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Sample records for ho dtpa-bis biotin

  1. Biotin

    PubMed Central

    Zempleni, Janos; Wijeratne, Subhashinee S.K.; Hassan, Yousef I.

    2016-01-01

    Biotin is a water-soluble vitamin and serves as a coenzyme for five carboxylases in humans. Biotin is also covalently attached to distinct lysine residues in histones, affecting chromatin structure and mediating gene regulation. This review describes mammalian biotin metabolism, biotin analysis, markers of biotin status, and biological functions of biotin. Proteins such as holocarboxylase synthetase, biotinidase, and the biotin transporters SMVT and MCT1 play crucial roles in biotin homeostasis, and these roles are reviewed here. Possible effects of inadequate biotin intake, drug interactions, and inborn errors of metabolism are discussed, including putative effects on birth defects. PMID:19319844

  2. Design and synthesis of novel adenine fluorescence probe based on Eu(III) complexes with dtpa-bis(guanine) ligand.

    PubMed

    Tian, Fengyun; Jiang, Xiaoqing; Dou, Xuekai; Wu, Qiong; Wang, Jun; Song, Youtao

    2017-02-24

    A novel adenine (Ad) fluorescence probe (Eu(III)-dtpa-bis(guanine)) was designed and synthesized by improving experimental method based on the Eu(III) complex and dtpa-bis(guanine) ligand. The dtpa-bis(guanine) ligand was first synthesized by the acylation action between dtpaa and guanine (Gu), and the corresponding Eu(III) complex was successfully prepared through heat-refluxing method with dtpa-bis(guanine) ligand. As a novel fluorescence probe, the Eu(III)-dtpa-bis(guanine) complex can detect adenine (Ad) with characteristics of strong targeting, high specificity and high recognition ability. The detection mechanism of the adenine (Ad) using this probe in buffer solution was studied by ultraviolet-visible (UV-vis) and fluorescence spectroscopy. When the Eu(III)-dtpa-bis(guanine) was introduced to the adenine (Ad) solution, the fluorescence emission intensity was significantly enhanced. However, adding other bases such as guanine (Gu), xanthine (Xa), hypoxanthine (Hy) and uric acid (Ur) with similar composition and structure to that of adenine (Ad) to the Eu(III)-dtpa-bis(guanine) solution, the fluorescence emission intensities are nearly invariable. Meanwhile, the interference of guanine (Gu), xanthine (Xa), hypoxanthine (Hy) and uric acid (Ur) on the detection of the adenine using Eu(III)-dtpa-bis(guanine) probe was also studied. It was found that presence of these bases does not affect the detection of adenine (Ad). A linear response of fluorescence emission intensities of Eu(III)-dtpa-bis(guanine) at 570nm as a function of adenine (Ad) concentration in the range of 0.00-5.00×10(-5)molL(-1) was observed. The detection limit is about 4.70×10(-7)molL(-1).

  3. LAT-1 Based Primary Breast Cancer Detection by [99m]Tc-Labeled DTPA-Bis-Methionine Scintimammography: First Results Using Indigenously Developed Single Vial Kit Preparation

    PubMed Central

    Sharma, Sarika; Mishra, Anil K.; Rathod, Deepti; Hazari, Puja Panwar; Chuttani, Krishna; Chopra, Shalini; Singh, Paramvir Mangat; Abrar, M.L.; Mittal, Bhagwant R.; Singh, Gurpreet

    2014-01-01

    Abstract Objective: To evaluate the diagnostic utility of a single vial ready to label with [99m]Tc kit preparation of DTPA-bis-methionine (DTPA-bis-MET) for the detection of primary breast cancer. Methods: The conjugate (DTPA-bis-MET) was synthesized by covalently conjugating two molecules of methionine to DTPA and formulated as a single vial ready to label with [99m]Tc lyophilized kit preparations. Thirty female patients (mean age=47.5±11.8 years; range=21–69 years) with radiological/clinical evidence of having primary breast carcinoma were subjected to [99m]Tc-methionine scintigraphy. The whole body (anterior and posterior) imaging was performed on all the patients at 5 minutes, 10 minutes, 1 hour, 2 hours, and 4 hours following an intravenous administration of 555–740 MBq radioactivity of [99m]Tc-methionine. In addition, scintimammography (static images; 256×256 matrix) at 1, 2, and 4 hours was also performed on all the patients. Results: The resultant radiolabel, that is, [99m]Tc-DTPA-bis-MET, yielded high radiolabeling efficiency (>97.0%), radiochemical purity (166–296 MBq/μmol), and shelf life (>3 months). The radiotracer primarily gets excreted through the kidneys and localizes in the breast cancer lesions with high target-to-nontarget ratios. The mean±SD ratios on the scan-positive lesions acquired at 1, 2, and 4 hours postinjection were 3.6±0.48, 3.10±0.24, and 2.5±0.4, respectively. [99m]Tc-methionine scintimammography demonstrated an excellent sensitivity and positive predictive value of 96.0% each for the detection of primary breast cancer. Conclusion: Ready to label single vial kit formulations of DTPA-bis-MET can be easily synthesized as in-house production and conveniently used for the scintigraphic detection of breast cancer and other methionine-dependent tumors expressing the L-type amino acid transporter-1 receptor. The imaging technique thus could be a potential substitute for the conventional single-photon emission computed

  4. Biological comparison of 149Pm-, 166Ho-, and 177Lu-DOTA-biotin pretargeted by CC49 scFv-streptavidin fusion protein in xenograft-bearing nude mice.

    PubMed

    Lewis, Michael R; Zhang, Jiuli; Jia, Fang; Owen, Nellie K; Cutler, Cathy S; Embree, Mary F; Schultz, Jody; Theodore, Louis J; Ketring, Alan R; Jurisson, Silvia S; Axworthy, Donald B

    2004-02-01

    The radiolanthanides (149)Pm, (166)Ho, and (177)Lu possess a range of half-lives and alpha(-) beta(-) energies for targeted radiotherapy of cancer. (149)Pm-, (166)Ho-, and (177)Lu-DOTA-biotin were pretargeted to LS174T colorectal tumors in nude mice with CC49 scFvSA antibody-streptavidin fusion protein. Tumor uptakes of (149)Pm (22.9% ID/g), (166)Ho (30.2% ID/g), and (177)Lu (35.4% ID/g) peaked at 1-4 h. Rapid blood disappearance was accompanied by urinary excretion of 59-66% ID within 1 h. Biodistributions of these agents show promise for pretargeted radioimmunotherapy of cancer.

  5. Gd3+-DTPA-bis (N-methylamine) - anionic linear globular Dendrimer-G1; a more efficient MRI contrast media.

    PubMed

    Ghalandarlaki, N; Mohammadi, T D; Agha Babaei, R; Tabasi, M A; Keyhanvar, P; Mehravi, B; Yaghmaei, P; Cohan, R A; Ardestani, M S

    2014-02-01

    By advancing of molecular imaging techniques, magnetic resonance imaging (MRI) is becoming an increasingly important tool in early diagnosis. Researchers have found new ways to increase contrast of MRI images.Therefore some types of drug known as contrast media are produced. Contrast media improve the visibility of internal body structures in MRI images. Gadodiamide (Omniscan®) is one of these contrast media which is produced commercially and used clinically. In this study Gadodiamide was first synthesized and then qualitative and quantitative methods were carried out to ensure the proper synthesis of this drug then to increase the efficiency of this contrast medium use dendrimer that is one kind of nano particle. This dendrimer has a polyethylene glycol (PEG) core and citric acid branches. After dendrimer attached to Gadodiamide to ensure the proper efficient connection between them the stability studies were carried out and cytotoxicity of the drug was evaluated. Finally, after ensuring the non-toxicity of the drug, in vivo studies (injected into mice) MR imaging was performed to examine the impact of synthesis drug on the resolution of image.The result obtained from this study demonstrated that the attachment of Gadodiamide to dendrimer reduces its cytotoxicity and also improved resolution of image. Also the new contrast media (Gd3+-DTPA- bis [N-methylamine] - Dendrimer) - unlike Omniscan® - is biodegradable and able to enter the HEPG2 cell line. The results confirm the hypothesis that using dendrimer to synthesize this new nano contrast medium increases its effectiveness.

  6. 21 CFR 182.8159 - Biotin.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Biotin. 182.8159 Section 182.8159 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8159 Biotin. (a) Product. Biotin. (b) Conditions of use. This substance...

  7. A versatile Escherichia coli strain for identification of biotin transporters and for biotin quantification.

    PubMed

    Finkenwirth, Friedrich; Kirsch, Franziska; Eitinger, Thomas

    2014-01-01

    Biotin is an essential cofactor of carboxylase enzymes in all kingdoms of life. The vitamin is produced by many prokaryotes, certain fungi, and plants. Animals depend on biotin uptake from their diet and in humans lack of the vitamin is associated with serious disorders. Many aspects of biotin metabolism, uptake, and intracellular transport remain to be elucidated. In order to characterize the activity of novel biotin transporters by a sensitive assay, an Escherichia coli strain lacking both biotin synthesis and its endogenous high-affinity biotin importer was constructed. This strain requires artificially high biotin concentrations for growth. When only trace levels of biotin are available, it is viable only if equipped with a heterologous high-affinity biotin transporter. This feature was used to ascribe transport activity to members of the BioY protein family in previous work. Here we show that this strain together with its parent is also useful as a diagnostic tool for wide-concentration-range bioassays.

  8. Sequential, solid-phase assay for biotin in physiologic fluids that correlates with expected biotin status

    SciTech Connect

    Mock, D.M.; DuBois, D.B.

    1986-03-01

    Interest in accurate measurement of biotin concentrations in plasma and urine has been stimulated by recent advances in the understanding of biotin-responsive inborn errors of metabolism and by several reports describing acquired biotin deficiency during parenteral alimentation. This paper presents a biotin assay utilizing radiolabeled avidin in a sequential, solid-phase method; the assay has increased sensitivity compared to previous methods (greater than or equal to 10 fmol/tube), correlates with expected trends in biotin concentrations in blood and urine in a rat model of biotin deficiency, and can utilize commercially available radiolabeled avidin.

  9. Intestinal absorption of biotin in the rat

    SciTech Connect

    Bowman, B.B.; Selhub, J.; Rosenberg, I.H.

    1986-07-01

    We examined the absorption of biotin using the in vivo intestinal loop technique. Jejunal segments from male rats were filled with solutions containing (/sup 3/H)biotin and (/sup 14/C)inulin in Krebs-Ringer phosphate buffer, pH 6.5. Absorption was determined on the basis of luminal tritium disappearance after correction for inulin recovery. At biotin concentrations of 0.1 and 5.0 microM, luminal biotin disappearance was linear for at least 10 min. At biotin concentrations ranging from 2.3 nM to 75 microM, 10-28% of the administered dose was absorbed in 10 min. The concentration dependence of luminal biotin disappearance is consistent with the presence of both saturable and nonsaturable (linear) components of biotin uptake, with estimated Km = 9.6 microM and Jmax = 75.2 pmol/(2.5 cm loop X min). The rate constant for nonsaturable uptake is 3.1 pmol/(2.5 cm loop X min X microM). We conclude that at biotin concentrations less than 5 microM, biotin absorption proceeds largely by the saturable process, whereas at concentrations above 25 microM, nonsaturable uptake predominates. Additional studies demonstrated significantly less biotin uptake in the ileum than in the jejunum, a finding in agreement with previous in vitro studies.

