sephadex G-50 column chromatography and thin-layer chromatography (TLC). Radioactivity of [14C]phenylalanine was always associated with a peptide containing 4'-phosphopantetheine. Furthermore, the position of radioactivity was distinct from the position of 4'-phosphopantetheine on TLC after alkaline treatment or performic acid oxidation of the digests.

21 CFR 201.21 - Declaration of presence of phenylalanine as a component of aspartame in over-the-counter and...

Code of Federal Regulations, 2013 CFR

2013-04-01

... acids are so combined to form aspartame (1-methyl N-L-α-aspartyl-L-phenylalanine), they produce an... 21 Food and Drugs 4 2013-04-01 2013-04-01 false Declaration of presence of phenylalanine as a...: GENERAL LABELING General Labeling Provisions § 201.21 Declaration of presence of phenylalanine as a...

21 CFR 201.21 - Declaration of presence of phenylalanine as a component of aspartame in over-the-counter and...

Code of Federal Regulations, 2012 CFR

2012-04-01

... acids are so combined to form aspartame (1-methyl N-L-α-aspartyl-L-phenylalanine), they produce an... 21 Food and Drugs 4 2012-04-01 2012-04-01 false Declaration of presence of phenylalanine as a...: GENERAL LABELING General Labeling Provisions § 201.21 Declaration of presence of phenylalanine as a...

21 CFR 201.21 - Declaration of presence of phenylalanine as a component of aspartame in over-the-counter and...

Code of Federal Regulations, 2011 CFR

2011-04-01

... acids are so combined to form aspartame (1-methyl N-L-α-aspartyl-L-phenylalanine), they produce an... 21 Food and Drugs 4 2011-04-01 2011-04-01 false Declaration of presence of phenylalanine as a...: GENERAL LABELING General Labeling Provisions § 201.21 Declaration of presence of phenylalanine as a...

21 CFR 201.21 - Declaration of presence of phenylalanine as a component of aspartame in over-the-counter and...

Code of Federal Regulations, 2010 CFR

2010-04-01

... acids are so combined to form aspartame (1-methyl N-L-α-aspartyl-L-phenylalanine), they produce an... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Declaration of presence of phenylalanine as a...: GENERAL LABELING General Labeling Provisions § 201.21 Declaration of presence of phenylalanine as a...

21 CFR 201.21 - Declaration of presence of phenylalanine as a component of aspartame in over-the-counter and...

Code of Federal Regulations, 2014 CFR

2014-04-01

... acids are so combined to form aspartame (1-methyl N-L-α-aspartyl-L-phenylalanine), they produce an... 21 Food and Drugs 4 2014-04-01 2014-04-01 false Declaration of presence of phenylalanine as a...: GENERAL LABELING General Labeling Provisions § 201.21 Declaration of presence of phenylalanine as a...

Ethylene: Indicator but Not Inducer of Phytoalexin Synthesis in Soybean 1

PubMed Central

Paradies, Inge; Konze, Jörg R.; Elstner, Erich F.; Paxton, Jack

1980-01-01

Cell wall preparations (elicitors) from Phytophthora megasperma var. sojae increase C2H4 formation, phenylalanine ammonia lyase activity, and glyceollin accumulation in soybean cotyledons within about 1.5, 3, and 6 hours after treatment, respectively. The immediate precursor of C2H4, 1-aminocyclopropane-1-carboxylic acid, stimulates C2H4 formation like the elicitor within 1.5 hours after administration, whereas phenylalanine ammonia lyase activity and glyceollin concentration remain unchanged. Aminoethoxyvinylglycine, a specific inhibitor of C2H4 formation in higher plants, inhibits elicitor-induced C2H4 formation by about 95% but has no effects on phenylalanine ammonia lyase or glyceollin accumulation. It was concluded that C2H4 is a signal accompanying the specific recognition process which finally leads to the induction of phytoalexin formation, but it is not functioning as a link or messenger in the induction sequence of glyceollin accumulation. Images PMID:16661585

Clinical utility of breath ammonia for evaluation of ammonia physiology in healthy and cirrhotic adults

PubMed Central

Spacek, Lisa A; Mudalel, Matthew; Tittel, Frank; Risby, Terence H; Solga, Steven F

2016-01-01

Blood ammonia is routinely used in clinical settings to assess systemic ammonia in hepatic encephalopathy and urea cycle disorders. Despite its drawbacks, blood measurement is often used as a comparator in breath studies because it is a standard clinical test. We sought to evaluate sources of measurement error and potential clinical utility of breath ammonia compared to blood ammonia. We measured breath ammonia in real time by quartz enhanced photoacoustic spectrometry and blood ammonia in 10 healthy and 10 cirrhotic participants. Each participant contributed 5 breath samples and blood for ammonia measurement within 1 h. We calculated the coefficient of variation (CV) for 5 breath ammonia values, reported medians of healthy and cirrhotic participants, and used scatterplots to display breath and blood ammonia. For healthy participants, mean age was 22 years (±4), 70% were men, and body mass index (BMI) was 27 (±5). For cirrhotic participants, mean age was 61 years (±8), 60% were men, and BMI was 31 (±7). Median blood ammonia for healthy participants was within normal range, 10 μmol L−1 (interquartile range (IQR), 3–18) versus 46 μmol L−1 (IQR, 23–66) for cirrhotic participants. Median breath ammonia was 379 pmol mL−1 CO2 (IQR, 265–765) for healthy versus 350 pmol mL−1 CO2 (IQR, 180–1013) for cirrhotic participants. CV was 17 ± 6%. There remains an important unmet need in the evaluation of systemic ammonia, and breath measurement continues to demonstrate promise to fulfill this need. Given the many differences between breath and blood ammonia measurement, we examined biological explanations for our findings in healthy and cirrhotic participants. We conclude that based upon these preliminary data breath may offer clinically important information this is not provided by blood ammonia. PMID:26658550

Copper nanocluster-enhanced luminol chemiluminescence for high-selectivity sensing of tryptophan and phenylalanine.

PubMed

Borghei, Yasaman-Sadat; Hosseini, Morteza; Khoobi, Mehdi; Ganjali, Mohammad Reza

2017-09-01

A remarkable method for the highly sensitive detection of phenylalanine and tryptophan based on a chemiluminescence (CL) assay was reported. It was found that fluorescent copper nanoclusters capped with cysteine (Cys-CuNCs) strongly enhance the weak CL signal resulting from the reaction between luminol and H 2 O 2 . Of the amino acids tested, phenylalanine and tryptophan could enhance the above CL system sensitively. Under optimum conditions, this method was satisfactorily described by a linear calibration curve over a range of 1.0 × 10 -6 to 2.7 × 10 -5  M for phenylalanine and 1.0 × 10 -7 to 3.0 × 10 -5  M for tryptophan, respectively. The effect of various parameters such as Cys-CuNC concentration, H 2 O 2 concentration and pH on the intensity of the CL system were also studied. The main experimental advantage of the proposed method was its selectivity for two amino acids compared with others. To evaluate the applicability of the method to the analysis of a real biological sample it was used to determine tryptophan and phenylalanine in human serum and remarkable results were obtained. Copyright © 2017 John Wiley & Sons, Ltd.

Influence of anoxia on the induction of mutations by phenylalanine radicals during gamma-irradiation of plasmid DNA in aqueous solution.

PubMed

Kuipers, Gitta K; Slotman, Ben J; Reitsma-Wijker, Carola A; van Andel, Rob J; Poldervaart, Hester A; Lafleur, M Vincent M

2004-12-21

When DNA is irradiated in aqueous solution, most of the damage is inflicted by water-derived radicals. This is called the indirect effect of ionizing radiation. However in whole cells not only the primary formed water radicals play a role, because some cellular compounds form secondary radicals which can also damage DNA. It is known that the amino acid phenylalanine is able to react with water radicals, resulting in the production of secondary phenylalanine radicals which can damage and inactivate DNA. In a previous study the influence of the presence of phenylalanine during gamma-irradiation of DNA in aqueous solution under oxic conditions was studied. Under anoxic irradiation conditions different amounts and types of reactive water-derived radicals are formed compared to oxic conditions and also different phenylalanine radicals are formed. Therefore, this study examines the influence of the presence of phenylalanine under anoxic conditions on the gamma-radiation-induced mutation spectrum. The results indicate that phenylalanine radicals are damaging to DNA, but less effective compared to primary water radicals. On the mutational level, in the presence of phenylalanine radicals under anoxic conditions, the amount of mutations on G:C base pairs was significantly decreased as compared to oxic conditions. Furthermore, the results of this study indicate that nucleotide excision repair is involved in repair of both inactivating and mutagenic damage induced by phenylalanine radicals under anoxic conditions.

Effects of chronic ammonia exposure on ammonia metabolism and excretion in marine medaka Oryzias melastigma.

PubMed

Gao, Na; Zhu, Limei; Guo, Zhiqiang; Yi, Meisheng; Zhang, Li

2017-06-01

Ammonia is highly toxic to aquatic organisms, but whether ammonia excretion or ammonia metabolism to less toxic compounds is the major strategy for detoxification in marine fish against chronic ammonia exposure is unclear to date. In this study, we investigated the metabolism and excretion of ammonia in marine medaka Oryzias melastigma during chronic ammonia exposure. The fish were exposed to 0, 0.1, 0.3, 0.6, and 1.1 mmol l -1  NH 4 Cl spiked seawater for 8 weeks. Exposure of 0.3-1.1 mmol l -1  NH 4 Cl had deleterious effects on the fish, including significant reductions in growth, feed intake, and total protein content. However, the fish could take strategies to detoxify ammonia. The tissue ammonia (T Amm ) in the 0.3-1.1 mmol l -1  NH 4 Cl treatments was significantly higher than those in the 0 and 0.1 mmol l -1  NH 4 Cl treatments after 2 weeks of exposure, but it recovered with prolonged exposure time, ultimately reaching the control level after 8 weeks. The amino acid catabolic rate decreased to reduce the gross ammonia production with the increasing ambient ammonia concentration. The concentrations of most metabolites remained constant in the 0-0.6 mmol l -1  NH 4 Cl treatments, whereas 5 amino acids and 3 energy metabolism-related metabolites decreased in the 1.1 mmol l -1  NH 4 Cl treatment. J Amm steadily increased in ambient ammonia from 0 to 0.6 mmol l -1 and slightly decreased when the ambient ammonia concentration increased to 1.1 mmol l -1 . Overall, marine medaka cope with sublethal ammonia environment by regulating the tissue T Amm via reducing the ammonia production and increasing ammonia excretion. Copyright © 2017 Elsevier Ltd. All rights reserved.

Terahertz spectra of l-phenylalanine and its monohydrate.

PubMed

Pan, Tingting; Li, Shaoping; Zou, Tao; Yu, Zheng; Zhang, Bo; Wang, Chenyang; Zhang, Jianbing; He, Mingxia; Zhao, Hongwei

2017-05-05

The low-frequency vibrational property of l-phenylalanine (l-Phe) and l-phenylalanine monohydrate (l-Phe·H 2 O) has been investigated by terahertz time-domain spectroscopy (THz-TDS) at room and low temperature ranging from 0.5 to 4.5THz. Distinctive THz absorption spectra of the two compounds were observed. Density functional theory (DFT) calculations based on the crystal structures have been performed to simulate the vibrational modes of l-Phe and l-Phe·H 2 O and the results agree well with the experimental observations. The study indicates that the characterized features of l-Phe mainly originate from the collective vibration of molecules. And the characterized features of l-Phe·H 2 O mainly come from hydrogen bond interactions between l-Phe and water molecules. l-Phe and l-Phe·H 2 O were also verified by differential scanning calorimetry and thermogravimetry (DSC-TG) and powder X-ray diffraction (PXRD) examinations. Copyright © 2017. Published by Elsevier B.V.

Terahertz spectra of L-phenylalanine and its monohydrate

NASA Astrophysics Data System (ADS)

Pan, Tingting; Li, Shaoping; Zou, Tao; Yu, Zheng; Zhang, Bo; Wang, Chenyang; Zhang, Jianbing; He, Mingxia; Zhao, Hongwei

2017-05-01

The low-frequency vibrational property of L-phenylalanine (L-Phe) and L-phenylalanine monohydrate (L-Phe·H2O) has been investigated by terahertz time-domain spectroscopy (THz-TDS) at room and low temperature ranging from 0.5 to 4.5 THz. Distinctive THz absorption spectra of the two compounds were observed. Density functional theory (DFT) calculations based on the crystal structures have been performed to simulate the vibrational modes of L-Phe and L-Phe·H2O and the results agree well with the experimental observations. The study indicates that the characterized features of L-Phe mainly originate from the collective vibration of molecules. And the characterized features of L-Phe·H2O mainly come from hydrogen bond interactions between L-Phe and water molecules. L-Phe and L-Phe·H2O were also verified by differential scanning calorimetry and thermogravimetry (DSC-TG) and powder X-ray diffraction (PXRD) examinations.

Ionization state of L-phenylalanine at the air-water interface.

PubMed

Griffith, Elizabeth C; Vaida, Veronica

2013-01-16

The ionization state of organic molecules at the air-water interface and the related problem of the surface pH of water have significant consequences on the catalytic role of the surface in chemical reactions and are currently areas of intense research and controversy. In this work, infrared reflection-absorption spectroscopy (IRRAS) is used to identify changes in the ionization state of L-phenylalanine in the surface region versus the bulk aqueous solution. L-phenylalanine has the unique advantage of possessing two different hydrophilic groups, a carboxylic acid and an amine base, which can deprotonate and protonate respectively depending on the ionic environment they experience at the water surface. In this work, the polar group vibrations in the surface region are identified spectroscopically in varying bulk pH solutions, and are subsequently compared with the ionization state of the polar groups of molecules residing in the bulk environment. The polar groups of L-phenylalanine at the surface transition to their deprotonated state at bulk pH values lower than the molecules residing in the bulk, indicating a decrease in their pK(a) at the surface, and implying an enhanced hydroxide ion concentration in the surface region relative to the bulk.

The Transcriptome of the Zoanthid Protopalythoa variabilis (Cnidaria, Anthozoa) Predicts a Basal Repertoire of Toxin-like and Venom-Auxiliary Polypeptides

PubMed Central

Huang, Chen; Morlighem, Jean-Étienne RL; Zhou, Hefeng; Lima, Érica P; Gomes, Paula B; Cai, Jing; Lou, Inchio; Pérez, Carlos D; Lee, Simon Ming; Rádis-Baptista, Gandhi

2016-01-01

Abstract Protopalythoa is a zoanthid that, together with thousands of predominantly marine species, such as hydra, jellyfish, and sea anemones, composes the oldest eumetazoan phylum, i.e., the Cnidaria. Some of these species, such as sea wasps and sea anemones, are highly venomous organisms that can produce deadly toxins for preying, for defense or for territorial disputes. Despite the fact that hundreds of organic and polypeptide toxins have been characterized from sea anemones and jellyfish, practically nothing is known about the toxin repertoire in zoanthids. Here, based on a transcriptome analysis of the zoanthid Protopalythoa variabilis, numerous predicted polypeptides with canonical venom protein features are identified. These polypeptides comprise putative proteins from different toxin families: neurotoxic peptides, hemostatic and hemorrhagic toxins, membrane-active (pore-forming) proteins, protease inhibitors, mixed-function venom enzymes, and venom auxiliary proteins. The synthesis and functional analysis of two of these predicted toxin products, one related to the ShK/Aurelin family and the other to a recently discovered anthozoan toxin, displayed potent in vivo neurotoxicity that impaired swimming in larval zebrafish. Altogether, the complex array of venom-related transcripts that are identified in P. variabilis, some of which are first reported in Cnidaria, provides novel insight into the toxin distribution among species and might contribute to the understanding of composition and evolution of venom polypeptides in toxiferous animals. PMID:27566758

Highly efficient drug delivery nanosystem via L-phenylalanine triggering based on supramolecular polymer micelles.

PubMed

Dong, Haiqing; Li, Yongyong; Wen, Huiyun; Xu, Meng; Liu, Lijian; Li, Zhuoquan; Guo, Fangfang; Shi, Donglu

2011-03-16

An intelligent drug delivery nanosystem has been developed based on biodegradable supramolecular polymer micelles (SMPMs). The drug release can be triggered from SMPMs responsively by a bioactive agent, L-phenylalanine in a controlled fashion. The SMPMs are constructed from ethylcellulose-graft-poly(ε-caprolactone) (EC-g-PCL) and α-cyclodextrin (α-CD) derivate via host-guest and hydrophobic interactions. It has been found that these SMPMs have disassembled rapidly in response to an additional L-phenylalanine, due to great affinity discrepancy to α-CD between L-phenylalanine and PCL. Experiments have been carried out on trigger-controlled in vitro drug release of the SMPMs loaded with a model porphyrin based photosensitizer THPP. The result shows that the SMPMs released over 85% THPP in 6 h, which is two orders magnitudes faster than that of control. Also investigated is the photodynamic therapy (PDT) of THPP-loaded SMPMs with and without L-phenylalanine on MCF-7 carcinoma cell line. An effective trigger-concentration dependent lethal effect has been found showing promise in clinical photodynamic therapy. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ENGINEERING THE BIOSYNTHESIS OF STYRENE IN YEAST

EPA Science Inventory

The strategy pursued was to insert genes for phenylalanine ammonia lysase (pal) and phenolic acid decarboxylase (pad) into the yeast that would convert phenylalanine to styrene through a cinnamic acid intermediate.

A resolution approach of racemic phenylalanine with aqueous two-phase systems of chiral tropine ionic liquids.

PubMed

Wu, Haoran; Yao, Shun; Qian, Guofei; Yao, Tian; Song, Hang

2015-10-30

Aqueous two-phase systems (ATPS) based on tropine type chiral ionic liquids and inorganic salt solution were designed and prepared for the enantiomeric separation of racemic phenylalanine. The phase behavior of IL-based ATPS was comprehensive investigated, and phase equilibrium data were correlated by Merchuk equation. Various factors were also systematically investigated for their influence on separation efficiency. Under the appropriate conditions (0.13g/g [C8Tropine]pro, 35mg/g Cu(Ac)2, 20mg/g d,l-phenylalanine, 0.51g/g H2O and 0.30g/g K2HPO4), the enantiomeric excess value of phenylalanine in solid phase (mainly containing l-enantiomer) was 65%. Finally, the interaction mechanism was studied via 1D and 2D NMR. The results indicate that d-enantiomer of phenylalanine interacts more strongly with chiral ILs and Cu(2+) based on the chiral ion-pairs space coordination mechanism, which makes it tend to remain in the top IL-rich phase. By contrast, l-enantiomer is transferred into the solid phase. Above chiral ionic liquids aqueous two-phase systems have demonstrated obvious resolution to racemic phenylalanine and could be promising alterative resolution approach for racemic amino acids in aqueous circumstance. Copyright © 2015. Published by Elsevier B.V.

Phenylalanine containing hydrophobic nanospheres for antibody purification.

PubMed

Türkmen, Deniz; Denizli, Adil; Oztürk, Nevra; Akgöl, Sinan; Elkak, Assem

2008-01-01

In this study, novel hydrophobic nanospheres with an average size of 158 nm utilizing N-methacryloyl-(L)-phenylalanine methyl ester (MAPA) as a hydrophobic monomer were produced by surfactant free emulsion polymerization of 2-hydroxyethyl methacrylate (HEMA) and MAPA conducted in an aqueous dispersion medium. MAPA was synthesized using methacryloyl chloride and L-phenylalanine methyl ester. Specific surface area of the nonporous nanospheres was found to be 1874 m2/g. Poly(HEMA-MAPA) nanospheres were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Average particle size, size distribution, and surface charge measurements were also performed. Elemental analysis of MAPA for nitrogen was estimated as 0.42 mmol/g polymer. Then, poly(HEMA-MAPA) nanospheres were used in the adsorption of immunoglobulin G (IgG) in batch system. Higher adsorption values (780 mg/g) were obtained when the poly (HEMA-MAPA) nanospheres were used from both aqueous solutions and human plasma. The adsorption phenomena appeared to follow a typical Langmuir isotherm. It was observed that IgG could be repeatedly adsorbed and desorbed without significant loss in adsorption amount. These findings show considerable promise for this material as a hydrophobic support in industrial processes.

Mis-Regulation of 3-Deoxy-d-Arabino-Heptulosonate 7-Phosphate Synthetase Does Not Account for Growth Inhibition by Phenylalanine in Agmenellum quadruplicatum

PubMed Central

Jensen, Roy A.; Stenmark-Cox, S.; Ingram, Lonnie O.

1974-01-01

The growth of the blue-green bacterium, Agmenellum quadruplicatum, is inhibited in the presence of l-phenylalanine. This species has a single, constitutively synthesized 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthetase. l-Phenylalanine inhibits DAHP synthetase non-competitively with respect to both substrate reactants. Other aromatic amino acids do not inhibit the activity of DAHP synthetase. A common expectation for branch-point enzymes such as DAHP synthetase is a balanced pattern of feedback control by all of the ultimate end products. It seemed likely that growth inhibition might equate with defective regulation within the branched aromatic pathway. Accordingly, the possibility was examined that mis-regulation of DAHP synthetase by l-phenylalanine in wild-type cells causes starvation for precursors of the other aromatic end products. However, the molecular basis for growth inhibition cannot be attributed to l-phenylalanine inhibition of DAHP synthetase for the following reasons: (i) DAHP synthetase enzymes from l-phenylalanine-resistant mutants are more, rather than less, sensitive to feedback inhibition by l-phenylalanine. (ii) Shikimate not only fails to antagonize inhibition, but is itself inhibitory. (iii) Neither the sensitivity nor the completeness of l-phenylalanine inhibition of the wild-type enzyme in vitro appears sufficient to account for the potent inhibition of growth in vivo by l-phenylalanine. The dominating effect of l-phenylalanine in the control of DAHP synthetase appears to reflect a mechanism that prevents rather than causes growth inhibition by l-phenylalanine. The alteration of the control of DAHP synthetase in mutants selected for resistance to growth inhibition by l-phenylalanine did indicate that the cause for this metabolite vulnerability can be localized within the aromatic amino acid pathway. Apparently, an aromatic intermediate (between shikimate and the end products) accumulates in the presence of l-phenylalanine

Better Absorbents for Ammonia Separation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malmali, Mahdi; Le, Giang; Hendrickson, Jennifer

Making ammonia from renewable wind energy at a competitive price may be possible if the conventional ammonia condenser is replaced with an ammonia absorber. Such a process change requires an ammonia selective absorbent. Supported metal halide sorbents for this separation display outstanding dynamic capacity close to their equilibrium thermodynamic limits. Alkaline earth chlorides and bromides supported on silica and zeolite Y are the most promising. MgCl 2 and CaBr 2 at 40% loading on silica show capacities of 60-70 mg NH3/gsorbent at 150 °C and 4 bar. Overall, cations with smaller atomic numbers show more affinity to ammonia; bromides holdmore » ammonia more strongly than chlorides. Different solvents and metal halide mixtures do not show significant changes in the absorption capacity. Finally, these absorbents can be incorporated into ammonia reaction-absorption syntheses to achieve faster production rates.« less

Better Absorbents for Ammonia Separation

DOE PAGES

Malmali, Mahdi; Le, Giang; Hendrickson, Jennifer; ...

2018-03-30

Making ammonia from renewable wind energy at a competitive price may be possible if the conventional ammonia condenser is replaced with an ammonia absorber. Such a process change requires an ammonia selective absorbent. Supported metal halide sorbents for this separation display outstanding dynamic capacity close to their equilibrium thermodynamic limits. Alkaline earth chlorides and bromides supported on silica and zeolite Y are the most promising. MgCl 2 and CaBr 2 at 40% loading on silica show capacities of 60-70 mg NH3/gsorbent at 150 °C and 4 bar. Overall, cations with smaller atomic numbers show more affinity to ammonia; bromides holdmore » ammonia more strongly than chlorides. Different solvents and metal halide mixtures do not show significant changes in the absorption capacity. Finally, these absorbents can be incorporated into ammonia reaction-absorption syntheses to achieve faster production rates.« less

Structure-activity relationships among substituted N-benzoyl derivatives of phenylalanine and its analogs in a microbial antitumor prescreen I: Derivatives of o-fluoro-DL-phenylalanine.

PubMed

Otani, T T; Briley, M R

1982-02-01

Twelve derivatives of 0-fluoro-dl-phenylalanine containing fluorine, chlorine, methoxy, and nitro radicals in various positions of the aromatic ring of the benzoyl group were prepared and tested in a Lactobacillus casei system. It was found that most substitutions in the benzoyl phenyl ring resulted in a compound exhibiting greater growth-inhibiting activity than the nonsubstituted benzoyl-o-fluorophenylalanine. The greatest activity was observed in the ortho-substituted fluoro compound and the meta- and para-substituted chloro and nitro compounds. With the methoxy group, the position of substitution appeared unimportant, since all three methoxy isomers exhibited essentially equal inhibition. Nitro substitution in the ortho position had a protective effect in that the product was less active than the unsubstituted benzoyl-o-fluoro-dl-phenylalanine.

Alternative E ammonia feedstock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lentz, M.J.; Wright, R.A.

1999-07-01

Power plants are using more Ammonia for increasing precipitator and baghouse efficiency, for SCR and SNCR processes, and for controlling acid stack plumes and dewpoint corrosion. These simple systems inject ammonia and air into the furnace or the precipitator or baghouse inlet ductwork. The common feedstocks in use today are Anhydrous ammonia [NH{sub 3}] and Aqueous ammonia [NH{sub 4}OH], both defined as poison gases by US authorities and most Western nations. Storage and handling procedures for these products are strictly regulated. Wilhelm Environmental Technologies Inc. is developing use of solid, formed or prilled Urea [CO(NH{sub 2}){sub 2}] as the feedstock.more » When heated in moist air, Urea sublimes to ammonia [NH{sub 3}] and carbon dioxide [CO{sub 2}]. Urea is stored and handled without restrictions or environmental concerns. Urea is a more expensive feedstock than NH{sub 3}, but much less expensive than [NH{sub 4}OH]. The design, and operating results, of a pilot system at Jacksonville Electric St. John's River Plant [Unit 2] are described. The pilot plant successfully sublimed Urea up to 100 pounds/hour. Further testing is planned. Very large ammonia use may favor NH{sub 3}, but smaller quantities can be produced at attractive prices with Urea based ammonia systems. Storage costs are far less. Many fluidized-bed boilers can use pastille or solid urea metered directly into the existing cyclones for NO{sub x} control. This is more economical than aqueous ammonia or aqueous urea based technology.« less

Three-dimensional tertiary structure of yeast phenylalanine transfer RNA

NASA Technical Reports Server (NTRS)

Kim, S. H.; Sussman, J. L.; Suddath, F. L.; Quigley, G. J.; Mcpherson, A.; Wang, A. H. J.; Seeman, N. C.; Rich, A.

1974-01-01

Results of an analysis and interpretation of a 3-A electron density map of yeast phenylalanine transfer RNA. Some earlier detailed assignments of nucleotide residues to electron density peaks are found to be in error, even though the overall tracing of the backbone conformation of yeast phenylalanine transfer RNA was generally correct. A new, more comprehensive interpretation is made which makes it possible to define the tertiary interactions in the molecule. The new interpretation makes it possible to visualize a number of tertiary interactions which not only explain the structural role of most of the bases which are constant in transfer RNAs, but also makes it possible to understand in a direct and simple fashion the chemical modification data on transfer RNA. In addition, this pattern of tertiary interactions provides a basis for understanding the general three-dimensional folding of all transfer RNA molecules.

Resolving Phenylalanine Metabolism Sheds Light on Natural Synthesis of Penicillin G in Penicillium chrysogenum

PubMed Central

Veiga, Tânia; Solis-Escalante, Daniel; Romagnoli, Gabriele; ten Pierick, Angela; Hanemaaijer, Mark; Deshmuhk, Amit; Wahl, Aljoscha; Pronk, Jack T.

2012-01-01

The industrial production of penicillin G by Penicillium chrysogenum requires the supplementation of the growth medium with the side chain precursor phenylacetate. The growth of P. chrysogenum with phenylalanine as the sole nitrogen source resulted in the extracellular production of phenylacetate and penicillin G. To analyze this natural pathway for penicillin G production, chemostat cultures were switched to [U-13C]phenylalanine as the nitrogen source. The quantification and modeling of the dynamics of labeled metabolites indicated that phenylalanine was (i) incorporated in nascent protein, (ii) transaminated to phenylpyruvate and further converted by oxidation or by decarboxylation, and (iii) hydroxylated to tyrosine and subsequently metabolized via the homogentisate pathway. The involvement of the homogentisate pathway was supported by the comparative transcriptome analysis of P. chrysogenum cultures grown with phenylalanine and with (NH4)2SO4 as the nitrogen source. This transcriptome analysis also enabled the identification of two putative 2-oxo acid decarboxylase genes (Pc13g9300 and Pc18g01490). cDNAs of both genes were cloned and expressed in the 2-oxo-acid-decarboxylase-free Saccharomyces cerevisiae strain CEN.PK711-7C (pdc1 pdc5 pdc6Δ aro10Δ thi3Δ). The introduction of Pc13g09300 restored the growth of this S. cerevisiae mutant on glucose and phenylalanine, thereby demonstrating that Pc13g09300 encodes a dual-substrate pyruvate and phenylpyruvate decarboxylase, which plays a key role in an Ehrlich-type pathway for the production of phenylacetate in P. chrysogenum. These results provide a basis for the metabolic engineering of P. chrysogenum for the production of the penicillin G side chain precursor phenylacetate. PMID:22158714

Mechanistic, Mutational, and Structural Evaluation of a Taxus Phenylalanine Aminomutase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Lei; Wanninayake, Udayanga; Strom, Susan

The structure of a phenylalanine aminomutase (TcPAM) from Taxus canadensis has been determined at 2.4 {angstrom} resolution. The active site of the TcPAM contains the signature 4-methylidene-1H-imidazol-5(4H)-one prosthesis, observed in all catalysts of the class I lyase-like family. This catalyst isomerizes (S)-{alpha}-phenylalanine to the (R)-{beta}-isomer by exchange of the NH{sub 2}/H pair. The stereochemistry of the TcPAM reaction product is opposite of the (S)-{beta}-tyrosine made by the mechanistically related tyrosine aminomutase (SgTAM) from Streptomyces globisporus. Since TcPAM and SgTAM share similar tertiary- and quaternary-structures and have several highly conserved aliphatic residues positioned analogously in their active sites for substrate recognition,more » the divergent product stereochemistries of these catalysts likely cannot be explained by differences in active site architecture. The active site of the TcPAM structure also is in complex with (E)-cinnamate; the latter functions as both a substrate and an intermediate. To account for the distinct (3R)-{beta}-amino acid stereochemistry catalyzed by TcPAM, the cinnamate skeleton must rotate the C{sub 1}-C{sub {alpha}} and C{sub ipso}-C{sub {beta}} bonds 180{sup o} in the active site prior to exchange and rebinding of the NH{sub 2}/H pair to the cinnamate, an event that is not required for the corresponding acrylate intermediate in the SgTAM reaction. Moreover, the aromatic ring of the intermediate makes only one direct hydrophobic interaction with Leu-104. A L104A mutant of TcPAM demonstrated an 1.5-fold increase in k{sub cat} and a decrease in K{sub M} values for sterically demanding 3'-methyl-{alpha}-phenylalanine and styryl-{alpha}-alanine substrates, compared to the kinetic parameters for TcPAM. These parameters did not change significantly for the mutant with 4'-methyl-{alpha}-phenylalanine compared to those for TcPAM.« less

Renal Ammonia Metabolism and Transport

PubMed Central

Weiner, I. David; Verlander, Jill W.

2015-01-01

Renal ammonia metabolism and transport mediates a central role in acid-base homeostasis. In contrast to most renal solutes, the majority of renal ammonia excretion derives from intrarenal production, not from glomerular filtration. Renal ammoniagenesis predominantly results from glutamine metabolism, which produces 2 NH4+ and 2 HCO3− for each glutamine metabolized. The proximal tubule is the primary site for ammoniagenesis, but there is evidence for ammoniagenesis by most renal epithelial cells. Ammonia produced in the kidney is either excreted into the urine or returned to the systemic circulation through the renal veins. Ammonia excreted in the urine promotes acid excretion; ammonia returned to the systemic circulation is metabolized in the liver in a HCO3−-consuming process, resulting in no net benefit to acid-base homeostasis. Highly regulated ammonia transport by renal epithelial cells determines the proportion of ammonia excreted in the urine versus returned to the systemic circulation. The traditional paradigm of ammonia transport involving passive NH3 diffusion, protonation in the lumen and NH4+ trapping due to an inability to cross plasma membranes is being replaced by the recognition of limited plasma membrane NH3 permeability in combination with the presence of specific NH3-transporting and NH4+-transporting proteins in specific renal epithelial cells. Ammonia production and transport are regulated by a variety of factors, including extracellular pH and K+, and by several hormones, such as mineralocorticoids, glucocorticoids and angiotensin II. This coordinated process of regulated ammonia production and transport is critical for the effective maintenance of acid-base homeostasis. PMID:23720285

Renal ammonia metabolism and transport.