  10. Microarray analysis of pancreatic gene expression during biotin repletion in biotin-deficient rats.

    PubMed

    Dakshinamurti, Krishnamurti; Bagchi, Rushita A; Abrenica, Bernard; Czubryt, Michael P

    2015-12-01

    Biotin is a B vitamin involved in multiple metabolic pathways. In humans, biotin deficiency is relatively rare but can cause dermatitis, alopecia, and perosis. Low biotin levels occur in individuals with type-2 diabetes, and supplementation with biotin plus chromium may improve blood sugar control. The acute effect on pancreatic gene expression of biotin repletion following chronic deficiency is unclear, therefore we induced biotin deficiency in adult male rats by feeding them a 20% raw egg white diet for 6 weeks. Animals were then randomized into 2 groups: one group received a single biotin supplement and returned to normal chow lacking egg white, while the second group remained on the depletion diet. After 1 week, pancreata were removed from biotin-deficient (BD) and biotin-repleted (BR) animals and RNA was isolated for microarray analysis. Biotin depletion altered gene expression in a manner indicative of inflammation, fibrosis, and defective pancreatic function. Conversely, biotin repletion activated numerous repair and anti-inflammatory pathways, reduced fibrotic gene expression, and induced multiple genes involved in pancreatic endocrine and exocrine function. A subset of the results was confirmed by quantitative real-time PCR analysis, as well as by treatment of pancreatic AR42J cells with biotin. The results indicate that biotin repletion, even after lengthy deficiency, results in the rapid induction of repair processes in the pancreas.

  11. Biotin biosynthesis, transport and utilization in rhizobia.

    PubMed

    Guillén-Navarro, Karina; Encarnación, Sergio; Dunn, Michael F

    2005-05-15

    Biotin, a B-group vitamin, performs an essential metabolic function in all organisms. Rhizobia are alpha-proteobacteria with the remarkable ability to form a nitrogen-fixing symbiosis in combination with a compatible legume host, a process in which the importance of biotin biosynthesis and/or transport has been demonstrated for some rhizobia-legume combinations. Rhizobia have also been used to delimit the biosynthesis, metabolic effects and, more recently, transport of biotin. Molecular genetic analysis shows that an orthodox biotin biosynthesis pathway occurs in some rhizobia while others appear to synthesize the vitamin using alternative pathways. In addition to its well established function as a prosthetic group for biotin-dependent carboxylases, we are beginning to delineate a role for biotin as a metabolic regulator in rhizobia.

  12. Biotin transport in the rat central nervous system.

    PubMed

    Lo, W; Kadlecek, T; Packman, S

    1991-12-01

    Previous studies in the biotin-deficient rat have shown that brain biotin concentrations and the activity of biotin-dependent carboxylases are relatively preserved in the face of biotin starvation and systemic biotin deficiency. These data suggested the existence of a concentration mechanism for biotin in brain, and the present studies were undertaken to further characterize brain biotin transport. We presently show that rat cerebrospinal fluid biotin concentrations are 2.5 times higher than serum concentrations, consistent with the existence of a concentrative mechanism for biotin. Further, we demonstrate uptake of 3H-biotin into rat brain from blood at physiologic biotin concentrations, using single pass clearance measurements of a brain uptake index. The calculated brain uptake indices for biotin, and the inhibition kinetics, are consistent with the possible existence of a low affinity mediated uptake mechanism. The results have implications for the pathophysiology of human biotin-responsive multiple carboxylase deficiency.

  13. Biotin

    MedlinePlus

    ... nose, and mouth. Other symptoms include depression, listlessness, hallucinations, and tingling in the arms and legs. There ... and mouth. Nervous system symptoms include depression, exhaustion, hallucinations, and tingling of the arms and legs. There ...

  14. 21 CFR 182.8159 - Biotin.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Biotin. 182.8159 Section 182.8159 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8159 Biotin. (a)...

  15. 21 CFR 182.8159 - Biotin.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Biotin. 182.8159 Section 182.8159 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8159 Biotin. (a)...

  16. 21 CFR 182.8159 - Biotin.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Biotin. 182.8159 Section 182.8159 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8159 Biotin. (a)...

  17. 21 CFR 182.8159 - Biotin.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Biotin. 182.8159 Section 182.8159 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8159 Biotin. (a)...

  18. Stimulation of Nitrobacter agilis by Biotin

    PubMed Central

    Krulwich, Terry A.; Funk, Helen B.

    1965-01-01

    Krulwich, Terry A. (Goucher College, Baltimore, Md.), and Helen B. Funk. Stimulation of Nitrobacter agilis by biotin. J. Bacteriol. 90:729–733. 1965.—Addition of biotin to nitrite-mineral medium greatly stimulated the autotrophic growth of four strains of Nitrobacter agilis. Comparisons of cultures of the organisms grown in parallel at 30 C in nitrite medium and in the medium supplemented with 150 mμg of biotin per ml showed that the vitamin promoted: (i) 2- to 4-fold greater rates of utilization of nitrite, and (ii) 100- to 1,000-fold greater populations of cells per milliliter. Avidin specifically inhibited the biotin stimulation of nitrite utilization at an avidin-biotin ratio of 133:1. Incubation of the four strains of N. agilis at 37 C imposed a requirement for biotin that could be met by daily addition of 150 mμg of the vitamin per ml of medium. The stimulatory effects of the vitamin at 30 C suggest that in N. agilis the synthesis of biotin is rate-limiting for growth. PMID:16562074

  19. Biotin absorption by distal rat intestine

    SciTech Connect

    Bowman, B.B.; Rosenberg, I.H.

    1987-12-01

    We used the in vivo intestinal loop approach, with short (10-min) and long (3-h) incubations, to examine biotin absorption in proximal jejunum, distal ileum, cecum and proximal colon. In short-term studies, luminal biotin disappearance from rat ileum was about half that observed in the jejunum, whereas absorption by proximal colon was about 12% of that in the jejunum. In 3-h closed-loop studies, the absorption of 1.0 microM biotin varied regionally. Biotin absorption was nearly complete in the small intestine after 3 h; however, only about 15% of the dose had been absorbed in the cecum and 27% in the proximal colon after 3 h. Independent of site of administration, the major fraction of absorbed biotin was recovered in the liver; measurable amounts of radioactive biotin were also present in kidney and plasma. The results support the potential nutritional significance for the rat of biotin synthesized by bacteria in the distal intestine, by demonstrating directly an absorptive capability of mammalian large bowel for this vitamin.

  20. Altered glucagon release in biotin deficiency.

    PubMed

    Klandorf, H; Clarke, B L; Brown, J

    1987-01-01

    Classical biotin deficiency in young chickens is characterized by a reduction in the activity of liver biotin-dependent enzymes which thus impairs gluconeogenesis during periods of food withdrawal. Because the normal bird maintains an elevated fasting blood glucose level, the ability of the classically biotin-deficient animal to resist changes induced by fasting has not been established. Whether the release of insulin and/or glucagon is affected by biotin deficiency has not been investigated and so determining the importance of these hormones in maintaining fasting glucose levels as well as their ability to respond to a challenge is the objective of the present study. Experimental animals (15-week-old cockerels) were fed a biotin-deficient diet for 9 weeks while control animals (n = 8) were pair-fed biotin-supplemented diets. Before fasting, concentrations of plasma glucose, insulin, and glucagon were not different between the two groups. After 72 h of fasting basal glucose levels remained the same in both groups and concentrations of plasma insulin were equally suppressed but concentrations of glucagon were significantly elevated in biotin-deficient animals (P less than 0.025). Ten minutes after an iv glucose challenge the magnitude of the increase in plasma insulin concentrations was equivalent for both groups of animals whereas the magnitude of the decline in plasma glucagon concentrations was greater for biotin-deficient birds. Twenty minutes after a protein challenge (purified casein diet) the levels of plasma glucagon in both groups were maximally increased although the concentrations remained elevated only in control animals. In conclusion the release of insulin and glucagon is not impaired in biotin-deficient animals.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. A versatile Escherichia coli strain for identification of biotin transporters and for biotin quantification

    PubMed Central

    Finkenwirth, Friedrich; Kirsch, Franziska; Eitinger, Thomas

    2014-01-01

    Biotin is an essential cofactor of carboxylase enzymes in all kingdoms of life. The vitamin is produced by many prokaryotes, certain fungi, and plants. Animals depend on biotin uptake from their diet and in humans lack of the vitamin is associated with serious disorders. Many aspects of biotin metabolism, uptake, and intracellular transport remain to be elucidated. In order to characterize the activity of novel biotin transporters by a sensitive assay, an Escherichia coli strain lacking both biotin synthesis and its endogenous high-affinity biotin importer was constructed. This strain requires artificially high biotin concentrations for growth. When only trace levels of biotin are available, it is viable only if equipped with a heterologous high-affinity biotin transporter. This feature was used to ascribe transport activity to members of the BioY protein family in previous work. Here we show that this strain together with its parent is also useful as a diagnostic tool for wide-concentration-range bioassays. PMID:24256712

  2. Intersubunit contacts made by tryptophan 120 with biotin are essential for both strong biotin binding and biotin-induced tighter subunit association of streptavidin

    SciTech Connect

    Sano, Takeshi; Cantor, C.R.

    1995-04-11

    In natural streptavidin, tryptophan 120 of each subunit makes contacts with the biotin bound by an adjacent subunit through the dimer-dimer interface. To understand quantitatively the role of tryptophan 120 and its intersubunit communication in the properties of streptavidin, a streptavidin mutant in which tryptophan 120 is converted to phenylalanine was produced and characterized. The streptavidin mutant forms a tetrameric molecule and binds one biotin per subunit, as does natural streptavidin, indicating that the mutation of tryptophan 120 to phenylalanine has no significant effect on the basic properties of streptavidin. However, its biotin-binding affinity was reduced substantially, to approximately 10{sup 8} M{sup {minus}1}, indicating that the contact made by tryptophan 120 to biotin has a considerable contribution o the extremely tight biotin binding by streptavidin. The mutant retained bound biotin over a wide pH range or with the addition of urea up to 6 M at neutral pH. However, bound biotin was efficiently released by the addition of excess free biotin due, presumably, to exchange reactions. Electrophoretic analysis revealed that the intersubunit contact made by tryptophan 120 to biotin through the dimer-dimer interface is the major interaction responsible for the biotin-induced, tighter subunit association of streptavidin. In addition, the mutant has weaker subunit association than natural streptavidin even in the absence of biotin, indicating that tryptophan 120 also contributes to the subunit association of tetramers in the absence of biotin. 37 refs., 6 figs.

  3. Biosynthesis of Biotin in Microorganisms V. Control of Vitamer Production

    PubMed Central

    Birnbaum, Jerome; Pai, Chik H.; Lichstein, Herman C.

    1967-01-01

    Use of a yeast-lactobacillus differential microbiological assay permitted investigation into the synthesis of biotin vitamers by a variety of bacteria. A major portion of the biotin activity was found extracellularly. The level of total biotin (assayable with yeast) greatly exceeded the level of true biotin (assayed with lactobacillus). Values for intracellular biotin generally showed good agreement between the assays, suggesting the presence of only true biotin within the cells. Bioautographic analysis of the medium after growth of each organism revealed the presence of large amounts of a vitamer which corresponded to dl-desthiobiotin on the basis of Rf value and biological activity. Biotin, when detected at all, was at very low concentrations. Also, an avidin-uncombinable vitamer was synthesized by a majority of the bacteria. Addition of d-biotin to the growth medium prevented completely the synthesis of both vitamers of biotin. d-Biotin-d-sulfoxide had no effect on the synthesis of desthiobiotin or the avidin-uncombinable vitamer. Addition of dl-desthiobiotin did not prevent its own synthesis nor that of the other vitamer. Control of vitamer synthesis is therefore highly specific for d-biotin. The avidin-uncombinable vitamer was produced only at repressed levels in the presence of high concentrations of both d-biotin and dl-desthiobiotin, which suggested that it is not a degradation product of these substances. A possible mechanism for the overproduction of the biosynthetic precursors of biotin is presented. PMID:4965364

  4. Serum Biotin Levels in Women Complaining of Hair Loss

    PubMed Central

    Trüeb, Ralph M

    2016-01-01

    Biotin is a coenzyme for carboxylase enzymes that assist various metabolic reactions involved in fatty acid synthesis, branched-chain amino acid catabolism, and gluconeogenesis important for maintenance of healthy skin and hair. Due to its availability, affordability, and effective marketing for this purpose, biotin is a popular nutritional supplement for treatment of hair loss. However, there are little data on the frequency of biotin deficiency in patients complaining of hair loss and on the value of oral biotin for treatment of hair loss that is not due to an inborn error of biotin metabolism or deficiency. The aim of this study was to determine the frequency and significance of biotin deficiency in women complaining of hair loss. Biotin deficiency was found in 38% of women complaining of hair loss. Of those showing diffuse telogen effluvium in trichograms (24%), 35% had evidence of associated seborrheic-like dermatitis. About 11% of patients with biotin deficiency had a positive personal history for risk factors for biotin deficiency. The custom of treating women complaining of hair loss in an indiscriminate manner with oral biotin supplementation is to be rejected, unless biotin deficiency and its significance for the complaint of hair loss in an individual has been demonstrated on the basis of a careful patient history, clinical examination, determination of serum biotin levels, and exclusion of alternative factors responsible for hair loss. PMID:27601860

  5. 21 CFR 582.5159 - Biotin.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Biotin. 582.5159 Section 582.5159 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...

  6. 21 CFR 582.5159 - Biotin.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Biotin. 582.5159 Section 582.5159 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...

  7. 21 CFR 582.5159 - Biotin.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Biotin. 582.5159 Section 582.5159 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...

  8. 21 CFR 582.5159 - Biotin.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Biotin. 582.5159 Section 582.5159 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...

  9. 21 CFR 582.5159 - Biotin.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Biotin. 582.5159 Section 582.5159 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...

  10. Biotin selective polymer nano-films

    PubMed Central

    2014-01-01

    Background The interaction between biotin and avidin is utilized in a wide range of assay and diagnostic systems. A robust material capable of binding biotin should offer scope in the development of reusable assay materials and biosensor recognition elements. Results Biotin-selective thin (3–5 nm) films have been fabricated on hexadecanethiol self assembled monolayer (SAM) coated Au/quartz resonators. The films were prepared based upon a molecular imprinting strategy where N,N'-methylenebisacrylamide and 2-acrylamido-2-methylpropanesulfonic acid were copolymerized and grafted to the SAM-coated surface in the presence of biotin methyl ester using photoinitiation with physisorbed benzophenone. The biotinyl moiety selectivity of the resonators efficiently differentiated biotinylated peptidic or carbohydrate structures from their native counterparts. Conclusions Molecularly imprinted ultra thin films can be used for the selective recognition of biotinylated structures in a quartz crystal microbalance sensing platform. These films are stable for periods of at least a month. This strategy should prove of interest for use in other sensing and assay systems. PMID:24655809

  11. On the intermediacy of carboxyphosphate in biotin-dependent carboxylations

    SciTech Connect

    Ogita, Takeshi ); Knowles, J.R. )

    1988-10-18

    In the ATP-dependent carboxylation of biotin that is catalyzed by most biotin-dependent carboxylases, a fundamental mechanistic question is whether the ATP activates bicarbonate (via the formation of carboxyphosphate as an intermediate) or whether the ATP activates biotin (via the formation of O-phosphobiotin). The authors have resorted to three mechanistic tests using the biotin carboxylase subunit of acetyl-CoA carboxylase from Escherichia coli: positional isotope exchange, intermediate trapping, and {sup 18}O tracer experiments on the ATPase activity. First, no catalysis of positional isotope exchange in adenosine 5{prime}-(({alpha},{beta}-{sup 18}O,{beta},{beta}-{sup 18}O{sub 2})triphosphate) was observed when either biotin or bicarbonate was absent, nor was any exchange seen in the presence of both N-1-methylbiotin and bicarbonate. Second, the putative carboxyphosphate intermediate could not be trapped as its trimethyl ester, under conditions of incubation and analysis where the authentic triester was shown to be adequately stable. In the third test, however, they showed that the ATPase activity of biotin carboxylase that is seen in the absence of biotin, an activity that is known to parallel the normal carboxylase reaction when biotin is present, occurs with the transfer of an {sup 18}O label directly from ({sup 18}O)bicarbonate into the product P{sub i}. This result suggests that the bicarbonate-dependent biotin-independent ATPase reaction catalyzed by biotin carboxylase goes via carboxyphosphate and that the carboxylation of biotin itself may proceed analogously.

  12. Pre-hybridisation: an efficient way of suppressing endogenous biotin-binding activity inherent to biotin-streptavidin detection system.

    PubMed

    Ahmed, Raju; Spikings, Emma; Zhou, Shaobo; Thompsett, Andrew; Zhang, Tiantian

    2014-04-01

    Endogenous biotin or biotinylated protein binding activity is a major drawback to biotin-avidin/streptavidin detection system. The avidin/streptavidin conjugate used to detect the complex of the biotinylated secondary antibody and the primary antibody binds to endogenous biotin or biotinylated proteins leading to non-specific signals. In Western blot, the endogenous biotin or biotinylated protein binding activity is usually manifested in the form of ~72kDa, ~75kDa and ~150kDa protein bands, which often mask the signals of interest. To overcome this problem, a method based on prior hybridisation of the biotinylated secondary antibody and the streptavidin conjugate was developed. The method was tested alongside the conventional biotin-streptavidin method on proteins extracted from zebrafish (Danio rerio) embryos. Results showed that the newly developed method efficiently suppresses the endogenous biotin or biotinylated protein binding activity inherent to the biotin-streptavidin detection system.

  13. Design and synthesis of biotin analogues reversibly binding with streptavidin.

    PubMed

    Yamamoto, Tomohiro; Aoki, Kiyoshi; Sugiyama, Akira; Doi, Hirofumi; Kodama, Tatsuhiko; Shimizu, Yohei; Kanai, Motomu

    2015-04-01

    Two new biotin analogues, biotin carbonate 5 and biotin carbamate 6, have been synthesized. These molecules were designed to reversibly bind with streptavidin by replacing the hydrogen-bond donor NH group(s) of biotin's cyclic urea moiety with oxygen. Biotin carbonate 5 was synthesized from L-arabinose (7), which furnishes the desired stereochemistry at the 3,4-cis-dihydroxy groups, in 11% overall yield (over 10 steps). Synthesis of biotin carbamate 6 was accomplished from L-cysteine-derived chiral aldehyde 33 in 11% overall yield (over 7 steps). Surface plasmon resonance analysis of water-soluble biotin carbonate analogue 46 and biotin carbamate analogue 47 revealed that KD values of these compounds for binding to streptavidin were 6.7×10(-6)  M and 1.7×10(-10)  M, respectively. These values were remarkably greater than that of biotin (KD =10(-15)  M), and thus indicate the importance of the nitrogen atoms for the strong binding between biotin and streptavidin.

  14. Regulation of immunological and inflammatory functions by biotin.

    PubMed

    Kuroishi, Toshinobu

    2015-12-01

    Biotin is a water-soluble B-complex vitamin and is well-known as a co-factor for 5 indispensable carboxylases. Holocarboxylase synthetase (HLCS) catalyzes the biotinylation of carboxylases and other proteins, whereas biotinidase catalyzes the release of biotin from biotinylated peptides. Previous studies have reported that nutritional biotin deficiency and genetic defects in either HLCS or biotinidase induces cutaneous inflammation and immunological disorders. Since biotin-dependent carboxylases involve various cellular metabolic pathways including gluconeogenesis, fatty acid synthesis, and the metabolism of branched-chain amino acids and odd-chain fatty acids, metabolic abnormalities may play important roles in immunological and inflammatory disorders caused by biotin deficiency. Transcriptional factors, including NF-κB and Sp1/3, are also affected by the status of biotin, indicating that biotin regulates immunological and inflammatory functions independently of biotin-dependent carboxylases. An in-vivo analysis with a murine model revealed the therapeutic effects of biotin supplementation on metal allergies. The novel roles of biotinylated proteins and their related enzymes have recently been reported. Non-carboxylase biotinylated proteins induce chemokine production. HLCS is a nuclear protein involved in epigenetic and chromatin regulation. In this review, comprehensive knowledge on the regulation of immunological and inflammatory functions by biotin and its potential as a therapeutic agent is discussed.

  15. In vivo studies of biotin absorption in distal rat intestine

    SciTech Connect

    Bowman, B.B.; Rosenberg, I.H.

    1986-03-01

    The authors have extended their previous studies of biotin absorption in rat proximal jejunum (PJ) to examine biotin absorptive capacity of rat ileum (I) and proximal colon (PC) using in vivo intestinal loop technique. Intestinal loops (2.5 cm) were filled with 0.3 ml of solution containing (/sup 3/H)-biotin and (/sup 14/C)-inulin in phosphate buffer, pH 6.5. Biotin absorption was determined on the basis of luminal biotin disappearance after correction for inulin recovery and averaged (pmol/loop-10 min; X +/- SEM). In related experiments, 5-cm loops of PJ, distal I (DI), or PC were filled with 0.5 ml of solution of similar composition (1.0 ..mu..M biotin). The abdominal cavity was closed and the rats were allowed to recover from anesthesia, then sacrificed 3 hr after injection. Biotin absorption averaged 96.2% (PJ), 93.2% (DI), and 25.8% (PC) of the dose administered. These differences were reflected in the radioactive biotin content of plasma and intestinal loop, kidney, and liver. These data demonstrate significant biotin absorption in rat DI and PC, as required if the intestinal microflora are to be considered as a source of biotin for the host.

  16. Effects of biotin supplementation on serum biotin levels and physical properties of samples of solar horn of Holstein cows

    PubMed Central

    2004-01-01

    Abstract Effects of dietary biotin supplementation on serum biotin levels and physical properties of sole horn of 40 Holstein cows were evaluated. The mean serum biotin level in biotin-supplemented cows after 10 mo of biotin supplementation (1163.2 ± 76.2 pg/mL) was significantly higher (P = 0.007) than that in control cows (382.0 ± 76.2 pg/mL). The sole horn of biotin-supplemented cows was significantly harder (P = 0.026) and had a significantly lower moisture content (P = 0.021) than that of control cows. No morphologic differences in horn tubules or intertubular horn were found between the biotin-supplemented and control cows. The total lipid content of sole horn was significantly higher (P = 0.030) in the biotin-supplemented cows than in the control cows. These results suggest that dietary biotin supplementation causes increases in serum biotin levels and changes in physical properties and fat content of sole horn. PMID:15188952

  17. Biotin nutritional status of vegans, lactoovovegetarians, and nonvegetarians.

    PubMed

    Lombard, K A; Mock, D M

    1989-09-01

    Urinary excretion of biotin (total avidin-binding substances) was measured in adults and children who were adhering to one of the following self-selected diets: strict vegetarian (vegan), lactoovovegetarian, or mixed (containing meat and dairy products as well as plant-derived foods). In a subset of subjects, plasma biotin concentrations were also measured. In adults the biotin excretion rate was significantly greater in the vegan group than in either the lactoovovegetarian or the mixed-diet groups; the latter were not significantly different from one another. In children the biotin excretion rates in both the vegan group and the lactoovovegetarin group were significantly greater than in the mixed-diet group. A similar trend (vegan greater than lactoovovegetarian greater than mixed) was detected in the plasma concentrations of biotin of adults and children but differences were not generally statistically significant. These observations provide evidence that the biotin nutritional status of vegans is not impaired.