PubMed

Weiner, I David; Verlander, Jill W

2013-01-01

Renal ammonia metabolism and transport mediates a central role in acid-base homeostasis. In contrast to most renal solutes, the majority of renal ammonia excretion derives from intrarenal production, not from glomerular filtration. Renal ammoniagenesis predominantly results from glutamine metabolism, which produces 2 NH4(+) and 2 HCO3(-) for each glutamine metabolized. The proximal tubule is the primary site for ammoniagenesis, but there is evidence for ammoniagenesis by most renal epithelial cells. Ammonia produced in the kidney is either excreted into the urine or returned to the systemic circulation through the renal veins. Ammonia excreted in the urine promotes acid excretion; ammonia returned to the systemic circulation is metabolized in the liver in a HCO3(-)-consuming process, resulting in no net benefit to acid-base homeostasis. Highly regulated ammonia transport by renal epithelial cells determines the proportion of ammonia excreted in the urine versus returned to the systemic circulation. The traditional paradigm of ammonia transport involving passive NH3 diffusion, protonation in the lumen and NH4(+) trapping due to an inability to cross plasma membranes is being replaced by the recognition of limited plasma membrane NH3 permeability in combination with the presence of specific NH3-transporting and NH4(+)-transporting proteins in specific renal epithelial cells. Ammonia production and transport are regulated by a variety of factors, including extracellular pH and K(+), and by several hormones, such as mineralocorticoids, glucocorticoids and angiotensin II. This coordinated process of regulated ammonia production and transport is critical for the effective maintenance of acid-base homeostasis.

RESULTS OF INITIAL AMMONIA OXIDATION TESTING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nash, C.; Fowley, M.

This memo presents an experimental survey of aqueous phase chemical processes to remove aqueous ammonia from waste process streams. Ammonia is generated in both the current Hanford waste flowsheet and in future waste processing. Much ammonia will be generated in the Low Activity Waste (LAW) melters.i Testing with simulants in glass melters at Catholic University has demonstrated the significant ammonia production.ii The primary reaction there is the reducing action of sugar on nitrate in the melter cold cap. Ammonia has been found to be a problem in secondary waste stabilization. Ammonia vapors are noxious and destruction of ammonia could reducemore » hazards to waste treatment process personnel. It is easily evolved especially when ammonia-bearing solutions are adjusted to high pH.« less

The self-assembling zwitterionic form of L-phenylalanine at neutral pH.

PubMed

Mossou, Estelle; Teixeira, Susana C M; Mitchell, Edward P; Mason, Sax A; Adler-Abramovich, Lihi; Gazit, Ehud; Forsyth, V Trevor

2014-03-01

The title zwitterion (2S)-2-azaniumyl-1-hydroxy-3-phenylpropan-1-olate, C9H11NO2, also known as L-phenylalanine, was characterized using synchrotron X-rays. It crystallized in the monoclinic space group P21 with four molecules in the asymmetric unit. The 0.62 Å resolution structure is assumed to be closely related to the fibrillar form of phenylalanine, as observed by electron microscopy and electron diffraction. The structure exists in a zwitterionic form in which π-π stacking and hydrogen-bonding interactions are believed to form the basis of the self-assembling properties.

Ammonia toxicity: from head to toe?

PubMed

Dasarathy, Srinivasan; Mookerjee, Rajeshwar P; Rackayova, Veronika; Rangroo Thrane, Vinita; Vairappan, Balasubramaniyan; Ott, Peter; Rose, Christopher F

2017-04-01

Ammonia is diffused and transported across all plasma membranes. This entails that hyperammonemia leads to an increase in ammonia in all organs and tissues. It is known that the toxic ramifications of ammonia primarily touch the brain and cause neurological impairment. However, the deleterious effects of ammonia are not specific to the brain, as the direct effect of increased ammonia (change in pH, membrane potential, metabolism) can occur in any type of cell. Therefore, in the setting of chronic liver disease where multi-organ dysfunction is common, the role of ammonia, only as neurotoxin, is challenged. This review provides insights and evidence that increased ammonia can disturb many organ and cell types and hence lead to dysfunction.

The Transcriptome of the Zoanthid Protopalythoa variabilis (Cnidaria, Anthozoa) Predicts a Basal Repertoire of Toxin-like and Venom-Auxiliary Polypeptides.

PubMed

Huang, Chen; Morlighem, Jean-Étienne Rl; Zhou, Hefeng; Lima, Érica P; Gomes, Paula B; Cai, Jing; Lou, Inchio; Pérez, Carlos D; Lee, Simon Ming; Rádis-Baptista, Gandhi

2016-10-05

Protopalythoa is a zoanthid that, together with thousands of predominantly marine species, such as hydra, jellyfish, and sea anemones, composes the oldest eumetazoan phylum, i.e., the Cnidaria. Some of these species, such as sea wasps and sea anemones, are highly venomous organisms that can produce deadly toxins for preying, for defense or for territorial disputes. Despite the fact that hundreds of organic and polypeptide toxins have been characterized from sea anemones and jellyfish, practically nothing is known about the toxin repertoire in zoanthids. Here, based on a transcriptome analysis of the zoanthid Protopalythoa variabilis, numerous predicted polypeptides with canonical venom protein features are identified. These polypeptides comprise putative proteins from different toxin families: neurotoxic peptides, hemostatic and hemorrhagic toxins, membrane-active (pore-forming) proteins, protease inhibitors, mixed-function venom enzymes, and venom auxiliary proteins. The synthesis and functional analysis of two of these predicted toxin products, one related to the ShK/Aurelin family and the other to a recently discovered anthozoan toxin, displayed potent in vivo neurotoxicity that impaired swimming in larval zebrafish. Altogether, the complex array of venom-related transcripts that are identified in P. variabilis, some of which are first reported in Cnidaria, provides novel insight into the toxin distribution among species and might contribute to the understanding of composition and evolution of venom polypeptides in toxiferous animals. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Ammonia concentration determines differential growth of ammonia-oxidising archaea and bacteria in soil microcosms.

PubMed

Verhamme, Daniel T; Prosser, James I; Nicol, Graeme W

2011-06-01

The first step of nitrification, oxidation of ammonia to nitrite, is performed by both ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) in soil, but their relative contributions to ammonia oxidation and existence in distinct ecological niches remain to be determined. To determine whether available ammonia concentration has a differential effect on AOA and AOB growth, soil microcosms were incubated for 28 days with ammonium at three concentrations: native (control), intermediate (20 μg NH(4)(+)-N per gram of soil) and high (200 μg NH(4)(+)-N per gram of soil). Quantitative PCR demonstrated growth of AOA at all concentrations, whereas AOB growth was prominent only at the highest concentration. Similarly, denaturing gradient gel electrophoresis (DGGE) analysis revealed changes in AOA communities at all ammonium concentrations, whereas AOB communities changed significantly only at the highest ammonium concentration. These results provide evidence that ammonia concentration contributes to the definition of distinct ecological niches of AOA and AOB in soil.

Ammonia concentration determines differential growth of ammonia-oxidising archaea and bacteria in soil microcosms

PubMed Central

Verhamme, Daniel T; Prosser, James I; Nicol, Graeme W

2011-01-01

The first step of nitrification, oxidation of ammonia to nitrite, is performed by both ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) in soil, but their relative contributions to ammonia oxidation and existence in distinct ecological niches remain to be determined. To determine whether available ammonia concentration has a differential effect on AOA and AOB growth, soil microcosms were incubated for 28 days with ammonium at three concentrations: native (control), intermediate (20 μg NH4+-N per gram of soil) and high (200 μg NH4+-N per gram of soil). Quantitative PCR demonstrated growth of AOA at all concentrations, whereas AOB growth was prominent only at the highest concentration. Similarly, denaturing gradient gel electrophoresis (DGGE) analysis revealed changes in AOA communities at all ammonium concentrations, whereas AOB communities changed significantly only at the highest ammonium concentration. These results provide evidence that ammonia concentration contributes to the definition of distinct ecological niches of AOA and AOB in soil. PMID:21228892

Genetically engineered probiotic for the treatment of phenylketonuria (PKU); assessment of a novel treatment in vitro and in the PAHenu2 mouse model of PKU.

PubMed

Durrer, Katherine E; Allen, Michael S; Hunt von Herbing, Ione

2017-01-01

Phenylketonuria (PKU) is a genetic disease characterized by the inability to convert dietary phenylalanine to tyrosine by phenylalanine hydroxylase. Given the importance of gut microbes in digestion, a genetically engineered microbe could potentially degrade some ingested phenylalanine from the diet prior to absorption. To test this, a phenylalanine lyase gene from Anabaena variabilis (AvPAL) was codon-optimized and cloned into a shuttle vector for expression in Lactobacillus reuteri 100-23C (pHENOMMenal). Functional expression of AvPAL was determined in vitro, and subsequently tested in vivo in homozygous PAHenu2 (PKU model) mice. Initial trials of two PAHenu2 homozygous (PKU) mice defined conditions for freeze-drying and delivery of bacteria. Animals showed reduced blood phe within three to four days of treatment with pHENOMMenal probiotic, and blood phe concentrations remained significantly reduced (P < 0.0005) compared to untreated controls during the course of experiments. Although pHENOMMenal probiotic could be cultured from fecal samples at four months post treatment, it could no longer be cultivated from feces at eight months post treatment, indicating eventual loss of the microbe from the gut. Preliminary screens during experimentation found no immune response to AvPAL. Collectively these studies provide data for the use of a genetically engineered probiotic as a potential treatment for PKU.

Ammonia Leak Locator Study

NASA Technical Reports Server (NTRS)

Dodge, Franklin T.; Wuest, Martin P.; Deffenbaugh, Danny M.

1995-01-01

The thermal control system of International Space Station Alpha will use liquid ammonia as the heat exchange fluid. It is expected that small leaks (of the order perhaps of one pound of ammonia per day) may develop in the lines transporting the ammonia to the various facilities as well as in the heat exchange equipment. Such leaks must be detected and located before the supply of ammonia becomes critically low. For that reason, NASA-JSC has a program underway to evaluate instruments that can detect and locate ultra-small concentrations of ammonia in a high vacuum environment. To be useful, the instrument must be portable and small enough that an astronaut can easily handle it during extravehicular activity. An additional complication in the design of the instrument is that the environment immediately surrounding ISSA will contain small concentrations of many other gases from venting of onboard experiments as well as from other kinds of leaks. These other vapors include water, cabin air, CO2, CO, argon, N2, and ethylene glycol. Altogether, this local environment might have a pressure of the order of 10(exp -7) to 10(exp -6) torr. Southwest Research Institute (SwRI) was contracted by NASA-JSC to provide support to NASA-JSC and its prime contractors in evaluating ammonia-location instruments and to make a preliminary trade study of the advantages and limitations of potential instruments. The present effort builds upon an earlier SwRI study to evaluate ammonia leak detection instruments [Jolly and Deffenbaugh]. The objectives of the present effort include: (1) Estimate the characteristics of representative ammonia leaks; (2) Evaluate the baseline instrument in the light of the estimated ammonia leak characteristics; (3) Propose alternative instrument concepts; and (4) Conduct a trade study of the proposed alternative concepts and recommend promising instruments. The baseline leak-location instrument selected by NASA-JSC was an ion gauge.

Phenylpropanoids, Phenylalanine Ammonia Lyase and Peroxidases in Elicitor‐challenged Cassava (Manihot esculenta) Suspension Cells and Leaves

PubMed Central

GÓMEZ‐VÁSQUEZ, ROCÍO; DAY, ROBERT; BUSCHMANN, HOLGER; RANDLES, SOPHIE; BEECHING, JOHN R.; COOPER, RICHARD M.

2004-01-01

• Background and aims Control of diseases in the key tropical staple, cassava, is dependent on resistant genotypes, but the innate mechanisms are unknown. The aim was to study phenylpropanoids and associated enzymes as possible defence components. • Methods Phenylalanine ammonia‐lyase (PAL), phenylpropanoids and peroxidases (POD) were investigated in elicited cassava suspension cells and leaves. Yeast elicitor was the most effective of several microbial and endogenous elicitors. Fungitoxicity was determined against the cassava pathogens Fusarium solani, F. oxysporum and the saprotroph Trichoderma harzianum. • Key results A single and rapid (≥2–3 min) oxidative burst, measured as hydrogen peroxide, occurred in elicited cells. PAL activity was induced maximally at 15 h and was preceded by PAL mRNA accumulation, which peaked at 9 h. Symplasmic POD activity increased four‐fold in cells, 48 h post‐elicitation. POD isoforms (2–7 isoforms, pI 3·1–8·8) were detected in elicited and unelicited cells, extracellular medium and leaves but two extracellular isoforms were enhanced post‐elicitation. Also expression of a cassava peroxidase gene MecPOD1 increased in elicited cells. Only anionic forms oxidized scopoletin, with highest activity by isoform pI 3·6, present in all samples. Unidentified phenolics and possibly scopolin increased post‐elicitation, but there was no enhancement of scopoletin, rutin or kaempferol‐3‐O‐rutinoside concentration. Fungal germ tube elongation was inhibited more than germination by esculetin, ferulic acid, quercetin and scopoletin. T. harzianum was generally more sensitive than the pathogens and was inhibited by ≥50 µg mL–1 of ferulic acid and quercetin and ≥10 µg mL–1 of scopoletin. • Conclusions Phenolic levels in cells were not enhanced and were, theoretically, too low to be inhibitory. However, in combination and when oxidized they may contribute to defence, because oxidation of esculetin and

Enhancement of bioavailability of cinnarizine from its beta-cyclodextrin complex on oral administration with DL-phenylalanine as a competing agent.

PubMed

Tokumura, T; Nanba, M; Tsushima, Y; Tatsuishi, K; Kayano, M; Machida, Y; Nagai, T

1986-04-01

The present investigation is concerned with an improvement of the bioavailability of cinnarizine by administering its beta-cyclodextrin complex together with another compound which competes with the beta-cyclodextrin molecule in complex formation in aqueous solution (competing agent). The bioavailability of cinnarizine on oral administration of the cinnarizine-beta-cyclodextrin inclusion complex was enhanced by the simultaneous administration of DL-phenylalanine as a competing agent, e.g., the AUC was 1.9 and 2.7 times as large as those of the cinnarizine-beta-cyclodextrin complex alone and cinnarizine alone, respectively. The enhancement of AUC and Cmax completely depended on the dose of DL-phenylalanine. It was found from these results that DL-phenylalanine acted as a competing agent in the GI tract and the minimum effective dose required of DL-phenylalanine might be 1 g for 50 mg of cinnarizine in the cinnarizine-beta-cyclodextrin complex. Evaluating the competing effect of DL-phenylalanine in vitro using an absorption simulator, it was found that the decreased penetration rate of cinnarizine through the artificial lipid barrier with addition of beta-cyclodextrin was restored with the addition of DL-phenylalanine.

Enhancement of L-phenylalanine production by engineered Escherichia coli using phased exponential L-tyrosine feeding combined with nitrogen source optimization.

PubMed

Yuan, Peipei; Cao, Weijia; Wang, Zhen; Chen, Kequan; Li, Yan; Ouyang, Pingkai

2015-07-01

Nitrogen source optimization combined with phased exponential L-tyrosine feeding was employed to enhance L-phenylalanine production by a tyrosine-auxotroph strain, Escherichia coli YP1617. The absence of (NH4)2SO4, the use of corn steep powder and yeast extract as composite organic nitrogen source were more suitable for cell growth and L-phenylalanine production. Moreover, the optimal initial L-tyrosine level was 0.3 g L(-1) and exponential L-tyrosine feeding slightly improved L-phenylalanine production. Nerveless, L-phenylalanine production was greatly enhanced by a strategy of phased exponential L-tyrosine feeding, where exponential feeding was started at the set specific growth rate of 0.08, 0.05, and 0.02 h(-1) after 12, 32, and 52 h, respectively. Compared with exponential L-tyrosine feeding at the set specific growth rate of 0.08 h(-1), the developed strategy obtained a 15.33% increase in L-phenylalanine production (L-phenylalanine of 56.20 g L(-1)) and a 45.28% decrease in L-tyrosine supplementation. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Ammonia Emissions from Agriculture in China

NASA Astrophysics Data System (ADS)

Chen, Y.; Zhang, L.; Zhao, Y.; Huang, B.

2016-12-01

Ammonia (NH3) is an important alkaline pollutant in the atmosphere and it has various environmental and climatic effects. We will present an improved bottom-up estimate of ammonia emissions from agriculture in China at 0.5°×0.5° horizontal resolution and monthly variability. Ammonia emissions from fertilizer use are derived using data of crop planting area, fertilizer application time and rate for 18 main crops. Ammonia emission factors from fertilizer use are estimated as a function of soil properties such as soil pH, cation exchange capacity (CEC), and agricultural activity information such as crop type, fertilizer type, and application mode. We further consider ambient temperature and wind speed to account for the meteorological influences on ammonia emission factors of fertilizer use. We also estimate the ammonia emission from livestock over China using the mass-flow methodology. The derived ammonia emissions in China for the year 2005 are 4.55 Tg NH3 from fertilizer use and 6.96 Tg from livestock. Henan and Jiangsu provinces are the two largest emitting areas for ammonia from fertilizer use (470 Gg NH3 and 365 Gg NH3). Henan (621 Gg NH3) and Shandong (533 Gg NH3) have the largest ammonia emissions from livestock. Both ammonia emissions from fertilizer use and livestock have distinct seasonal variations; peaking in June for fertilizer use (822 Gg NH3) and in July for livestock (1244 Gg NH3), and are both lowest in January (80 Gg and 241 Gg, respectively). Combining with other ammonia source (eg. human waste and transport) estimates from the REAS v2.1 emission inventory, we show that total ammonia emissions in China for the year 2005 are 14.0 Tg NH3 a-1. Comparisons with satellite measurements of ammonia columns will also be presented.

Improvement of constraint-based flux estimation during L-phenylalanine production with Escherichia coli using targeted knock-out mutants.

PubMed

Weiner, Michael; Tröndle, Julia; Albermann, Christoph; Sprenger, Georg A; Weuster-Botz, Dirk

2014-07-01

Fed-batch production of the aromatic amino acid L-phenylalanine was studied with recombinant Escherichia coli strains on a 15 L-scale using glycerol as carbon source. Flux Variability Analysis (FVA) was applied for intracellular flux estimation to obtain an insight into intracellular flux distribution during L-phenylalanine production. Variability analysis revealed great flux uncertainties in the central carbon metabolism, especially concerning malate consumption. Due to these results two recombinant strains were genetically engineered differing in the ability of malate degradation and anaplerotic reactions (E. coli FUS4.11 ΔmaeA pF81kan and E. coli FUS4.11 ΔmaeA ΔmaeB pF81kan). Applying these malic enzyme knock-out mutants in the standardized L-phenylalanine production process resulted in almost identical process performances (e.g., L-phenylalanine concentration, production rate and byproduct formation). This clearly highlighted great redundancies in central metabolism in E. coli. Uncertainties of intracellular flux estimations by constraint-based analyses during fed-batch production of L-phenylalanine were drastically reduced by application of the malic enzyme knock-out mutants. © 2014 Wiley Periodicals, Inc.

Metabolism of C14-labeled phenylalanine and tyrosine in malaria-infected Culex-females (in German)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maier, W.A.; Nassif-Makki, H.

1975-01-01

Culex females are fed on C14-phenylalanine or C14-tyrosine in sugar solution. Autoradiographic studies on homogenated females 1 or 4 days after feeding, show that the labeled amino acids are metabolized on the first day and are not detectable on the fourth day. After increase of the amino acid concentration by saturation of the sugar solution with the unlabeled amino acid, the labeled acid and its metabolites are visible over a longer period of time. Phenylalanine is metabolized to tyrosine and at least four other substances. Radioactivity on the starting point of the chromatogram can be interpreted as incorporation of tyrosinemore » into proteins. After infection with Plasmodium cathemerium, and feeding of C14-phenylalanine C14-tyrosine is demonstrable over a longer period. (orig.)« less

Stable Isotope-Assisted Metabolic Profiling Reveals Growth Mode Dependent Differential Metabolism and Multiple Catabolic Pathways of l-Phenylalanine in Rubrivivax benzoatilyticus JA2.

PubMed

Mekala, Lakshmi Prasuna; Mohammed, Mujahid; Chintalapati, Sasikala; Chintalapati, Venkata Ramana

2018-01-05

Anoxygenic phototrophic bacteria are metabolically versatile and survive under different growth modes using diverse organic compounds, yet their metabolic diversity is largely unexplored. In the present study, we employed stable-isotope-assisted metabolic profiling to unravel the l-phenylalanine catabolism in Rubrivivax benzoatilyticus JA2 under varying growth modes. Strain JA2 grows under anaerobic and aerobic conditions by utilizing l-phenylalanine as a nitrogen source. Furthermore, ring-labeled 13 C 6 -phenylalanine feeding followed by liquid chromatography-mass spectrometry exometabolite profiling revealed 60 labeled metabolic features (M + 6, M + 12, and M + 18) derived solely from l-phenylalanine, of which 11 were identified, 7 putatively identified, and 42 unidentified under anaerobic and aerobic conditions. However, labeled metabolites were significantly higher in aerobic compared to anaerobic conditions. Furthermore, detected metabolites and enzyme activities indicated multiple l-phenylalanine catabolic routes mainly Ehrlich, homogentisate-dependent melanin, benzenoid, and unidentified pathways operating under anaerobic and aerobic conditions in strain JA2. Interestingly, the study indicated l-phenylalanine-dependent and independent benzenoid biosynthesis in strain JA2 and a differential flux of l-phenylalanine to Ehrlich and benzenoid pathways under anaerobic and aerobic conditions. Additionally, unidentified labeled metabolites strongly suggest the presence of unknown phenylalanine catabolic routes in strain JA2. Overall, the study uncovered the l-phenylalanine catabolic diversity in strain JA2 and demonstrated the potential of stable isotope-assisted metabolomics in unraveling the hidden metabolic repertoire.

Defences against ammonia toxicity in tropical air-breathing fishes exposed to high concentrations of environmental ammonia: a review.

PubMed

Ip, Y K; Chew, S F; Wilson, J M; Randall, D J

2004-10-01

In the tropics, air-breathing fishes can be exposed to environmental ammonia when stranded in puddles of water during the dry season, during a stay inside a burrow, or after agricultural fertilization. At low concentrations of environmental ammonia, NH(3) excretion is impeded, as in aerial exposure, leading to the accumulation of endogenous ammonia. At high concentrations of environmental ammonia, which results in a reversed NH(3) partial pressure gradient (DeltaP(NH3)), there is retention of endogenous ammonia and uptake of exogenous ammonia. In this review, several tropical air-breathing fishes (giant mudskipper, African catfish, oriental weatherloach, swamp eel, four-eyed sleeper, abehaze and slender African lungfish), which can tolerate high environmental ammonia exposure, are used as examples to demonstrate how eight different adaptations can be involved in defence against ammonia toxicity. Four of these adaptations deal with ammonia toxicity at branchial and/or epithelial surfaces: (1) active excretion of NH(4)(+); (2) lowering of environmental pH; (3) low NH(3) permeability of epithelial surfaces; and (4) volatilization of NH(3), while another four adaptations ameliorate ammonia toxicity at the cellular and subcellular levels: (5) high tolerance of ammonia at the cellular and subcellular levels; (6) reduction in ammonia production; (7) glutamine synthesis; and (8) urea synthesis. The responses of tropical air-breathing fishes to high environmental ammonia are determined apparently by behavioural adaptations and the nature of their natural environments.

Plasma phenylalanine and tyrosine responses to different nutritional conditions (fasting/postprandial) in patients with phenylketonuria: effect of sample timing.

PubMed

van Spronsen, F J; van Rijn, M; van Dijk, T; Smit, G P; Reijngoud, D J; Berger, R; Heymans, H S

1993-10-01

To evaluate the adequacy of dietary treatment in patients with phenylketonuria, the monitoring of plasma phenylalanine and tyrosine concentrations is of great importance. The preferable time of blood sampling in relation to the nutritional condition during the day, however, is not known. It was the aim of this study to define guidelines for the timing of blood sampling with a minimal burden for the patient. Plasma concentrations of phenylalanine and tyrosine were measured in nine patients with phenylketonuria who had no clinical evidence of tyrosine deficiency. These values were measured during the day both after a prolonged overnight fast, and before and after breakfast. Phenylalanine showed a small rise during prolonged fasting, while tyrosine decreased slightly. After an individually tailored breakfast, phenylalanine remained stable, while tyrosine showed large fluctuations. It is concluded that the patient's nutritional condition (fasting/postprandial) is not important in the evaluation of the phenylalanine intake. To detect a possible tyrosine deficiency, however, a single blood sample is not sufficient and a combination of a preprandial and postprandial blood sample on the same day is advocated.

Attempted transmission of Ehrlichia risticii, causative agent of Potomac horse fever, by the ticks, Dermacentor variabilis, Rhipicephalus sanguineus, Ixodes scapularis and Amblyomma americanum.

PubMed

Hahn, N E; Fletcher, M; Rice, R M; Kocan, K M; Hansen, J W; Hair, J A; Barker, R W; Perry, B D

1990-01-01

Dermacentor variabilis, Rhipicephalus sanguineus, Amblyomma americanum, and Ixodes scapularis ticks were investigated for their ability to transmit Potomac horse fever. Larval and nymphal ticks were exposed to Ehrlichia risticii by feeding on mice inoculated with the organism. Molted exposed ticks were then allowed to feed on susceptible ponies or mice. No evidence of transmission, either clinically or by detection of antibodies to E. risticii in mice or ponies, was observed for any tick species examined.

The Holo-Transcriptome of the Zoantharian Protopalythoa variabilis (Cnidaria: Anthozoa): A Plentiful Source of Enzymes for Potential Application in Green Chemistry, Industrial and Pharmaceutical Biotechnology.

PubMed

R L Morlighem, Jean-Étienne; Huang, Chen; Liao, Qiwen; Braga Gomes, Paula; Daniel Pérez, Carlos; de Brandão Prieto-da-Silva, Álvaro Rossan; Ming-Yuen Lee, Simon; Rádis-Baptista, Gandhi

2018-06-13

Marine invertebrates, such as sponges, tunicates and cnidarians (zoantharians and scleractinian corals), form functional assemblages, known as holobionts, with numerous microbes. This type of species-specific symbiotic association can be a repository of myriad valuable low molecular weight organic compounds, bioactive peptides and enzymes. The zoantharian Protopalythoa variabilis (Cnidaria: Anthozoa) is one such example of a marine holobiont that inhabits the coastal reefs of the tropical Atlantic coast and is an interesting source of secondary metabolites and biologically active polypeptides. In the present study, we analyzed the entire holo-transcriptome of P. variabilis , looking for enzyme precursors expressed in the zoantharian-microbiota assemblage that are potentially useful as industrial biocatalysts and biopharmaceuticals. In addition to hundreds of predicted enzymes that fit into the classes of hydrolases, oxidoreductases and transferases that were found, novel enzyme precursors with multiple activities in single structures and enzymes with incomplete Enzyme Commission numbers were revealed. Our results indicated the predictive expression of thirteen multifunctional enzymes and 694 enzyme sequences with partially characterized activities, distributed in 23 sub-subclasses. These predicted enzyme structures and activities can prospectively be harnessed for applications in diverse areas of industrial and pharmaceutical biotechnology.

Intramolecular interactions of L-phenylalanine: Valence ionization spectra and orbital momentum distributions of its fragment molecules.

PubMed

Ganesan, Aravindhan; Wang, Feng; Falzon, Chantal

2011-02-01

Intramolecular interactions between fragments of L-phenylalanine, i.e., phenyl and alaninyl, have been investigated using dual space analysis (DSA) quantum mechanically. Valence space photoelectron spectra (PES), orbital energy topology and correlation diagram, as well as orbital momentum distributions (MDs) of L-phenylalanine, benzene and L-alanine are studied using density functional theory methods. While fully resolved experimental PES of L-phenylalanine is not yet available, our simulated PES reproduces major features of the experimental measurement. For benzene, the simulated orbital MDs for 1e(1g) and 1a(2u) orbitals also agree well with those measured using electron momentum spectra. Our theoretical models are then applied to reveal intramolecular interactions of the species on an orbital base, using DSA. Valence orbitals of L-phenylalanine can be essentially deduced into contributions from its fragments such as phenyl and alaninyl as well as their interactions. The fragment orbitals inherit properties of their parent species in energy and shape (ie., MDs). Phenylalanine orbitals show strong bonding in the energy range of 14-20 eV, rather than outside of this region. This study presents a competent orbital based fragments-in-molecules picture in the valence space, which supports the fragment molecular orbital picture and building block principle in valence space. The optimized structures of the molecules are represented using the recently developed interactive 3D-PDF technique. Copyright © 2010 Wiley Periodicals, Inc.

Ammonia Ice Clouds on Jupiter

NASA Technical Reports Server (NTRS)

2007-01-01

The top cloud layer on Jupiter is thought to consist of ammonia ice, but most of that ammonia 'hides' from spectrometers. It does not absorb light in the same way ammonia does. To many scientists, this implies that ammonia churned up from lower layers of the atmosphere 'ages' in some way after it condenses, possibly by being covered with a photochemically generated hydrocarbon mixture. The New Horizons Linear Etalon Imaging Spectral Array (LEISA), the half of the Ralph instrument that is able to 'see' in infrared wavelengths that are absorbed by ammonia ice, spotted these clouds and watched them evolve over five Jupiter days (about 40 Earth hours). In these images, spectroscopically identified fresh ammonia clouds are shown in bright blue. The largest cloud appeared as a localized source on day 1, intensified and broadened on day 2, became more diffuse on days 3 and 4, and disappeared on day 5. The diffusion seemed to follow the movement of a dark spot along the boundary of the oval region. Because the source of this ammonia lies deeper than the cloud, images like these can tell scientists much about the dynamics and heat conduction in Jupiter's lower atmosphere.

Sources of atmospheric ammonia

NASA Technical Reports Server (NTRS)

Harriss, R. C.; Michaels, J. T.

1982-01-01

The information available on factors that influence emissions from the principal societal sources of ammonia to the atmosphere, namely combustion processes, volatilization of farm animal wastes, and volatilization of fertilizers, is reviewed. Emission factors are established for each major source of atmospheric ammonia. The factors are then multiplied by appropriate source characterization descriptors to obtain calculated fluxes of ammonia to the atmosphere on a state-by-state basis for the United States.

Non-invasive estimation of 10 B-4-borono-L-phenylalanine-derived boron concentration in tumors by PET using 4-borono-2-18 F-fluoro-phenylalanine.

PubMed

Yoshimoto, Mitsuyoshi; Honda, Natsuki; Kurihara, Hiroaki; Hiroi, Kenta; Nakamura, Satoshi; Ito, Masashi; Shikano, Naoto; Itami, Jun; Fujii, Hirofumi

2018-05-01

In boron neutron capture therapy (BNCT), 10 B-4-borono-L-phenylalanine (BPA) is commonly used as a 10 B carrier. PET using 4-borono-2- 18 F-fluoro-phenylalanine ( 18 F-FBPA PET) has been performed to estimate boron concentration and predict the therapeutic effects of BNCT; however, the association between tumor uptake of 18 F-FBPA and boron concentration in tumors remains unclear. The present study investigated the transport mechanism of 18 F-FBPA and BPA, and evaluated the utility of 18 F-FBPA PET in predicting boron concentration in tumors. The transporter assay revealed that 2-aminobicyclo-(2.2.1)-heptane-2-carboxylic acid, an inhibitor of the L-type amino acid transporter, significantly inhibited 18 F-FBPA and 14 C-4-borono-L-phenylalanine ( 14 C-BPA) uptake in FaDu and LN-229 human cancer cells. 18 F-FBPA uptake strongly correlated with 14 C-BPA uptake in 7 human tumor cell lines (r = .93; P < .01). PET experiments demonstrated that tumor uptake of 18 F-FBPA was independent of the administration method, and uptake of 18 F-FBPA by bolus injection correlated well with BPA uptake by continuous intravenous infusion. The results of this study revealed that evaluating tumor uptake of 18 F-FBPA by PET was useful for estimating 10 B concentration in tumors. © 2018 The Authors.Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

Ammonia-oxidizing archaea have more important role than ammonia-oxidizing bacteria in ammonia oxidation of strongly acidic soils

PubMed Central

Zhang, Li-Mei; Hu, Hang-Wei; Shen, Ju-Pei; He, Ji-Zheng

2012-01-01

Increasing evidence demonstrated the involvement of ammonia-oxidizing archaea (AOA) in the global nitrogen cycle, but the relative contributions of AOA and ammonia-oxidizing bacteria (AOB) to ammonia oxidation are still in debate. Previous studies suggest that AOA would be more adapted to ammonia-limited oligotrophic conditions, which seems to be favored by protonation of ammonia, turning into ammonium in low-pH environments. Here, we investigated the autotrophic nitrification activity of AOA and AOB in five strongly acidic soils (pH<4.50) during microcosm incubation for 30 days. Significantly positive correlations between nitrate concentration and amoA gene abundance of AOA, but not of AOB, were observed during the active nitrification. 13CO2-DNA-stable isotope probing results showed significant assimilation of 13C-labeled carbon source into the amoA gene of AOA, but not of AOB, in one of the selected soil samples. High levels of thaumarchaeal amoA gene abundance were observed during the active nitrification, coupled with increasing intensity of two denaturing gradient gel electrophoresis bands for specific thaumarchaeal community. Addition of the nitrification inhibitor dicyandiamide (DCD) completely inhibited the nitrification activity and CO2 fixation by AOA, accompanied by decreasing thaumarchaeal amoA gene abundance. Bacterial amoA gene abundance decreased in all microcosms irrespective of DCD addition, and mostly showed no correlation with nitrate concentrations. Phylogenetic analysis of thaumarchaeal amoA gene and 16S rRNA gene revealed active 13CO2-labeled AOA belonged to groups 1.1a-associated and 1.1b. Taken together, these results provided strong evidence that AOA have a more important role than AOB in autotrophic ammonia oxidation in strongly acidic soils. PMID:22134644

Ammonia transformations and abundance of ammonia oxidizers in a clay soil underlying a manure pond.