  18. Functional loop dynamics of the streptavidin-biotin complex.

    PubMed

    Song, Jianing; Li, Yongle; Ji, Changge; Zhang, John Z H

    2015-01-20

    Accelerated molecular dynamics (aMD) simulation is employed to study the functional dynamics of the flexible loop(3-4) in the strong-binding streptavidin-biotin complex system. Conventional molecular (cMD) simulation is also performed for comparison. The present study reveals the following important properties of the loop dynamics: (1) The transition of loop(3-4) from open to closed state is observed in 200 ns aMD simulation. (2) In the absence of biotin binding, the open-state streptavidin is more stable, which is consistent with experimental evidences. The free energy (ΔG) difference is about 5 kcal/mol between two states. But with biotin binding, the closed state is more stable due to electrostatic and hydrophobic interactions between the loop(3-4) and biotin. (3) The closure of loop(3-4) is concerted to the stable binding of biotin to streptavidin. When the loop(3-4) is in its open-state, biotin moves out of the binding pocket, indicating that the interactions between the loop(3-4) and biotin are essential in trapping biotin in the binding pocket. (4) In the tetrameric streptavidin system, the conformational change of the loop(3-4) in each monomer is independent of each other. That is, there is no cooperative binding for biotin bound to the four subunits of the tetramer.

  19. Functional Loop Dynamics of the Streptavidin-Biotin Complex

    NASA Astrophysics Data System (ADS)

    Song, Jianing; Li, Yongle; Ji, Changge; Zhang, John Z. H.

    2015-01-01

    Accelerated molecular dynamics (aMD) simulation is employed to study the functional dynamics of the flexible loop3-4 in the strong-binding streptavidin-biotin complex system. Conventional molecular (cMD) simulation is also performed for comparison. The present study reveals the following important properties of the loop dynamics: (1) The transition of loop3-4 from open to closed state is observed in 200 ns aMD simulation. (2) In the absence of biotin binding, the open-state streptavidin is more stable, which is consistent with experimental evidences. The free energy (ΔG) difference is about 5 kcal/mol between two states. But with biotin binding, the closed state is more stable due to electrostatic and hydrophobic interactions between the loop3-4 and biotin. (3) The closure of loop3-4 is concerted to the stable binding of biotin to streptavidin. When the loop3-4 is in its open-state, biotin moves out of the binding pocket, indicating that the interactions between the loop3-4 and biotin are essential in trapping biotin in the binding pocket. (4) In the tetrameric streptavidin system, the conformational change of the loop3-4 in each monomer is independent of each other. That is, there is no cooperative binding for biotin bound to the four subunits of the tetramer.

  20. Biotin ameliorates muscle cramps of hemodialysis patients: a prospective trial.

    PubMed

    Oguma, Shiro; Ando, Itiro; Hirose, Takuo; Totsune, Kazuhito; Sekino, Hiroshi; Sato, Hiroshi; Imai, Yutaka; Fujiwara, Masako

    2012-01-01

    Patients with renal failure undergoing hemodialysis often have muscle cramps during and after the dialysis therapy. Muscle cramps are defined as the sudden onset of a prolonged involuntary muscle contraction accompanied with severe pain, resulting in early termination of a HD session and inadequate dialysis. The etiology of the cramps is unknown and effective anti-cramp medicine is not available. We have hypothesized that water-soluble vitamins are deficient in HD patients. Accordingly, we administrated biotin to 14 patients who had frequent muscle cramps during HD sessions. Oral administration of 1 mg/day biotin promptly reduced the onset and the severity of cramps in 12 patients both during and after HD. Then, the plasma biotin levels were measured by an enzyme-linked immunosorbent assay method (ELISA) in HD patients, including 14 patients with cramps and 13 patients without cramps, and 11 healthy volunteers. Plasma biotin levels were elevated in 27 HD patients at baseline compared with healthy volunteers [451 (377 - 649) vs. 224 (148 - 308) ng/l, median (lower-upper quartiles); p < 0.0001]. Unexpectedly, among the 14 cramp patients, the biotin levels were significantly higher in biotin-ineffective 7 patients than biotin-effective 7 patients [1,064 (710 - 1,187) vs. 445 (359 - 476) ng/l; p < 0.001]. Thus, the biotins measured by ELISA may consist of not only intact biotin but also its metabolites that do not function as a vitamin. In conclusion, biotin administration is one choice to relieve HD patients from muscle cramps regardless of their elevated plasma biotin levels.

  1. A Biotin Biosynthesis Gene Restricted to Helicobacter.

    PubMed

    Bi, Hongkai; Zhu, Lei; Jia, Jia; Cronan, John E

    2016-02-12

    In most bacteria the last step in synthesis of the pimelate moiety of biotin is cleavage of the ester bond of pimeloyl-acyl carrier protein (ACP) methyl ester. The paradigm cleavage enzyme is Escherichia coli BioH which together with the BioC methyltransferase allows synthesis of the pimelate moiety by a modified fatty acid biosynthetic pathway. Analyses of the extant bacterial genomes showed that bioH is absent from many bioC-containing bacteria and is replaced by other genes. Helicobacter pylori lacks a gene encoding a homologue of the known pimeloyl-ACP methyl ester cleavage enzymes suggesting that it encodes a novel enzyme that cleaves this intermediate. We isolated the H. pylori gene encoding this enzyme, bioV, by complementation of an E. coli bioH deletion strain. Purified BioV cleaved the physiological substrate, pimeloyl-ACP methyl ester to pimeloyl-ACP by use of a catalytic triad, each member of which was essential for activity. The role of BioV in biotin biosynthesis was demonstrated using a reconstituted in vitro desthiobiotin synthesis system. BioV homologues seem the sole pimeloyl-ACP methyl ester esterase present in the Helicobacter species and their occurrence only in H. pylori and close relatives provide a target for development of drugs to specifically treat Helicobacter infections.

  2. A Biotin Biosynthesis Gene Restricted to Helicobacter

    PubMed Central

    Bi, Hongkai; Zhu, Lei; Jia, Jia; Cronan, John E.

    2016-01-01

    In most bacteria the last step in synthesis of the pimelate moiety of biotin is cleavage of the ester bond of pimeloyl-acyl carrier protein (ACP) methyl ester. The paradigm cleavage enzyme is Escherichia coli BioH which together with the BioC methyltransferase allows synthesis of the pimelate moiety by a modified fatty acid biosynthetic pathway. Analyses of the extant bacterial genomes showed that bioH is absent from many bioC-containing bacteria and is replaced by other genes. Helicobacter pylori lacks a gene encoding a homologue of the known pimeloyl-ACP methyl ester cleavage enzymes suggesting that it encodes a novel enzyme that cleaves this intermediate. We isolated the H. pylori gene encoding this enzyme, bioV, by complementation of an E. coli bioH deletion strain. Purified BioV cleaved the physiological substrate, pimeloyl-ACP methyl ester to pimeloyl-ACP by use of a catalytic triad, each member of which was essential for activity. The role of BioV in biotin biosynthesis was demonstrated using a reconstituted in vitro desthiobiotin synthesis system. BioV homologues seem the sole pimeloyl-ACP methyl ester esterase present in the Helicobacter species and their occurrence only in H. pylori and close relatives provide a target for development of drugs to specifically treat Helicobacter infections. PMID:26868423

  3. The Bacillus thuringiensis insecticidal toxin binds biotin-containing proteins.

    PubMed Central

    Du, C; Nickerson, K W

    1996-01-01

    Brush border membrane vesicles from larvae of the tobacco hornworm, Manduca sexta, contain protein bands of 85 and 120 kDa which react directly with streptavidin conjugated to alkaline phosphatase. The binding could be prevented either by including 10 microM biotin in the reaction mixture or by prior incubation of the brush border membrane vesicles with an activated 60- to 65-kDa toxin from Bacillus thuringiensis HD-73. The ability of B. thuringiensis toxins to recognize biotin-containing proteins was confirmed by their binding to pyruvate carboxylase, a biotin-containing enzyme, as well as to biotinylated ovalbumin and biotinylated bovine serum albumin but not to their nonbiotinylated counterparts. Activated HD-73 toxin also inhibited the enzymatic activity of pyruvate carboxylase. The biotin binding site is likely contained in domain III of the toxin. Two highly conserved regions within domain III are similar in sequence to the biotin binding sites of avidin, streptavidin, and a biotin-specific monoclonal antibody. In particular, block 4 of the B. thuringiensis toxin contains the YAS biotin-specific motif. On the basis of its N-terminal amino acid sequence, the 120-kDa biotin-containing protein is totally distinct from the 120-kDa aminopeptidase N reported to be a receptor for Cry1Ac toxin. PMID:8702286

  4. Structural origins of high-affinity biotin binding to streptavidin.

    PubMed

    Weber, P C; Ohlendorf, D H; Wendoloski, J J; Salemme, F R

    1989-01-06

    The high affinity of the noncovalent interaction between biotin and streptavidin forms the basis for many diagnostic assays that require the formation of an irreversible and specific linkage between biological macromolecules. Comparison of the refined crystal structures of apo and a streptavidin:biotin complex shows that the high affinity results from several factors. These factors include the formation of multiple hydrogen bonds and van der Waals interactions between biotin and the protein, together with the ordering of surface polypeptide loops that bury the biotin in the protein interior. Structural alterations at the biotin binding site produce quaternary changes in the streptavidin tetramer. These changes apparently propagate through cooperative deformations in the twisted beta sheets that link tetramer subunits.

  5. Biotin Production and Utilization in a Sewage Treatment Lagoon 1

    PubMed Central

    Fillipi, Gordon M.; Vennes, John W.

    1971-01-01

    Biotin, in a sewage oxidation lagoon also receiving potato processing wastes, was observed to increase two logs during the summer period of waste stabilization and then to decline to near earlier concentrations. Three organisms, Aerobacter aerogenes, Chlorella vulgaris, and Thiocapsa floridana, were at least partially responsible for these fluctuations; the latter two organisms were associated with biotin utilization and the former with biotin production. Since copious quantities of biotin are produced in these waste treatment facilities, the vitamin may act as a useful indicator of microbial action on certain organic molecules, especially in domestic and industrial wastes such as those from municipalities and potato and sugar beet processing plants. Furthermore, the presence of biotin in rivers and streams may be indicative of the discharge of incompletely stabilized wastes from these sources. PMID:4939123

  6. Minfong Ho: Politics in Prose

    ERIC Educational Resources Information Center

    Wiggins, Joy L.

    2006-01-01

    In this article, the author interviews Minfong Ho, an award-winning Thai writer of children's and young adult novels. Ho was born in Burma to Chinese parents in 1951, raised in Singapore and Thailand, educated in Bangkok, Taiwan, and at Cornell University in New York. Ho's first novel, "Sing to the Dawn," won first prize from the Council of…

  7. The Biotin/Avidin complex adhesion force

    NASA Astrophysics Data System (ADS)

    Balsera, Manel A.; Izrailev, Sergei; Stepaniants, Sergey; Oono, Yoshitsugu; Schulten, Klaus

    1997-03-01

    The vitamin Biotin and the protein avidin form one of the strongest non-covalent bonds between biological molecules. We have performed molecular and stochastic dynamic modeling of the unbinding of this complex(Izrailev et al., Biophysical Journal, In press). These simulations provide insight into the effect of particular residues and water on the tight binding of the system. With the aid of simple phenomenological models we have related qualitatively our results to Atomic Force Microscopy adhesion force measurements (E.-L. Florin, V. T. Moy and H. E. Gaub Science) 264:415-417 and kinetic dissociation experiments( A. Chilcotti and P. S. Stayton, J. Am. Chem. Soc.) 117:10622-10628. We will discuss the difficulties preventing a more quantitative understanding of the unbinding force and kinetics.

  8. Tropospheric HO determination by FAGE

    NASA Technical Reports Server (NTRS)

    Hard, T. M.; Obrien, R. J.; Chan, C. Y.; Mehrabzadeh, A. A.

    1986-01-01

    In the detection of tropospheric HO by laser excited fluorescence, and alternative air-sampling method, named FAGE (Fluorescence Assay with Gas Expansion) was introduced. Here the air is expanded through a nozzle prior to excitation, in order to improve the ratio of the HO signal to the scattered, fluorescent, and photolytic backgrounds. The improvement comes from the differing pressure dependence of the intensities of these four terms, as well as the distinguishability of their temporal waveforms at low pressures when excited by a pulsed laser. HO has been excited by a YAG/dye laser. Other lasers and pumping paths may perform as well or better in this method. With FAGE, chemical modulation of the HO signal was achieved by hydrocarbon addition to the nozzle flow, converting photolytic HO from an interference to a background. Chemical calibration of the instrumental response to external HO was also achieved, by hydrocarbon decay, at HO concentrations within the ambient range.

  9. Early Mechanistic Events in Biotin Dissociation from Streptavidin

    SciTech Connect

    Hyre, D. E.

    2002-01-01

    The streptavidin-biotin system has provided a unique opportunity to investigate the molecular details of ligand dissociation pathways. An underlying mechanistic question is whether ligand dissociation proceeds with a relatively ordered process of bond breaking and ligand escape. Here we report a joint computational and crystallographic study of the earliest events in biotin dissociation. In molecular dynamics potential of mean force simulations, a water molecule from a defined access channel intercalated into the hydrogen bond between Asp 128 and biotin, bridging them and stabilizing an intermediate state. In forced biotin dissociation simulations, this event led to subsequent bond breaking steps and ligand escape. In equilibrium simulations, the water molecule was sometimes observed to move back to the access channel with re-formation of the biotin hydrogen bond. Analysis of streptavidin crystal structures revealed a close overlap of crystallographically defined and simulated waters in the water access channel. These results suggest that biotin dissociation is initiated by stochastic coupling of water entry with lengthening of a specific biotin hydrogen-bonding interaction.

  10. Marginal Biotin Deficiency Is Teratogenic in ICR Mice1,2

    PubMed Central

    Mock, Donald M.; Mock, Nell I.; Stewart, Christopher W.; LaBorde, James B.; Hansen, Deborah K.

    2006-01-01

    The incidence of marginal biotin deficiency in normal human gestation is approximately one in three. In ICR mice, maternal biotin deficiency results in cleft palate, micrognathia, microglossia and limb hypoplasia. However, the relationships among the severity of maternal biotin deficiency, fetal biotin status and malformations have not been reported. This study utilized validated indices of biotin status to investigate the relationships among maternal biotin status, fetal biotin status and the rate of fetal malformations in ICR mice. Biotin status was controlled by feeding diets with varying egg white concentration. In dams and fetuses, biotin status was assessed by hepatic biotin content and hepatic activity of the biotin-dependent enzyme propionyl-CoA carboxylase; in dams, status was also assessed by urinary excretion of biotin and 3-hydroxyisovaleric acid. Malformations were assessed morphologically. Biotin was measured by HPLC/avidin-binding assay. Propionyl-CoA carboxylase (PCC) activity was determined by H14CO3 incorporation. 3-Hydroxyisovaleric acid concentration was determined by GC/MS. Although no overt signs of deficiency appeared, metabolic disturbances caused by biotin deficiency were detectable in dams and fetuses. These disturbances increased with increasing egg white. Fetal biotin status correlated significantly with maternal biotin status (fetal vs. dam hepatic biotin, r = 0.671; fetal vs. dam PCC activity, r = 0.70). The incidences of malformations were strikingly dependent on egg white concentration. We conclude that in ICR mice, marginal maternal biotin deficiency causes fetal biotin deficiency. We speculate that the fetal malformations are primarily the consequence of fetal biotin deficiency. Because murine malformations appeared at degrees of biotin deficiency that are similar to those in human gestation, we speculate that some human fetal malformations may be caused by biotin deficiency. PMID:12888630

  11. Biotin-dependent Enzymes: the Work of Feodor Lynen

    PubMed Central

    Kresge, Nicole; Simoni, Robert D.; Hill, Robert L.

    2009-01-01

    The Enzymatic Synthesis of Holotranscarboxylase from Apotranscarboxylase and (+)-Biotin. I. Purification of the Apoenzyme and Synthetase; Characteristics of the Reaction (Lane, M. D., Young, D. L., and Lynen, F. (1964)J. Biol. Chem.239, 2858–2864)

  12. Preparation of Conjugates of Cytotoxic Lupane Triterpenes with Biotin.

    PubMed

    Soural, Miroslav; Hodon, Jiri; Dickinson, Niall J; Sidova, Veronika; Gurska, Sona; Dzubak, Petr; Hajduch, Marian; Sarek, Jan; Urban, Milan

    2015-12-16

    To better understand the mechanism of action of antitumor triterpenes, we are developing methods to identify their molecular targets. A promising method is based on combination of quantitative proteomics with SILAC and uses active compounds anchored to magnetic beads via biotin-streptavidin interaction. We developed a simple and fast solid-phase synthetic technique to connect terpenes to biotin through a linker. Betulinic acid was biotinylated from three different conjugation sites for use as a standard validation tool since many molecular targets of this triterpene are already known. Then, a set of four other cytotoxic triterpenoids was biotinylated. Biotinylated terpenes were similarly cytotoxic to their nonbiotinylated parents, which suggests that the target identification should not be influenced by linker or biotin. The developed solid-phase synthetic approach is the first attempt to use solid-phase synthesis to connect active triterpenes to biotin and is applicable as a general procedure for routine conjugation of triterpenes with other molecules of choice.

  13. Fluorescent Biotin Analogues for Microstructure Patterning and Selective Protein Immobilization.

    PubMed

    Krishna, K Vijaya; Ghosh, Subhadip; Sharma, Bikramjit; Singh, Leeju; Mukherjee, Saptarshi; Verma, Sandeep

    2015-11-24

    Benzyl substitution on ureido nitrogens of biotin led to manifestation of aggregation-induced emission, which was studied by steady-state fluorescence, microscopy, and TD-DFT, providing a rationale into the observed photophysical behavior. Besides exhibiting solvatochromism, the biotin derivatives revealed emission peaks centered at ∼430 and 545 nm, which has been attributed to the π-π stacking interactions. Our TD-DFT results also correlate the spectroscopic data and quantify the nature of transitions involved. The isothermal titration calorimetry data substantiates that the binding of the biotin derivatives with avidin are pretty strong. These derivatives on lithographic patterning present a platform for site specific strept(avidin) immobilization, thus opening avenues for potential applications exploiting these interactions. The fluorescent biotin derivatives can thus find applications in cellular biology and imaging.

  14. Kinetic spectrophotometric determination of biotin in pharmaceutical preparations.

    PubMed

    Walash, M I; Rizk, M; Sheribah, Z A; Salim, M M

    2008-09-01

    A simple accurate kinetic spectrophotometric method was developed for the determination of biotin in pure form and pharmaceutical preparations. The proposed method is based on a catalytic acceleration of biotin on the reaction between sodium azide and tri-iodide in an aqueous solution. Concentration range of 4-16 μg/mL for biotin was determined by measuring the decrease in the absorbance of tri-iodide at 348 nm by a fixed time method. The decrease in absorbance after 14 min from the initiation of the reaction was markedly correlated to the concentration with correlation coefficient of 0.9999. The detection limit (LOD) of biotin was 0.18 μg/mL while quantitation limit (LOQ) was 0.54 μg/mL. The percentage recovery of the spiked samples was 100.08 ± 0.761. The proposed procedure was successfully applied for the determination of biotin in its pharmaceutical preparations with mean recoveries of 101.17 ± 2.05 and 97.87 ± 1.50 for biotin ampoules and capsules, respectively. The results obtained were in good agreement with those obtained using official method.

  15. Link between intraphagosomal biotin and rapid phagosomal escape in Francisella

    PubMed Central

    Napier, Brooke A.; Meyer, Lena; Bina, James E.; Miller, Mark A.; Sjöstedt, Anders; Weiss, David S.

    2012-01-01

    Cytosolic bacterial pathogens require extensive metabolic adaptations within the host to replicate intracellularly and cause disease. In phagocytic cells such as macrophages, these pathogens must respond rapidly to nutrient limitation within the harsh environment of the phagosome. Many cytosolic pathogens escape the phagosome quickly (15–60 min) and thereby subvert this host defense, reaching the cytosol where they can replicate. Although a great deal of research has focused on strategies used by bacteria to resist antimicrobial phagosomal defenses and transiently pass through this compartment, the metabolic requirements of bacteria in the phagosome are largely uncharacterized. We previously identified a Francisella protein, FTN_0818, as being essential for intracellular replication and involved in virulence in vivo. We now show that FTN_0818 is involved in biotin biosynthesis and required for rapid escape from the Francisella-containing phagosome (FCP). Addition of biotin complemented the phagosomal escape defect of the FTN_0818 mutant, demonstrating that biotin is critical for promoting rapid escape during the short time that the bacteria are in the phagosome. Biotin also rescued the attenuation of the FTN_0818 mutant during infection in vitro and in vivo, highlighting the importance of this process. The key role of biotin in phagosomal escape implies biotin may be a limiting factor during infection. We demonstrate that a bacterial metabolite is required for phagosomal escape of an intracellular pathogen, providing insight into the link between bacterial metabolism and virulence, likely serving as a paradigm for other cytosolic pathogens. PMID:23071317

  16. Biotin and Lipoic Acid: Synthesis, Attachment and Regulation

    PubMed Central

    Cronan, John E.

    2014-01-01

    Summary Two vitamins, biotin and lipoic acid, are essential in all three domains of life. Both coenzymes function only when covalently attached to key metabolic enzymes. There they act as “swinging arms” that shuttle intermediates between two active sites (= covalent substrate channeling) of key metabolic enzymes. Although biotin was discovered over 100 years ago and lipoic acid 60 years ago, it was not known how either coenzyme is made until recently. In Escherichia coli the synthetic pathways for both coenzymes have now been worked out for the first time. The late steps of biotin synthesis, those involved in assembling the fused rings, were well-described biochemically years ago, although recent progress has been made on the BioB reaction, the last step of the pathway in which the biotin sulfur moiety is inserted. In contrast, the early steps of biotin synthesis, assembly of the fatty acid-like “arm” of biotin were unknown. It has now been demonstrated that the arm is made by using disguised substrates to gain entry into the fatty acid synthesis pathway followed by removal of the disguise when the proper chain length is attained. The BioC methyltransferase is responsible for introducing the disguise and the BioH esterase for its removal. In contrast to biotin, which is attached to its cognate proteins as a finished molecule, lipoic acid is assembled on its cognate proteins. An octanoyl moiety is transferred from the octanoyl-ACP of fatty acid synthesis to a specific lysine residue of a cognate protein by the LipB octanoyl transferase followed by sulfur insertion at carbons C6 and C8 by the LipA lipoyl synthetase. Assembly on the cognate proteins regulates the amount of lipoic acid synthesized and thus there is no transcriptional control of the synthetic genes. In contrast transcriptional control of the biotin synthetic genes is wielded by a remarkably sophisticated, yet simple, system, exerted through BirA a dual function protein that both represses

  17. Salmonella infection inhibits intestinal biotin transport: cellular and molecular mechanisms.

    PubMed

    Ghosal, Abhisek; Jellbauer, Stefan; Kapadia, Rubina; Raffatellu, Manuela; Said, Hamid M

    2015-07-15

    Infection with the nontyphoidal Salmonella is a common cause of food-borne disease that leads to acute gastroenteritis/diarrhea. Severe/prolonged cases of Salmonella infection could also impact host nutritional status, but little is known about its effect on intestinal absorption of vitamins, including biotin. We examined the effect of Salmonella enterica serovar Typhimurium (S. typhimurium) infection on intestinal biotin uptake using in vivo (streptomycin-pretreated mice) and in vitro [mouse (YAMC) and human (NCM460) colonic epithelial cells, and human intestinal epithelial Caco-2 cells] models. The results showed that infecting mice with wild-type S. typhimurium, but not with its nonpathogenic isogenic invA spiB mutant, leads to a significant inhibition in jejunal/colonic biotin uptake and in level of expression of the biotin transporter, sodium-dependent multivitamin transporter. In contrast, infecting YAMC, NCM460, and Caco-2 cells with S. typhimurium did not affect biotin uptake. These findings suggest that the effect of S. typhimurium infection is indirect and is likely mediated by proinflammatory cytokines, the levels of which were markedly induced in the intestine of S. typhimurium-infected mice. Consistent with this hypothesis, exposure of NCM460 cells to the proinflammatory cytokines TNF-α and IFN-γ led to a significant inhibition of biotin uptake, sodium-dependent multivitamin transporter expression, and activity of the SLC5A6 promoter. The latter effects appear to be mediated, at least in part, via the NF-κB signaling pathway. These results demonstrate that S. typhimurium infection inhibits intestinal biotin uptake, and that the inhibition is mediated via the action of proinflammatory cytokines.