PubMed

Sher, Yonatan; Baram, Shahar; Dahan, Ofer; Ronen, Zeev; Nejidat, Ali

2012-07-01

Unlined manure ponds are constructed on clay soil worldwide to manage farm waste. Seepage of ammonia-rich liquor into underlying soil layers contributes to groundwater contamination by nitrate. To identify the possible processes that lead to the production of nitrate from ammonia in this oxygen-limited environment, we studied the diversity and abundance of ammonia-transforming microorganisms under an unlined manure pond. The numbers of ammonia-oxidizing bacteria and anammox bacteria were most abundant in the top of the soil profile and decreased significantly with depth (0.5 m), correlating with soil pore-water ammonia concentrations and soil ammonia concentrations, respectively. On the other hand, the numbers of ammonia-oxidizing archaea were relatively constant throughout the soil profile (10(7) amoA copies per g(soil)). Nitrite-oxidizing bacteria were detected mainly in the top 0.2 m. The results suggest that nitrate accumulation in the vadose zone under the manure pond could be the result of complete aerobic nitrification (ammonia oxidation to nitrate) and could exist as a byproduct of anammox activity. While the majority of the nitrogen was removed within the 0.5-m soil section, possibly by combined anammox and heterotrophic denitrification, a fraction of the produced nitrate leached into the groundwater. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Human (13)N-ammonia PET studies: the importance of measuring (13)N-ammonia metabolites in blood.

PubMed

Keiding, Susanne; Sørensen, Michael; Munk, Ole Lajord; Bender, Dirk

2010-03-01

Dynamic (13)N-ammonia PET is used to assess ammonia metabolism in brain, liver and muscle based on kinetic modeling of metabolic pathways, using arterial blood (13)N-ammonia as input function. Rosenspire et al. (1990) introduced a solid phase extraction procedure for fractionation of (13)N-content in blood into (13)N-ammonia, (13)N-urea, (13)N-glutamine and (13)N-glutamate. Due to a radioactive half-life for (13)N of 10 min, the procedure is not suitable for blood samples taken beyond 5-7 min after tracer injection. By modifying Rosenspire's method, we established a method enabling analysis of up to 10 blood samples in the course of 30 min. The modified procedure was validated by HPLC and by 30-min reproducibility studies in humans examined by duplicate (13)N-ammonia injections with a 60-min interval. Blood data from a (13)N-ammonia brain PET study (from Keiding et al. 2006) showed: (1) time courses of (13)N-ammonia fractions could be described adequately by double exponential functions; (2) metabolic conversion of (13)N-ammonia to (13)N-metabolites were in the order: healthy subjects > cirrhotic patients without HE > cirrhotic patients with HE; (3) kinetics of initial tracer distribution in tissue can be assessed by using total (13)N-concentration in blood as input function, whereas assessment of metabolic processes requires (13)N-ammonia measurements.

Ammonia-water cation and ammonia dimer cation.

PubMed

Kim, Hahn; Lee, Han Myoung

2009-06-25

We have investigated the structure, interaction energy, electronic properties, and IR spectra of the ammonia-water cation (NH(3)H(2)O)(+) using density functional theory (DFT) and high-level ab initio theory. The ammonia-water cation has three minimum-energy structures of (a) H(2)NH(+)...OH(2), (b) H(3)N(+)...OH(2), and (c) H(3)NH(+)...OH. The lowest-energy structure is (a), followed by (c) and (b). The ammonia dimer cation has two minimum-energy structures [the lowest H(3)NH(+)...NH(2) structure and the second lowest (H(3)N...NH(3))(+) structure]. The minimum transition barrier for the interconversion between (a), (b), and (c) is approximately 6 kcal/mol. Most DFT calculations with various functionals, except a few cases, overstabilize the N...O and N...N binding, predicting different structures from Moller-Plesset second-order perturbation (MP2) theory and the most reliable complete basis set (CBS) limit of coupled cluster theory with single, double, and perturbative triple excitations [CCSD(T)]. Thus, the validity test of the DFT functionals for these ionized molecular systems would be of importance.

Shape Memory Properties and Enzymatic Degradability of Poly(ε-caprolactone)-Based Polyurethane Urea Containing Phenylalanine-Derived Chain Extender.

PubMed

Wang, Rong; Zhang, Fanjun; Lin, Weiwei; Liu, Wenkai; Li, Jiehua; Luo, Feng; Wang, Yaning; Tan, Hong

2018-06-01

Biodegradable shape memory polymers are promising biomaterials for minimally invasive surgical procedures. Herein, a series of linear biodegradable shape memory poly(ε-caprolactone) (PCL)-based polyurethane ureas (PUUs) containing a novel phenylalanine-derived chain extender is synthesized. The phenylalanine-derived chain extender, phenylalanine-hexamethylenediamine-phenylalanine (PHP), contains two chymotrypsin cleaving sites to enhance the enzymatic degradation of PUUs. The degradation rate, the crystallinity, and mechanical properties of PUUs are tailored by the content of PHP. Meanwhile, semicrystalline PCL is not only hydrolytically degradable but also vital for shape memory. Good shape memory ability under body temperature is achieved for PUUs due to the strong interactions in hard segments for permanent crosslinking and the crystallization-melt transition of PCL to switch temporary shape. The PUUs would have a great potential in application as implanting stent. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Response to pentagastrin after acute phenylalanine and tyrosine depletion in healthy men: a pilot study.

PubMed Central

Coupland, N; Zedkova, L; Sanghera, G; Leyton, M; Le Mellédo, J M

2001-01-01

OBJECTIVE: To assess the effects of the acute depletion of the catecholamine precursors phenylalanine and tyrosine on mood and pentagastrin-induced anxiety. DESIGN: Randomized, double-blind controlled multiple crossover study. SETTING: University department of psychiatry. PARTICIPANTS: 6 healthy male volunteers. INTERVENTIONS: 3 treatments were compared: pretreatment with a nutritionally balanced amino acid mixture, followed 5 hours later by a bolus injection of normal saline placebo; pretreatment with a balanced amino acid mixture, followed by a bolus injection of pentagastrin (0.6 microgram/kg); and pretreatment with an amino acid mixture without the catecholamine precursors phenylalanine or tyrosine, followed by pentagastrin (0.6 microgram/kg). OUTCOME MEASURES: Scores on the panic symptom scale, a visual analogue scale for anxiety, the Borg scale of respiratory exertion and the Profile of Mood States Elation-Depression Scale. RESULTS: Pentagastrin produced the expected increases in anxiety symptoms, but there was no significant or discernible influence of acute phenylalanine and tyrosine depletion on anxiety or mood. CONCLUSIONS: These pilot data do not support further study using the same design in healthy men. Under these study conditions, phenylalanine and tyrosine depletion may have larger effects on dopamine than noradrenaline. Alternative protocols to assess the role of catecholamines in mood and anxiety are proposed. PMID:11394194

Long-term beneficial effects of the phenylalanine-restricted diet in late-diagnosed individuals with phenylketonuria.

PubMed

Koch, R; Moseley, K; Ning, J; Romstad, A; Guldberg, P; Guttler, F

1999-06-01

The potential benefits to society of treating late-diagnosed mentally retarded persons with phenylketonuria were investigated. In order to ascertain the effects of late dietary intervention, the charts of 124 adults with PKU seen in the metabolic service at the Childrens Hospital of Los Angeles were reviewed. Fifty-nine were diagnosed later than 3 months of age and were over the age of 18 years. They were followed up with medical, psychological, and nutritional assessments. Genotyping was also performed. Twenty-eight have remained on a phenylalanine-restricted diet during the intervening years. All but 3 of the 28 late-diagnosed PKU persons who remained on a restricted diet showed significant intellectual improvement. Seven are able to attend college, 9 are employed, and 12 are attending workshops and/or day care programs. The result of treatment with the phenylalanine-restricted diet was that these individuals could participate in society and were able to arrest the neurodegenerative course characteristic of persons with mutations classified as severe in the phenylalanine hydroxylase gene. We conclude that society could benefit substantially by providing a phenylalanine-restricted diet for late-diagnosed mentally retarded persons with phenylketonuria. Eighteen of 28 such persons who otherwise would have required residential care are living independently. Copyright 1999 Academic Press.

The Kinetic Mechanism of Phenylalanine Hydroxylase: Intrinsic Binding and Rate Constants from Single Turnover Experiments†

PubMed Central

Roberts, Kenneth M.; Pavon, Jorge Alex; Fitzpatrick, Paul F.

2013-01-01

Phenylalanine hydroxylase (PheH) catalyzes the key step in the catabolism of dietary phenylalanine, its hydroxylation to tyrosine using tetrahydrobiopterin (BH4) and O2. A complete kinetic mechanism for PheH was determined by global analysis of single turnover data in the reaction of PheHΔ117, a truncated form of the enzyme lacking the N-terminal regulatory domain. Formation of the productive PheHΔ117-BH4-phenylalanine complex begins with the rapid binding of BH4 (Kd = 65 µM). Subsequent addition of phenylalanine to the binary complex to form the productive ternary complex (Kd = 130 µM) is approximately ten-fold slower. Both substrates can also bind to the free enzyme to form inhibitory binary complexes. O2 rapidly binds to the productive ternary complex; this is followed by formation of an unidentified intermediate, detectable as a decrease in absorbance at 340 nm, with a rate constant of 140 s−1. Formation of the 4a-hydroxypterin and Fe(IV)O intermediates is ten-fold slower and is followed by the rapid hydroxylation of the amino acid. Product release is the rate-determining step and largely determines kcat. Similar reactions using 6-methyltetrahydropterin indicate a preference for the physiological pterin during hydroxylation. PMID:23327364

Nitric oxide scavengers differentially inhibit ammonia oxidation in ammonia-oxidizing archaea and bacteria.

PubMed

Sauder, Laura A; Ross, Ashley A; Neufeld, Josh D

2016-04-01

Differential inhibitors are important for measuring the relative contributions of microbial groups, such as ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), to biogeochemical processes in environmental samples. In particular, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) represents a nitric oxide scavenger used for the specific inhibition of AOA, implicating nitric oxide as an intermediate of thaumarchaeotal ammonia oxidation. This study investigated four alternative nitric oxide scavengers for their ability to differentially inhibit AOA and AOB in comparison to PTIO. Caffeic acid, curcumin, methylene blue hydrate and trolox were tested onNitrosopumilus maritimus, two unpublished AOA representatives (AOA-6f and AOA-G6) as well as the AOB representative Nitrosomonas europaea All four scavengers inhibited ammonia oxidation by AOA at lower concentrations than for AOB. In particular, differential inhibition of AOA and AOB by caffeic acid (100 μM) and methylene blue hydrate (3 μM) was comparable to carboxy-PTIO (100 μM) in pure and enrichment culture incubations. However, when added to aquarium sponge biofilm microcosms, both scavengers were unable to inhibit ammonia oxidation consistently, likely due to degradation of the inhibitors themselves. This study provides evidence that a variety of nitric oxide scavengers result in differential inhibition of ammonia oxidation in AOA and AOB, and provides support to the proposed role of nitric oxide as a key intermediate in the thaumarchaeotal ammonia oxidation pathway. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Sources and sinks for ammonia and nitrite on the early Earth and the reaction of nitrite with ammonia

NASA Technical Reports Server (NTRS)

Summers, D. P.

1999-01-01

An analysis of sources and sinks for ammonia and nitrite on the early Earth was conducted. Rates of formation and destruction, and steady state concentrations of both species were determined by steady state kinetics. The importance of the reaction of nitrite with ammonia on the feasibility of ammonia formation from nitrite was evaluated. The analysis considered conditions such as temperature, ferrous iron concentration, and pH. For sinks we considered the reduction of nitrite to ammonia, reaction between nitrite and ammonia, photochemical destruction of both species, and destruction at hydrothermal vents. Under most environmental conditions, the primary sink for nitrite is reduction to ammonia. The reaction between ammonia and nitrite is not an important sink for either nitrite or ammonia. Destruction at hydrothermal vents is important at acidic pH's and at low ferrous iron concentrations. Photochemical destruction, even in a worst case scenario, is unimportant under many conditions except possibly under acidic, low iron concentration, or low temperature conditions. The primary sink for ammonia is photochemical destruction in the atmosphere. Under acidic conditions, more of the ammonia is tied up as ammonium (reducing its vapor pressure and keeping it in solution) and hydrothermal destruction becomes more important.

21 CFR 862.1065 - Ammonia test system.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ammonia test system. 862.1065 Section 862.1065....1065 Ammonia test system. (a) Identification. An ammonia test system is a device intended to measure ammonia levels in blood, serum, and plasma, Ammonia measurements are used in the diagnosis and treatment...

Antihypertension and anti-cardiovascular remodeling by phenylalanine in spontaneously hypertensive rats: effectiveness and mechanisms.

PubMed

Zhao, G; Li, Z; Gu, T

2001-03-01

To investigate mechanisms of anti-hypertension and anti-cardiovascular remodeling by phenylalanine (phe) in spontaneously hypertensive rats (SHRs). The comparison of blood pressure (BP) increment with the ages and cardiovascular changes of SHRs was made between the 3% phe-intervented group (SHR-phe) and the control SHRs group. Detection of the structural changes with the VIDAS digital vedio-frequency processing technique and light and electron microscopy were made. The cell growth and proliferation of cultured smooth muscle cells (CSMCs) of the thoracic aortas or myocardial fibroblasts were evaluated by measuring the 3H-thymidine counts per minute (cpm) incorporated into the new synthesized desoxyribonucleic acid (DNA) and determining the cell number with the crystal violet stain technique. The Ca2+ influx was measured in counts/min of 45CaCl2 after incubating it with 5 different concentrations of phenylalanine and the intracellular [Ca2+]i by Fura-II/Am indicator. The total messenger ribonucleic acid (mRNA) of the myocardium was extracted and Northern blot analysis was performed with the probe collagen alpha 2 (I) cDNA. The tyrosine hydroxylase (TH) activity was measured by high-performance liquid chromatography (HPLC) with electrochemical detector after having reacted with its substrate tyrosine and other reagents. The catecholamine contents in brain homogenat were detected by HPLC method. The comparison of pharmacokinetics of phenylalanine among SHR-phe, SHRs and control Wistar Kyoto (WKY) rats was made after intravenous injection of 3H-L-phe (1 ml/kg) by PK-GRAPH Program for kinetic calculation. The 3H-L-phe uptake by CSMCs after incubating for definite intervals was also detected and compared. Phenylalanine could prevent the increase of BP with ages and the heart weight (heart/body weight index). The aortic media thickness and the collagen content in the myocardium were decreased significantly in SHR-phe. Whereas the dearranged cardiovascular structure was

Ammonia in London: is it increasing and what is the relevance of urban ammonia for air quality impacts?

NASA Astrophysics Data System (ADS)

Braban, Christine; Tang, Sim; Poskitt, Janet; Van Dijk, Netty; Leeson, Sarah; Dragosits, Ulli; Hutchings, Torben; Twigg, Marsailidh; Di Marco, Chiara; Langford, Ben; Tremper, Anja; Nemitz, Eiko; Sutton, Mark

2017-04-01

Emissions of ammonia affect both rural and urban air quality primarily via reaction of ammonia in the atmosphere forming secondary ammonium salts in particulate matter (PM). Urban ammonia emissions come from a variety of sources including biological decomposition, human waste, industrial processes and combustion engines. In the UK, the only long-term urban ammonia measurement is a UK National Ammonia Monitoring Network site at London Cromwell Road, recording monthly average concentrations. Short term measurements have also been made in the past decade at Marylebone Road, North Kensington and on the BT Tower. Cromwell Road is a kerbside site operational since 1999. The Cromwell Road data indicates that ammonia concentrations may be increasing since 2010-2012 after a long period of decreasing. Data from the National Atmospheric Emissions Inventory indicates ammonia emissions from diesel fleet exhausts increasing over this time period but an overall net decrease in ammonia emissions. With changes in engine and exhaust technology to minimise pollutant emissions and the importance of ammonia as a precursor gas for secondary PM, there is a challenge to understand urban ammonia concentrations and subsequent impacts on urban air quality. In this paper the long term measurements are assessed in conjunction with the short-term measurements.The challenges to assess the relative importance of local versus long range ammonia emission are discussed.

Facile and efficient electrochemical enantiomer recognition of phenylalanine using β-Cyclodextrin immobilized on reduced graphene oxide.

PubMed

Zaidi, Shabi Abbas

2017-08-15

This work demonstrates the facile and efficient preparation protocol of β-Cyclodextrin-reduced graphene oxide modified glassy carbon electrode (β-CD/RGO/GCE) sensor for an impressive chiral selectivity analysis for phenylalanine enantiomers. In this work, the immobilization of β-CD over graphene sheets allows the excellent enantiomer recognition due to the large surface area and high conductivity of graphene sheets and extraordinary supramolecular (host-guest interaction) property of β-CD. The proposed sensor was well characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and electrochemical impedance spectroscopy (EIS) techniques. The analytical studies demonstrated that the β-CD/RGO/GCE exhibit superior chiral recognition toward L-phenylalanine as compared to D-phenylalanine. Under optimum conditions, the developed sensor displayed a good linear range from 0.4 to 40µM with the limit of detection (LOD) values of 0.10µM and 0.15µM for l- and D-phenylalanine, respectively. Furthermore, the proposed sensor exhibits good stability and regeneration capacity. Thus, the as-synthesized material can be exploited for electrochemical enantiomer recognition successfully. Copyright © 2017 Elsevier B.V. All rights reserved.

Stimulation of thaumarchaeal ammonia oxidation by ammonia derived from organic nitrogen but not added inorganic nitrogen.

PubMed

Levičnik-Höfferle, Spela; Nicol, Graeme W; Ausec, Luka; Mandić-Mulec, Ines; Prosser, James I

2012-04-01

Ammonia oxidation, the first step in nitrification, is performed by autotrophic bacteria and thaumarchaea, whose relative contributions vary in different soils. Distinctive environmental niches for the two groups have not been identified, but evidence from previous studies suggests that activity of thaumarchaea, unlike that of bacterial ammonia oxidizers, is unaffected by addition of inorganic N fertilizer and that they preferentially utilize ammonia generated from the mineralization of organic N. This hypothesis was tested by determining the influence of both inorganic and organic N sources on nitrification rate and ammonia oxidizer growth and community structure in microcosms containing acidic, forest soil in which ammonia oxidation was dominated by thaumarchaea. Nitrification rate was unaffected by the incubation of soil with inorganic ammonium but was significantly stimulated by the addition of organic N. Oxidation of ammonia generated from native soil organic matter or added organic N, but not added inorganic N, was accompanied by increases in abundance of the thaumarchaeal amoA gene, a functional gene for ammonia oxidation, but changes in community structure were not observed. Bacterial amoA genes could not be detected. Ammonia oxidation was completely inhibited by 0.01% acetylene in all treatments, indicating ammonia monooxygenase-dependent activity. The findings have implications for current models of soil nitrification and for nitrification control strategies to minimize fertilizer loss and nitrous oxide production. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Aquatic Life Criteria - Ammonia

EPA Pesticide Factsheets

Documents related to EPA's final 2013 Aquatic Life Ambient Water Quality Criteria for Ammonia (Freshwater). These documents pertain to the safe levels of Ammonia in water that should protect to the majority of species.

The Ammonia-Soda Process.

ERIC Educational Resources Information Center

Tingle, M.

1979-01-01

This article is a condensed version of a commentary written to accompany a set of slides which describes the ammonia-soda process used by the ammonia-soda plant at Northwich of the United Kingdom. (HM)

Nucleation kinetics from metastable zone widths for sonocrystallization of l-phenylalanine.

PubMed

Hazi Mastan, T; Lenka, Maheswata; Sarkar, Debasis

2017-05-01

This study investigates the effect of ultrasound on metastable zone width (MSZW) during crystallization of l-phenylalanine from aqueous solution. The solubility of l-phenylalanine in water was measured gravimetrically in the temperature range of 293.15-333.15K. The MSZW was measured by conventional polythermal method for four different cooling rates at five different saturation temperatures in absence and presence of ultrasound. The MSZW increased with increase in cooling rates and decreased with increase in saturation temperature. The application of ultrasound considerably reduced the MSZW for all the experiments. The obtained MSZW data are analysed using four different approaches to calculate various nucleation parameters. In presence of ultrasound, the apparent nucleation order decreased and nucleation rate constant increased significantly. Copyright © 2016 Elsevier B.V. All rights reserved.

Improving the extraction of l-phenylalanine by the use of ionic liquids as adjuvants in aqueous biphasic systems.

PubMed

Yang, Hongpeng; Chen, Li; Zhou, Cunshan; Yu, Xiaojie; Yagoub, Abu ElGasim A; Ma, Haile

2018-04-15

Polyethylene glycol (PEG) is widely used in the polymer-salt systems. However, the low polarity of the PEG-rich phase limits the application of aqueous biphasic systems (ABS). To overcome this disadvantage, a small quantity of ionic liquid (IL) was used as an adjuvant in ABS to enlarge the polarity range. Therefore, an innovative study involving addition of 4wt% imidazolium-based ILs to the PEG 600/NaH 2 PO 4 ABS, aiming at controlling the phase behavior and extraction ability, was carried out. The phase diagrams, the tie-lines and the partitioning behavior of l-phenylalanine and ILs were studied in these systems. The results reveal that l-phenylalanine preferentially partitions for the PEG-rich phase. The addition of 4wt% IL to ABS controls the partitioning behavior of l-phenylalanine, which depends on the type of IL employed. Moreover, it is verified that increasing temperature lead to a decrease in the partition coefficient of l-phenylalanine. Copyright © 2017 Elsevier Ltd. All rights reserved.

Calcium Sensing Receptors Mediate Local Inhibitory Reflexes Evoked by L-Phenylalanine in Guinea Pig Jejunum.

PubMed

Gwynne, Rachel M; Ly, Kenny D K N; Parry, Laura J; Bornstein, Joel C

2017-01-01

Amino acids applied to the mucosa evoke inhibitory reflexes in guinea-pig jejunum, but the receptors involved in sensory transduction are still unclear. One promising candidate is the extracellular calcium sensing receptor (CaSR), which is expressed by mucosal enteroendocrine cells and is preferentially activated by aromatic L-amino acids. We tested this by applying various amino acids to the mucosa and recording the resulting inhibitory junction potentials (IJPs) in nearby circular smooth muscle via intracellular recording. The CaSR is stereospecific and L-Phenylalanine evoked a significantly larger response than D-Phenylalanine when both were applied to the same site. The same pattern was seen with L- and D-Tryptophan, another aromatic amino acid. The CaSR is preferentially activated by aromatic amino acids and responses to L-Leucine and L-Lysine were significantly lower than those to L-Phenylalanine applied to the same site. Responses to L-Phenylalanine were dose-dependently suppressed by blockade of the CaSR with NPS2143, a CaSR antagonist, and mimicked by mucosal application of cinacalcet, a CaSR agonist. Responses to cinacalcet had similar pharmacology to that of responses to L-Phenylalanine, in that each requires both P2 purinoreceptors and 5-HT receptors. L-Glutamate evoked IJPs similar to those produced by L-Phenylalanine and these were depressed by blockade of P2 receptors and 5-HT 3 plus 5-HT 4 receptors, but NPS2143 was ineffective. The AMPA receptor antagonists DNQX (10 μM) and CNQX (10 μM) reduced IJPs evoked by L-Glutamate by 88 and 79% respectively, but neither BAY367260 (mGluR5 antagonist) nor 2APV (NMDA antagonist) affected IJPs evoked by L-Glutamate. We conclude that local inhibitory reflexes evoked by aromatic L-amino acids in guinea pig jejunum involve activation of CaSRs which triggers release of ATP and 5-HT from the mucosa. L-Glutamate also evokes inhibitory reflexes, via a pathway that does not involve CaSRs. It is likely there are

Synthesis and characterisation of hetero-bimetallic organometallic phenylalanine and PNA monomer derivatives.

PubMed

Gasser, Gilles; Brosch, Oliver; Ewers, Alexandra; Weyhermüller, Thomas; Metzler-Nolte, Nils

2009-06-14

The rational, sequential synthesis of two hetero-bimetallic derivatives of the amino acid phenylalanine and one thymine (T) peptide nucleic acid (PNA) monomer is reported. Ferrocene carboxylic acid and (eta-ethene)bis(triphenylphosphine)platinum(0) were successfully reacted with propargylamide amino acid (1a and 1b) or a T PNA monomer derivative (6) to give the expected three bimetallic compounds 4a, 4b and 9 in good yield. An enzymatic route using cross-linked enzyme crystals (CLEC) of subtilopeptidase A in organic solvents gave the ferrocene carboxylate phenylalanine propargylamide precursor (Fc-CO-Phe-NH-CH(2)-CCH, 3a) in comparable yield and purity to the traditional deprotection-peptide coupling sequence. (31)P NMR spectra of these bioorganometallics showed two doublets with (195)Pt satellites corresponding to two chemically different (31)P atoms. Interestingly, in the case of the T PNA monomer derivative 9, these signals were also doubled in a 60 : 40 ratio as a consequence of the existence of two slowly interconverting isomers in solution. Furthermore, the single-crystal X-ray structures of 3a and the hetero-bimetallic phenylalanine derivative 4b were determined, showing the presence of the two organometallics moieties separated by ca. 8.5 A in 4b as well as illustrating the stability of such compounds.

Sensitive, site-specific, and stable vibrational probe of local protein environments: 4-azidomethyl-L-phenylalanine.

PubMed

Bazewicz, Christopher G; Liskov, Melanie T; Hines, Kevin J; Brewer, Scott H

2013-08-01

We have synthesized the unnatural amino acid (UAA), 4-azidomethyl-L-phenylalanine (pN₃CH₂Phe), to serve as an effective vibrational reporter of local protein environments. The position, extinction coefficient, and sensitivity to local environment of the azide asymmetric stretch vibration of pN₃CH₂Phe are compared to the vibrational reporters: 4-cyano-L-phenylalanine (pCNPhe) and 4-azido-L-phenylalanine (pN₃Phe). This UAA was genetically incorporated in a site-specific manner utilizing an engineered, orthogonal aminoacyl-tRNA synthetase in response to an amber codon with high efficiency and fidelity into two distinct sites in superfolder green fluorescent protein (sfGFP). This allowed for the dependence of the azide asymmetric stretch vibration of pN₃CH₂Phe to different protein environments to be measured. The photostability of pN₃CH₂Phe was also measured relative to the photoreactive UAA, pN₃Phe.

CADDIS Volume 2. Sources, Stressors and Responses: Ammonia

EPA Pesticide Factsheets

Introduction to the ammonia module, when to list ammonia as a candidate cause, ways to measure ammonia, simple and detailed conceptual diagrams for ammonia, literature reviews and references for the ammonia module.

ENGINEERING DESIGN CONFIGURATIONS FOR BIOLOGICAL AMMONIA REMOVAL

EPA Science Inventory

Many regions in the United States have excessive levels of nutrients including ammonia in their source waters. For example, farming and agricultural sources of ammonia in the Midwest contribute to relatively high levels of ammonia in many ground waters. Although ammonia in water ...

Autotrophic ammonia oxidation by soil thaumarchaea.

PubMed

Zhang, Li-Mei; Offre, Pierre R; He, Ji-Zheng; Verhamme, Daniel T; Nicol, Graeme W; Prosser, James I

2010-10-05

Nitrification plays a central role in the global nitrogen cycle and is responsible for significant losses of nitrogen fertilizer, atmospheric pollution by the greenhouse gas nitrous oxide, and nitrate pollution of groundwaters. Ammonia oxidation, the first step in nitrification, was thought to be performed by autotrophic bacteria until the recent discovery of archaeal ammonia oxidizers. Autotrophic archaeal ammonia oxidizers have been cultivated from marine and thermal spring environments, but the relative importance of bacteria and archaea in soil nitrification is unclear and it is believed that soil archaeal ammonia oxidizers may use organic carbon, rather than growing autotrophically. In this soil microcosm study, stable isotope probing was used to demonstrate incorporation of (13)C-enriched carbon dioxide into the genomes of thaumarchaea possessing two functional genes: amoA, encoding a subunit of ammonia monooxygenase that catalyses the first step in ammonia oxidation; and hcd, a key gene in the autotrophic 3-hydroxypropionate/4-hydroxybutyrate cycle, which has been found so far only in archaea. Nitrification was accompanied by increases in archaeal amoA gene abundance and changes in amoA gene diversity, but no change was observed in bacterial amoA genes. Archaeal, but not bacterial, amoA genes were also detected in (13)C-labeled DNA, demonstrating inorganic CO(2) fixation by archaeal, but not bacterial, ammonia oxidizers. Autotrophic archaeal ammonia oxidation was further supported by coordinate increases in amoA and hcd gene abundance in (13)C-labeled DNA. The results therefore provide direct evidence for a role for archaea in soil ammonia oxidation and demonstrate autotrophic growth of ammonia oxidizing archaea in soil.

Ammonia Synthesis at Low Pressure.

PubMed

Cussler, Edward; McCormick, Alon; Reese, Michael; Malmali, Mahdi

2017-08-23

Ammonia can be synthesized at low pressure by the use of an ammonia selective absorbent. The process can be driven with wind energy, available locally in areas requiring ammonia for synthetic fertilizer. Such wind energy is often called "stranded," because it is only available far from population centers where it can be directly used. In the proposed low pressure process, nitrogen is made from air using pressure swing absorption, and hydrogen is produced by electrolysis of water. While these gases can react at approximately 400 °C in the presence of a promoted conventional catalyst, the conversion is often limited by the reverse reaction, which makes this reaction only feasible at high pressures. This limitation can be removed by absorption on an ammine-like calcium or magnesium chloride. Such alkaline metal halides can effectively remove ammonia, thus suppressing the equilibrium constraints of the reaction. In the proposed absorption-enhanced ammonia synthesis process, the rate of reaction may then be controlled not by the chemical kinetics nor the absorption rates, but by the rate of the recycle of unreacted gases. The results compare favorably with ammonia made from a conventional small scale Haber-Bosch process.

Stabilizing and destabilizing effects of phenylalanine --> F5-phenylalanine mutations on the folding of a small protein.

PubMed

Woll, Matthew G; Hadley, Erik B; Mecozzi, Sandro; Gellman, Samuel H

2006-12-20

We report a systematic evaluation of phenylalanine-to-pentafluorophenylalanine (Phe --> F5-Phe) mutants for the 35-residue chicken villin headpiece subdomain (c-VHP), the hydrophobic core of which features a cluster of three Phe side chains (residues 6, 10, and 17). Phe --> F5-Phe mutations are interesting because aryl-perfluoroaryl interactions of optimal geometry are intrinsically more favorable than aryl-aryl interactions and because perfluoroaryl units are more hydrophobic than are analogous aryl units. One mutant, Phe-10 --> F5-Phe, provides enhanced tertiary structural stability relative to the native sequence. The other six mutants analyzed caused a decrease in stability.

Short-term effect of ammonia concentration and salinity on activity of ammonia oxidizing bacteria.

PubMed

Claros, J; Jiménez, E; Borrás, L; Aguado, D; Seco, A; Ferrer, J; Serralta, J

2010-01-01

A continuously aerated SHARON (single reactor high activity ammonia removal over nitrite) system has been operated to achieve partial nitritation. Two sets of batch experiments were carried out to study the effect of ammonia concentration and salinity on the activity of ammonia-oxidizing bacteria (AOB). Activity of AOB raised as free ammonia concentration was increased reaching its maximum value at 4.5 mg NH3-N l(-1). The half saturation constant for free ammonia was determined (K(NH3)=0.32 mg NH3-N l(-1)). Activity decreased at TAN (total ammonium-nitrogen) concentration over 2,000 mg NH4-N l(-1). No free ammonia inhibition was detected. The effect of salinity was studied by adding different concentrations of different salts to the biomass. No significant differences were observed between the experiments carried out with a salt containing or not containing NH4. These results support that AOB are inhibited by salinity, not by free ammonia. A mathematical expression to represent this inhibition is proposed. To compare substrate affinity and salinity inhibitory effect on different AOB populations, similar experiments were carried out with biomass from a biological nutrient removal pilot plant. The AOB activity reached its maximum value at 0.008 mg NH3-N l(-1) and decreased at TAN concentration over 400 mg NH4-N l(-1). These differences can be explained by the different AOB predominating species: Nitrosomonas europaea and N. eutropha in the SHARON biomass and Nitrosomonas oligotropha in the pilot plant.

Serum phenylalanine in preterm newborns fed different diets of human milk.

PubMed

Thomaz, Débora M; Serafin, Paula O; Palhares, Durval B; Tavares, Luciana V M; Grance, Thayana R S

2014-01-01

To evaluate phenylalanine plasma profile in preterm newborns fed different human milk diets. Twenty-four very-low weight preterm newborns were distributed randomly in three groups with different feeding types: Group I: banked human milk plus 5% commercial fortifier with bovine protein, Group II: banked human milk plus evaporated fortifier derived from modified human milk, Group III: banked human milk plus lyophilized fortifier derived from modified human milk. The newborns received the group diet when full diet was attained at 15 ± 2 days. Plasma amino acid analysis was performedon the first and last day of feeding. Comparison among groups was performed by statistical tests: one way ANOVA with Tukey's post-test using SPSS software, version 20.0 (IBM Corp, NY, USA), considering a significance level of 5%. Phenylalanine levels in the first and second analysis were, respectively, in Group I: 11.9 ± 1.22 and 29.72 ± 0.73; in Group II: 11.72 ± 1.04 and 13.44 ± 0.61; and in Group III: 11.3 ± 1.18 and 15.42 ± 0.83 μmol/L. The observed results demonstrated that human milk with fortifiers derived from human milk acted as a good substratum for preterm infant feeding both in the evaporated or the lyophilized form, without significant increases in plasma phenylalanine levels in comparison to human milk with commercial fortifier. Copyright © 2014 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

Determination of phenylalanine isotope ratio enrichment by liquid chromatography/time- of-flight mass spectrometry.