  18. Salmonella infection inhibits intestinal biotin transport: cellular and molecular mechanisms

    PubMed Central

    Ghosal, Abhisek; Jellbauer, Stefan; Kapadia, Rubina; Raffatellu, Manuela

    2015-01-01

    Infection with the nontyphoidal Salmonella is a common cause of food-borne disease that leads to acute gastroenteritis/diarrhea. Severe/prolonged cases of Salmonella infection could also impact host nutritional status, but little is known about its effect on intestinal absorption of vitamins, including biotin. We examined the effect of Salmonella enterica serovar Typhimurium (S. typhimurium) infection on intestinal biotin uptake using in vivo (streptomycin-pretreated mice) and in vitro [mouse (YAMC) and human (NCM460) colonic epithelial cells, and human intestinal epithelial Caco-2 cells] models. The results showed that infecting mice with wild-type S. typhimurium, but not with its nonpathogenic isogenic invA spiB mutant, leads to a significant inhibition in jejunal/colonic biotin uptake and in level of expression of the biotin transporter, sodium-dependent multivitamin transporter. In contrast, infecting YAMC, NCM460, and Caco-2 cells with S. typhimurium did not affect biotin uptake. These findings suggest that the effect of S. typhimurium infection is indirect and is likely mediated by proinflammatory cytokines, the levels of which were markedly induced in the intestine of S. typhimurium-infected mice. Consistent with this hypothesis, exposure of NCM460 cells to the proinflammatory cytokines TNF-α and IFN-γ led to a significant inhibition of biotin uptake, sodium-dependent multivitamin transporter expression, and activity of the SLC5A6 promoter. The latter effects appear to be mediated, at least in part, via the NF-κB signaling pathway. These results demonstrate that S. typhimurium infection inhibits intestinal biotin uptake, and that the inhibition is mediated via the action of proinflammatory cytokines. PMID:25999427

  19. Biotin-deficient diet induces chromosome misalignment and spindle defects in mouse oocytes.

    PubMed

    Tsuji, Ai; Nakamura, Toshinobu; Shibata, Katsumi

    2015-01-01

    Increased abnormal oocytes due to meiotic chromosome misalignment and spindle defects lead to elevated rates of infertility, miscarriage, and trisomic conceptions. Here, we investigated the effect of biotin deficiency on oocyte quality. Three-week-old female ICR mice were fed a biotin-deficient or control diet (0, 0.004 g biotin/kg diet) for 21 days. On day 22, these mouse oocytes were analyzed by immunofluorescence. Due to biotin, undernutrition increased the frequency of abnormal oocytes (the biotin deficient vs. control: 40 vs. 16%). Next, the remaining mice in the biotin-deficient group were fed a control or biotin-deficient diet from day 22 to 42. Although biotin nutritional status in the recovery group was restored, the frequency of abnormal oocytes in the recovery group was still higher than that in the control group (48 vs. 18%). Our results indicate that steady, sufficient biotin intake is required for the production of high-quality oocytes in mice.

  20. Functionally diverse biotin-dependent enzymes with oxaloacetate decarboxylase activity.

    PubMed

    Lietzan, Adam D; St Maurice, Martin

    2014-02-15

    Biotin-dependent enzymes catalyze carboxylation, decarboxylation and transcarboxylation reactions that participate in the primary metabolism of a wide range of organisms. In all cases, the overall reaction proceeds via two half reactions that take place in physically distinct active sites. In the first half-reaction, a carboxyl group is transferred to the 1-N' of a covalently tethered biotin cofactor. The tethered carboxybiotin intermediate subsequently translocates to a second active site where the carboxyl group is either transferred to an acceptor substrate or, in some bacteria and archaea, is decarboxylated to biotin and CO2 in order to power the export of sodium ions from the cytoplasm. A homologous carboxyltransferase domain is found in three enzymes that catalyze diverse overall reactions: carbon fixation by pyruvate carboxylase, decarboxylation and sodium transport by the biotin-dependent oxaloacetate decarboxylase complex, and transcarboxylation by transcarboxylase from Propionibacterium shermanii. Over the past several years, structural data have emerged which have greatly advanced the mechanistic description of these enzymes. This review assembles a uniform description of the carboxyltransferase domain structure and catalytic mechanism from recent studies of pyruvate carboxylase, oxaloacetate decarboxylase and transcarboxylase, three enzymes that utilize an analogous carboxyltransferase domain to catalyze the biotin-dependent decarboxylation of oxaloacetate.

  1. Molecular origins of the slow streptavidin-biotin dissociation kinetics

    SciTech Connect

    Chilkoti, A.; Stayton, P.S.

    1995-11-01

    The association of streptavidin and avidin with biotin is among the strongest known noncovalent protein-ligand interactions (K{sub a} nearly equals 2.5 x 10{sup 13} M{sup -1}) and is controlled by an exceptionally slow off-rate. We have used this model system to elucidate the role of aromatic tryptophan side-chain binding contacts in the dissociation reaction coordinate and relatedly to the construction of the activation barrier and to the structure of the transition state. We have also conducted a transition state analysis of the temperature-dependent dissociation kinetics, which along with the independent estimation of the equilibrium biotin-binding free energies and enthalpies has provided thermodynamic profiles defining the enthalpic, entropic, and free energy barriers to dissociation for the mutants relative to wild-type streptavidin. The increased biotin off-rate for W79F, which contacts the valeric acid moiety of biotin, and for W120F, which partially caps the bicyclic ring system, is caused largely by free energy destabilization of the ligand-bound ground state relative to wild-type streptavidin. W79F displays an increased equilibrium binding enthalpy relative to wild-type, and thus streptavidin sacrifices potential binding enthalpy to minimize the entropic costs of biotin immobilization. 26 refs., 5 figs., 4 tabs.

  2. Biotin determination in food supplements by an electrochemical magneto biosensor.

    PubMed

    Kergaravat, Silvina V; Gómez, Gabriel A; Fabiano, Silvia N; Laube Chávez, Tamara I; Pividori, María I; Hernández, Silvia R

    2012-08-15

    An electrochemical magneto biosensor for the rapid determination of biotin in food samples is reported. The affinity reaction was performed on streptavidin-modified magnetic microbeads as a solid support in a direct competitive format. The biotinylated horseradish peroxidase enzyme (biotin-HRP) competes with free biotin in the sample for the binding sites of streptavidin on the magnetic microbeads. The modified magnetic beads were then easily captured by a magneto graphite-epoxy composite electrode and the electrochemical signal was based on the enzymatic activity of the HRP enzyme under the addition of H(2)O(2) as the substrate and o-phenilendiamine as cosubstrate. The response was electrochemically detected by square wave voltammetry. The limit of detection was 8.4×10(-8) mol L(--1) of biotin (20 μg L(--1)) with a dynamic range from 0.94 to 2.4×10(-7) mol L(--1). Biotin-fortified commercial dietary supplement and infant formula samples were evaluated obtaining good performances in the results. Total time of analysis was 40 min per 20 assays.

  3. Recent development of biotin conjugation in biological imaging, sensing, and target delivery.

    PubMed

    Ren, Wen Xiu; Han, Jiyou; Uhm, Soojin; Jang, Yu Jin; Kang, Chulhun; Kim, Jong-Hoon; Kim, Jong Seung

    2015-07-04

    Despite encouraging results from preliminary studies of anticancer therapies, the lack of tumor specificity remains an important issue in the modern pharmaceutical industry. New findings indicate that biotin or biotin-conjugates could be favorably assimilated by tumor cells that over-express biotin-selective transporters. Furthermore, biotin can form stable complexes with avidin and its bacterial counterpart streptavidin. The strong bridging between avidin and biotin moieties on other molecules is a proven adaptable tool with broad biological applications. Under these circumstances, a biotin moiety is certainly an attractive choice for live-cell imaging, biosensing, and target delivery.

  4. HO:LULF and HO:LULF Laser Materials

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P. (Inventor); Morrison, Clyde A. (Inventor); Filer, Elizabeth D. (Inventor); Jani, Mahendra G. (Inventor); Murray, Keith E. (Inventor); Lockard, George E. (Inventor)

    1998-01-01

    A laser host material LULF (LuLiF4) is doped with holmium (Ho) and thulium (Tm) to produce a new laser material that is capable of laser light production in the vicinity of 2 microns. The material provides an advantage in efficiency over conventional Ho lasers because the LULF host material allows for decreased threshold and upconversion over such hosts as YAG and YLF. The addition of Tm allows for pumping by commonly available GaAlAs laser diodes. For use with flashlamp pumping, erbium (Er) may be added as an additional dopant. For further upconversion reduction, the Tm can be eliminated and the Ho can be directly pumped.

  5. MORPHOLOGICAL ABERRATION OF ARTHROBACTER GLOBIFORMIS CELLS DUE TO BIOTIN DEFICIENCY.

    PubMed

    CHAN, E C

    1964-03-01

    Chan, E. C. S. (University of New Brunswick, Fredericton, New Brunswick, Canada). Morphological aberration of Arthrobacter globiformis cells due to biotin deficiency. J. Bacteriol. 87:641-651. 1964.-Morphological aberration of Arthrobacter globiformis strain 425 was shown to occur during growth in a chemically defined medium without added biotin. Such aberrant cells could revert back to normal coccoid forms upon inoculation into fresh medium supplemented with the vitamin. This abnormal cellular development occurred even when there was good growth (turbidity) or increase in total cell mass. Light photomicrographs of negative and cell-wall stains of the organism at different times of the morphological growth cycle are presented in support of these observations. The relationship between cellular aberration and the biochemical role of biotin is briefly discussed.

  6. Streptavidin and its biotin complex at atomic resolution

    SciTech Connect

    Le Trong, Isolde; Wang, Zhizhi; Hyre, David E.; Lybrand, Terry P.; Stayton, Patrick S.; Stenkamp, Ronald E.