PubMed

Wu, Zhanpin; Zhang, Xiao-Jun; Cody, Robert B; Wolfe, Robert R

2004-01-01

The application of time-of-flight mass spectrometry to isotope ratio measurements has been limited by the relatively low dynamic range of the time-to-digital converter detectors available on commercial LC/ToF-MS systems. Here we report the measurement of phenylalanine isotope ratio enrichment by using a new LC/ToF-MS system with wide dynamic range. Underivatized phenylalanine was injected onto a C18 column directly with 0.1% formic acid/acetonitrile as the mobile phase. The optimal instrument parameters for the time-of-flight mass spectrometer were determined by tuning the instrument with a phenylalanine standard. The accuracy of the isotope enrichment measurement was determined by the injection of standard solutions with known isotope ratios ranging from 0.02% to 9.2%. A plot of the results against the theoretical values gave a linear curve with R2 of 0.9999. The coefficient of variation for the isotope ratio measurement was below 2%. The method is simple, rapid, and accurate and presents an attractive alternative to traditional GC/MS applications.

Oxidation of L-phenylalanine by diperiodatoargentate(III) in aqueous alkaline medium. A Mechanistic approach

NASA Astrophysics Data System (ADS)

Lamani, S. D.; Veeresh, T. M.; Nandibewoor, S. T.

2009-12-01

The kinetics of oxidation of L-phenylalanine (L-Phe) by diperiodatoargentate(III) (DPA) in alkaline medium at a constant ionic strength of 0.25 mol/dm-3 has been studied spectrophotometrically. The reaction between DPA and L-phenylalanine in alkaline medium exhibits 1: 1 stoichiometry (L-phenylalanine: DPA). The reaction shows first order in [DPA] and has less than unit order dependence each in both [L-Phe] and [Alkali] and retarding effect of [IO{4/-}] under the reaction conditions. The active species of DPA is understood to be as monoperiodatoargentate(III) (MPA). The reaction is shown to proceed via a MPA-L-Phe complex, which decomposes in a rate-determining step to give intermediates followed by a fast step to give the products. The products were identified by spot and spectroscopic studies. The reaction constants involved in the different steps of the mechanisms were calculated. The activation parameters with respect to slow step of the mechanism were computed and discussed. The thermodynamic quantities were also determined for the reaction.

Binding of radiation-induced phenylalanine radicals to DNA: influence on the biological activity of the DNA and on its sensitivity to the induction of breaks by gamma rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vanderschans, G.P.; Vanrijn, C.J.S.; Bleichrodt, J.F.

1975-11-01

When an aqueous solution of double-stranded deoxyribonucleic acid (DNA) of bacteriophage PM2 containing phenylalanine and saturated with N2O is irradiated with gamma rays, radiation induced phenylalanine radicals are bound covalently. Under the conditions used about 25 phenylalanine molecules may be bound per lethal hit. Also for single-stranded PM2 DNA most of the phenylalanine radicals bound are nonlethal. Evidence is presented that in double-stranded DNA an appreciable fraction of the single-strand breaks is induced by phenylalanine radicals. Radiation products of phenylalanine and the phenylalanine bound to the DNA decrease the sensitivity of the DNA to the induction of single-strand breaks. Theremore » are indications that the high efficiency of protection by radiation products of phenylalanine is due to their positive charge, which will result in a relatively high concentration of these compounds in the vicinity of the negatively charged DNA molecules. (Author) (GRA)« less

Beta-lactamase-catalyzed aminolysis of depsipeptides: Proof of the nonexistence of a specific D-phenylalanine/enzyme complex by double-label isotope trapping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pazhanisamy, S.; Pratt, R.F.

The steady-state kinetics of the Enterobacter cloacae P99 beta-lactamase-catalyzed aminolysis of the depsipeptide m-(((phenylacetyl)glycyl)oxy)benzoic acid by D-phenylalanine were consistent with an ordered sequential mechanism with D-phenylalanine binding first. In terms of this mechanism, the kinetics data required that in 20 mM MOPS buffer, pH 7.5, the dissociation constant of the initially formed enzyme/D-phenylalanine complex be around 1.3 mM; at pH 9.0 in 0.1 M carbonate buffer, the complex should be somewhat more stable. Attempts to detect this complex in a binary mixture by spectroscopic methods (fluorescence, circular dichroic, and nuclear magnetic resonance spectra) failed. Kinetic methods were also unsuccessful--the presencemore » of 20 mM D-phenylalanine did not appear to affect beta-lactamase activity nor inhibition of the enzyme by phenylmethanesulfonyl fluoride, phenylboronic acid, or (3-dansylamidophenyl)boronic acid. Equilibrium dialysis experiments appeared to indicate that the dissociation constant of any binary enzyme/D-phenylalanine complex must be somewhat higher than the kinetics allowed (greater than 2 mM). Since the kinetics also required that, at high depsipeptide concentrations, and again with the assumption of the ordered sequential mechanism, the reaction of the enzyme/D-phenylalanine complex to aminolysis products be faster than its reversion to enzyme and D-phenylalanine, a double-label isotope-trapping experiment was performed.« less

The in vivo anti-fibrotic function of calcium sensitive receptor (CaSR) modulating poly(p-dioxanone-co-l-phenylalanine) prodrug.

PubMed

Wang, Bing; Wen, Aiping; Feng, Chengmin; Niu, Lijing; Xiao, Xin; Luo, Le; Shen, Chengyi; Zhu, Jiang; Lei, Jun; Zhang, Xiaoming

2018-06-01

In present study, the apoptosis induction and proliferation suppression effects of l-phenylalanine (l-Phe) on fibroblasts were confirmed. The action sites of l-Phe on fibroblasts suppression were deduced to be calcium sensitive receptor (CaSR) which could cause the release of endoplasmic reticulum (ER) Ca 2+ stores; disruption of intracellular Ca 2+ homeostasis triggers cell apoptosis via the ER or mitochondrial pathways. The down-regulation of CaSR were observed after the application of l-Phe, and the results those l-Phe triggered the increasing of intracellular Ca 2+ concentration and calcineurin expression, and then the apoptosis and increasing G1 fraction of fibroblasts have verified our deduction. Hence, l-Phe could be seen as a kind of anti-fibrotic drugs for the crucial participation of fibroblast in the occurrence of fibrosis. And then, poly(p-dioxanone-co-l-phenylalanine) (PDPA) which could prolong the in-vivo anti-fibrotic effect of l-Phe for the sustained release of l-Phe during its degradation could be treated as anti-fibrotic polymer prodrugs. Based on the above, the in vivo anti-fibrotic function of PDPA was evaluated in rabbit ear scarring, rat peritoneum lipopolysaccharide, and rat sidewall defect/cecum abrasion models. PDPA reduced skin scarring and suppressed peritoneal fibrosis and post operation adhesion as well as secretion of transforming growth factor-β1 in injured tissue. These results indicate that PDPA is an effective agent for preventing fibrosis following tissue injury. We have previously demonstrated that poly(p-dioxanone-co-l-phenylalanine) (PDPA) could induce apoptosis to fibroblast and deduced that the inhibitory effect comes from l-phenylalanine. In present study, the inhibition mechanism of l-phenylalanine on fibroblast proliferation was demonstrated. The calcium sensitive receptor (CaSR) was found to be the action site. The CaSR was downregulated after the application of l-phenylalanine, and then the ER Ca 2+ stores were released

Assessing Ammonia Treatment Options

EPA Science Inventory

This is the second of three articles to help water system operators understand ammonia and how to monitor and control its effects at the plant and in the distribution system. The first article (Opflow, April 2012) provided an overview of ammonia's chemistry, origins, and water sy...

Higher serum phenylalanine concentration is associated with more rapid telomere shortening in men.

PubMed

Eriksson, Johan G; Guzzardi, Maria-Angela; Iozzo, Patricia; Kajantie, Eero; Kautiainen, Hannu; Salonen, Minna K

2017-01-01

Telomere length and telomere shortening are associated with age-related health outcomes. Only a few studies have been able to longitudinally report on factors that are associated with changes in telomere length in an aging population. We studied the longitudinal relation between telomere length, the change in telomere length, and circulating amino acids. A total of 812 subjects from the Helsinki Birth Cohort Study (born from 1934 to 1944), who underwent 3 clinical visits during a 10-y interval that included measurements of cardiometabolic risk factors, were included in the study. Leukocyte telomere length (LTL) was measured with the use of quantitative real-time polymerase chain reaction. Circulating branched-chain and aromatic amino acids (alanine, glycine, histidine, phenylalanine, leucine, isoleucine, valine, and tyrosine) were assessed with the use of high-throughput nuclear magnetic resonance spectroscopy. The relative ± SD LTL at a mean age of 71 y was 0.79 ± 0.27 in men and 0.89 ± 0.35 in women (P < 0.001). Of the studied amino acids, the strongest inverse association was observed between the phenylalanine concentration that was measured 5 y earlier and the LTL. This finding was significant in men (P = 0.021) and remained significant after adjustment for multiple comparisons, but it was not significant in women (P = 0.39). Longitudinally, the change in LTL over 10 y was inversely associated with the phenylalanine concentration in men (P = 0.007) but not in women (P = 0.58) after adjustment for baseline LTL, age, smoking, and percentage of body fat. The serum phenylalanine concentration is associated with telomere length and, therefore, potentially with the aging process. Because the associations reported are observational, no conclusions can be made regarding causality. Our findings support the hypothesis that cellular pathways that regulate aging are sex specific. © 2017 American Society for Nutrition.

Ammonia excretion in Caenorhabditis elegans: mechanism and evidence of ammonia transport of the Rhesus protein CeRhr-1

PubMed Central

Adlimoghaddam, Aida; Boeckstaens, Mélanie; Marini, Anna-Maria; Treberg, Jason R.; Brassinga, Ann-Karen C.; Weihrauch, Dirk

2015-01-01

ABSTRACT The soil-dwelling nematode Caenorhabditis elegans is a bacteriovorous animal, excreting the vast majority of its nitrogenous waste as ammonia (25.3±1.2 µmol gFW−1 day−1) and very little urea (0.21±0.004 µmol gFW−1 day−1). Although these roundworms have been used for decades as genetic model systems, very little is known about their strategy to eliminate the toxic waste product ammonia from their bodies into the environment. The current study provides evidence that ammonia is at least partially excreted via the hypodermis. Starvation reduced the ammonia excretion rates by more than half, whereas mRNA expression levels of the Rhesus protein CeRhr-2, V-type H+-ATPase (subunit A) and Na+/K+-ATPase (α-subunit) decreased correspondingly. Moreover, ammonia excretion rates were enhanced in media buffered to pH 5 and decreased at pH 9.5. Inhibitor experiments, combined with enzyme activity measurements and mRNA expression analyses, further suggested that the excretion mechanism involves the participation of the V-type H+-ATPase, carbonic anhydrase, Na+/K+-ATPase, and a functional microtubule network. These findings indicate that ammonia is excreted, not only by apical ammonia trapping, but also via vesicular transport and exocytosis. Exposure to 1 mmol l−1 NH4Cl caused a 10-fold increase in body ammonia and a tripling of ammonia excretion rates. Gene expression levels of CeRhr-1 and CeRhr-2, V-ATPase and Na+/K+-ATPase also increased significantly in response to 1 mmol l−1 NH4Cl. Importantly, a functional expression analysis showed, for the first time, ammonia transport capabilities for CeRhr-1 in a phylogenetically ancient invertebrate system, identifying these proteins as potential functional precursors to the vertebrate ammonia-transporting Rh-glycoproteins. PMID:25740900

46 CFR 154.1760 - Liquid ammonia.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Liquid ammonia. 154.1760 Section 154.1760 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR....1760 Liquid ammonia. The master shall ensure that no person sprays liquid ammonia into a cargo tank...

46 CFR 154.1760 - Liquid ammonia.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Liquid ammonia. 154.1760 Section 154.1760 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR....1760 Liquid ammonia. The master shall ensure that no person sprays liquid ammonia into a cargo tank...

46 CFR 154.1760 - Liquid ammonia.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Liquid ammonia. 154.1760 Section 154.1760 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR....1760 Liquid ammonia. The master shall ensure that no person sprays liquid ammonia into a cargo tank...

46 CFR 154.1760 - Liquid ammonia.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Liquid ammonia. 154.1760 Section 154.1760 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR....1760 Liquid ammonia. The master shall ensure that no person sprays liquid ammonia into a cargo tank...

46 CFR 154.1760 - Liquid ammonia.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Liquid ammonia. 154.1760 Section 154.1760 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR....1760 Liquid ammonia. The master shall ensure that no person sprays liquid ammonia into a cargo tank...

Ammonia emissions from cattle feeding operations.

USDA-ARS?s Scientific Manuscript database

Ammonia is a colorless gas with an pungent odor that occurs naturally in trace amounts in the atmosphere, where it is the dominant base. Ammonia is produced during the decomposition of livestock manure. There is concern about atmospheric ammonia because of its potential effects on air quality, wat...

[Microbial ecology of archaeal ammonia oxidation--a review].

PubMed

Jia, Zhongjun; Weng, Jiahua; Lin, Xiangui; Conrad, Ralf

2010-04-01

Bacteria have long been considered as the key driver of ammonia oxidation on earth. This concept has been challenged recently by the discovery of chemolithoautotrophic isolate of ammonia-oxidizing archaeon in marine. The relative contribution of bacteria and archaea to ammonia oxidation is essential for our understanding of global nitrogen cycle. Recent study suggested a key role of archaeal ammonia oxidation in the marine nitrogen cycle. Our work however revealed the predominace of bacterial ammonia oxidation in agricultural soil. From the biogeochemical perspective, here we summarized the discovery, progress and prospect of archaeal ammonia oxidation. Of great interest in the future would be to elucidate the metabolisms of ammonia-oxidizing archaeon in natural environment and the underlying mechanism that leads to the physiological divergence of ammonia oxidizers.

Stabilities of protonated water-ammonia clusters

NASA Astrophysics Data System (ADS)

Sundén, A. E. K.; Støchkel, K.; Hvelplund, P.; Brøndsted Nielsen, S.; Dynefors, B.; Hansen, K.

2018-05-01

Branching ratios of water and ammonia evaporation have been measured for spontaneous evaporation from protonated mixed clusters H+(H2O)n(NH3)m in the size range 0 ≤ n ≤ 11 and 0 ≤ m ≤ 7. Mixed clusters evaporate water except for clusters containing six or more ammonia molecules, indicating the formation of a stable core of one ammonium ion surrounded by four ammonia molecules and a second shell consisting predominantly of water. We relate evaporative branching ratios to free energy differences between the products of competing channels and determine the free energy differences for clusters with up to seven ammonia molecules. Clusters containing up to five ammonia molecules show a very strong scaling of these free energy differences.

Copper-induced ammonia N-H functionalization.

PubMed

Álvarez, María; Álvarez, Eleuterio; Fructos, Manuel R; Urbano, Juan; Pérez, Pedro J

2016-10-07

The activation of ammonia has been achieved with the aid of the Tp(Ms)Cu core (Tp(Ms) = hydrotris(3-mesityl-pyrazolyl)borate). Complexes of the general composition Tp(Ms)Cu(amine) (1-4) including the ammonia adduct Tp(Ms)Cu(NH3) (1) have been synthesized and fully spectroscopical- and structurally characterized. Coordinated ammonia in 1 has been reacted with Ph3CPF6 yielding Tp(Ms)Cu(NH2CPh3) (5) as a result of N-H cleavage and N-C bond formation. In a parallel manner the catalytic functionalization of ammonia with ethyl diazoacetate leading to glycinate derivatives has been developed with Tp(Ms)Cu(THF) as the catalyst, in the first example of this transformation with ammonia and a copper-based system.

Titan's Ammonia Feature

NASA Technical Reports Server (NTRS)

Smythe, W.; Nelson, R.; Boryta, M.; Choukroun, M.

2011-01-01

NH3 has long been considered an important component in the formation and evolution of the outer planet satellites. NH3 is particularly important for Titan, since it may serve as the reservoir for atmospheric nitrogen. A brightening seen on Titan starting in 2004 may arise from a transient low-lying fog or surface coating of ammonia. The spectral shape suggests the ammonia is anhydrous, a molecule that hydrates quickly in the presence of water.

Beta-lactamase-catalyzed aminolysis of depsipeptides: proof of the nonexistence of a specific D-phenylalanine/enzyme complex by double-label isotope trapping.

PubMed

Pazhanisamy, S; Pratt, R F

1989-08-22

The steady-state kinetics of the Enterobacter cloacae P99 beta-lactamase-catalyzed aminolysis of the depsipeptide m-[[(phenylacetyl)glycyl]oxy]benzoic acid by D-phenylalanine were consistent with an ordered sequential mechanism with D-phenylalanine binding first [Pazhanisamy, S., Govardhan, C. P., & Pratt, R. F. (1989) Biochemistry (first of three papers in this issue)]. In terms of this mechanism, the kinetics data required that in 20 mM MOPS buffer, pH 7.5, the dissociation constant of the initially formed enzyme/D-phenylalanine complex be around 1.3 mM; at pH 9.0 in 0.1 M carbonate buffer, the complex should be somewhat more stable. Attempts to detect this complex in a binary mixture by spectroscopic methods (fluorescence, circular dichroic, and nuclear magnetic resonance spectra) failed. Kinetic methods were also unsuccessful--the presence of 20 mM D-phenylalanine did not appear to affect beta-lactamase activity nor inhibition of the enzyme by phenylmethanesulfonyl fluoride, phenylboronic acid, or (3-dansylamidophenyl)boronic acid. Equilibrium dialysis experiments appeared to indicate that the dissociation constant of any binary enzyme/D-phenylalanine complex must be somewhat higher than the kinetics allowed (greater than 2 mM). Since the kinetics also required that, at high depsipeptide concentrations, and again with the assumption of the ordered sequential mechanism, the reaction of the enzyme/D-phenylalanine complex to aminolysis products be faster than its reversion to enzyme and D-phenylalanine, a double-label isotope-trapping experiment was performed.(ABSTRACT TRUNCATED AT 250 WORDS)

27 CFR 21.96 - Ammonia, aqueous.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Ammonia, aqueous. 21.96 Section 21.96 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT... Ammonia, aqueous. (a) Alkalinity. Strongly alkaline to litmus. (b) Ammonia content. 27 to 30 percent by...

27 CFR 21.96 - Ammonia, aqueous.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Ammonia, aqueous. 21.96 Section 21.96 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT... Ammonia, aqueous. (a) Alkalinity. Strongly alkaline to litmus. (b) Ammonia content. 27 to 30 percent by...

27 CFR 21.96 - Ammonia, aqueous.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Ammonia, aqueous. 21.96 Section 21.96 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT... Ammonia, aqueous. (a) Alkalinity. Strongly alkaline to litmus. (b) Ammonia content. 27 to 30 percent by...

27 CFR 21.96 - Ammonia, aqueous.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Ammonia, aqueous. 21.96 Section 21.96 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT... Ammonia, aqueous. (a) Alkalinity. Strongly alkaline to litmus. (b) Ammonia content. 27 to 30 percent by...

27 CFR 21.96 - Ammonia, aqueous.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Ammonia, aqueous. 21.96 Section 21.96 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT... Ammonia, aqueous. (a) Alkalinity. Strongly alkaline to litmus. (b) Ammonia content. 27 to 30 percent by...

Thermodynamics of the complex formation of copper(II) with L-phenylalanine in aqueous ethanol solutions

NASA Astrophysics Data System (ADS)

Burov, D. M.; Ledenkov, S. F.; Vandyshev, V. N.

2013-05-01

Constants of the acid dissociation and complexation of L-phenylalanine (HPhe) with copper(II) ions are determined by potentiometry in aqueous ethanol solutions containing 0 to 0.7 molar fraction of alcohol. Changes in the Gibbs energy for the transfer from water to a binary solvent of L-phenylalanine, Phe- anion, and [CuPhe]+ complex are calculated. It is found that the weakening of solvation of the ligand donor groups in solvents with high ethanol contents is accompanied by an increase in the stability of [CuPhe]+ complex.

The measurement of muscle protein synthesis in broilers with a flooding dose technique: use of 15N-labelled phenylalanine, GC-MS and GC-C-IRMS.

PubMed

Dänicke, S; Böttcher, W; Simon, O; Jeroch, H

2001-01-01

An experiment was carried out to measure fractional muscle protein synthesis rates (k(s)) in broilers with injection of a flooding dose of phenylalanine (1 ml/100 g body weight of 150 mM phenylalanine; 38 atom percent excess (APE) [15N]phenylalanine). K(s) was calculated from the [15N] enrichment in phenylalanine of tissue-free and protein-bound phenylalanine using both gas chromatography mass spectrometry (GC-MS) and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) for measurements after a 10 min isotope incorporation period. The tertiary-butyldimethylsilyl (t-BDMS) derivatives of phenylalanine were used for gas chromatographic separation in both systems. GC-MS and GC-C-IRMS were calibrated for a range of 7 to 37 [15N]APE and 0 to 0.62 [15N]APE, respectively, and for sample sizes of 0.45 to 4.5 nmol phenylalanine and 7 to 40 nmol phenylalanine, respectively. Reproducibility of standards as a measure of precision varied from 0.06 to 0.29 [15N]APE and from 0.0004 to 0.0018 [15N]APE in GC-MS and GC-C-IRMS, respectively. K(s) was measured in the m. pectoralis major of broilers fed rye based diets (56%) which were provided either unsupplemented (-) or supplemented (+) with an enzyme preparation containing xylanase. K(s) in breast muscles was significantly increased from 21.8%/d to 23.9%/d due to enzyme supplementation. It can be concluded from the study that the measurement of protein synthesis in broilers with the flooding dose technique can be carried out by using [15N]phenylalanine, GC-MS and GC-C-IRMS.

Recent Advances in Renal Ammonia Metabolism and Transport

PubMed Central

Weiner, I. David; Verlander, Jill W.

2016-01-01

Purpose of review The purpose of this review is to provide a succinct description of recent findings that advance our understanding of the fundamental renal process of ammonia metabolism and transport in conditions relevant to the clinician. Recent findings Recent studies advance our understanding of renal ammonia metabolism. Mechanisms through which chronic kidney disease and altered dietary protein intake alter ammonia excretion have been identified. Lithium, although it can acutely cause distal RTA, was shown with long-term use to increase urinary ammonia excretion, and this appeared to be mediated, at least in part, by increased Rhcg expression. Gene deletion studies showed that the ammonia recycling enzyme, glutamine synthetase, has a critical role in normal and acidosis-stimulated ammonia metabolism and that the proximal tubule basolateral bicarbonate transporter, NBCe1, is necessary for normal ammonia metabolism. Finally, our understanding of the molecular ammonia species, NH3 versus NH4+, transported by Rh glycoproteins continues to be advanced. Summary Fundamental studies have been recently published that advance our understanding of the regulation of ammonia metabolism in clinically important circumstances and our understanding of the mechanisms and regulation of proximal tubule ammonia generation and the mechanisms through which Rh glycoproteins contribute to ammonia secretion. PMID:27367914

Ammonia synthesis using magnetic induction method (MIM)

NASA Astrophysics Data System (ADS)

Puspitasari, P.; Razak, J. Abd; Yahya, N.

2012-09-01

The most challenging issues for ammonia synthesis is to get the high yield. New approach of ammonia synthesis by using Magnetic Induction Method (MIM) and the Helmholtz Coils has been proposed. The ammonia detection was done by using Kjeldahl Method and FTIR. The system was designed by using Autocad software. The magnetic field of MIM was vary from 100mT-200mT and the magnetic field for the Helmholtz coils was 14mT. The FTIR result shows that ammonia has been successfully formed at stretching peaks 1097,1119,1162,1236, 1377, and 1464 cm-1. UV-VIS result shows the ammonia bond at 195nm of wavelength. The ammonia yield was increase to 244.72μmole/g.h by using the MIM and six pairs of Helmholtz coils. Therefore this new method will be a new promising method to achieve the high yield ammonia at ambient condition (at 25δC and 1atm), under the Magnetic Induction Method (MIM).

Calcium binding to calmodulin mutants monitored by domain-specific intrinsic phenylalanine and tyrosine fluorescence.

PubMed Central

VanScyoc, Wendy S; Sorensen, Brenda R; Rusinova, Elena; Laws, William R; Ross, J B Alexander; Shea, Madeline A

2002-01-01

Cooperative calcium binding to the two homologous domains of calmodulin (CaM) induces conformational changes that regulate its association with and activation of numerous cellular target proteins. Calcium binding to the pair of high-affinity sites (III and IV in the C-domain) can be monitored by observing calcium-dependent changes in intrinsic tyrosine fluorescence intensity (lambda(ex)/lambda(em) of 277/320 nm). However, calcium binding to the low-affinity sites (I and II in the N-domain) is more difficult to measure with optical spectroscopy because that domain of CaM does not contain tryptophan or tyrosine. We recently demonstrated that calcium-dependent changes in intrinsic phenylalanine fluorescence (lambda(ex)/lambda(em) of 250/280 nm) of an N-domain fragment of CaM reflect occupancy of sites I and II (VanScyoc, W. S., and M. A. Shea, 2001, Protein Sci. 10:1758-1768). Using steady-state and time-resolved fluorescence methods, we now show that these excitation and emission wavelength pairs for phenylalanine and tyrosine fluorescence can be used to monitor equilibrium calcium titrations of the individual domains in full-length CaM. Calcium-dependent changes in phenylalanine fluorescence specifically indicate ion occupancy of sites I and II in the N-domain because phenylalanine residues in the C-domain are nonemissive. Tyrosine emission from the C-domain does not interfere with phenylalanine fluorescence signals from the N-domain. This is the first demonstration that intrinsic fluorescence may be used to monitor calcium binding to each domain of CaM. In this way, we also evaluated how mutations of two residues (Arg74 and Arg90) located between sites II and III can alter the calcium-binding properties of each of the domains. The mutation R74A caused an increase in the calcium affinity of sites I and II in the N-domain. The mutation R90A caused an increase in calcium affinity of sites III and IV in the C-domain whereas R90G caused an increase in calcium affinity

Ammonia chemistry in a flameless jet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zieba, Mariusz; Schuster, Anja; Scheffknecht, Guenter

2009-10-15

In this paper, the nitrogen chemistry in an ammonia (NH{sub 3}) doped flameless jet is investigated using a kinetic reactor network model. The reactor network model is used to explain the main differences in ammonia chemistry for methane (CH{sub 4})-containing fuels and methane-free fuels. The chemical pathways of nitrogen oxides (NO{sub x}) formation and destruction are identified using rate-of-production analysis. The results show that in the case of natural gas, ammonia reacts relatively late at fuel lean condition leading to high NO{sub x} emissions. In the pre-ignition zone, the ammonia chemistry is blocked due to the absence of free radicalsmore » which are consumed by methane-methyl radical (CH{sub 3}) conversion. In the case of methane-free gas, the ammonia reacted very rapidly and complete decomposition was reached in the fuel rich region of the jet. In this case the necessary radicals for the ammonia conversion are generated from hydrogen (H{sub 2}) oxidation. (author)« less

Polyaniline-based optical ammonia detector

DOEpatents

Duan, Yixiang; Jin, Zhe; Su, Yongxuan

2002-01-01

Electronic absorption spectroscopy of a polyaniline film deposited on a polyethylene surface by chemical oxidation of aniline monomer at room temperature was used to quantitatively detect ammonia gas. The present optical ammonia gas detector was found to have a response time of less than 15 s, a regeneration time of less than 2 min. at room temperature, and a detection limit of 1 ppm (v/v) for ammonia, with a linear dynamic range from 180 ppm to 18,000 ppm.

Satellite Observations of Tropospheric Ammonia

NASA Astrophysics Data System (ADS)

Shephard, M. W.; Luo, M.; Rinsland, C. P.; Cady-Pereira, K. E.; Beer, R.; Pinder, R. W.; Henze, D.; Payne, V. H.; Clough, S.; Rodgers, C. D.; Osterman, G. B.; Bowman, K. W.; Worden, H. M.

2008-12-01

Global high-spectral resolution (0.06 cm-1) nadir measurements from TES-Aura enable the simultaneous retrieval of a number of tropospheric pollutants and trace gases in addition to the TES standard operationally retrieved products (e.g. carbon monoxide, ozone). Ammonia (NH3) is one of the additional species that can be retrieved in conjunction with the TES standard products, and is important for local, regional, and global tropospheric chemistry studies. Ammonia emissions contribute significantly to several well-known environmental problems, yet the magnitude and seasonal/spatial variability of the emissions are poorly constrained. In the atmosphere, an important fraction of fine particulate matter is composed of ammonium nitrate and ammonium sulfate. These particles are statistically associated with health impacts. When deposited to ecosystems in excess, nitrogen, including ammonia can cause nutrient imbalances, change in ecosystem species composition, eutrophication, algal blooms and hypoxia. Ammonia is also challenging to measure in-situ. Observations of surface concentrations are rare and are particularly sparse in North America. Satellite observations of ammonia are therefore highly desirable. We recently demonstrated that tropospheric ammonia is detectable in the TES spectra and presented some corresponding preliminary retrievals over a very limited range of conditions (Beer et al., 2008). Presented here are results that expand upon these initial TES ammonia retrievals in order to evaluate/validate the retrieval results utilizing in-situ surface observations (e.g. LADCO, CASTNet, EPA /NC State) and chemical models (e.g. GEOS-Chem and CMAQ). We also present retrievals over regions of interest that have the potential to help further understand air quality and the active nitrogen cycle. Beer, R., M. W. Shephard, S. S. Kulawik, S. A. Clough, A. Eldering, K. W. Bowman, S. P. Sander, B. M. Fisher, V. H. Payne, M. Luo, G. B. Osterman, and J. R. Worden, First

Identification of regions of rabbit muscle pyruvate kinase important for allosteric regulation by phenylalanine, detected by H/D exchange mass spectrometry†

PubMed Central

Prasannan, Charulata B.; Villar, Maria T.; Artigues, Antonio; Fenton, Aron W.

2013-01-01

Mass spectrometry has been used to determine the number of exchangeable backbone amide protons and the associated rate constants that are altered when rabbit muscle pyruvate kinase (rM1-PYK) binds either the allosteric inhibitor (phenylalanine) or a non-allosteric analogue of the inhibitor. Alanine is used as the non-allosteric analogue since it binds competitively with phenylalanine, but elicits a negligible allosteric inhibition, i.e. a negligible reduction of the affinity of rM1-PYK for the substrate, phosphoenolpyruvate (PEP). This experimental design is expected to distinguish changes in the protein caused by effector binding (i.e. those changes common upon the addition of alanine vs. phenylalanine) from changes associated with allosteric regulation (i.e. those elicited by the addition of phenylalanine binding, but not alanine binding). High quality peptic fragments covering 98% of the protein were identified. Changes in both the number of exchangeable protons per peptide and in the rate constant associated with exchange highlight regions of the protein with allosteric roles. The set of allosterically relevant peptides identified by this technique include residues previously identified by mutagenesis to have roles in the allosteric regulation by phenylalanine. PMID:23418858

Method for forming ammonia

DOEpatents

Kong, Peter C.; Pink, Robert J.; Zuck, Larry D.

2008-08-19

A method for forming ammonia is disclosed and which includes the steps of forming a plasma; providing a source of metal particles, and supplying the metal particles to the plasma to form metal nitride particles; and providing a substance, and reacting the metal nitride particles with the substance to produce ammonia, and an oxide byproduct.

N-(L-2-aminopentanoyl)-L-phenylalanine dihydrate, a hydrophobic dipeptide with a nonproteinogenic residue.

PubMed

Görbitz, Carl Henrik; Yadav, Vitthal N

2013-09-01

The title dipeptide, better known as L-norvalyl-L-phenylalanine {systematic name: (S)-2-[(S)-2-aminopentanamido]-3-phenylpropanoic acid dihydrate}, C14H20N2O3·2H2O, has a nonproteinogenic N-terminal residue. In the solid state, it takes on a molecular conformation typical for one of the three classes of nanoporous dipeptides, but like two related compounds with a hydrophobic N-terminal residue and a C-terminal L-phenylalanine, it fails to form channels or pores. Instead, the crystal structure is divided into distinct hydrophobic and hydrophilic layers, the latter encompassing cocrystallized water molecules connecting the charged N- and C-terminal groups.

Biosynthesis and Metabolic Fate of Phenylalanine in Conifers

PubMed Central

Pascual, María B.; El-Azaz, Jorge; de la Torre, Fernando N.; Cañas, Rafael A.; Avila, Concepción; Cánovas, Francisco M.

2016-01-01

The amino acid phenylalanine (Phe) is a critical metabolic node that plays an essential role in the interconnection between primary and secondary metabolism in plants. Phe is used as a protein building block but it is also as a precursor for numerous plant compounds that are crucial for plant reproduction, growth, development, and defense against different types of stresses. The metabolism of Phe plays a central role in the channeling of carbon from photosynthesis to the biosynthesis of phenylpropanoids. The study of this metabolic pathway is particularly relevant in trees, which divert large amounts of carbon into the biosynthesis of Phe-derived compounds, particularly lignin, an important constituent of wood. The trunks of trees are metabolic sinks that consume a considerable percentage of carbon and energy from photosynthesis, and carbon is finally immobilized in wood. This paper reviews recent advances in the biosynthesis and metabolic utilization of Phe in conifer trees. Two alternative routes have been identified: the ancient phenylpyruvate pathway that is present in microorganisms, and the arogenate pathway that possibly evolved later during plant evolution. Additionally, an efficient nitrogen recycling mechanism is required to maintain sustained growth during xylem formation. The relevance of phenylalanine metabolic pathways in wood formation, the biotic interactions, and ultraviolet protection is discussed. The genetic manipulation and transcriptional regulation of the pathways are also outlined. PMID:27468292

Biosynthesis and Metabolic Fate of Phenylalanine in Conifers.

PubMed

Pascual, María B; El-Azaz, Jorge; de la Torre, Fernando N; Cañas, Rafael A; Avila, Concepción; Cánovas, Francisco M

2016-01-01

The amino acid phenylalanine (Phe) is a critical metabolic node that plays an essential role in the interconnection between primary and secondary metabolism in plants. Phe is used as a protein building block but it is also as a precursor for numerous plant compounds that are crucial for plant reproduction, growth, development, and defense against different types of stresses. The metabolism of Phe plays a central role in the channeling of carbon from photosynthesis to the biosynthesis of phenylpropanoids. The study of this metabolic pathway is particularly relevant in trees, which divert large amounts of carbon into the biosynthesis of Phe-derived compounds, particularly lignin, an important constituent of wood. The trunks of trees are metabolic sinks that consume a considerable percentage of carbon and energy from photosynthesis, and carbon is finally immobilized in wood. This paper reviews recent advances in the biosynthesis and metabolic utilization of Phe in conifer trees. Two alternative routes have been identified: the ancient phenylpyruvate pathway that is present in microorganisms, and the arogenate pathway that possibly evolved later during plant evolution. Additionally, an efficient nitrogen recycling mechanism is required to maintain sustained growth during xylem formation. The relevance of phenylalanine metabolic pathways in wood formation, the biotic interactions, and ultraviolet protection is discussed. The genetic manipulation and transcriptional regulation of the pathways are also outlined.

Novel strategy for phenyllactic acid biosynthesis from phenylalanine by whole cell recombinant Escherichia coli coexpressing L-phenylalanine oxidase and L-lactate dehydrogenase.

PubMed

Zhang, Jianzhi; Li, Xi

2018-01-01

To enhance the efficiency of phenyllactic acid (PLA) production from L-phenylalanine (L-Phe) by introducing a novel artificial pathway into Escherichia coli RESULTS: The production of PLA from L-Phe by recombinant E. coli (ldh-lpox) coexpressing L-phenylalanine oxidase and L-lactate dehydrogenase was studied. The new PLA synthesis pathway was confirmed to be efficient in recombinant E. coli. Subsequently, two different biocatalyst processes were carried out and optimized for PLA production. In the whole cell biosynthesis process at high cell density using collected recombinant cells as catalyst, at optimal conditions (L-Phe 6 g/l, pH 7.5, 35 °C, CDW 24.5 g/l and 200 rpm), the recombinant E. coli (ldh-lpox) produced 1.62 g PLA/l with a conversion of 28% from L-Phe. Similarly, during the two-temperature-stage fermentation process in flasks using IPTG-induced cells, the temperature in the second stage was increased to 35 °C to benefit the biocatalyst process, and comparable phenyllactic acid production of 1.47 g/l was obtained from 12 g L-Phe/l. Recombinant E. coli (ldh-lpox) was efficient in PLA production realizing a high titer of several folds compared with studies using L-Phe as substrate.

The Effects of Acute Copper and Ammonia Challenges on Ammonia and Urea Excretion by the Blue Crab Callinectes sapidus.

PubMed

Zimmer, Alex M; Jorge, Marianna Basso; Wood, Chris M; Martins, Camila M G; Bianchini, Adalto

2017-04-01

Copper (Cu) is a persistent environmental contaminant that elicits several physiological disturbances in aquatic organisms, including a disruption in ammonia regulation. We hypothesized that exposure to Cu in a model crustacean (blue crab, Callinectes sapidus) acclimated to brackish water (2 ppt) would lead to hyperammonemia by stimulating an increase in ammonia production and/or by inhibiting ammonia excretion. We further hypothesized that urea production would represent an ammonia detoxification strategy in response to Cu. In a pilot experiment, exposure to 0, 100, and 200 µg/L Cu for 6 h caused significant concentration-dependent increases in ammonia excretion (J amm ). Based on these results, an acute 24-h 100 µg/L Cu exposure was conducted and this similarly caused an overall stimulation of J amm during the 24-h period, indicative of an increase in ammonia production. Terminal haemolymph total ammonia content (T amm ) was unchanged, suggesting that while ammonia production was increased, there was no inhibition of the excretion mechanism. In support of our second hypothesis, urea excretion (J urea ) increased in response to Cu exposure; haemolymph [urea] was unaffected. This suggested that urea production also was increased. To further test the hypothesis that J urea increased to prevent hyperammonemia during Cu exposure, crabs were exposed to high environmental ammonia (HEA; 2.5 mmol/L NH 4 HCO 3 ) for 12 h in a separate experiment. This led to a fourfold increase in haemolymph T amm , whereas J urea increased only transiently and haemolymph [urea] was unchanged, indicating that urea production likely does not contribute to the attenuation of hyperammonemia in blue crabs. Overall, Cu exposure in blue crabs led to increased ammonia and urea production, which were both eliminated by excretion. These results may have important implications in aquaculture systems where crabs may be exposed to elevated Cu and/or ammonia.

Estimating ammonia volatilization and deposition from fertilized vegetation

NASA Astrophysics Data System (ADS)

Heuer, M. W.; Myles, L.

2010-12-01

Deposition of reactive nitrogen in the form of atmospheric ammonia (NH3) affects ecosystem dynamics. Large amounts of atmospheric ammonia can volatilize from fertilized vegetation and deposit to adjacent areas, contributing to changes in soil and plant chemistry. To study the air-surface exchange of ammonia, instrumentation was installed from February 15 through April 12, 2010 at an agricultural research area of managed crops and grassland near Knoxville, TN. A Picarro ammonia analyzer was deployed to measure ammonia at two heights (z = 0.5 m and 2 m) near a plot of winter wheat fertilized with urea. Integrated samples of ammonia were also collected with annular denuder systems at both heights. Concentrations from the Picarro averaged 3-4 ppb of ammonia, but increased by a factor of 20 during fertilization. Fluxes were derived from concurrent measurements of ammonia concentration and air temperature using the flux-gradient method.

Effects of crude oil on the feeding behaviour of the zoanthid Palythoa variabilis.

PubMed

Reimer, A A

1975-01-01

Palythoa variabilis (Duerden 1898) has a well-coordinated, sterotyped feeding response similar to that described for other zoanthids. The feeding reaction can be elicited by the heterocyclic amino acid proline and by some of its analogs. The addition of an OH group (hydroxyproline) or of a glycyl group (prolylglycine) annuls the activity of the proline molecule. Substitutions (thiazolidine-4-carboxylic acid) or additions (glycylproline) to the amino group do not alter the effectivity of the activator. The size of the ring can be altered within certain limits (azetidine-2-carbocylic acid and pipecolic acid) without affecting the activity of the molecule. Feeding reactions culminating with ingestion can be elicited by Marine Diesel and Bunker-C oils. Exposure to oil affects the ability of polyps to discriminate between inert and chemically active particles for 3 to 5 days; responses to proline are not altered for at least 3 days following the exposure, but become slower and are present in fewer polyps after that period. Oil is retained in the coelenteron for several days following exposure and is periodically released in the form of timy droplets.

Folate Biofortification in Hydroponically Cultivated Spinach by the Addition of Phenylalanine.

PubMed

Watanabe, Sho; Ohtani, Yuta; Tatsukami, Yohei; Aoki, Wataru; Amemiya, Takashi; Sukekiyo, Yasunori; Kubokawa, Seiichi; Ueda, Mitsuyoshi

2017-06-14

Folate is an important vitamin mainly ingested from vegetables, and folate deficiency causes various health problems. Recently, several studies demonstrated folate biofortification in plants or food crops by metabolic engineering through genetic modifications. However, the production and sales of genetically modified foods are under strict regulation. Here, we developed a new approach to achieve folate biofortification in spinach (Spinacia oleracea) without genetic modification. We hydroponically cultivated spinach with the addition of three candidate compounds expected to fortify folate. As a result of liquid chromatography tandem mass spectrometry analysis, we found that the addition of phenylalanine increased the folate content up to 2.0-fold (306 μg in 100 g of fresh spinach), representing 76.5% of the recommended daily allowance for adults. By measuring the intermediates of folate biosynthesis, we revealed that phenylalanine activated folate biosynthesis in spinach by increasing the levels of pteridine and p-aminobenzoic acid. Our approach is a promising and practical approach to cultivate nutrient-enriched vegetables.

Ammonia

Integrated Risk Information System (IRIS)

EPA / 635 / R - 16 / 163Fa www.epa.gov / iris Toxicological Review of Ammonia Noncancer Inhalation [ CASRN 7664 - 41 - 7 ] September 2016 Integrated Risk Information System National Center for Environmental Assessment Office of Research and Development U.S . Environmental Protection Agency Washingto

Ammonia gas permeability of meat packaging materials.

PubMed

Karim, Faris; Hijaz, Faraj; Kastner, Curtis L; Smith, J Scott

2011-03-01

Meat products are packaged in polymer films designed to protect the product from exterior contaminants such as light, humidity, and harmful chemicals. Unfortunately, there is almost no data on ammonia permeability of packaging films. We investigated ammonia permeability of common meat packaging films: low-density polyethylene (LDPE; 2.2 mil), multilayer polyolefin (MLP; 3 mil), and vacuum (V-PA/PE; 3 mil, 0.6 mil polyamide/2.4 mil polyethylene). The films were fabricated into 10 × 5 cm pouches and filled with 50 mL deionized water. Pouches were placed in a plexiglass enclosure in a freezer and exposed to 50, 100, 250, or 500 ppm ammonia gas for 6, 12, 24, and 48 h at -17 ± 3 °C and 21 ± 3 °C. At freezing temperatures, no ammonia residues were detected and no differences in pH were found in the water. At room temperature, ammonia levels and pH of the water increased significantly (P < 0.05) with increasing exposure times and ammonia concentrations. Average ammonia levels in the water were 7.77 ppm for MLP, 5.94 ppm for LDPE, and 0.89 ppm for V-PA/PE at 500 ppm exposure for 48 h at 21 ± 3 °C. Average pH values were 8.64 for MLP, 8.38 for LDPE, and 7.23 for V-PA/PE (unexposed ranged from 5.49 to 6.44) at 500 ppm exposure for 48 h. The results showed that temperature influenced ammonia permeability. Meat packaging materials have low ammonia permeability and protect meat products exposed to ammonia leaks during frozen storage.

Peripheral Ammonia as a Mediator of Methamphetamine Neurotoxicity

PubMed Central

Halpin, Laura E.; Yamamoto, Bryan K.

2012-01-01

Ammonia is metabolized by the liver and has established neurological effects. The current study examined the possibility that ammonia contributes to the neurotoxic effects of methamphetamine (METH). The results show that a binge dosing regimen of METH to the rat increased plasma and brain ammonia concentrations that were paralleled by evidence of hepatotoxicity. The role of peripheral ammonia in the neurotoxic effects of METH was further substantiated by the demonstration that the enhancement of peripheral ammonia excretion blocked the increases in brain and plasma ammonia and attenuated the long term depletions of dopamine and serotonin typically produced by METH. Conversely, the localized perfusion of ammonia in combination with METH, but not METH alone or ammonia alone, into the striatum recapitulated the neuronal damage produced by the systemic administration of METH. Furthermore, this damage produced by the local administration of ammonia and METH was blocked by the GYKI 52466, an AMPA receptor antagonist. These findings highlight the importance of ammonia derived from the periphery as a small molecule mediator of METH neurotoxicity and more broadly emphasize the importance of peripheral organ damage as a possible mechanism that mediates the neuropathology produced by drugs of abuse and other neuroactive molecules. PMID:22993432

Root Growth and Enzymes Related to the Lignification of Maize Seedlings Exposed to the Allelochemical L-DOPA

PubMed Central

Siqueira-Soares, Rita de Cássia; Parizotto, Angela Valderrama; Ferrarese, Maria de Lourdes Lucio

2013-01-01

L-3,4-Dihydroxyphenylalanine (L-DOPA) is a known allelochemical exuded from the roots of velvet bean (Mucuna pruriens L. Fabaceae). In the current work, we analyzed the effects of L-DOPA on the growth, the activities of phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL), and peroxidase (POD), and the contents of phenylalanine, tyrosine, and lignin in maize (Zea mays) roots. Three-day-old seedlings were cultivated in nutrient solution with or without 0.1 to 2.0 mM L-DOPA in a growth chamber (25°C, light/dark photoperiod of 12/12, and photon flux density of 280 μmol m−2 s−1) for 24 h. The results revealed that the growth (length and weight) of the roots, the PAL, TAL, and soluble and cell wall-bound POD activities decreased, while phenylalanine, tyrosine, and lignin contents increased after L-DOPA exposure. Together, these findings showed the susceptibility of maize to L-DOPA. In brief, these results suggest that the inhibition of PAL and TAL can accumulate phenylalanine and tyrosine, which contribute to enhanced lignin deposition in the cell wall followed by a reduction of maize root growth. PMID:24348138

Changes in bioactive compounds and oxidative enzymes of fresh-cut pomegranate arils during storage as affected by deficit irrigation and postharvest vapor heat treatments.

PubMed

Peña-Estévez, María E; Gómez, Perla A; Artés, Francisco; Aguayo, Encarna; Martínez-Hernández, Ginés Benito; Galindo, Alejandro; Torecillas, Arturo; Artés-Hernández, Francisco

2016-12-01

The effect of postharvest vapor heat treatments at 95℃ (4, 7, and 10 s) regarding a conventional sanitizing treatment with 100 mg NaClO l -1 on enzyme activities (phenylalanine ammonia lyase, polyphenol oxidase, and peroxidase), phenolic content, and total antioxidant capacity of fresh-cut pomegranates arils throughout 18 days at 5℃ was studied. Furthermore, the effect of two sustained deficit irrigation (SDI) strategies, compared to a standardly irrigated control (CTRL), was also studied on such quality parameters throughout storage. Arils from CTRL-irrigated fruit registered phenylalanine ammonia lyase, peroxidase, and polyphenol oxidase initial activities of 60.6, 382, and 14.4 U g -1  fw, respectively. Arils from sustained deficit irrigation fruit registered 46-58% lower phenylalanine ammonia lyase values while polyphenol oxidase and peroxidase activities did not register great variants (<9%) among both sustained deficit irrigation treatments. Postharvest vapor heat treatments enhanced phenylalanine ammonia lyase activity in those samples from sustained deficit irrigation fruit although no great peroxidase and polyphenol oxidase (<2-5%) increases were observed. Arils from SDI 1 fruit registered higher phenolic content than those values reported for CTRL samples. However, phenolic compounds decreased during storage, in a greater extent for sustained deficit irrigation samples, although 7 s arils achieved better phenolic compounds retention in sustained deficit irrigation samples. Vapor heat treatments reduced up to twofold the total antioxidant capacity losses observed in samples sanitized by conventional NaOCl treatment during shelf life. Conclusively, postharvest vapor heat treatment for 7 and 10 s used to extend the shelf life of pomegranate arils up to 18 days at 5℃ reduced the losses of health-promoting compounds during storage compared to conventional NaOCl sanitizing treatment. © The Author(s) 2016.

The Chemistry of Liquid Ammonia.

ERIC Educational Resources Information Center

Lagowski, J. J.

1978-01-01

The solvent and chemical properties of liquid ammonia are presented. In a certain sense, ammonia is a more versatile solvent than is water because of its ability to solubilize, without reaction, highly negative or reducing species. (Author/BB)

Combined effects of cotyledon excision and nursery fertilization on root growth, nutrient status and outplanting performance of Quercus variabilis container seedlings.

PubMed

Shi, Wenhui; Bloomberg, Mark; Li, Guolei; Su, Shuchai; Jia, Liming

2017-01-01

Artificial excision of the distal part of acorns in order to promote germination is well researched in oak seedling cultivation studies. However, studies of combined effects of cotyledon excision and nursery fertilization on container seedlings are lacking, especially for seedling root growth and outplanting performance. This study aimed to explore the main effects of cotyledon excision on Quercus variabilis seedling emergence characteristics and demonstrated the combined effects of cotyledon excision and nursery fertilization on seedling quality to improve Quercus variabilis seedling outplanting performance. Four cotyledon excision treatments and two classes of nursery fertilization were implemented. Seedling emergence was noted every week after sowing. Seedling dry mass, morphology, and nutrient status were assessed at the end of the nursery season. After the first outplanting season, the aforementioned measurements along with seedling survival were determined once again. The results showed that cotyledon excision generally induced greater and more rapid seedling emergence, but did not affect shoot emergence synchronicity. The highest total emergence and emergence rate occurred with Intermediate excision (1/2 of the distal end of acorn was excised). Effects of nutrient loss due to cotyledon excision on seedling quality and outplanting performance were somewhat compensated by nursery fertilization. Nursery fertilization promoted dry mass increment (the net increment from T0 to T2 for dry mass) for excised seedlings after outplanting, resulting in better performance for Slight (1/3 of the distal end of acorn was excised) and Intermediate excision treatments in the field. Thus we conclude Intermediate excision combined with reasonable nursery fertilization can be recommended for production of nursery grown seedlings for afforestation.

Combined effects of cotyledon excision and nursery fertilization on root growth, nutrient status and outplanting performance of Quercus variabilis container seedlings

PubMed Central

Shi, Wenhui; Bloomberg, Mark; Li, Guolei; Su, Shuchai; Jia, Liming

2017-01-01

Artificial excision of the distal part of acorns in order to promote germination is well researched in oak seedling cultivation studies. However, studies of combined effects of cotyledon excision and nursery fertilization on container seedlings are lacking, especially for seedling root growth and outplanting performance. This study aimed to explore the main effects of cotyledon excision on Quercus variabilis seedling emergence characteristics and demonstrated the combined effects of cotyledon excision and nursery fertilization on seedling quality to improve Quercus variabilis seedling outplanting performance. Four cotyledon excision treatments and two classes of nursery fertilization were implemented. Seedling emergence was noted every week after sowing. Seedling dry mass, morphology, and nutrient status were assessed at the end of the nursery season. After the first outplanting season, the aforementioned measurements along with seedling survival were determined once again. The results showed that cotyledon excision generally induced greater and more rapid seedling emergence, but did not affect shoot emergence synchronicity. The highest total emergence and emergence rate occurred with Intermediate excision (1/2 of the distal end of acorn was excised). Effects of nutrient loss due to cotyledon excision on seedling quality and outplanting performance were somewhat compensated by nursery fertilization. Nursery fertilization promoted dry mass increment (the net increment from T0 to T2 for dry mass) for excised seedlings after outplanting, resulting in better performance for Slight (1/3 of the distal end of acorn was excised) and Intermediate excision treatments in the field. Thus we conclude Intermediate excision combined with reasonable nursery fertilization can be recommended for production of nursery grown seedlings for afforestation. PMID:28545103

Getter materials for cracking ammonia

DOEpatents

Boffito, Claudio; Baker, John D.

1999-11-02

A method is provided for cracking ammonia to produce hydrogen. The method includes the steps of passing ammonia over an ammonia-cracking catalyst which is an alloy including (1) alloys having the general formula Zr.sub.1-x Ti.sub.x M.sub.1 M.sub.2, wherein M.sub.1 and M.sub.2 are selected independently from the group consisting of Cr, Mn, Fe, Co, and Ni, and x is between about 0.0 and about 1.0 inclusive; and between about 20% and about 50% Al by weight. In another aspect, the method of the invention is used to provide methods for operating hydrogen-fueled internal combustion engines and hydrogen fuel cells. In still another aspect, the present invention provides a hydrogen-fueled internal combustion engine and a hydrogen fuel cell including the above-described ammonia-cracking catalyst.

D-phenylalanine and other enkephalinase inhibitors as pharmacological agents: implications for some important therapeutic application.

PubMed

Ehrenpreis, S

1982-01-01

A number of compounds have been shown to inhibit the degradation of enkephalins. As expected, these compounds produce naloxone reversible analgesia and potentiate the analgesia produced by enkephalins and by acupuncture. One of these, D-phenylalanine, is also anti-inflammatory. D-phenylalanine has proven to be beneficial in many human patients with chronic, intractable pain. It is proposed the enkephalinase inhibitors may be effective in a number of human "endorphin deficiency diseases" such as depression, schizophrenia, convulsive disorders and arthritis. Such compounds may alleviate other conditions associated with decreased endorphin levels such as opiate withdrawal symptoms.

Changes of Ammonia-Metabolizing Enzyme Activity and Gene Expression of Two Strains in Shrimp Litopenaeus vannamei Under Ammonia Stress

PubMed Central

Qiu, Liguo; Shi, Xiang; Yu, Simeng; Han, Qian; Diao, Xiaoping; Zhou, Hailong

2018-01-01

Ammonia stress can inhibit the survival and growth, and even cause mortality of shrimp. In this study, ammonia-metabolizing enzyme activities and gene expression were compared between two strains of L. vannamei under different ammonia-N (NH4+) concentrations (3.4, 13.8, and 24.6 mg/L). The results showed that elevated ammonia concentrations mainly increased glutamine synthetase (GSase) activities while inhibiting transglutaminase (TGase) activities in the muscle of both strains. Thus, we concluded that L. vannamei could accelerate the synthesis of glutamine from glutamate and NH4+ to alleviate ammonia stress. Compared with the muscle, the hepatopancreas plays a major role in ammonia stress and might be a target tissue to respond to the ammonia stress. Compared to the control group, the treatment of high ammonia concentrations reduced the hepatopancreas TGase (TG) gene expression and increased the gene expression rates of glutamate dehydrogenase-β (GDH-β) and GSase (GS) in both the muscle and the hepatopancreas of the two strains (p < 0.05). These genes (GDH-β and GS) in strain B were not only expressed earlier but also at levels higher than the expression range of strain A. At the gene level, strain B showed a more rapid and positive response than strain A. These data might help reveal the physiological responses mechanisms of shrimp adapt to ammonia stress and speed up the selective breeding process in L. vannamei. PMID:29628893

Ammonia stress under high environmental ammonia induces Hsp70 and Hsp90 in the mud eel, Monopterus cuchia.

PubMed

Hangzo, Hnunlalliani; Banerjee, Bodhisattwa; Saha, Shrabani; Saha, Nirmalendu

2017-02-01

The obligatory air-breathing mud eel (Monopterus cuchia) is frequently being challenged with high environmental ammonia (HEA) exposure in its natural habitats. The present study investigated the possible induction of heat shock protein 70 and 90 (hsp70, hsc70, hsp90α and hsp90β) genes and more expression of Hsp70 and Hsp90 proteins under ammonia stress in different tissues of the mud eel after exposure to HEA (50 mM NH 4 Cl) for 14 days. HEA resulted in significant accumulation of toxic ammonia in different body tissues and plasma, which was accompanied with the stimulation of oxidative stress in the mud eel as evidenced by more accumulation of malondialdehyde (MDA) and hydrogen peroxide (H 2 O 2 ) during exposure to HEA. Further, hyper-ammonia stress led to significant increase in the levels of mRNA transcripts for inducible hsp70 and hsp90α genes and also their translated proteins in different tissues probably as a consequence of induction of hsp70 and hsp90α genes in the mud eel. However, hyper-ammonia stress was neither associated with any significant alterations in the levels of mRNA transcripts for constitutive hsc70 and hsp90β genes nor their translated proteins in any of the tissues studied. More abundance of Hsp70 and Hsp90α proteins might be one of the strategies adopted by the mud eel to defend itself from the ammonia-induced cellular damages under ammonia stress. Further, this is the first report of ammonia-induced induction of hsp70 and hsp90α genes under hyper-ammonia stress in any freshwater air-breathing teleost.

Submersible microbial desalination cell for simultaneous ammonia recovery and electricity production from anaerobic reactors containing high levels of ammonia.

PubMed

Zhang, Yifeng; Angelidaki, Irini

2015-02-01

High ammonia concentration in anaerobic reactors can seriously inhibit the anaerobic digestion process. In this study, a submersible microbial desalination cell (SMDC) was developed as an innovative method to lower the ammonia level in a continuous stirred tank reactor (CSTR) by in situ ammonia recovery and electricity production. In batch experiment, the ammonia concentration in the CSTR decreased from 6 to 0.7 g-N/L during 30 days, resulting in an average recovery rate of 80 g-N/m(2)/d. Meanwhile, a maximum power density of 0.71±0.5 W/m(2) was generated at 2.85 A/m(2). Both current driven NH4(+) migration and free NH3 diffusion were identified as the mechanisms responsible for the ammonia transportation. With an increase in initial ammonia concentration and a decrease in external resistance, the SMDC performance was enhanced. In addition, the coexistence of other cations in CSTR or cathode had no negative effect on the ammonia transportation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ammonia Excretion in an Osmoregulatory Syncytium Is Facilitated by AeAmt2, a Novel Ammonia Transporter in Aedes aegypti Larvae

PubMed Central

Durant, Andrea C.; Donini, Andrew

2018-01-01

The larvae of the mosquito Aedes aegypti inhabit ammonia rich septic tanks in tropical regions of the world that make extensive use of these systems, explaining the prevalence of disease during dry seasons. Since ammonia (NH3/NH4+) is toxic to animals, an understanding of the physiological mechanisms of ammonia excretion permitting the survival of A. aegypti larvae in high ammonia environments is important. We have characterized a novel ammonia transporter, AeAmt2, belonging to the Amt/MEP/Rh family of ammonia transporters. Based on the amino acid sequence, the predicted topology of AeAmt2 consists of 11 transmembrane helices with an extracellular N-terminus and a cytoplasmic C-terminus region. Alignment of the predicted AeAmt2 amino acid sequence with other Amt/MEP proteins from plants, bacteria, and yeast highlights the presence of conserved residues characteristic of ammonia conducting channels in this protein. AeAmt2 is expressed in the ionoregulatory anal papillae of A. aegypti larvae where it is localized to the apical membrane of the epithelium. dsRNA-mediated knockdown of AeAmt2 results in a significant decrease in NH4+ efflux from the anal papillae, suggesting a key role in facilitating ammonia excretion. The effect of high environmental ammonia (HEA) on expression of AeAmt2, along with previously characterized AeAmt1, AeRh50-1, and AeRh50-2 in the anal papillae was investigated. We show that changes in expression of ammonia transporters occur in response to acute and chronic exposure to HEA, which reflects the importance of these transporters in the physiology of life in high ammonia habitats. PMID:29695971

Ammonia and ammonium hydroxide sensors for ammonia/water absorption machines: Literature review and data compilation

NASA Astrophysics Data System (ADS)

Anheier, N. C., Jr.; McDonald, C. E.; Cuta, J. M.; Cuta, F. M.; Olsen, K. B.

1995-05-01

This report describes an evaluation of various sensing techniques for determining the ammonia concentration in the working fluid of ammonia/water absorption cycle systems. The purpose was to determine if any existing sensor technology or instrumentation could provide an accurate, reliable, and cost-effective continuous measure of ammonia concentration in water. The resulting information will be used for design optimization and cycle control in an ammonia-absorption heat pump. Pacific Northwest Laboratory (PNL) researchers evaluated each sensing technology against a set of general requirements characterizing the potential operating conditions within the absorption cycle. The criteria included the physical constraints for in situ operation, sensor characteristics, and sensor application. PNL performed an extensive literature search, which uncovered several promising sensing technologies that might be applicable to this problem. Sixty-two references were investigated, and 33 commercial vendors were identified as having ammonia sensors. The technologies for ammonia sensing are acoustic wave, refractive index, electrode, thermal, ion-selective field-effect transistor (ISFET), electrical conductivity, pH/colormetric, and optical absorption. Based on information acquired in the literature search, PNL recommends that follow-on activities focus on ISFET devices and a fiber optic evanescent sensor with a colormetric indicator. The ISFET and fiber optic evanescent sensor are inherently microminiature and capable of in situ measurements. Further, both techniques have been demonstrated selective to the ammonium ion (NH4(+)). The primary issue remaining is how to make the sensors sufficiently corrosion-resistant to be useful in practice.

Metabolic engineering of Escherichia coli for production of 2-Phenylethylacetate from L-phenylalanine.

PubMed

Guo, Daoyi; Zhang, Lihua; Pan, Hong; Li, Xun

2017-08-01

In order to meet the need of consumer preferences for natural flavor compounds, microbial synthesis method has become a very attractive alternative to the chemical production. The 2-phenylethanol (2-PE) and its ester 2-phenylethylacetate (2-PEAc) are two extremely important flavor compounds with a rose-like odor. In recent years, Escherichia coli and yeast have been metabolically engineered to produce 2-PE. However, a metabolic engineering approach for 2-PEAc production is rare. Here, we designed and expressed a 2-PEAc biosynthetic pathway in E. coli. This pathway comprised four steps: aminotransferase (ARO8) for transamination of L-phenylalanine to phenylpyruvate, 2-keto acid decarboxylase KDC for the decarboxylation of the phenylpyruvate to phenylacetaldehyde, aldehyde reductase YjgB for the reduction of phenylacetaldehyde to 2-PE, alcohol acetyltransferase ATF1 for the esterification of 2-PE to 2-PEAc. Using the engineered E. coli strain for shake flasks cultivation with 1 g/L L-phenylalanine, we achieved co-production of 268 mg/L 2-PEAc and 277 mg/L 2-PE. Our results suggest that approximately 65% of L-phenylalanine was utilized toward 2-PEAc and 2-PE biosynthesis and thus demonstrate potential industrial applicability of this microbial platform. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Flexible ammonia handling strategies using both cutaneous and branchial epithelia in the highly ammonia-tolerant Pacific hagfish.

PubMed

Clifford, Alexander M; Weinrauch, Alyssa M; Edwards, Susan L; Wilkie, Michael P; Goss, Greg G

2017-08-01

Hagfish consume carrion, potentially exposing them to hypoxia, hypercapnia, and high environmental ammonia (HEA). We investigated branchial and cutaneous ammonia handling strategies by which Pacific hagfish ( Eptatretus stoutii ) tolerate and recover from high ammonia loading. Hagfish were exposed to HEA (20 mmol/l) for 48 h to elevate plasma total ammonia (T Amm ) levels before placement into divided chambers for a 4-h recovery period in ammonia-free seawater where ammonia excretion ( J Amm ) was measured independently in the anterior and posterior compartments. Localized HEA exposures were also conducted by subjecting hagfish to HEA in either the anterior or posterior compartments. During recovery, HEA-exposed animals increased J Amm in both compartments, with the posterior compartment comprising ~20% of the total J Amm compared with ~11% in non-HEA-exposed fish. Plasma T Amm increased substantially when whole hagfish and the posterior regions were exposed to HEA. Alternatively, plasma T Amm did not elevate after anterior localized HEA exposure. J Amm was concentration dependent (0.05-5 mmol/l) across excised skin patches at up to eightfold greater rates than in skin sections that were excised from HEA-exposed hagfish. Skin excised from more posterior regions displayed greater J Amm than those from more anterior regions. Immunohistochemistry with hagfish-specific anti-rhesus glycoprotein type c (α-hRhcg; ammonia transporter) antibody was characterized by staining on the basal aspect of hagfish epidermis while Western blotting demonstrated greater expression of Rhcg in more posterior skin sections. We conclude that cutaneous Rhcg proteins are involved in cutaneous ammonia excretion by Pacific hagfish and that this mechanism could be particularly important during feeding. Copyright © 2017 the American Physiological Society.

Crystal Structure of an Ammonia-Permeable Aquaporin

PubMed Central

Kirscht, Andreas; Kaptan, Shreyas S.; Bienert, Gerd Patrick; Chaumont, François; Nissen, Poul; de Groot, Bert L.; Kjellbom, Per; Gourdon, Pontus; Johanson, Urban

2016-01-01

Aquaporins of the TIP subfamily (Tonoplast Intrinsic Proteins) have been suggested to facilitate permeation of water and ammonia across the vacuolar membrane of plants, allowing the vacuole to efficiently sequester ammonium ions and counteract cytosolic fluctuations of ammonia. Here, we report the structure determined at 1.18 Å resolution from twinned crystals of Arabidopsis thaliana aquaporin AtTIP2;1 and confirm water and ammonia permeability of the purified protein reconstituted in proteoliposomes as further substantiated by molecular dynamics simulations. The structure of AtTIP2;1 reveals an extended selectivity filter with the conserved arginine of the filter adopting a unique unpredicted position. The relatively wide pore and the polar nature of the selectivity filter clarify the ammonia permeability. By mutational studies, we show that the identified determinants in the extended selectivity filter region are sufficient to convert a strictly water-specific human aquaporin into an AtTIP2;1-like ammonia channel. A flexible histidine and a novel water-filled side pore are speculated to deprotonate ammonium ions, thereby possibly increasing permeation of ammonia. The molecular understanding of how aquaporins facilitate ammonia flux across membranes could potentially be used to modulate ammonia losses over the plasma membrane to the atmosphere, e.g., during photorespiration, and thereby to modify the nitrogen use efficiency of plants. PMID:27028365

Chirality dependent interaction of ammonia with carbon nanotubes

NASA Astrophysics Data System (ADS)

Talukdar, Keka; Shantappa, Anil

2018-04-01

For the specific structure and extraordinary properties, carbon nanotubes (CNTs) have many applications in diversified fields. The interaction of CNTs with ammonia is a very interesting matter to study as it is related to the application of CNTs as ammonia sensor. Here the interaction of single walled zigzag, armchair and chiral carbon nanotubes is studied in respect of the change in energies before and after binding with ammonia by molecular dynamics simulation. Their deformation after simulation is modeled. The change of thermal conductivity of the CNTs is also found by simulation. The potential energy before and after absorption of ammonia gives useful information of the system. Thermal conductivities of the ammonia bound CNTs are changed considerably. It is observed that the potential energy and thermal conductivity both are changing for the interaction with ammonia and hence they are sensitive to ammonia binding.