    2011-09-01

    Analysis of atomic resolution crystal structures of wild-type streptavidin (1.03 Å) and its biotin complex (0.95 Å) indicate the range of conformational states taken on by this protein in the solid state. Most of the structural variation is found in the polypeptide loops between the strands in this β-sandwich protein. Atomic resolution crystallographic studies of streptavidin and its biotin complex have been carried out at 1.03 and 0.95 Å, respectively. The wild-type protein crystallized with a tetramer in the asymmetric unit, while the crystals of the biotin complex contained two subunits in the asymmetric unit. Comparison of the six subunits shows the various ways in which the protein accommodates ligand binding and different crystal-packing environments. Conformational variation is found in each of the polypeptide loops connecting the eight strands in the β-sandwich subunit, but the largest differences are found in the flexible binding loop (residues 45–52). In three of the unliganded subunits the loop is in an ‘open’ conformation, while in the two subunits binding biotin, as well as in one of the unliganded subunits, this loop ‘closes’ over the biotin–binding site. The ‘closed’ loop contributes to the protein’s high affinity for biotin. Analysis of the anisotropic displacement parameters included in the crystallographic models is consistent with the variation found in the loop structures and the view that the dynamic nature of the protein structure contributes to the ability of the protein to bind biotin so tightly.

  7. {sup 163}Ho based experiments

    SciTech Connect

    Gastaldo, Loredana

    2015-07-15

    The analysis of the endpoint region of the calorimetrically measured {sup 163}Ho electron capture spectrum is a very promising way to determine the mass of the electron neutrino. The achievable sensitivity of {sup 163}Ho-based experiments and the experimental challenges will be presented. Three large collaborations aim at developing large scale experiments able to reach sub-eV sensitivity. Presently pilot experiments are performed to demonstrate the possibility to calorimetrically measure high precision and high statistics {sup 163}Ho spectra. The different approaches as well as the state of the art of the experimental efforts for the three collaborations will be discussed.

  8. Biochemical Hyperthyroidism in a Newborn Baby Caused by Assay Interaction from Biotin Intake

    PubMed Central

    Bülow Pedersen, Inge; Laurberg, Peter

    2016-01-01

    We describe a case of biochemical neonatal thyrotoxicosis caused by biotin supplementation. Biotin may interact with thyroid function testing to imitate thyrotoxicosis with low thyroid-stimulating hormone and elevated triiodothyronine and thyroxine levels. PMID:27843813

  9. Plasma Levels of Biotin Metabolites Are Elevated in Hemodialysis Patients with Cramps.

    PubMed

    Fujiwara, Masako; Ando, Itiro; Yagi, Shigeaki; Nishizawa, Manabu; Oguma, Shiro; Satoh, Keisuke; Sato, Hiroshi; Imai, Yutaka

    2016-01-01

    Patients with renal failure undergoing hemodialysis (HD) are susceptible to muscle cramps during and after HD. Muscle cramps are defined as the sudden onset of a prolonged involuntary muscle contraction accompanied by severe pain. Through HD, water-soluble vitamins are drawn out with water. Since biotin, a water-soluble vitamin, plays an essential role as one of the coenzymes in producing energy, we have hypothesized that deficiency of biotin may be responsible for HD-associated cramps. We previously reported that biotin administration ameliorated the muscle cramps, despite the elevated plasma biotin levels before HD and biotin administration, as judged by an enzyme-linked immunosorbent assay (ELISA). However, the ELISA measures not only biotin but also total avidin-binding substances (TABS) including biotin metabolites. In the present study, we determined biotin in HD patients as well as healthy controls, using a newly developed method with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The plasma samples were collected from 28 HD patients (16 patients with cramps and 12 patients without cramps) before HD and biotin administration and from 11 controls. The results showed that the accumulation of biotin and TABS in plasma of HD patients compared to controls. Importantly, the levels of biotin metabolites, i.e. TABS subtracted by biotin, increased significantly in patients with cramps over those without cramps. Moreover, the levels of biotin metabolites were significantly higher in patients with a poor response to administered biotin, compared to those with a good response. We propose that accumulated biotin metabolites impair biotin's functions as a coenzyme.

  10. Two New Antimetabolites of Biotin: α-Methyldethiobiotin and α-Methylbiotin

    PubMed Central

    Hanka, L. J.; Martin, D. G.; Reineke, L. M.

    1972-01-01

    Two new antimetabolites of biotin were isolated from culture filtrates of Streptomyces lydicus: β-methyldethiobiotin and β-methylbiotin. 14C-biotin or 14C-pimelic acid was not incorporated into either of these antimetabolites by the growing culture. Neither of the compounds could substitute for the biotin requirement in Saccharomyces cerevisiae. Both compounds had a strong and rather specific antimicrobial effect against mycobacteria. Their antimicrobial activities were reversed by biotin. Both compounds had an affinity for avidin. PMID:4680803

  11. Compact Ho:YLF Laser

    NASA Technical Reports Server (NTRS)

    Hemmati, H.

    1988-01-01

    Longitudinal pumping by laser diodes increases efficiency. Improved holmium:yttrium lithium fluoride laser radiates as much as 56 mW of power at wavelength of 2.1 micrometer. New Ho:YLF laser more compact and efficient than older, more powerful devices of this type. Compact, efficient Ho:YLF laser based on recent successes in use of diode lasers to pump other types of solid-state lasers.

  12. Systematic evaluation of avidin-biotin interaction by fluorescence spectrophotometry

    NASA Astrophysics Data System (ADS)

    Sun, Shuguo; Huang, Xi; Ma, Meihu; Qiu, Ning; Cai, Zhaoxia; Luo, Zhang; Alies, Nichia Primadani

    2012-04-01

    The avidin-biotin interaction was evaluated systematically by fluorescence spectroscopy under different conditions of temperature, pressure, pH, metal ions, incubation time and initial avidin concentration. The binding constant was calculated according to the modified Stern-Volmer equation, which deduced the existence of static quenching mechanism. The data obtained revealed that avidin-biotin interaction exhibited temperature, pH, metal ions, incubation time and initial avidin concentration sensitivity. The binding constants decreased with increase in temperature, while the binding sites were independent of temperature. The values of thermodynamic parameter ΔH (-149.85 kJ mol-1) and ΔS (-284.26 J mol-1 K-1) suggested hydrogen bonds and van der Waals played a major role in the reaction. The binding constants between avidin and biotin increased firstly and then decreased gradually with the increase of pH values. Metal ions can also affected the binding constants between avidin and biotin. The association kinetics firstly acquired by the combination of the change in fluorescence per unit time and the modified Stern-Volmer equation indicated that the reaction time required to reach equilibrium was 2200 s, and the average reaction rate for the binding process was very high in the first 180 s. Reaction of the avidin in the first 180 s was more than 40% of the total avidin involved in the whole process.

  13. Measurement of posttransfusion red cell survival with the biotin label.

    PubMed

    Mock, Donald M; Widness, John A; Veng-Pedersen, Peter; Strauss, Ronald G; Cancelas, Jose A; Cohen, Robert M; Lindsell, Christopher J; Franco, Robert S

    2014-07-01

    The goal of this review is to summarize and critically assess information concerning the biotin method to label red blood cells (RBC) for use in studies of RBC and transfusion biology-information that will prove useful to a broad audience of clinicians and scientists. A review of RBC biology, with emphasis on RBC senescence and in vivo survival, is included, followed by an analysis of the advantages and disadvantages of biotin-labeled RBC (BioRBC) for measuring circulating RBC volume, posttransfusion RBC recovery, RBC life span, and RBC age-dependent properties. The advantages of BioRBC over (51)Cr RBC labeling, the current reference method, are discussed. Because the biotin method is straightforward and robust, including the ability to follow the entire life spans of multiple RBC populations concurrently in the same subject, BioRBC offers distinct advantages for studying RBC biology and physiology, particularly RBC survival. The method for biotin labeling, validation of the method, and application of BioRBCs to studies of sickle cell disease, diabetes, and anemia of prematurity are reviewed. Studies documenting the safe use of BioRBC are reviewed; unanswered questions requiring future studies, remaining concerns, and regulatory barriers to broader application of BioRBC including adoption as a new reference method are also presented.

  14. Genetics Home Reference: biotin-thiamine-responsive basal ganglia disease

    MedlinePlus

    ... in the SLC19A3 gene likely result in a protein with impaired ability to transport thiamine into cells, resulting in decreased absorption of the vitamin and leading to neurological dysfunction. In this disorder, ... protein. Others propose that biotin transporter proteins may interact ...

  15. Biotin deficiency blocks thymocyte maturation, accelerates thymus involution, and decreases nose-rump length in mice.

    PubMed

    Báez-Saldaña, Armida; Ortega, Enrique

    2004-08-01

    Biotin deficiency in experimental animals causes low body weight as well as several phenomena suggestive of an altered immune system. We reported previously that chronic biotin deficiency in mice decreases body weight and alters the number and proportion of lymphocyte subpopulations in the spleen. To further characterize the effects of biotin deficiency, we studied in detail the maturation of thymocytes and the status of biotin in the thymus, as well as the body length of biotin-deficient mice. Male Balb/cAnN mice were fed for up to 20 wk either standard control diet, a biotin-deficient diet, or a biotin-sufficient diet. At different times, nose-rump length, weight of the thymus, spleen and liver, total number of cells in the spleen and thymus, pyruvate carboxylase (PC) and propionyl CoA carboxylase (PCC) activity in thymus cells, and the proportion of distinct thymocyte subsets were determined. These variables did not differ between mice fed the control and biotin-sufficient diets. In contrast, biotin-deficient mice differed from biotin-sufficient mice in all of the analyzed variables. PC and PCC specific activities of thymocytes of mice fed the biotin-depleting diet decreased during the first 4 wk by 84.5%. The maturation of thymocytes in biotin-deficient mice was arrested at the double-negative stage. Our results suggest that biotin deficiency in mice causes an accelerated involution of the thymus and decreases nose-rump length, but these effects do not correlate in magnitude or in temporality with the sharp decrease in the activity of the biotin-dependent carboxylases. As such, the possibility that the aforementioned effects are not related directly to the prosthetic function of biotin should be considered.

  16. Fluorescence enhancement of fluorescent unnatural streptavidin by binding of a biotin analogue with spacer tail and its application to biotin sensing.

    PubMed

    Zhu, Xianwei; Shinohara, Hiroaki

    2014-01-01

    We designed a novel molecular biosensing system for the detection of biotin, an important vitamin by the combination of fluorescent unnatural streptavidin with a commercialized biotin-(AC5)2-hydrazide. A fluorescent unnatural amino acid, BODIPY-FL-aminophenylalanine (BFLAF), was position-specifically incorporated into Trp120 of streptavidin by four-base codon method. Fluorescence of the Trp120BFLAF mutant streptavidin was enhanced by the addition of biotin-(AC5)2-hydrazide with the concentration dependent, whereas fluorescence enhancement was not observed at all by the addition of natural biotin. It was considered that the spacer tail of biotin-(AC5)2-hydrazide may disturb the fluorescence quenching of the Trp120BFLAF by Trp79 and Trp108 of the neighbor subunit. Therefore, biotin sensing was carried out by the competitive binding reaction of biotin-(AC5)2-hydrazide and natural biotin to the fluorescent mutant streptavidin. The fluorescence intensity decreased by increasing free biotin concentration. The result suggested that molecular biosensor for small ligand could be successfully designed by the pair of fluorescent mutant binding protein and ligand analogue.