Effect of dietary protein restriction on renal ammonia metabolism

PubMed Central

Lee, Hyun-Wook; Osis, Gunars; Handlogten, Mary E.; Guo, Hui; Verlander, Jill W.

2015-01-01

Dietary protein restriction has multiple benefits in kidney disease. Because protein intake is a major determinant of endogenous acid production, it is important that net acid excretion change in parallel during protein restriction. Ammonia is the primary component of net acid excretion, and inappropriate ammonia excretion can lead to negative nitrogen balance. Accordingly, we examined ammonia excretion in response to protein restriction and then we determined the molecular mechanism of the changes observed. Wild-type C57Bl/6 mice fed a 20% protein diet and then changed to 6% protein developed an 85% reduction in ammonia excretion within 2 days, which persisted during a 10-day study. The expression of multiple proteins involved in renal ammonia metabolism was altered, including the ammonia-generating enzymes phosphate-dependent glutaminase (PDG) and phosphoenolpyruvate carboxykinase (PEPCK) and the ammonia-metabolizing enzyme glutamine synthetase. Rhbg, an ammonia transporter, increased in expression in the inner stripe of outer medullary collecting duct intercalated cell (OMCDis-IC). However, collecting duct-specific Rhbg deletion did not alter the response to protein restriction. Rhcg deletion did not alter ammonia excretion in response to dietary protein restriction. These results indicate 1) dietary protein restriction decreases renal ammonia excretion through coordinated regulation of multiple components of ammonia metabolism; 2) increased Rhbg expression in the OMCDis-IC may indicate a biological role in addition to ammonia transport; and 3) Rhcg expression is not necessary to decrease ammonia excretion during dietary protein restriction. PMID:25925252

Ambient ammonia measurements using laser photo-acoustic spectroscopy

NASA Technical Reports Server (NTRS)

Aldridge, M. D., III; Copeland, G. E.; Harward, C. N.

1981-01-01

Ammonia concentrations reached minimal levels (approximately 0.1 ppb) in early winter, followed by a sudden later winter increase. A direct relationship between ambient ammonia levels and air temperature was inferred from the data (linear correlation coefficient r=0.53). Ammonia concentrations were determined to be directly related to the absolute humidity of the air (r=0.72); a weaker relationship between ammonia concentrations and relative humidity was discovered (r=0.37). The data also indicated that ammonia levels were generally higher within continental air masses than those of maritime origin. Soil parameters such as pH and moisture content were found to have a major bearing on the release of gaseous ammonia from soils in the region.

Corrosion inhibitor for aqueous ammonia absorption system

DOEpatents

Phillips, Benjamin A.; Whitlow, Eugene P.

1998-09-22

A method of inhibiting corrosion and the formation of hydrogen and thus improving absorption in an ammonia/water absorption refrigeration, air conditioning or heat pump system by maintaining the hydroxyl ion concentration of the aqueous ammonia working fluid within a selected range under anaerobic conditions at temperatures up to 425.degree. F. This hydroxyl ion concentration is maintained by introducing to the aqueous ammonia working fluid an inhibitor in an amount effective to produce a hydroxyl ion concentration corresponding to a normality of the inhibitor relative to the water content ranging from about 0.015 N to about 0.2 N at 25.degree. C. Also, working fluids for inhibiting the corrosion of carbon steel and resulting hydrogen formation and improving absorption in an ammonia/water absorption system under anaerobic conditions at up to 425.degree. F. The working fluids may be aqueous solutions of ammonia and a strong base or aqueous solutions of ammonia, a strong base, and a specified buffer.

Corrosion inhibitor for aqueous ammonia absorption system

DOEpatents

Phillips, B.A.; Whitlow, E.P.

1998-09-22

A method is described for inhibiting corrosion and the formation of hydrogen and thus improving absorption in an ammonia/water absorption refrigeration, air conditioning or heat pump system by maintaining the hydroxyl ion concentration of the aqueous ammonia working fluid within a selected range under anaerobic conditions at temperatures up to 425 F. This hydroxyl ion concentration is maintained by introducing to the aqueous ammonia working fluid an inhibitor in an amount effective to produce a hydroxyl ion concentration corresponding to a normality of the inhibitor relative to the water content ranging from about 0.015 N to about 0.2 N at 25 C. Also, working fluids for inhibiting the corrosion of carbon steel and resulting hydrogen formation and improving absorption in an ammonia/water absorption system under anaerobic conditions at up to 425 F. The working fluids may be aqueous solutions of ammonia and a strong base or aqueous solutions of ammonia, a strong base, and a specified buffer. 5 figs.

[Ammonia as a cause for hepatic encephalopathy].

PubMed

Naimushin, Alexey; Livneh, Avi

2010-02-01

In a patient with cirrhosis of the liver, associated with hepatitis B virus, who was admitted for confusion and acute elevation of liver enzymes, a diagnosis of hepatic encephalopathy was made. A serum ammonia level of 54 (normal less than 33) microgram/liter, supported the diagnosis, but puzzled the medical staff regarding the possibility that ammonia may directly induce the confusion. While it is widely accepted that the ammonia level is a marker that usually parallels the amount of toxins and metabolites that bypasses the liver, its role in causing brain dysfunction is debated. However, since ammonia may directly hinder the metabolism of neuro-transmitters, and drugs and treatments specifically aimed at reducing ammonia levels may minimize the time interval for recovery from the acute brain insult, it is assumed that ammonia by itself had a role in bringing about the encephalopathy manifestations in our patients and other patients with cirrhosis of the liver.

Preparation of "dummy" l-phenylalanine molecularly imprinted microspheres by using ionic liquid as a template and functional monomer.

PubMed

Li, Ji; Hu, Xiaoling; Guan, Ping; Song, Dongmen; Qian, Liwei; Du, Chunbao; Song, Renyuan; Wang, Chaoli

2015-07-07

In this study, dummy imprinting technology was employed for the preparation of l-phenylalanine-imprinted microspheres. Ionic liquids were utilized as both a "dummy" template and functional monomer, and 4-vinylpyridine and ethylene glycol dimethacrylate were used as the assistant monomer and cross-linker, respectively, for preparing a surface-imprinted polymer on poly(divinylbenzene) microspheres. By the results obtained by theoretical investigation, the interaction between the template and monomer complex was improved as compared with that between the template and the traditional l-phenylalanine-imprinted polymer. The batch experiments indicated that the imprinting factor reached 2.5. Scatchard analysis demonstrated that the obtained "dummy" molecularly imprinted microspheres exhibited an affinity of 77.4 M·10 -4 , significantly higher that of a traditional polymer directly prepared by l-phenylalanine, which is in agreement with theoretical results. Competitive adsorption experiments also showed that the molecularly imprinted polymer with the dummy template effectively isolated l-phenylalanine from l-histidine and l-tryptophan with separation factors of 5.68 and 2.68, respectively. All these results demonstrated that the polymerizable ionic liquid as the dummy template could enhance the affinity and selectivity of molecularly imprinted polymer, thereby promoting the development of imprinting technology for biomolecules. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of dietary leucine and phenylalanine on pancreas development, enzyme activity, and relative gene expression in milk-fed Holstein dairy calves.

PubMed

Cao, Y C; Yang, X J; Guo, L; Zheng, C; Wang, D D; Cai, C J; Liu, S M; Yao, J H

2018-05-01

This study aimed to investigate the effect of dietary supplementation with leucine and phenylalanine on pancreas development, enzyme activity, and related gene expression in male Holstein calves. Twenty male Holstein calves [1 d of age, 38 ± 3 kg of body weight (BW)] were randomly assigned to 1 of the following 4 treatment groups with 5 calves in each group: control, leucine supplementation (1.435 g/L of milk), phenylalanine supplementation (0.725 g/L of milk), and leucine and phenylalanine (1.435 + 0.725 g/L of milk). The diets were made isonitrogenous with the inclusion of alanine in each respective treatment. The feeding trial lasted for 8 wk, including 1 wk for adaption and 7 wk for the feeding experiment. Leucine tended to increase the concentration of total pancreatic protein (mg/kg of BW). Phenylalanine increased the concentrations of plasma insulin, cholecystokinin, and pancreatic DNA (mg/g) and the expression of trypsin gene but decreased the pancreatic protein:DNA ratio and tended to decrease the pancreas weight (g/kg of BW). No differences were observed in total pancreatic DNA (mg/pancreas and mg/kg of BW), pancreatic protein (mg/pancreas), or activities of α-amylase, trypsin, and lipase. The relative expression levels of the genes encoding α-amylase and lipase did not differ among the 4 groups. The supplementation of both leucine and phenylalanine showed an interaction on the pancreas weight (g and g/kg of BW) and a tendency of an interaction on the pancreatic protein concentration (mg/g of pancreas and mg/kg of BW) and the plasma glucose concentration. Leucine tended to increase the size of the pancreatic cells, whereas phenylalanine tended to increase the number of pancreatic cells. However, neither AA affected the activities of the pancreatic enzymes of the calves. These results indicate that leucine and phenylalanine supplementation in milk-fed Holstein calves differentially affect pancreatic growth and development. Copyright © 2018 American

Influence of additive L-phenylalanine on stabilization of metastable α-form of L-glutamic acid in cooling crystallization

NASA Astrophysics Data System (ADS)

Quang, Khuu Chau; Nhan, Le Thi Hong; Huyen, Trinh Thi Thanh; Tuan, Nguyen Anh

2017-09-01

The influence of additive amino acid L-phenylalanine on stabilization of metastable α-form of L-glutamic acid was investigated in cooling crystallization. The present study found that the additive L-phenylalanine could be used to stabilize the pure metastable α-form in L-glutamic acid crystallization, where the additive concentration of 0.05-0.1 (g/L) was sufficient to stabilize the 100% wt metastable α-form in solid product at L-glutamic acid concentration of 30-45 (g/L). Additionally, the present results indicated that the adsorption of additive L-phenylalanine on the (001) surface of α-form was more favorable than that of the β-form molecular, so the nucleation sites of stable β-form was occupied by additive molecular, which resulted in inhibition of nucleation and growth of β-form, allowing stabilization of metastable α-form.

Ammonia synthesis. Ammonia synthesis by N₂ and steam electrolysis in molten hydroxide suspensions of nanoscale Fe₂O₃.

PubMed

Licht, Stuart; Cui, Baochen; Wang, Baohui; Li, Fang-Fang; Lau, Jason; Liu, Shuzhi

2014-08-08

The Haber-Bosch process to produce ammonia for fertilizer currently relies on carbon-intensive steam reforming of methane as a hydrogen source. We present an electrochemical pathway in which ammonia is produced by electrolysis of air and steam in a molten hydroxide suspension of nano-Fe2O3. At 200°C in an electrolyte with a molar ratio of 0.5 NaOH/0.5 KOH, ammonia is produced at 1.2 volts (V) under 2 milliamperes per centimeter squared (mA cm(-2)) of applied current at coulombic efficiency of 35% (35% of the applied current results in the six-electron conversion of N2 and water to ammonia, and excess H2 is cogenerated with the ammonia). At 250°C and 25 bar of steam pressure, the electrolysis voltage necessary for 2 mA cm(-2) current density decreased to 1.0 V. Copyright © 2014, American Association for the Advancement of Science.

Palyosulfonoceramides A and B: Unique Sulfonylated Ceramides from the Brazilian Zoanthids Palythoa caribaeorum and Protopalyhtoa variabilis

PubMed Central

Almeida, Jose Gustavo L.; Maia, Ana Isabel V.; Wilke, Diego V.; Silveira, Edilberto R.; Braz-Filho, Raimundo; La Clair, James J.; Costa-Lotufo, Leticia V.; Pessoa, Otília Deusdenia L.

2012-01-01

The zoanthids Palythoa caribaeorum and Protopalythoa variabilis are among the most abundant marine species along the Brazilian coast. We now report the isolation and structure elucidation of two unprecedented sulfonylated ceramides, palyosulfonoceramide A (1) and palyosulfonoceramide B (2) from specimens collected off Brazil’s northeastern coast. The structures of 1 and 2 were established using a combination of NMR analyses, including: evaluation of 1H, 13C, 1H–1H COSY, 1H–13C HSQC, 1H–13C HMBC, and 1H–15N HMBC NMR spectra, high-resolution mass spectrometry and chemical degradation. In addition, we also isolated the corresponding known ceramides, N-((2S,3R,4E,8E)-1,3-dihydroxyoctadeca-4,8-dien-2-yl)-hexadecanamide (3) and N-((2S,3R,4E)-1,3-dihydroxyoctadeca-4-en-2-yl)-hexadecanamide (4), which provided further support for the assignments of 1 and 2. PMID:23242205

Palyosulfonoceramides A and B: unique sulfonylated ceramides from the Brazilian zoanthids Palythoa caribaeorum and Protopalythoa variabilis.

PubMed

Almeida, Jose Gustavo L; Maia, Ana Isabel V; Wilke, Diego V; Silveira, Edilberto R; Braz-Filho, Raimundo; La Clair, James J; Costa-Lotufo, Leticia V; Pessoa, Otília Deusdenia L

2012-12-14

The zoanthids Palythoa caribaeorum and Protopalythoa variabilis are among the most abundant marine species along the Brazilian coast. We now report the isolation and structure elucidation of two unprecedented sulfonylated ceramides, palyosulfonoceramide A (1) and palyosulfonoceramide B (2) from specimens collected off Brazil's northeastern coast. The structures of 1 and 2 were established using a combination of NMR analyses, including: evaluation of 1H, 13C, ¹H--¹H COSY, ¹H--¹³C HSQC, ¹H--¹³C HMBC, and ¹H--¹⁵N HMBC NMR spectra, high-resolution mass spectrometry and chemical degradation. In addition, we also isolated the corresponding known ceramides, N-((2S,3R,4E,8E)-1, 3-dihydroxyoctadeca-4,8-dien-2-yl)-hexadecanamide (3) and N-((2S,3R,4E)-1,3-dihydroxy octadeca-4-en-2-yl)-hexadecanamide (4), which provided further support for the assignments of 1 and 2.

Ammonia and ammonium hydroxide sensors for ammonia/water absorption machines: Literature review and data compilation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anheier, N.C. Jr.; McDonald, C.E.; Cuta, J.M.

1995-05-01

This report describes an evaluation of various sensing techniques for determining the ammonia concentration in the working fluid of ammonia/water absorption cycle systems. The purpose of this work was to determine if any existing sensor technology or instrumentation could provide an accurate, reliable, and cost-effective continuous measure of ammonia concentration in water. The resulting information will be used for design optimization and cycle control in an ammonia-absorption heat pump. PNL researchers evaluated each sensing technology against a set of general requirements characterizing the potential operating conditions within the absorption cycle. The criteria included the physical constraints for in situ operation,more » sensor characteristics, and sensor application. PNL performed an extensive literature search, which uncovered several promising sensing technologies that might be applicable to this problem. Sixty-two references were investigated, and 33 commercial vendors were identified as having ammonia sensors. The technologies for ammonia sensing are acoustic wave, refractive index, electrode, thermal, ion-selective field-effect transistor (ISFET), electrical conductivity, pH/colormetric, and optical absorption. Based on information acquired in the literature search, PNL recommends that follow-on activities focus on ISFET devices and a fiber optic evanescent sensor with a colormetric indicator. The ISFET and fiber optic evanescent sensor are inherently microminiature and capable of in situ measurements. Further, both techniques have been demonstrated selective to the ammonium ion (NH{sub 4}{sup +}). The primary issue remaining is how to make the sensors sufficiently corrosion-resistant to be useful in practice.« less

Chiral zinc phenylalanine nanofibers with fluorescence.

PubMed

Chen, Erdan; Guo, Beidou; Zhang, Baohong; Gan, Li-Hua; Gong, Jian Ru

2011-09-01

Chiral Zn(II)/D-,L-phenylalanine (Phe) bio-coordination polymer nanofibers with fluorescence were prepared by fast coordination-assisted assembly. The synthetic strategy is based on the fact that the Zn2+ ions were linked to oxygen atoms from carboxylate groups of the D- or L-amino acid by coordination interactions to form the chiral polymers. The Zn(II)/D-,L-Phe nanofibers had homogeneous diameters in the range of 700-900 nm and ultra-long length in several hundred micrometers, and the surface of the fiber was extremely smooth. In addition, the enantiomers of Zn(II)/Phe nanofibers exhibited both optical activity and fluorescent property in the solid state, which has great potential for application in the field of biomimetic nanofabrication and micro-/nano-optoelectronics.

Ammonia in comet P/Halley

NASA Technical Reports Server (NTRS)

Meier, R.; Eberhardt, P.; Krankowsky, D.; Hodges, R. R.

1994-01-01

In comet P/Halley the abundances of ammonia relative to water reported in the literature differ by about one order of magnitude from roughly 0.1% up to 2%. Different observational techniques seem to have inherent systematic errors. Using the ion mass channels m/q = 19 amu/e, 18 amu/e and 17 amu/e of the Neutral Mass Spectrometer experiment aboard the spacecraft Giotto, we derive a production rate of ammonia of (1.5(sub -0.7)(sup +0.5))% relative to water. Inside the contact surface we can explain our data by a nuclear source only. The uncertainty in our abundance of ammonia is primarily a result of uncertainties in some key reaction coefficients. We discuss in detail these reactions and the range of error indicated results from extreme assumptions in the rate coefficients. From our data, even in the worst case, we can exclude the ammonia abundance to be only of the order of a few per mill.

USE OF ZEOLITE FOR REMOVING AMMONIA AND AMMONIA-CAUSED TOXCITY IN MARINE TOXICITY IDENTIFCATION EVALUATIONS (TIES)

EPA Science Inventory

Ammonia occurs in marine waters including effluents, receiving waters, and sediment interstitial waters. At sufficiently high concentrations, ammonia can be toxic to aquatic species. Toxicity identification evaluation (TIE) methods provide researchers with tools for identifyi...

46 CFR 151.50-32 - Ammonia, anhydrous.

Code of Federal Regulations, 2014 CFR

2014-10-01

... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-32 Ammonia, anhydrous. (a) The anhydrous ammonia tanks may be installed in the bulk liquid cargo tanks provided the liquid surrounding the...) Noncorrosive in the liquid and vapor phase to the ammonia tanks and piping. (b) Copper, copper alloys, and...

46 CFR 151.50-32 - Ammonia, anhydrous.

Code of Federal Regulations, 2011 CFR

2011-10-01

... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-32 Ammonia, anhydrous. (a) The anhydrous ammonia tanks may be installed in the bulk liquid cargo tanks provided the liquid surrounding the...) Noncorrosive in the liquid and vapor phase to the ammonia tanks and piping. (b) Copper, copper alloys, and...

46 CFR 151.50-32 - Ammonia, anhydrous.

Code of Federal Regulations, 2010 CFR

2010-10-01

... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-32 Ammonia, anhydrous. (a) The anhydrous ammonia tanks may be installed in the bulk liquid cargo tanks provided the liquid surrounding the...) Noncorrosive in the liquid and vapor phase to the ammonia tanks and piping. (b) Copper, copper alloys, and...

46 CFR 151.50-32 - Ammonia, anhydrous.

Code of Federal Regulations, 2013 CFR

2013-10-01

... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-32 Ammonia, anhydrous. (a) The anhydrous ammonia tanks may be installed in the bulk liquid cargo tanks provided the liquid surrounding the...) Noncorrosive in the liquid and vapor phase to the ammonia tanks and piping. (b) Copper, copper alloys, and...

46 CFR 151.50-32 - Ammonia, anhydrous.

Code of Federal Regulations, 2012 CFR

2012-10-01

... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-32 Ammonia, anhydrous. (a) The anhydrous ammonia tanks may be installed in the bulk liquid cargo tanks provided the liquid surrounding the...) Noncorrosive in the liquid and vapor phase to the ammonia tanks and piping. (b) Copper, copper alloys, and...

Metabolism of Primed, Constant Infusions of [1,2-13C2] Glycine and [1-13C1] Phenylalanine to Urinary Oxalate

PubMed Central

Knight, John; Assimos, Dean G.; Callahan, Michael F.; Holmes, Ross P.

2010-01-01

Objective Experiments in humans and rodents using oral doses of glycine and phenylalanine have suggested that the metabolism of these amino acids contributes to urinary oxalate excretion. To better define this contribution we have examined the primed, constant infusion of [1-13C1] phenylalanine and [1,2-13C2] glycine in the post-absorptive state in healthy adults. Materials/Methods Subjects were infused for 5 hours, collected hourly urines and had blood drawn every 30 minutes. Ion chromatography/mass spectrometry was used to measure [13C] enrichment in urinary oxalate, glycolate and hippurate, and the enrichment of 13C-amino acids in plasma samples was measured by gas chromatography/mass spectrometry. Results Following infusion with either 6 µmoles/kg/hr [1-13C1] phenylalanine or 6 µmoles/kg/hr [1,2-13C2] glycine, no isotopic glycolate or oxalate was detected in urine. Based on the limits of detection of our ion chromatography/mass spectroscopy method, these data indicate that < 0.7% of the urinary oxalate could be derived from phenylalanine catabolism and < 5% from glycine catabolism. Infusions with high levels of [1,2-13C2] glycine, 60 µmoles/kg/hr, increased mean plasma glycine by 29% and the whole body flux of glycine by 72%. Under these conditions glycine contributed 16.0 ± 1.6% and 16.6 ± 3.2% to urinary oxalate and glycolate excretion, respectively. Experiments using cultured hepatoma cells demonstrated that only at supra-physiological levels (>1mM) did glycine and phenylalanine metabolism increase oxalate synthesis. Conclusions These data suggest glycine and phenylalanine metabolism make only minor contributions to oxalate synthesis and urinary oxalate excretion. PMID:21036374

Industrial ammonia gassing

PubMed Central

Walton, M.

1973-01-01

Walton, M. (1972).British Journal of Industrial Medicine,30, 78-86. Industrial ammonia gassing. Seven cases of ammonia gassing are described with follow-up for five years of the six survivors and the post-mortem findings of the fatal case. All the survivors attributed continuing symptoms to the gassing. The study failed to demonstrate permanent ill effects in the one case of mild exposure. Of the more serious cases one has stopped smoking and taken up physical training teaching. He now has above average lung function. Two serious cases who continued to smoke have the lung function abnormalities expected from their smoking. In the other two seriously exposed cases, who also continued to smoke, there is a persistent reduction in ventilation and gas transfer which seems to be due to the ammonia gassing. The post-mortem findings in the fatal case showed acute congestion and oedema of the mucosa of the respiratory tract, the bronchial walls being stripped of their lining epithelium and the alveoli stuffed with red blood cells and oedema fluid. Images PMID:4685304

Resveratrol Prevents Ammonia Toxicity in Astroglial Cells

PubMed Central

Guerra, Maria Cristina; Leite, Marina Concli; Souza, Diogo Onofre; Gonçalves, Carlos-Alberto; Gottfried, Carmem

2012-01-01

Ammonia is implicated as a neurotoxin in brain metabolic disorders associated with hyperammonemia. Acute ammonia toxicity can be mediated by an excitotoxic mechanism, oxidative stress and nitric oxide (NO) production. Astrocytes interact with neurons, providing metabolic support and protecting against oxidative stress and excitotoxicity. Astrocytes also convert excess ammonia and glutamate into glutamine via glutamine synthetase (GS). Resveratrol, a polyphenol found in grapes and red wines, exhibits antioxidant and anti-inflammatory properties and modulates glial functions, such as glutamate metabolism. We investigated the effect of resveratrol on the production of reactive oxygen species (ROS), GS activity, S100B secretion, TNF-α, IL-1β and IL-6 levels in astroglial cells exposed to ammonia. Ammonia induced oxidative stress, decreased GS activity and increased cytokines release, probably by a mechanism dependent on protein kinase A (PKA) and extracellular signal-regulated kinase (ERK) pathways. Resveratrol prevented ammonia toxicity by modulating oxidative stress, glial and inflammatory responses. The ERK and nuclear factor-κB (NF-κB) are involved in the protective effect of resveratrol on cytokines proinflammatory release. In contrast, other antioxidants (e.g., ascorbic acid and trolox) were not effective against hyperammonemia. Thus, resveratrol could be used to protect against ammonia-induced neurotoxicity. PMID:23284918

Structure-activity relationships among substituted N-benzoyl derivatives of phenylalanine and its analogues in a microbial antitumor prescreen III: derivatives of p-fluoro-DL-phenylalanine.

PubMed

Otani, T T; Briley, M R

1985-01-01

Twelve substituted benzoyl derivatives of p-fluoro-DL-phenylalanine were prepared and tested for growth-inhibitory activity in a Lactobacillus casei system used as an antitumor prescreen. The 12 substituted benzoyl groups were the same as those attached to o-fluorophenylalanine and m-fluorophenylalanine studied earlier. The activity of these compounds was compared vertically among themselves and horizontally with the corresponding derivatives of o-fluorophenylalanine and of m-fluorophenylalanine. It was found that the derivatives of p-fluorophenylalanine, like those of o- and m-fluorophenylalanine, exhibited remarkable inhibition, all but one, i.e., the o-nitrobenzoyl derivative, showing inhibition that is considered to be positive in the prescreen. Particularly potent compounds in this group were the m-chlorobenzoyl-, p-chlorobenzoyl, m-nitrobenzoyl, and p-nitrobenzoyl derivatives. Comparison of the activity of the substituted benzoyl derivatives of all three structural isomers of fluorophenylalanine at equimolar concentrations showed that the derivatives of m-fluorophenylalanine were generally better inhibitors than those of o-fluoro- or p-fluorophenylalanine. Study of the ID50 values of the more active substituted benzoyl derivatives of the fluorophenylalanines showed that the most active of this group was m-chlorobenzoyl-p-fluoro-DL-phenylalanine.

Ammonia transport in the kidney by Rhesus glycoproteins

PubMed Central

Verlander, Jill W.

2014-01-01

Renal ammonia metabolism is a fundamental element of acid-base homeostasis, comprising a major component of both basal and physiologically altered renal net acid excretion. Over the past several years, a fundamental change in our understanding of the mechanisms of renal epithelial cell ammonia transport has occurred, replacing the previous model which was based upon diffusion equilibrium for NH3 and trapping of NH4+ with a new model in which specific and regulated transport of both NH3 and NH4+ across renal epithelial cell membranes via specific membrane proteins is required for normal ammonia metabolism. A major advance has been the recognition that members of a recently recognized transporter family, the Rhesus glycoprotein family, mediate critical roles in renal and extrarenal ammonia transport. The erythroid-specific Rhesus glycoprotein, Rh A Glycoprotein (Rhag), was the first Rhesus glycoprotein recognized as an ammonia-specific transporter. Subsequently, the nonerythroid Rh glycoproteins, Rh B Glycoprotein (Rhbg) and Rh C Glycoprotein (Rhcg), were cloned and identified as ammonia transporters. They are expressed in specific cell populations and membrane domains in distal renal epithelial cells, where they facilitate ammonia secretion. In this review, we discuss the distribution of Rhbg and Rhcg in the kidney, the regulation of their expression and activity in physiological disturbances, the effects of genetic deletion on renal ammonia metabolism, and the molecular mechanisms of Rh glycoprotein-mediated ammonia transport. PMID:24647713

L-Phenylalanine and L-tyrosine catabolism by selected Streptomyces species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pometto, A.L. III; Crawford, D.L.

L-Phenylalanine and L-tyrosine were completely catabolized through homogentisate by Streptomyces setonii 75Vi2 but only partially degraded by Streptomyces badius 252, Streptomyces sioyaensis P5, Streptomyces viridosporus T7A, and Streptomyces sp. strain V7. Intermediates of catabolism were confirmed by the thin-layer, gas, and high-pressure liquid chromatography. Homogentisate 1,2-dioxygenase was present in all cell extracts.

L-Phenylalanine and L-tyrosine catabolism by selected Streptomyces species.

PubMed Central

Pometto, A L; Crawford, D L

1985-01-01

L-Phenylalanine and L-tyrosine were completely catabolized through homogentisate by Streptomyces setonii 75Vi2 but only partially degraded by Streptomyces badius 252, Streptomyces sioyaensis P5, Streptomyces viridosporus T7A, and Streptomyces sp. strain V7. Intermediates of catabolism were confirmed by thin-layer, gas, and high-pressure liquid chromatography. Homogentisate 1,2-dioxygenase was present in all cell extracts. PMID:3994376

Interferon-alpha therapy in patients with hepatitis C virus infection increases plasma phenylalanine and the phenylalanine to tyrosine ratio.

PubMed

Zoller, Heinz; Schloegl, Anna; Schroecksnadel, Sebastian; Vogel, Wolfgang; Fuchs, Dietmar

2012-05-01

Higher blood levels of the essential amino acid phenylalanine (Phe) together with impaired conversion of Phe to tyrosine (Tyr) have been observed in patients suffering from inflammatory conditions. Data suggest that inflammatory responses may interfere with Phe metabolism. This study aimed to investigate whether treatment with cytokine interferon-α (IFN-α) influences Phe concentrations and the Phe to Tyr ratios (Phe/Tyr) measured by HPLC. Twenty-five patients (9 females, 16 males, aged mean ± SD: 44.5 ± 11.0 years) with hepatitis C virus (HCV) infection were examined before and after 1 month of effective antiviral therapy with pegylated IFN-α and weight-based ribavirin. Results were compared to HCV-RNA titers and concentrations of neopterin. IFN-α treatment was associated with a drop of HCV load (from median 6.3 to 3.2 log10 copies/μL; P<0.001) and an increase of neopterin concentrations (from median 4.83 to 12.1 nM; P=0.001) which confirms effectiveness of therapy. Before therapy, median Phe concentration were 123.9 μM, Tyr was 98.8 μM, and Phe/Tyr was 1.23 μmol/μmol, and under therapy median Phe concentrations increased to 132.6 μM and Phe/Tyr to 1.33 (both P<0.05; paired rank test), Tyr levels remained unchanged. The increase of Phe concentrations and of Phe/Tyr in HCV infected individuals is caused by IFN-α therapy. Data indicate that activity of enzyme phenylalanine 4-hydroxylase becomes impaired. Future studies should show whether side effects of IFN-α treatment such as mood changes and depression will be associated with the alterations of Phe metabolism.

Anomalous conformer dependent S 1 lifetime of L-phenylalanine

NASA Astrophysics Data System (ADS)

Hashimoto, Takayo; Takasu, Yuichi; Yamada, Yuji; Ebata, Takayuki

2006-04-01

The fluorescence lifetimes were measured for six conformers of L-phenylalanine cooled in a supersonic jet. It was found that the S 1 state lifetimes differ by a factor of three among the conformers. Especially, the most stable conformer (intramolecular hydrogen-bonded form) in S 0 had the shortest lifetime. Time-dependent DFT calculation suggested an importance of the mixing of the nπ ∗ character to S 1(ππ ∗) in this conformer dependent dynamics.

[Comparative characteristics of the functioning of brain structures exposed to morphine and D-phenylalanine].

PubMed

Iarosh, A K; Goruk, P S; Luk'ianov, E A

1987-01-01

In experiments on rats it was shown that morphine and D-phenylalanine in doses of 5 and 100 mg/kg, respectively, produce a similar by the degree increase of pain reaction thresholds at stimulation of paws through the electrified floor of the chamber. Experiments on rabbits demonstrated that the main factor in morphine action is a decrease of excitability and blood filling of the reticular formation of the midbrain and the central gray matter and an increase of excitability of the dorsal hippocamp without significant changes in the frontal cortex excitability. D-phenylalanine also caused a decrease of excitability of the reticular formation but in contrast to morphine failed to change excitability of the dorsal hippocamp and enhanced excitability of the central gray matter.

Electrochemical determination of L-phenylalanine at polyaniline modified carbon electrode based on β-cyclodextrin incorporated carbon nanotube composite material and imprinted sol-gel film.

PubMed

Hu, Yu-fang; Zhang, Zhao-hui; Zhang, Hua-bin; Luo, Li-juan; Yao, Shou-zhuo

2011-04-15

A sensitive and selective electrochemical sensor based on a polyaniline modified carbon electrode for the determination of L-phenylalanine has been proposed by utilizing β-cyclodextrin (β-CD) incorporated multi-walled carbon nanotube (MWNT) and imprinted sol-gel film. The electrochemical behavior of the sensor towards L-phenylalanine was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometric i-t curve. The surface morphologies of layer-by-layer assembly electrodes were displayed by scanning electron microscope (SEM). The response mechanism of the imprinted sensor for L-phenylalanine was based on the inclusion interaction of β-CD and molecular recognition capacity of the imprinted film for L-phenylalanine. A linear calibration plot was obtained covering the concentration range from 5.0 × 10(-7) to 1.0 × 10(-4) mol L(-1) with a detection limit of 1.0 × 10(-9) mol L(-1). With excellent sensitivity, selectivity, stability, reproducibility and recovery, the electrochemical imprinted sensor was used to detect L-phenylalanine in blood plasma samples successfully. Copyright © 2011 Elsevier B.V. All rights reserved.

Ammonia emissions in Europe, part II: How ammonia emission abatement strategies affect secondary aerosols

NASA Astrophysics Data System (ADS)

Backes, Anna M.; Aulinger, Armin; Bieser, Johannes; Matthias, Volker; Quante, Markus

2016-02-01

In central Europe, ammonium sulphate and ammonium nitrate make up a large fraction of fine particles which pose a threat to human health. Most studies on air pollution through particulate matter investigate the influence of emission reductions of sulphur- and nitrogen oxides on aerosol concentration. Here, we focus on the influence of ammonia (NH3) emissions. Emission scenarios have been created on the basis of the improved ammonia emission parameterization implemented in the SMOKE for Europe and CMAQ model systems described in part I of this study. This includes emissions based on future European legislation (the National Emission Ceilings) as well as a dynamic evaluation of the influence of different agricultural sectors (e.g. animal husbandry) on particle formation. The study compares the concentrations of NH3, NH4+, NO3 -, sulphur compounds and the total concentration of particles in winter and summer for a political-, technical- and behavioural scenario. It was found that a reduction of ammonia emissions by 50% lead to a 24% reduction of the total PM2.5 concentrations in northwest Europe. The observed reduction was mainly driven by reduced formation of ammonium nitrate. Moreover, emission reductions during winter had a larger impact than during the rest of the year. This leads to the conclusion that a reduction of the ammonia emissions from the agricultural sector related to animal husbandry could be more efficient than the reduction from other sectors due to its larger share in winter ammonia emissions.

Hydrogen bonding pattern in N-benzoyl(- DL-)- L-phenylalanines as revealed by solid-state NMR spectroscopy

NASA Astrophysics Data System (ADS)

Potrzebowski, M. J.; Schneider, C.; Tekely, P.

1999-11-01

The nature of the hydrogen bonding pattern has been investigated in N-benzoyl- DL-phenylalanine ( 1) and N-benzoyl- L-phenylalanine ( 2) polymorphes by solid-state NMR spectroscopy. It has been shown that the multiple resonances of carboxyl carbon in 2 are directly connected to different types of hydrogen bonding. The differences in intermolecular distances of carboxyl groups involved in different types of hydrogen bonding have been visualized by the 2D exchange and 1D ODESSA experiments. Potential applications of such a new approach include the exploration of intermolecular distances in hydrogen bonded compounds with singly labeled biomolecules.

Interaction of N-benzoyl-D-phenylalanine and related compounds with the sulphonylurea receptor of beta-cells.

PubMed

Schwanstecher, C; Meyer, M; Schwanstecher, M; Panten, U

1998-03-01

1. The structure activity relationships for the insulin secretagogues N-benzoyl-D-phenylalanine (NBDP) and related compounds were examined at the sulphonylurea receptor level by use of cultured HIT-T15 and mouse pancreatic beta-cells. The affinities of these compounds for the sulphonylurea receptor were compared with their potencies for K(ATP)-channel inhibition. In addition, the effects of cytosolic nucleotides on K(ATP)-channel inhibition by NBDP were investigated. 2. NBDP displayed a dissociation constant for binding to the sulphonylurea receptor (K(D) value) of 11 microM and half-maximally effective concentrations of K(ATP)-channel inhibition (EC50 values) between 2 and 4 microM (in the absence of cytosolic nucleotides or presence of 0.1 mM GDP or 1 mM ADP). 3. In the absence of cytosolic nucleotides or presence of GDP (0.1 mM) maximally effective concentrations of NBDP (0.1-1 mM) reduced K(ATP)-channel activity to 47% and 44% of control, respectively. In the presence of ADP (1 mM), K(ATP)-channel activity was completely suppressed by 0.1 mM NBDP. 4. The L-isomer of N-benzoyl-phenylalanine displayed a 20 fold lower affinity and an 80 fold lower potency than the D-isomer. 5. Introduction of a p-nitro substituent in the D-phenylalanine moiety of NBDP did not decrease lipophilicity but lowered affinity and potency by more than 30 fold. 6. Introduction of a p-amino substituent in the D-phenylalanine moiety of NBDP (N-benzoyl-p-amino-D-phenylalanine, NBADP) reduced lipophilicity and lowered affinity and potency by about 10 fold. This loss of affinity and potency was compensated for by formation of the phenylpropionic acid derivative of NBADP. A similar difference in affinity was observed for the sulphonylurea carbutamide and its phenylpropionic acid derivative. 7. Replacing the benzene ring in the D-phenylalanine moiety of NBDP by a cyclohexyl ring increased lipophilicity, and the K(D) and EC50 values were slightly lower than for NBDP. Exchange of both benzene rings

Interaction of N-benzoyl-D-phenylalanine and related compounds with the sulphonylurea receptor of β-cells

PubMed Central

Schwanstecher, Christina; Meyer, Miriam; Schwanstecher, Mathias; Panten, Uwe

1998-01-01

The structure activity relationships for the insulin secretagogues N-benzoyl-D-phenylalanine (NBDP) and related compounds were examined at the sulphonylurea receptor level by use of cultured HIT-T15 and mouse pancreatic β-cells. The affinities of these compounds for the sulphonylurea receptor were compared with their potencies for KATP-channel inhibition. In addition, the effects of cytosolic nucleotides on KATP-channel inhibition by NBDP were investigated.NBDP displayed a dissociation constant for binding to the sulphonylurea receptor (KD value) of 11 μM and half-maximally effective concentrations of KATP-channel inhibition (EC50 values) between 2 and 4 μM (in the absence of cytosolic nucleotides or presence of 0.1 mM GDP or 1 mM ADP).In the absence of cytosolic nucleotides or presence of GDP (0.1 mM) maximally effective concentrations of NBDP (0.1–1 mM) reduced KATP-channel activity to 47% and 44% of control, respectively. In the presence of ADP (1 mM), KATP-channel activity was completely suppressed by 0.1 mM NBDP.The L-isomer of N-benzoyl-phenylalanine displayed a 20 fold lower affinity and an 80 fold lower potency than the D-isomer.Introduction of a p-nitro substituent in the D-phenylalanine moiety of NBDP did not decrease lipophilicity but lowered affinity and potency by more than 30 fold.Introduction of a p-amino substituent in the D-phenylalanine moiety of NBDP (N-benzoyl-p-amino-D-phenylalanine, NBADP) reduced lipophilicity and lowered affinity and potency by about 10 fold. This loss of affinity and potency was compensated for by formation of the phenylpropionic acid derivative of NBADP. A similar difference in affinity was observed for the sulphonylurea carbutamide and its phenylpropionic acid derivative.Replacing the benzene ring in the D-phenylalanine moiety of NBDP by a cyclohexyl ring increased lipophilicity, and the KD and EC50 values were slightly lower than for NBDP. Exchange of both benzene rings in NBDP by cyclohexyl rings

Study on the mechanism of copper-ammonia complex decomposition in struvite formation process and enhanced ammonia and copper removal.

PubMed

Peng, Cong; Chai, Liyuan; Tang, Chongjian; Min, Xiaobo; Song, Yuxia; Duan, Chengshan; Yu, Cheng

2017-01-01

Heavy metals and ammonia are difficult to remove from wastewater, as they easily combine into refractory complexes. The struvite formation method (SFM) was applied for the complex decomposition and simultaneous removal of heavy metal and ammonia. The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper-ammonia complex ion. Ammonia was separated from solution as crystalline struvite, and the copper mainly co-precipitated as copper hydroxide together with struvite. Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide. Hydrogen bonding was concluded to be the key factor leading to the co-precipitation. In addition, incorporation of copper ions into the struvite crystal also occurred during the treatment process. Copyright © 2016. Published by Elsevier B.V.

Ammonia poisoning

MedlinePlus

... Ammonia gas Some household cleaners Some liniments Some fertilizers Note: This list may not be all-inclusive. ... care professional. Seek immediate medical help. If the chemical is on the skin or in the eyes, ...

Ammonia Test

MedlinePlus

... of hepatic encephalopathy, but there is not widespread agreement on its clinical utility. Since hepatic encephalopathy can ... more clinically useful, but there is not widespread agreement on this. Is ammonia testing used to detect ...

Synthesis and properties of poly(L-lactide)-b-poly (L-phenylalanine) hybrid copolymers.

PubMed

Planellas, Marc; Puiggalí, Jordi

2014-07-29

Hybrid materials constituted by peptides and synthetic polymers have nowadays a great interest since they can combine the properties and functions of each constitutive block, being also possible to modify the final characteristics by using different topologies. Poly(l-lactide-b-l-phenylalanine) copolymers with various block lengths were synthesized by sequential ring-opening polymerization of l-lactide and the N-carboxyanhydride of l-phenylalanine. The resulting block copolymers were characterized by NMR spectrometry, IR spectroscopy, gel permeation chromatography, MALDI-TOF and UV-vis, revealing the successful incorporation of the polyphenylalanine (PPhe) peptide into the previously formed poly(l-lactide) (PLLA) polymer chain. X-ray diffraction and DSC data also suggested that the copolymers were phase-separated in domains containing either crystalline PLLA or PPhe phases. A peculiar thermal behavior was also found by thermogravimetric analysis when polyphenylalanine blocks were incorporated into polylactide.

[Microbial synthesis of deuterium labelled L-phenylalanine with different levels of isotopic enrichment by facultative methylotrophic bacterium Brevibacterium methylicum with RMP assimilation of carbon].

PubMed

Mosin, O V; Shvets, V I; Skladnev, D A; Ignatov, I

2014-01-01

The preparative microbial synthesis of amino acids labelled with stable isotopes, including deuterium ( 2 H), suitable for biomedical applications by methylotrophic bacteria was studied using L-phenylalanine as example. This amino acid is secreted by Gram-negative aerobic facultative methylotrophic bacteria Brevibacterium methylicum, assimilating methanol via ribulose-5-monophosphate (RMP) cycle of assimilation of carbon, The data on adaptation of L-phenylalanine secreted by methylotrophic bacterium В. methylicum to the maximal concentration of deuterium in the growth medium with 98% 2 Н 2 O and 2% [ 2 Н]methanol, and biosynthesis of deuterium labelled L-phenylalanine With different levels of enrichment are presented. The strain was adapted by means of plating initial cells on firm (2% agarose) minimal growth media with an increasing gradient of 2 Н 2 O concentration from 0; 24.5; 49.0; 73.5 up to 98% 2 Н 2 O followed by subsequent selection of separate colonies stable to the action of 2 Н 2 O. These colonies were capable to produce L-phenylalanine. L-phenylalanine was extracted from growth medium by extraction with isopropanol with the subsequent crystallization in ethanol (output 0.65 g/l). The developed method of microbial synthesis allows to obtain deuterium labelled L-phenylalanine with different levels of isotopic enrichment, depending on concentration of 2 Н 2 O in growth media, from 17% (on growth medium with 24,5% 2 Н 2 O) up to 75% (on growth medium with 98% 2 Н 2 O) of deuterium in the molecule that is confirmed with the data of the electron impact (EI) mass- spectrometry analysis of methyl ethers of N-dimethylamino(naphthalene)-5-sulfochloride (dansyl) phenylalanine in these experimental conditions.

In vivo evaluation and dosimetry of 123I-2-iodo-D-phenylalanine, a new potential tumor-specific tracer for SPECT, in an R1M rhabdomyosarcoma athymic mouse model.

PubMed

Kersemans, Veerle; Cornelissen, Bart; Bacher, Klaus; Kersemans, Ken; Thierens, Hubert; Dierckx, Rudi A; De Spiegeleer, Bart; Slegers, Guido; Mertens, John

2005-12-01

Earlier reports described the preferential uptake of d-amino acids in tumor-bearing mice. Moreover, it was shown that in tumor cells in vitro the L-amino acid transporter system seemed to lack stereospecificity. Because of the successful results with 123/125I-2-iodo-L-phenylalanine, 123/125I-2-iodo-D-phenylalanine was developed, and its tumor-detecting characteristics were evaluated in vivo. 123I labeling of 2-iodo-D-phenylalanine was performed with a kit formulation by use of Cu1+-assisted nucleophilic exchange. 123I-2-Iodo-D-phenylalanine was evaluated in R1M tumor-bearing athymic mice by dynamic planar imaging (DPI) and dissection. The in vivo stability of the tracer was tested by high-performance liquid chromatography. Tumor tracer retention and tracer contrast were evaluated as a function of time. Two-compartment blood modeling from DPI results and dosimetric calculations from biodistribution results were carried out. Moreover, 125I-2-iodo-D-phenylalanine and 18F-FDG uptake in acute inflammation was investigated. 123I-2-Iodo-D-phenylalanine was metabolically stable. Fast, high, and specific tumor retention was observed. Two-compartment modeling confirmed the fast clearance of the tracer through the kidneys to the bladder, as observed by DPI and dissection. Moreover, compared with the L-isomer, 123I-2-iodo-D-phenylalanine demonstrated faster clearance and faster uptake in the peripheral compartment. No accumulation in the abdomen or in the brain was noted. Dosimetry revealed that 123I-2-iodo-D-phenylalanine demonstrated a low radiation burden comparable to those of 123I-2-iodo-L-phenylalanine and 123I-2-iodo-L-tyrosine. Although 123I-2-iodo-D-phenylalanine showed a tumor retention of only 4%, the tumor contrast was increased up to 350% at 19 h after injection. 123I-2-Iodo-D-phenylalanine is a promising tracer for diagnostic oncologic imaging because of its high, fast, and specific tumor uptake and fast clearance from blood.

Staging properties of potassium-ammonia ternary graphite intercalation compounds at high ammonia pressure

NASA Astrophysics Data System (ADS)

Qian, X. W.; Solin, S. A.

1989-04-01

The pressure dependence of the (00l) x-ray diffraction patterns of the ternary graphite intercalation compound K(NH3)xC24 has been studied in the range 0.5-11 kbar (for which x~4.5) using a diamond anvil cell. A special apparatus for loading the cell with liquid ammonia at room temperature has been constructed and is briefly described. In these experiments, the pressure-transmitting fluid was also an intercalant, namely ammonia. Therefore, the chemical potential of this species was linearly coupled to the applied pressure in contrast to the usual case where the pressure-transmitting fluid is chemically passive. The pressure dependences of the basal spacings and of the relative intensities of key reflections have been measured, as have the compressibilities of the stage-1 and stage-2 components of the two-phase system. Basal-spacing anomalies and anomalies in the relative intensities occur at pressures of ~3.5 and 8.0 kbar and are tentatively attributed to in-plane coordination changes in the potassium-ammonia ratio. Using thermodynamic arguments and Le Chatelier's principle we show quantitatively that a staging phase transition from pure stage-1 phase to an admixture of stage-1 and stage-2 is expected with increased pressure above 10 bar in agreement with experiment. The saturation ammonia compositions (x values) of the admixed stages are found to be 4.5 and 5.4 for the stage-1 and -2 components, respectively. This result is interpreted as evidence that the composition is not sterically limited but is determined by the binding energy of ammonia for potassium and by the perturbation to this energy from the guest-host interaction.

Mechanism of ammonia excretion in the freshwater leech Nephelopsis obscura: characterization of a primitive Rh protein and effects of high environmental ammonia

PubMed Central

Quijada-Rodriguez, Alex R.; Treberg, Jason R.

2015-01-01

Remarkably little is known about nitrogenous excretion in freshwater invertebrates. In the current study, the nitrogen excretion mechanism in the carnivorous ribbon leech, Nephelopsis obscura, was investigated. Excretion experiments showed that the ribbon leech is ammonotelic, excreting 166.0 ± 8.6 nmol·grams fresh weight (gFW)−1·h−1 ammonia and 14.7 ± 1.9 nmol·gFW−1·h−1 urea. Exposure to high and low pH hampered and enhanced, respectively, ammonia excretion rates, indicating an acid-linked ammonia trapping mechanism across the skin epithelia. Accordingly, compared with body tissues, the skin exhibited elevated mRNA expression levels of a newly identified Rhesus protein and at least in tendency the Na+/K+-ATPase. Pharmacological experiments and enzyme assays suggested an ammonia excretion mechanism that involves the V-ATPase, Na+/K+-ATPase, and carbonic anhydrase, but not necessarily a functional microtubule system. Most importantly, functional expression studies of the identified Rh protein cloned from leech skin tissue revealed an ammonia transport capability of this protein when expressed in yeast. The leech Rh-ammonia transporter (NoRhp) is a member of the primitive Rh protein family, which is a sister group to the common ancestor of vertebrate ammonia-transporting Rh proteins. Exposure to high environmental ammonia (HEA) caused a new adjustment of body ammonia, accompanied with a decrease in NoRhp and Na+/K+-ATPase mRNA levels, but unaltered ammonia excretion rates. To our knowledge, this is only the second comprehensive study regarding the ammonia excretion mechanisms in a freshwater invertebrate, but our results show that basic processes of ammonia excretion appear to also be comparable to those found in freshwater fish, suggesting an early evolution of ionoregulatory mechanisms in freshwater organisms. PMID:26180186

Mechanism of ammonia excretion in the freshwater leech Nephelopsis obscura: characterization of a primitive Rh protein and effects of high environmental ammonia.

PubMed

Quijada-Rodriguez, Alex R; Treberg, Jason R; Weihrauch, Dirk

2015-09-15

Remarkably little is known about nitrogenous excretion in freshwater invertebrates. In the current study, the nitrogen excretion mechanism in the carnivorous ribbon leech, Nephelopsis obscura, was investigated. Excretion experiments showed that the ribbon leech is ammonotelic, excreting 166.0 ± 8.6 nmol·grams fresh weight (gFW)(-1)·h(-1) ammonia and 14.7 ± 1.9 nmol·gFW(-1)·h(-1) urea. Exposure to high and low pH hampered and enhanced, respectively, ammonia excretion rates, indicating an acid-linked ammonia trapping mechanism across the skin epithelia. Accordingly, compared with body tissues, the skin exhibited elevated mRNA expression levels of a newly identified Rhesus protein and at least in tendency the Na(+)/K(+)-ATPase. Pharmacological experiments and enzyme assays suggested an ammonia excretion mechanism that involves the V-ATPase, Na(+)/K(+)-ATPase, and carbonic anhydrase, but not necessarily a functional microtubule system. Most importantly, functional expression studies of the identified Rh protein cloned from leech skin tissue revealed an ammonia transport capability of this protein when expressed in yeast. The leech Rh-ammonia transporter (NoRhp) is a member of the primitive Rh protein family, which is a sister group to the common ancestor of vertebrate ammonia-transporting Rh proteins. Exposure to high environmental ammonia (HEA) caused a new adjustment of body ammonia, accompanied with a decrease in NoRhp and Na(+)/K(+)-ATPase mRNA levels, but unaltered ammonia excretion rates. To our knowledge, this is only the second comprehensive study regarding the ammonia excretion mechanisms in a freshwater invertebrate, but our results show that basic processes of ammonia excretion appear to also be comparable to those found in freshwater fish, suggesting an early evolution of ionoregulatory mechanisms in freshwater organisms. Copyright © 2015 the American Physiological Society.

Ammonia Clouds on Jupiter

NASA Technical Reports Server (NTRS)

2007-01-01

[figure removed for brevity, see original site] Click on the image for movie of Ammonia Ice Clouds on Jupiter

In this movie, put together from false-color images taken by the New Horizons Ralph instrument as the spacecraft flew past Jupiter in early 2007, show ammonia clouds (appearing as bright blue areas) as they form and disperse over five successive Jupiter 'days.' Scientists noted how the larger cloud travels along with a small, local deep hole.

Design of a recombinant Escherichia coli for producing L-phenylalanine from glycerol.

PubMed

Thongchuang, Mayura; Pongsawasdi, Piamsook; Chisti, Yusuf; Packdibamrung, Kanoktip

2012-10-01

A recombinant Escherichia coli was engineered to produce the commercially important amino acid L-phenylalanine (L-Phe) using glycerol as the carbon source. Compared to the conventionally used glucose and sucrose, glycerol is a less expensive carbon source. As phenylalanine dehydrogenase (PheDH) activity is involved in the last step of L-Phe synthesis in E. coli, a phenylalanine dehydrogenase gene (phedh) from the thermotolerant Bacillus lentus was cloned into pRSFDuet-1 (pPheDH) and expressed in E. coli BL21(DE3). The resulting clone had a limited ability to produce L-Phe from glycerol, possibly because of a poor glycerol uptake by the cell, or an inability to excrete L-Phe, or both. Therefore, yddG gene encoding an aromatic amino acid exporter and glpF gene encoding a glycerol transport facilitator were coexpressed with the phedh in a reengineered E. coli. In a glycerol medium, the maximum L-Phe production rates of the clones pPY (phedh and yddG genes) and pPYF (phedh, yddG and glpF genes) were 1.4- and 1.8-fold higher than the maximum production rate of the pPheDH clone. The better producing pPYF clone was further evaluated in a 5 l stirred-tank fermenter (37 °C, an aeration rate of 1 vvm, an agitation speed of 400 rpm). In the fermenter, the maximum concentration of L-Phe (366 mg/l) was achieved in a much shorter period compared to in the shake flasks. In the latter, the highest titer of L-Phe was only 76 % of the maximum value attained in the fermenter.

Expanding the utility of 4-cyano-L-phenylalanine as a vibrational reporter of protein environments.

PubMed

Bazewicz, Christopher G; Lipkin, Jacob S; Smith, Emily E; Liskov, Melanie T; Brewer, Scott H

2012-09-06

The ability to genetically incorporate amino acids modified with spectroscopic reporters site-specifically into proteins with high efficiency and fidelity has greatly enhanced the ability to probe local protein structure and dynamics. Here, we have synthesized the unnatural amino acid (UAA), 4-cyano-L-phenylalanine (pCNPhe), containing the nitrile vibrational reporter and three isotopomers ((15)N, (13)C, (13)C(15)N) of this UAA to enhance the ability of pCNPhe to study local protein environments. Each pCNPhe isotopic variant was genetically incorporated in an efficient, site-specific manner into superfolder green fluorescent protein (sfGFP) in response to an amber codon with high fidelity utilizing an engineered, orthogonal aminoacyl-tRNA synthetase. The isotopomers of 4-cyano-L-phenylalanine permitted the nitrile symmetric stretch vibration of these UAAs to be unambiguously assigned utilizing the magnitude and direction of the isotopic shift of this vibration. The sensitivity of the nitrile symmetric stretching frequency of each isotopic variant to the local environment was measured by individually incorporating the probes into two distinct local environments of sfGFP. The UAAs were also utilized in concert to probe multiple local environments in sfGFP simultaneously to increase the utility of 4-cyano-L-phenylalanine.

Converting Wind Energy to Ammonia at Lower Pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malmali, Mahdi; Reese, Michael; McCormick, Alon V.

Renewable wind energy can be used to make ammonia. However, wind-generated ammonia costs about twice that made from a traditional fossil-fuel driven process. To reduce the production cost, we replace the conventional ammonia condensation with a selective absorber containing metal halides, e.g., calcium chloride, operating at near synthesis temperatures. With this reaction-absorption process, ammonia can be synthesized at 20 bar from air, water, and wind-generated electricity, with rates comparable to the conventional process running at 150–300 bar. In our reaction-absorption process, the rate of ammonia synthesis is now controlled not by the chemical reaction but largely by the pump usedmore » to recycle the unreacted gases. The results suggest an alternative route to distributed ammonia manufacture which can locally supply nitrogen fertilizer and also a method to capture stranded wind energy as a carbon-neutral liquid fuel.« less

Converting Wind Energy to Ammonia at Lower Pressure

DOE PAGES

Malmali, Mahdi; Reese, Michael; McCormick, Alon V.; ...

2017-11-07

Renewable wind energy can be used to make ammonia. However, wind-generated ammonia costs about twice that made from a traditional fossil-fuel driven process. To reduce the production cost, we replace the conventional ammonia condensation with a selective absorber containing metal halides, e.g., calcium chloride, operating at near synthesis temperatures. With this reaction-absorption process, ammonia can be synthesized at 20 bar from air, water, and wind-generated electricity, with rates comparable to the conventional process running at 150–300 bar. In our reaction-absorption process, the rate of ammonia synthesis is now controlled not by the chemical reaction but largely by the pump usedmore » to recycle the unreacted gases. The results suggest an alternative route to distributed ammonia manufacture which can locally supply nitrogen fertilizer and also a method to capture stranded wind energy as a carbon-neutral liquid fuel.« less

Ammonia Affects Astroglial Proliferation in Culture

PubMed Central

Bodega, Guillermo; Segura, Berta; Ciordia, Sergio; Mena, María del Carmen; López-Fernández, Luis Andrés; García, María Isabel; Trabado, Isabel; Suárez, Isabel

2015-01-01

Primary cultures of rat astroglial cells were exposed to 1, 3 and 5 mM NH4Cl for up to 10 days. Dose- and time-dependent reductions in cell numbers were seen, plus an increase in the proportion of cells in the S phase. The DNA content was reduced in the treated cells, and BrdU incorporation diminished. However, neither ammonia nor ammonia plus glutamine had any effect on DNA polymerase activity. iTRAQ analysis showed that exposure to ammonia induced a significant reduction in histone and heterochromatin protein 1 expression. A reduction in cell viability was also noted. The ammonia-induced reduction of proliferative activity in these cultured astroglial cells seems to be due to a delay in the completion of the S phase provoked by the inhibition of chromatin protein synthesis. PMID:26421615

IRIS Toxicological Review of Ammonia (Revised External ...

EPA Pesticide Factsheets

In August 2013, EPA submitted a revised draft IRIS assessment of ammonia to the agency's Science Advisory Board (SAB) and posted this draft on the IRIS website. EPA had previously released a draft of the assessment for public comment, held a public meeting about the draft, and then revised it based on the comments received. The SAB CAAC-Ammonia panel will review this draft assessment. Details about the meeting dates, times, and location are available via the Federal Register Notice posted on March 25, 2014. The SAB provided information on how the public can participate in the external peer review meetings, as well as instructions about how to provide comments to the SAB in the notice. Additional information on the SAB review of ammonia is on the SAB website. Report Information: The Toxicological Review of Ammonia was originally released for a 60-day public comment period on June 8, 2012. [Federal Register Notice Jun 8, 2012] EPA revised the toxicological review in response to the public comments received. EPA has released the revised external review draft ammonia assessment and the SAB CAAC is conducting a peer review of the scientific basis supporting the assessment that will appear in the Integrated Risk Information System (IRIS) database. Information regarding the peer review can be found at the SAB review of ammonia website. EPA is undertaking an Integrated Risk Information System (IRIS) health assessment for ammonia. IRIS is an EPA database cont

Synthesis and Properties of Poly(l-lactide)-b-poly (l-phenylalanine) Hybrid Copolymers

PubMed Central

Planellas, Marc; Puiggalí, Jordi

2014-01-01

Hybrid materials constituted by peptides and synthetic polymers have nowadays a great interest since they can combine the properties and functions of each constitutive block, being also possible to modify the final characteristics by using different topologies. Poly(l-lactide-b-l-phenylalanine) copolymers with various block lengths were synthesized by sequential ring-opening polymerization of l-lactide and the N-carboxyanhydride of l-phenylalanine. The resulting block copolymers were characterized by NMR spectrometry, IR spectroscopy, gel permeation chromatography, MALDI-TOF and UV-vis, revealing the successful incorporation of the polyphenylalanine (PPhe) peptide into the previously formed poly(l-lactide) (PLLA) polymer chain. X-ray diffraction and DSC data also suggested that the copolymers were phase-separated in domains containing either crystalline PLLA or PPhe phases. A peculiar thermal behavior was also found by thermogravimetric analysis when polyphenylalanine blocks were incorporated into polylactide. PMID:25075980

Changes of ammonia, urea contents and transaminase activity in the body during aerial exposure and ammonia loading in Chinese loach Paramisgurnus dabryanus.

PubMed

Zhang, Yun-Long; Zhang, Hai-Long; Wang, Ling-Yu; Gu, Bei-Yi; Fan, Qi-Xue

2017-04-01

The Paramisgurnus dabryanus was exposed to 30 mmol L -1 NH 4 Cl solution and air to assessing the change of body ammonia and urea contents and the activities of alanine aminotransferase (ALT) and aspartate transaminase (AST). After 48 h of ammonia exposure, ammonia concentration in the plasma, brain, liver and muscle were 3.3-fold, 5.6-fold, 3.5-fold and 4.2-fold, respectively, those of the control values. Plasma, brain, liver and muscle ammonia concentrations increased to 2.2-fold, 3.3-fold, 2.5-fold and 2.9-fold, respectively, those of control values in response to 48 h of aerial exposure. Within the given treatment (ammonia or aerial exposure), there was no change in plasma, brain and liver urea concentrations between exposure durations. The plasma ALT activity was significantly affected by exposure time during aerial exposure, while the liver ALT activity was not affected by ammonia or aerial exposure. Exposure to NH 4 Cl or air had no effect on either plasma or liver AST activity. Our results suggested that P. dabryanus could accumulate quite high level of internal ammonia because of the high ammonia tolerance in its cells and tissues, and NH 3 volatilization would be a possible ammonia detoxification strategy in P. dabryanus. Urea synthesis was not an effective mechanism to deal with environmental or internal ammonia problem. The significant increase of ALT activity in plasma during aerial exposure, indicating that alanine synthesis through certain amino acid catabolism may be subsistent in P. dabryanus.

Ammonia concentrations in canine whole blood, EDTA-anticoagulated whole blood, and plasma measured by use of a point-of-care ammonia meter.

PubMed

Odunayo, Adesola; Tobias, Karen M; Okafor, Chika C; Flatland, Bente

2017-11-01

OBJECTIVE To investigate the use of canine whole blood (WB) for measurement of ammonia concentration by use of a point-of-care ammonia meter and to compare results of measuring ammonia concentrations in WB, EDTA-anticoagulated WB, and plasma. ANIMALS 40 client-owned dogs. PROCEDURES A blood sample (2 mL) was obtained from each dog. One drop of WB was immediately applied to a test strip for evaluation with an ammonia meter. The remainder of the blood sample was placed in an EDTA-containing tube, and 1 drop of EDTA-anticoagulated WB was applied to a test strip. The remaining EDTA-anticoagulated WB sample was centrifuged, and the plasma was harvested and placed on ice. One drop of plasma was applied to a test strip; the remainder of the plasma sample was transported on ice and used for ammonia measurement with a reference laboratory instrument. All samples were tested within 1 hour after sample collection. Results were evaluated to detect significant differences in ammonia concentration. RESULTS Ammonia concentrations did not differ significantly between WB and EDTA-anticoagulated WB and between plasma samples measured with the meter and reference laboratory instrument. However, median ammonia concentration was significantly higher in plasma than in WB or EDTA-anti-coagulated WB. CONCLUSIONS AND CLINICAL RELEVANCE Anticoagulant-free WB was a valid sample for measurement by use of the ammonia meter. Plasma samples had higher ammonia concentrations than did WB samples. Results for each sample type should be interpreted by use of specimen- and method-specific reference intervals.

CADDIS Volume 2. Sources, Stressors and Responses: Ammonia - Detailed Conceptual Diagram

EPA Pesticide Factsheets

Introduction to the ammonia module, when to list ammonia as a candidate cause, ways to measure ammonia, simple and detailed conceptual diagrams for ammonia, literature reviews and references for the ammonia module.

CADDIS Volume 2. Sources, Stressors and Responses: Ammonia - Simple Conceptual Diagram

EPA Pesticide Factsheets

Introduction to the ammonia module, when to list ammonia as a candidate cause, ways to measure ammonia, simple and detailed conceptual diagrams for ammonia, literature reviews and references for the ammonia module.

Ammonia Transporters and Their Role in Acid-Base Balance

PubMed Central

2017-01-01

Acid-base homeostasis is critical to maintenance of normal health. Renal ammonia excretion is the quantitatively predominant component of renal net acid excretion, both under basal conditions and in response to acid-base disturbances. Although titratable acid excretion also contributes to renal net acid excretion, the quantitative contribution of titratable acid excretion is less than that of ammonia under basal conditions and is only a minor component of the adaptive response to acid-base disturbances. In contrast to other urinary solutes, ammonia is produced in the kidney and then is selectively transported either into the urine or the renal vein. The proportion of ammonia that the kidney produces that is excreted in the urine varies dramatically in response to physiological stimuli, and only urinary ammonia excretion contributes to acid-base homeostasis. As a result, selective and regulated renal ammonia transport by renal epithelial cells is central to acid-base homeostasis. Both molecular forms of ammonia, NH3 and NH4+, are transported by specific proteins, and regulation of these transport processes determines the eventual fate of the ammonia produced. In this review, we discuss these issues, and then discuss in detail the specific proteins involved in renal epithelial cell ammonia transport. PMID:28151423

A morphological method for ammonia detection in liver

PubMed Central

Gutiérrez-de-Juan, Virginia; López de Davalillo, Sergio; Fernández-Ramos, David; Barbier-Torres, Lucía; Zubiete-Franco, Imanol; Fernández-Tussy, Pablo; Simon, Jorge; Lopitz-Otsoa, Fernando; de las Heras, Javier; Iruzubieta, Paula; Arias-Loste, María Teresa; Villa, Erica; Crespo, Javier; Andrade, Raúl; Lucena, M. Isabel; Varela-Rey, Marta; Lu, Shelly C.; Mato, José M.; Delgado, Teresa Cardoso

2017-01-01

Hyperammonemia is a metabolic condition characterized by elevated levels of ammonia and a common event in acute liver injury/failure and chronic liver disease. Even though hepatic ammonia levels are potential predictive factors of patient outcome, easy and inexpensive methods aiming at the detection of liver ammonia accumulation in the clinical setting remain unavailable. Thus, herein we have developed a morphological method, based on the utilization of Nessler´s reagent, to accurately and precisely detect the accumulation of ammonia in biological tissue. We have validated our method against a commercially available kit in mouse tissue samples and, by using this modified method, we have confirmed the hepatic accumulation of ammonia in clinical and animal models of acute and chronic advanced liver injury as well as in the progression of fatty liver disease. Overall, we propose a morphological method for ammonia detection in liver that correlates well with the degree of liver disease severity and therefore can be potentially used to predict patient outcome. PMID:28319158

A morphological method for ammonia detection in liver.

PubMed

Gutiérrez-de-Juan, Virginia; López de Davalillo, Sergio; Fernández-Ramos, David; Barbier-Torres, Lucía; Zubiete-Franco, Imanol; Fernández-Tussy, Pablo; Simon, Jorge; Lopitz-Otsoa, Fernando; de Las Heras, Javier; Iruzubieta, Paula; Arias-Loste, María Teresa; Villa, Erica; Crespo, Javier; Andrade, Raúl; Lucena, M Isabel; Varela-Rey, Marta; Lu, Shelly C; Mato, José M; Delgado, Teresa Cardoso; Martínez-Chantar, María-Luz

2017-01-01

Hyperammonemia is a metabolic condition characterized by elevated levels of ammonia and a common event in acute liver injury/failure and chronic liver disease. Even though hepatic ammonia levels are potential predictive factors of patient outcome, easy and inexpensive methods aiming at the detection of liver ammonia accumulation in the clinical setting remain unavailable. Thus, herein we have developed a morphological method, based on the utilization of Nessler´s reagent, to accurately and precisely detect the accumulation of ammonia in biological tissue. We have validated our method against a commercially available kit in mouse tissue samples and, by using this modified method, we have confirmed the hepatic accumulation of ammonia in clinical and animal models of acute and chronic advanced liver injury as well as in the progression of fatty liver disease. Overall, we propose a morphological method for ammonia detection in liver that correlates well with the degree of liver disease severity and therefore can be potentially used to predict patient outcome.

Improving The Efficiency Of Ammonia Electrolysis For Hydrogen Production

NASA Astrophysics Data System (ADS)

Palaniappan, Ramasamy

Given the abundance of ammonia in domestic and industrial wastes, ammonia electrolysis is a promising technology for remediation and distributed power generation in a clean and safe manner. Efficiency has been identified as one of the key issues that require improvement in order for the technology to enter the market phase. Therefore, this research was performed with the aim of improving the efficiency of hydrogen production by finding alternative materials for the cathode and electrolyte. 1. In the presence of ammonia the activity for hydrogen evolution reaction (HER) followed the trend Rh>Pt>Ru>Ni. The addition of ammonia resulted in lower rates for HER for Pt, Ru, and Ni, which have been attributed to competition from the ammonia adsorption reaction. 2. The addition of ammonia offers insight into the role of metal-hydrogen underpotential deposition (M-Hupd) on HER kinetics. In addition to offering competition via ammonia adsorption it resulted in fewer and weaker M-Hupd bonds for all metals. This finding substantiates the theory that M-Hupd bonds favor HER on Pt electrocatalyst. However, for Rh results suggest that M-Hupd bond may hinder the HER. In addition, the presence of unpaired valence shell electrons is suggested to provide higher activity for HER in the presence of ammonia. 3. Bimetals PtxM1-x (M = Ir, Ru, Rh, and Ni) offered lower overpotentials for HER compared to the unalloyed metals in the presence of ammonia. The activity of HER in the presence of ammonia follows the trend Pt-Ir>Pt-Rh>Pt-Ru>Pt-Ni. The higher activity of HER is attributed to the synergistic effect of the alloy, where ammonia adsorbs onto the more electropositive alloying metal leaving Pt available for Hupd formation and HER to take place. Additionally, this supports the theory that the presence of a higher number of unpaired electrons favors the HER in the presence of ammonia. 4. Potassium polyacrylate (PAA-K) was successfully used as a substitute for aqueous KOH for ammonia

Synthesis and biological evaluation of asymmetric gramicidin S analogues containing modified D-phenylalanine residues.

PubMed

van der Knaap, Matthijs; Engels, Eefje; Busscher, Henk J; Otero, José M; Llamas-Saiz, Antonio L; van Raaij, Mark J; Mars-Groenendijk, Roos H; Noort, Daan; van der Marel, Gijsbert A; Overkleeft, Herman S; Overhand, Mark

2009-09-01

The synthesis of new analogues of the cationic antimicrobial peptide gramicidin S, having a modified D-phenylalanine residue, their antibacterial properties against several gram positive and negative strains, as well as their hemolytic activity is reported.

Regeneration of ammonia borane from polyborazylene

DOEpatents

Sutton, Andrew; Gordon, John C; Ott, Kevin C; Burrell, Anthony K

2013-02-05

Method of producing ammonia borane, comprising providing a reagent comprising a dehydrogenated material in a suitable solvent; and combining the reagent with a reducing agent comprising hydrazine, a hydrazine derivative, or combinations thereof, in a reaction which produces a mixture comprising ammonia borane.

Critical litter moisture maximizes ammonia generation

USDA-ARS?s Scientific Manuscript database

The natural breakdown of litter (bedding material mixed with deposits of feces, feathers, spilled feed and water) generates ammonia in poultry houses. Good management practices can reduce ammonia concentrations in poultry houses. Findings from a recent publication indicate there is a critical litt...

A novel chiral separation material: polymerized organogel formed by chiral gelators for the separation of D- and L-phenylalanine.

PubMed

Fu, Xinjian; Yang, Yang; Wang, Ningxia; Wang, Hong; Yang, Yajiang

2007-01-01

N-Stearine-N'-stearyl-L-phenylalanine, a chiral compound, was synthesized and used as a gelator for the gelation of polymerizable solvents, such as ss-hydroxyethyl methacrylate (HEMA), styrene, etc. The scanning electron microscope (SEM) images of the gelator aggregates show fibril-like helices, typical chiral aggregates with diameters of 100-200 nm. The solvent molecules were immobilized by capillary forces in the three-dimensional network structures of the organogels. The HEMA organogels containing crosslinker polyethylene glycol dimethacrylates (PEG200DMA) were subsequently polymerized by in situ UV irradiation. A porous polymerized organogels were obtained after removal of gelator aggregates through ethanol extraction. The chiral separation of D- and L-phenylalanine was carried out by the adsorption of the polymerized organogels. The adsorption efficiency of L-phenylalanine on the polymerized organogels was found to be dependent on the concentration of the gelator and crosslinker. (c) 2007 John Wiley & Sons, Ltd.

Effect of N-benzoyl-D-phenylalanine, a new potential oral antidiabetic agent, in neonatal streptozotocin-induced diabetes in rats.

PubMed

Pari, Leelavinothan; Ashokkumar, Natarajan

2005-01-01

The present investigation was undertaken to study the effect of treatment with D-phenylalanine derivative and metformin in neonatal streptozotocin (nSTZ)-induced non-insulin-dependent diabetes mellitus (NIDDM) in rats. To induce NIDDM, a single dose injection of streptozotozin (STZ) (100 mg kg(-1); ip) was given to 2-day-old rats. After 10-12 weeks, rats weighing above 150 g were selected for screening in NIDDM model. They were checked for fasting blood glucose levels to conform the status of NIDDM. D-phenylalanine derivative (50, 100 and 200 mg kg(-1)) was administered per os (po) for 6 weeks to the rats with confirmed diabetes. A group of diabetic rats was also maintained and this group received metformin as comparative drug. Significant decrease in blood glucose with significant increase in plasma insulin was observed in group receiving 100 mg of D-phenylalanine derivative plus 500 mg of metformin.

Review of Options for Ammonia/Ammonium Management

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nash, C. A.

This report is a review of literature supporting practical ammonia/ammonium destruction processes. Melter research supporting Hanford Low Activity Waste (LAW) glass production has shown that significant amounts of ammonia will be in the melter offgas condensate. Further work with secondary waste forms indicates the potential need to remove the ammonia, perhaps by an oxidative process. This review finds likely practical chemical methods to oxidize ammonia in aqueous solution at moderate temperatures and atmospheric pressure, using easily obtained reagents. Leading candidates include nitrite oxidation to produce nitrogen gas, various peroxide oxidative processes, and air stripping. This work reviews many other processesmore » and provides reasoning to not consider those processes further for this application.« less

Ammonia Movement in the Small Intestine: Preferential Transport by the Ileum *

PubMed Central

Mossberg, Sanford M.; Ross, George

1967-01-01

Isolated, surviving sacs of everted small intestine were used to characterize ammonia transport in the golden hamster. Jejunal and ileal sacs incubated aerobically in ammonia-free test solution liberated the same quantity of ammonia as did sacs that were filled and immediately emptied of their contents, indicating no significant evolution of metabolic ammonia. Under aerobic conditions, ileal sacs transferred a solution of high ammonia content from the mucosal surface to the serosal surface against a concentration gradient. This transport was not glucose dependent and exhibited first-order Michaelis-Menten kinetics. Inhibition of absorption occurred with anaerobiosis, 2,4-dinitrophenol, and sodium cyanide. In jejunal segments ammonia was not transported against an adverse chemical gradient. Ileal ammonia absorption was accompanied by bicarbonate secretion and acidification of the serosal solution. Both bicarbonate movement and pH gradients were abolished by inhibitors of ammonia transport. In the jejunum, the absence of ammonia movement occurred in association with minimal bicarbonate secretion and no appreciable change in serosal pH. Despite the creation of hydrogen ion gradients tending to augment or to retard ammonia absorption by nonionic diffusion, ammonia movement was unaffected, i.e., relative acidification of serosal contents did not augment ammonia absorption, and relative alkalinization of serosal fluid caused no inhibition of ammonia transport. In the absence of bicarbonate ion, ammonia transport did not occur. The significance of these findings is discussed with consideration of both ionic and nonionic mechanisms of ammonia movement. It is suggested that ammonia is absorbed in the ileum by active ionic transport. PMID:6021202

Effect of ammonia-generating diet on ovine serum and follicular fluid ammonia and urea levels, serum oestrogen and progesterone concentrations and granulosa cell functions.

PubMed

Nandi, S; Mondal, S; Pal, D T; Gupta, P S P

2016-04-01

This study was undertaken to elucidate the effect of ammonia-generating diet on serum and follicular fluid ammonia and urea levels, serum oestrogen and progesterone concentrations and granulosa cell growth and secretion parameters in ewes (Ovis aries). Ewes were fed with 14% CP diet (control) or ammonia-generating diet or ammonia-generating diet plus soluble sugar. The serum and follicular fluid ammonia and urea level, serum oestrogen and progesterone levels and granulosa cell (obtained from ovaries of slaughtered ewes) growth parameters and secretory activities were estimated. Ammonia-generating diet (high-protein diet) increased the serum ammonia and urea concentration. Supplementation of soluble sugar significantly reduced the ammonia concentration in serum with comparable levels as in control group; however, the urea level in the same group was higher than that observed in control group. Supplementation of soluble sugar significantly reduced the follicular fluid ammonia concentration; however, the level was significantly higher compared to control group. Supplementation of soluble sugar brought down the follicular fluid urea level comparable to that observed in control group. Oestrogen and progesterone levels remained unchanged in ewes fed with different types of diet. Oestrogen and progesterone secretion were significantly lowered from granulosa cells recovered from ewes fed with high ammonia-generating diet. Low metabolic activity and high incidence of apoptosis were observed in granulosa cells obtained from ovaries of ewes fed with ammonia-generating diet. Journal of Animal Physiology and Animal Nutrition © 2015 Blackwell Verlag GmbH.

A comparative study of the vibrational spectra of the anticancer drug melphalan and its fundamental molecules 3-phenylpropionic acid and L-phenylalanine

NASA Astrophysics Data System (ADS)

Badawi, Hassan M.; Khan, Ibrahim

2016-04-01

The structural stability and the vibrational spectra of the anticancer drug melphalan and its parent compounds 3-phenylpropionic acid and L-phenylalanine were investigated by the DFT B3LYP/6-311G** calculations. Melphalan and its fundamental compounds were predicted to exist predominantly in non-planar structures. The vibrational frequencies of the low energy structures of melphalan, 3-phenylpropionic acid, and phenylalanine were computed at the DFT B3LYP level of theory. Complete vibrational assignments of the normal modes of melphalan, 3-phenylpropionic acid, and phenylalanine were provided by combined theoretical and experimental data of the molecules. The experimental infrared spectra of phenylalanine and melphalan show a significantly different pattern of the Cdbnd O stretching mode as compared to those of normal carboxylic acids. A comparison of the 3700-2000 cm-1 infrared spectral region of the three molecules suggests the presence of similar intermolecular H-bonding in their condensed phases. The observed infrared and Raman spectra are consistent with the presence of one predominant melphalan conformation at room temperature.

The Ammonia Smoke Fountain: An Interesting Thermodynamic Adventure.

ERIC Educational Resources Information Center

Alexander, M. Dale

1999-01-01

Describes a new demonstration that uses an apparatus like the ammonia-fountain apparatus but with modifications designed to produce ammonium-chloride smoke. This demonstration is easy to perform, interesting to observe, and allows demonstration of the solubility of ammonia in water, the basic nature of ammonia, the acidic nature of hydrogen…

Pretreatment of Biomass by Aqueous Ammonia for Bioethanol Production

NASA Astrophysics Data System (ADS)

Kim, Tae Hyun; Gupta, Rajesh; Lee, Y. Y.

The methods of pretreatment of lignocellulosic biomass using aqueous ammonia are described. The main effect of ammonia treatment of biomass is delignification without significantly affecting the carbohydrate contents. It is a very effective pretreatment method especially for substrates that have low lignin contents such as agricultural residues and herbaceous feedstock. The ammonia-based pretreatment is well suited for simultaneous saccharification and co-fermentation (SSCF) because the treated biomass retains cellulose as well as hemicellulose. It has been demonstrated that overall ethanol yield above 75% of the theoretical maximum on the basis of total carbohydrate is achievable from corn stover pretreated with aqueous ammonia by way of SSCF. There are two different types of pretreatment methods based on aqueous ammonia: (1) high severity, low contact time process (ammonia recycle percolation; ARP), (2) low severity, high treatment time process (soaking in aqueous ammonia; SAA). Both of these methods are described and discussed for their features and effectiveness.

Mechanism of poliovirus inactivation by ammonia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, R.L.

1978-05-01

Poliovirus inactivation by ammonia causes a slight reduction in the sedimentation coefficients of viral particles, but has no detectable effect on either the electrophoretic pattern of viral capsid proteins or the isoelectric points of inactivated particles. These virions still attach to cells, but are unable to repress host translation or stimulate the synthesis of detectable amounts of viral RNA. Although ammonia has no detectable effect on naked poliovirus RNA, it causes cleavage of this RNA when still within viral particles. Therefore, the RNA genome appears to be the only component of poliovirus significantly affected by ammonia.

PpNAC1, a main regulator of phenylalanine biosynthesis and utilization in maritime pine.

PubMed

Pascual, María Belén; Llebrés, María-Teresa; Craven-Bartle, Blanca; Cañas, Rafael A; Cánovas, Francisco M; Ávila, Concepción

2018-05-01

The transcriptional regulation of phenylalanine metabolism is particularly important in conifers, long-lived species that use large amounts of carbon in wood. Here, we show that the Pinus pinaster transcription factor, PpNAC1, is a main regulator of phenylalanine biosynthesis and utilization. A phylogenetic analysis classified PpNAC1 in the NST proteins group and was selected for functional characterization. PpNAC1 is predominantly expressed in the secondary xylem and compression wood of adult trees. Silencing of PpNAC1 in P. pinaster results in the alteration of stem vascular radial patterning and the down-regulation of several genes associated with cell wall biogenesis and secondary metabolism. Furthermore, transactivation and EMSA analyses showed that PpNAC1 is able to activate its own expression and PpMyb4 promoter, while PpMyb4 is able to activate PpMyb8, a transcriptional regulator of phenylalanine and lignin biosynthesis in maritime pine. Together, these results suggest that PpNAC1 is a functional ortholog of the ArabidopsisSND1 and NST1 genes and support the idea that key regulators governing secondary cell wall formation could be conserved between gymnosperms and angiosperms. Understanding the molecular switches controlling wood formation is of paramount importance for fundamental tree biology and paves the way for applications in conifer biotechnology. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Branchial ammonia excretion in the Asian weatherloach Misgurnus anguillicaudatus.

PubMed

Moreira-Silva, J; Tsui, T K N; Coimbra, J; Vijayan, M M; Ip, Y K; Wilson, J M

2010-01-01

The weatherloach, Misgurnus anguillicaudatus, is a freshwater, facultative air-breathing fish that lives in streams and rice paddy fields, where it may experience drought and/or high environmental ammonia (HEA) conditions. The aim of this study was to determine what roles branchial Na(+)/K(+)-ATPase, H(+)-ATPase, and Rhcg have in ammonia tolerance and how the weatherloach copes with ammonia loading conditions. The loach's high ammonia tolerance was confirmed as was evident from its high 96 h LC(50) value and high tissue tolerance to ammonia. The weatherloach does not appear to make use of Na(+)/NH(4)(+)-ATPase facilitated transport to excrete ammonia when exposed to HEA or to high environmental pH since no changes in activity were observed. Using immunofluorescence microscopy, distinct populations of vacuolar (V)-type H(+)-ATPase and Na(+)/K(+)-ATPase immunoreactive cells were identified in branchial epithelia, with apical and basolateral staining patterns, respectively. Rhesus C glycoprotein (Rhcg1), an ammonia transport protein, immunoreactivity was also found in a similar pattern as H(+)-ATPase. Rhcg1 (Slc42a3) mRNA expression also increased significantly during aerial exposure, although not significantly under ammonia loading conditions. The colocalization of H(+)-ATPase and Rhcg1 to the similar non-Na(+)/K(+)-ATPase immunoreactive cell type would support a role for H(+)-ATPase in ammonia excretion via Rhcg by NH(4)(+) trapping. The importance of gill boundary layer acidification in net ammonia excretion was confirmed in this fish; however, it was not associated with an increase in H(+)-ATPase expression, since tissue activity and protein levels did not increase with high environmental pH and/or HEA. However the V-ATPase inhibitor, bafilomycin, did decrease net ammonia flux whereas other ion transport inhibitors (amiloride, SITS) had no effect. H(+)-ATPase inhibition also resulted in a consequent elevation in plasma ammonia levels and a decrease in the net acid

Ultrafast dynamics of electrons in ammonia.

PubMed

Vöhringer, Peter

2015-04-01

Solvated electrons were first discovered in solutions of metals in liquid ammonia. The physical and chemical properties of these species have been studied extensively for many decades using an arsenal of electrochemical, spectroscopic, and theoretical techniques. Yet, in contrast to their hydrated counterpart, the ultrafast dynamics of ammoniated electrons remained completely unexplored until quite recently. Femtosecond pump-probe spectroscopy on metal-ammonia solutions and femtosecond multiphoton ionization spectroscopy on the neat ammonia solvent have provided new insights into the optical properties and the reactivities of this fascinating species. This article reviews the nature of the optical transition, which gives the metal-ammonia solutions their characteristic blue appearance, in terms of ultrafast relaxation processes involving bound and continuum excited states. The recombination processes following the injection of an electron via photoionization of the solvent are discussed in the context of the electronic structure of the liquid and the anionic defect associated with the solvated electron.

L-phenylalanine binding and domain organization in human phenylalanine hydroxylase: a differential scanning calorimetry study.

PubMed

Thórólfsson, Matthías; Ibarra-Molero, Beatriz; Fojan, Peter; Petersen, Steffen B; Sanchez-Ruiz, Jose M; Martínez, Aurora

2002-06-18

Human phenylalanine hydroxylase (hPAH) is a tetrameric enzyme that catalyzes the hydroxylation of L-phenylalanine (L-Phe) to L-tyrosine; a dysfunction of this enzyme causes phenylketonuria. Each subunit in hPAH contains an N-terminal regulatory domain (Ser2-Ser110), a catalytic domain (Asp112-Arg410), and an oligomerization domain (Ser411-Lys452) including dimerization and tetramerization motifs. Two partially overlapping transitions are seen in differential scanning calorimetry (DSC) thermograms for wild-type hPAH in 0.1 M Na-Hepes buffer, 0.1 M NaCl, pH 7.0. Although these transitions are irreversible, studies on their scan-rate dependence support that the equilibrium thermodynamics analysis is permissible in this case. Comparison with the DSC thermograms for truncated forms of the enzyme, studies on the protein and L-Phe concentration effects on the transitions, and structure-energetic calculations based on a modeled structure support that the thermal denaturation of hPAH occurs in three stages: (i) unfolding of the four regulatory domains, which is responsible for the low-temperature calorimetric transition; (ii) unfolding of two (out of the four) catalytic domains, which is responsible for the high-temperature transition; and (iii) irreversible protein denaturation, which is likely responsible for the observed exothermic distortion in the high-temperature side of the high-temperature transition. Stages 1 and 2 do not appear to be two-state processes. We present an approach to the analysis of ligand effects on DSC transition temperatures, which is based on the general binding polynomial formalism and is not restricted to two-state transitions. Application of this approach to the L-Phe effect on the DSC thermograms for hPAH suggests that (i) there are no binding sites for L-Phe in the regulatory domains; therefore, contrary to the common belief, the activation of PAH by L-Phe seems to be the result of its homotropic cooperative binding to the active sites. (ii

Growth of ammonia-oxidizing archaea and bacteria in cattle manure compost under various temperatures and ammonia concentrations.

PubMed

Oishi, Ryu; Tada, Chika; Asano, Ryoki; Yamamoto, Nozomi; Suyama, Yoshihisa; Nakai, Yutaka

2012-05-01

A recent study showed that ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) coexist in the process of cattle manure composting. To investigate their physiological characteristics, liquid cultures seeded with fermenting cattle manure compost were incubated at various temperatures (37°C, 46°C, or 60°C) and ammonium concentrations (0.5, 1, 4, or 10 mM NH (4) (+) -N). The growth rates of the AOB and AOA were monitored using real-time polymerase chain reaction analysis targeting the bacterial and archaeal ammonia monooxygenase subunit A genes. AOB grew at 37°C and 4 or 10 mM NH (4) (+) -N, whereas AOA grew at 46°C and 10 mM NH (4) (+) -N. Incubation with allylthiourea indicated that the AOB and AOA grew by oxidizing ammonia. Denaturing gradient gel electrophoresis and subsequent sequencing analyses revealed that a bacterium related to Nitrosomonas halophila and an archaeon related to Candidatus Nitrososphaera gargensis were the predominant AOB and AOA, respectively, in the seed compost and in cultures after incubation. This is the first report to demonstrate that the predominant AOA in cattle manure compost can grow and can probably oxidize ammonia under moderately thermophilic conditions.

Ammonia as a respiratory gas in water and air-breathing fishes.

PubMed

Randall, David J; Ip, Yuen K

2006-11-01

Ammonia is produced in the liver and excreted as NH(3) by diffusion across the gills. Elevated ammonia results in an increase in gill ventilation, perhaps via stimulation of gill oxygen chemo-receptors. Acidification of the water around the fish by carbon dioxide and acid excretion enhances ammonia excretion and constitutes "environmental ammonia detoxification". Fish have difficulties in excreting ammonia in alkaline water or high concentrations of environmental ammonia, or when out of water. The mudskipper, Periphthalmodon schlosseri, is capable of active NH(4)(+) transport, maintaining low internal levels of ammonia. To prevent a back flux of NH(3), these air-breathing fish can increase gill acid excretion and reduce the membrane NH(3) permeability by modifying the phospholipid and cholesterol compositions of their skin. Several air-breathing fish species can excrete ammonia into air through NH(3) volatilization. Some fish detoxify ammonia to glutamine or urea. The brains of some fish can tolerate much higher levels of ammonia than other animals. Studies of these fish may offer insights into the nature of ammonia toxicity in general.

Hydrogen bonding in the benzene-ammonia dimer

NASA Technical Reports Server (NTRS)

Rodham, David A.; Suzuki, Sakae; Suenram, Richard D.; Lovas, Frank J.; Dasgupta, Siddharth; Goddard, William A., III; Blake, Geoffrey A.

1993-01-01

High-resolution optical and microwave spectra of the gas-phase benzene-ammonia dimer were obtained, showing that the ammonia molecule resides above the benzene plane and undergoes free, or nearly free, internal rotation. To estimate the binding energy (De) and other global properties of the intermolecular potential, theoretical calculations were performed for the benzene-ammonia dimer, using the Gaussian 92 (Fritsch, 1992) program at the MP2/6-31G** level. The predicted De was found to be at the lowest end of the range commonly accepted for hydrogen bonding and considerably below that of C6H6-H2O, consistent with the gas-phase acidities of ammonia and water. The observed geometry greatly resembles the amino-aromatic interaction found naturally in proteins.

Phosphoenolpyruvate Transporter Enables Targeted Perturbation During Metabolic Analysis of L-Phenylalanine Production With Escherichia coli.

PubMed

Tröndle, Julia; Albermann, Christoph; Weiner, Michael; Sprenger, Georg A; Weuster-Botz, Dirk

2018-05-01

Usually perturbation of the metabolism of cells by addition of substrates is applied for metabolic analysis of production organisms, but perturbation studies are restricted to the endogenous substrates of the cells under study. The goal of this study is to overcome this limitation by making phosphoenolpyruvate (PEP) available for perturbation studies with Escherichia coli producing L-phenylalanine. A production strain overexpressing a PEP-transporter variant (UhpT-D388C) is applied in a standardized fed-batch production-process on a 42 L-scale. Four parallel short-term perturbation experiments of 20 min are performed with glucose and glycerol as fed-batch carbon sources after rapid media transition of cells from the production-process. PEP is added after 9 min and is immediately consumed by the cells with up to 1.5 mmol g CDW -1  h -1 . L-phenylalanine production rates increased by up to 200% after addition of PEP. This clearly indicates an intracellular PEP-limitation in the L-phenylalanine production strain under study. Thus, it is shown that overexpressing specific transporters for analytical reasons makes exogenous substrates available as perturbation substrates for metabolic analyses of cells sampled from production-processes and thereby allows a very targeted perturbation of whole-cell metabolism. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Energy Efficient Operation of Ammonia Refrigeration Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohammed, Abdul Qayyum; Wenning, Thomas J; Sever, Franc

Ammonia refrigeration systems typically offer many energy efficiency opportunities because of their size and complexity. This paper develops a model for simulating single-stage ammonia refrigeration systems, describes common energy saving opportunities, and uses the model to quantify those opportunities. The simulation model uses data that are typically available during site visits to ammonia refrigeration plants and can be calibrated to actual consumption and performance data if available. Annual electricity consumption for a base-case ammonia refrigeration system is simulated. The model is then used to quantify energy savings for six specific energy efficiency opportunities; reduce refrigeration load, increase suction pressure, employmore » dual suction, decrease minimum head pressure set-point, increase evaporative condenser capacity, and reclaim heat. Methods and considerations for achieving each saving opportunity are discussed. The model captures synergistic effects that result when more than one component or parameter is changed. This methodology represents an effective method to model and quantify common energy saving opportunities in ammonia refrigeration systems. The results indicate the range of savings that might be expected from common energy efficiency opportunities.« less

Cerebrovascular, cardiovascular and strength responses to acute ammonia inhalation.

PubMed

Perry, Blake G; Pritchard, Hayden J; Barnes, Matthew J

2016-03-01

Ammonia is used as a stimulant in strength based sports to increase arousal and offset fatigue however little is known about its physiological and performance effects. The purpose of this study was twofold (1) establish the physiological response to acute ammonia inhalation (2) determine whether the timing of the physiological response corresponds with a performance enhancement, if any. Fifteen healthy males completed two trials. Trial one investigated the beat-to-beat middle cerebral artery blood flow velocity (MCAv), heart rate (HR) and mean arterial pressure (MAP) response to ammonia inhalation. During trial two, participants performed a maximal single mid-thigh pull (MTP) at various time points following ammonia inhalation in a randomised order: MTPs were conducted immediately, 15, 30 and 60 s following ammonia inhalation. A MTP with no ammonia inhalation served as the control. During this trial maximal MTP force, rate of force development (RFD) and electromyography (EMG) activity were recorded. MCAvmean increased and peaked on average by 6 cm s(-1) (P < 0.001), 9.4 ± 5.5 s following ammonia inhalation. Similarly, HR was increased by 6 ± 11 beats per minute 15 s following ammonia inhalation (P < 0.001). MAP remained unchanged following inhalation (P = 0.51). The use and timing of ammonia inhalation had no effect on maximal force, RFD or EMG (all P > 0.2) compared to control. MCAv was elevated despite no increase in MAP occurring; this is indicative of a cerebrovascular vasodilation. Despite the marked cerebrovascular and cardiovascular response to ammonia inhalation no ergogenic effect was observed during the MTP, irrespective of the timing of administration.

Nitrification resilience and community dynamics of ammonia-oxidizing bacteria with respect to ammonia loading shock in a nitrification reactor treating steel wastewater.

PubMed

Cho, Kyungjin; Shin, Seung Gu; Lee, Joonyeob; Koo, Taewoan; Kim, Woong; Hwang, Seokhwan

2016-08-01

The aim of this study was to investigate the nitrification resilience pattern and examine the key ammonia-oxidizing bacteria (AOB) with respect to ammonia loading shocks (ALSs) in a nitrification bioreactor treating steel wastewater. The perturbation experiments were conducted in a 4-L bioreactor operated in continuous mode with a hydraulic retention time of 10 d. Three sequential ALSs were given to the bioreactor (120, 180 and 180 mg total ammonia nitrogen (TAN)/L. When the first shock was given, the nitrification process completely recovered after 14 d of further operation. However, the resilience duration was significantly reduced to ∼1 d after the second and third ALSs. In the bioreactor, Nitrosomonas aestuarii dominated the other AOB species, Nitrosomonas europaea and N. nitrosa, throughout the process. In addition, the population of N. aestuarii increased with ammonia utilization following each ALS; i.e., this species responded to acute ammonia overloadings by contributing to ammonia oxidation. This finding suggests that N. aestuarii could be exploited to achieve stable nitrification in industrial wastewaters that contain high concentrations of ammonia. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Fiber-Optic Ammonia Sensors

NASA Technical Reports Server (NTRS)

Carter, Michael T.

2003-01-01

Reversible, colorimetric fiber-optic sensors are undergoing development for use in measuring concentrations of ammonia in air at levels relevant to human health [0 to 50 parts per million (ppm)]. A sensor of this type includes an optical fiber that has been modified by replacing a portion of its cladding with a polymer coat that contains a dye that reacts reversibly with ammonia and changes color when it does so. The change in color is measured as a change in the amount of light transmitted from one end of the fiber to the other. Responses are reversible and proportional to the concentration of ammonia over the range from 9 to 175 ppm and in some cases the range of reversibility extends up to 270 ppm. The characteristic time for the response of a sensor to rise from 10 to 90 percent of full scale is about 25 seconds. These sensors are fully operational in pure carbon dioxide and are not adversely affected by humidity. This work was done by Michael T. Carter

Temperature dependence of feedyard ammonia emissions: The Arrhenius equation

USDA-ARS?s Scientific Manuscript database

Ammonia emissions from beef cattle feedyards exhibit an annual pattern-like temperature. This suggests that ammonia emissions may obey the Arrhenius temperature relationship. Our objective was to determine the Arrhenius relationship between mean monthly ammonia emissions from cattle feedyards and me...

21 CFR 573.180 - Anhydrous ammonia.

Code of Federal Regulations, 2014 CFR

2014-04-01

... source of nonprotein nitrogen in cattle feed in accordance with paragraphs (a)(1), (2), or (3) as follows: (1)(i) The food additive anhydrous ammonia is applied as a component of an aqueous premix containing 16 to 17 percent ammonia, with molasses, minerals, and not less than 83 percent crude protein. The...

21 CFR 573.180 - Anhydrous ammonia.

Code of Federal Regulations, 2013 CFR

2013-04-01

... source of nonprotein nitrogen in cattle feed in accordance with paragraphs (a)(1), (2), or (3) as follows: (1)(i) The food additive anhydrous ammonia is applied as a component of an aqueous premix containing 16 to 17 percent ammonia, with molasses, minerals, and not less than 83 percent crude protein. The...

21 CFR 573.180 - Anhydrous ammonia.

Code of Federal Regulations, 2011 CFR

2011-04-01

... source of nonprotein nitrogen in cattle feed in accordance with paragraphs (a)(1), (2), or (3) as follows: (1)(i) The food additive anhydrous ammonia is applied as a component of an aqueous premix containing 16 to 17 percent ammonia, with molasses, minerals, and not less than 83 percent crude protein. The...

21 CFR 573.180 - Anhydrous ammonia.

Code of Federal Regulations, 2012 CFR

2012-04-01

... source of nonprotein nitrogen in cattle feed in accordance with paragraphs (a)(1), (2), or (3) as follows: (1)(i) The food additive anhydrous ammonia is applied as a component of an aqueous premix containing 16 to 17 percent ammonia, with molasses, minerals, and not less than 83 percent crude protein. The...