  17. Biotin decorated PLGA nanoparticles containing SN-38 designed for cancer therapy.

    PubMed

    Mehdizadeh, Mozhdeh; Rouhani, Hasti; Sepehri, Nima; Varshochian, Reyhaneh; Ghahremani, Mohammad Hossein; Amini, Mohsen; Gharghabi, Mehdi; Ostad, Seyed Nasser; Atyabi, Fatemeh; Baharian, Azin; Dinarvand, Rassoul

    2017-05-01

    Active targeted chemotherapy is expected to provide more specific delivery of cytotoxic drugs to the tumor cells and hence reducing the side effects on healthy tissues. Due to the over expression of biotin receptors on cancerous cells as a result of further requirement for rapid proliferations, biotin can be a good candidate as a targeting agent. In this study, biotin decorated PLGA nanoparticles (NPs) containing SN-38 were prepared and in vitro studies were evaluated for their improved anti-cancer properties. In conclusion, biotin targeted PLGA NPs containing SN-38 showed preferential anticancer properties against tumor cells with biotin receptor over expression.

  18. Dietary intake of high-dose biotin inhibits spermatogenesis in young rats.

    PubMed

    Sawamura, Hiromi; Ikeda, Chieko; Shimada, Ryoko; Yoshii, Yui; Watanabe, Toshiaki

    2015-02-01

    To characterize a new function of the water-soluble vitamin, biotin, in reproduction and early growth in mammals, the effects of high dietary doses of biotin on early spermatogenesis were biochemically and histologically investigated in male rats. Weaned rats were fed a CE-2 (control) diet containing 0.00004% biotin, or a control diet supplemented with 0.01%, 0.1%, or 1.0% biotin. Pair-fed rats were fed a control diet that was equal in calories to the amount ingested by the 1.0% biotin group, because food intake was decreased in the 1.0% biotin group. Food intake and body weight gain were lower in the 1.0% biotin group than in the control group. The kidney, brain and testis weights were significantly lower in the 1.0% biotin group than in the pair-fed group after 6 weeks of feeding. The accumulation of biotin in the liver and testis increased in a dose-dependent manner. In the 1.0% biotin group, the number of mature sperm was markedly lower, that of sperm with morphologically abnormal heads, mainly consisting of round heads, had increased. In addition, the development of seminiferous tubules was inhibited, and few spermatogonia and no spermatocytes were histologically observed. These results demonstrated that the long-term intake of high-dose biotin inhibited spermatogenesis in young male rats.

  19. A substrate-induced biotin binding pocket in the carboxyltransferase domain of pyruvate carboxylase.

    PubMed

    Lietzan, Adam D; St Maurice, Martin

    2013-07-05

    Biotin-dependent enzymes catalyze carboxyl transfer reactions by efficiently coordinating multiple reactions between spatially distinct active sites. Pyruvate carboxylase (PC), a multifunctional biotin-dependent enzyme, catalyzes the bicarbonate- and MgATP-dependent carboxylation of pyruvate to oxaloacetate, an important anaplerotic reaction in mammalian tissues. To complete the overall reaction, the tethered biotin prosthetic group must first gain access to the biotin carboxylase domain and become carboxylated and then translocate to the carboxyltransferase domain, where the carboxyl group is transferred from biotin to pyruvate. Here, we report structural and kinetic evidence for the formation of a substrate-induced biotin binding pocket in the carboxyltransferase domain of PC from Rhizobium etli. Structures of the carboxyltransferase domain reveal that R. etli PC occupies a symmetrical conformation in the absence of the biotin carboxylase domain and that the carboxyltransferase domain active site is conformationally rearranged upon pyruvate binding. This conformational change is stabilized by the interaction of the conserved residues Asp(590) and Tyr(628) and results in the formation of the biotin binding pocket. Site-directed mutations at these residues reduce the rate of biotin-dependent reactions but have no effect on the rate of biotin-independent oxaloacetate decarboxylation. Given the conservation with carboxyltransferase domains in oxaloacetate decarboxylase and transcarboxylase, the structure-based mechanism described for PC may be applicable to the larger family of biotin-dependent enzymes.

  20. Structural Analysis of Substrate, Reaction Intermediate, and Product Binding in Haemophilus influenzae Biotin Carboxylase.

    PubMed

    Broussard, Tyler C; Pakhomova, Svetlana; Neau, David B; Bonnot, Ross; Waldrop, Grover L

    2015-06-23

    Acetyl-CoA carboxylase catalyzes the first and regulated step in fatty acid synthesis. In most Gram-negative and Gram-positive bacteria, the enzyme is composed of three proteins: biotin carboxylase, a biotin carboxyl carrier protein (BCCP), and carboxyltransferase. The reaction mechanism involves two half-reactions with biotin carboxylase catalyzing the ATP-dependent carboxylation of biotin-BCCP in the first reaction. In the second reaction, carboxyltransferase catalyzes the transfer of the carboxyl group from biotin-BCCP to acetyl-CoA to form malonyl-CoA. In this report, high-resolution crystal structures of biotin carboxylase from Haemophilus influenzae were determined with bicarbonate, the ATP analogue AMPPCP; the carboxyphosphate intermediate analogues, phosphonoacetamide and phosphonoformate; the products ADP and phosphate; and the carboxybiotin analogue N1'-methoxycarbonyl biotin methyl ester. The structures have a common theme in that bicarbonate, phosphate, and the methyl ester of the carboxyl group of N1'-methoxycarbonyl biotin methyl ester all bound in the same pocket in the active site of biotin carboxylase and as such utilize the same set of amino acids for binding. This finding suggests a catalytic mechanism for biotin carboxylase in which the binding pocket that binds tetrahedral phosphate also accommodates and stabilizes a tetrahedral dianionic transition state resulting from direct transfer of CO₂ from the carboxyphosphate intermediate to biotin.

  1. Engineering biotin prototrophic Corynebacterium glutamicum strains for amino acid, diamine and carotenoid production.

    PubMed

    Peters-Wendisch, P; Götker, S; Heider, S A E; Komati Reddy, G; Nguyen, A Q; Stansen, K C; Wendisch, V F

    2014-12-20

    The Gram-positive Corynebacterium glutamicum is auxotrophic for biotin. Besides the biotin uptake system BioYMN and the transcriptional regulator BioQ, this bacterium possesses functional enzymes for the last three reactions of biotin synthesis starting from pimeloyl-CoA. Heterologous expression of bioF from the Gram-negative Escherichia coli enabled biotin synthesis from pimelic acid added to the medium, but expression of bioF together with bioC and bioH from E. coli did not entail biotin prototrophy. Heterologous expression of bioWAFDBI from Bacillus subtilis encoding another biotin synthesis pathway in C. glutamicum allowed for growth in biotin-depleted media. Stable growth of the recombinant was observed without biotin addition for eight transfers to biotin-depleted medium while the empty vector control stopped growth after the first transfer. Expression of bioWAFDBI from B. subtilis in C. glutamicum strains overproducing the amino acids l-lysine and l-arginine, the diamine putrescine, and the carotenoid lycopene, respectively, enabled formation of these products under biotin-depleted conditions. Thus, biotin-prototrophic growth and production by recombinant C. glutamicum were achieved.

  2. Energetic methods to study bifunctional biotin operon repressor.

    PubMed

    Beckett, D

    1998-01-01

    Application of a broad range of approaches and techniques to analysis of the functional energetics of the biotin regulatory system has enabled dissection of each of the steps in the assembly of this transcriptional repression complex. Although the molecular details of the interactions are not yet completely understood, the studies described in this article have laid a solid foundation for future studies of the system. The application of kinetic and equilibrium methods to studies of binding of the allosteric effector has allow determination of the kinetic parameters governing the interaction of the protein and ligand. The kinetic parameters have, furthermore, been utilized to calculate the equilibrium parameters associated with the binding. The great advantage of using kinetic methods to study the binding process is the additional information provide about the mechanism of allosteric activation of the protein. Based on the initial observation of a kinetic time course that is consistent with the occurrence of a structural change concomitant with effector binding, additional measurements have been performed that have allowed formulation of a testable hypothesis concerning the nature and location of one locus: the structural change in the three-dimensional structure of BirA. Studies of assembly of the protein indicate the bio-5-AMP is an allosteric activator of dimerization of the protein. The dimerization is, however, weak. These results have been critical in analyzing site-specific DNA binding measurements. Application of the DNase I footprinting technique has allowed formulation of a model for association of holoBirA with bioO. Results of studies of binding of the protein to mutant operator templates, although not yielding the anticipated results, provide further insight into the mechanism of association of the protein and DNA. Two models for binding, the validity of which can be tested via the application of kinetic techniques, have been derived from these

  3. [The avidin-biotin system. Its application in virology].

    PubMed

    Popa, L M; Kappel, D; Marcheş, F; Borza, B

    1989-01-01

    The report briefly reviews the strategies of utilisation of the avidin-biotin system and its variants, as well as the applications of this system in different fields, especially those linked to the diagnosis and the treatment of some viral and bacterial infections. Some of the techniques using the system are presented, as well as its advantages and the perspectives to ameliorate the methodologies and to enlarge the field of its applications.

  4. Directed evolution of the substrate specificity of biotin ligase.

    PubMed

    Lu, Wei-Cheng; Levy, Matthew; Kincaid, Rodney; Ellington, Andrew D

    2014-06-01

    We have developed selection scheme for directing the evolution of Escherichia coli biotin protein ligase (BPL) via in vitro compartmentalization, and have used this scheme to alter the substrate specificity of the ligase towards the utilization of the biotin analogue desthiobiotin. In this scheme, a peptide substrate (BAP) was conjugated to a DNA library encoding BirA, emulsified such that there was a single template per compartment, and protein variants were transcribed and translated in vitro. Those variants that could efficiently desthiobiotinylate their corresponding peptide:DNA conjugate were subsequently captured and amplified. Following just six rounds of selection and amplification several variants that demonstrated higher activity with desthiobiotin were identified. The best variants from Round 6, BirA6-40 and BirA6-47 , showed 17-fold and 10-fold higher activity, respectively, their abilities to use desthiobiotin as a substrate. While selected enzymes contained a number of substitutions, a single mutation, M157T, proved sufficient to provide much greater activity with desthiobiotin. Further characterization of BirA6-40 and the single substitution variant BirAM157T revealed that they had twoto threefold higher kcat values for desthiobiotin. These variants had also lost much of their ability to utilize biotin, resulting in orthogonal enzymes that in conjunction with streptavidin variants that can utilize desthiobiotin may prove to be of great use in developing additional, robust conjugation handles for a variety of biological and biotechnological applications.

  5. Structure and function of biotin-dependent carboxylases

    PubMed Central

    Tong, Liang

    2012-01-01

    Biotin-dependent carboxylases include acetyl-CoA carboxylase (ACC), propionyl-CoA carboxylase (PCC), 3-methylcrotonyl-CoA carboxylase (MCC), geranyl-CoA carboxylase (GCC), pyruvate carboxylase (PC), and urea carboxylase (UC). They contain biotin carboxylase (BC), carboxyltransferase (CT) and biotin-carboxyl carrier protein (BCCP) components. These enzymes are widely distributed in nature and have important functions in fatty acid metabolism, amino acid metabolism, carbohydrate metabolism, polyketide biosynthesis, urea utilization, and other cellular processes. ACCs are also attractive targets for drug discovery against type 2 diabetes, obesity, cancer, microbial infections, and other diseases, and the plastid ACC of grasses is the target of action of three classes of commercial herbicides. Deficiencies in the activities of PCC, MCC or PC are linked to serious diseases in humans. Our understanding of these enzymes has been greatly enhanced over the past few years by the crystal structures of the holoenzymes of PCC, MCC, PC, and UC. The structures reveal unanticipated features in the architectures of the holoenzymes, including the presence of previously unrecognized domains, and provide a molecular basis for understanding their catalytic mechanism as well as the large collection of disease-causing mutations in PCC, MCC and PC. This review will summarize the recent advances in our knowledge on the structure and function of these important metabolic enzymes. PMID:22869039

  6. Single and multiple bonds in (strept)avidin-biotin interactions.

    PubMed

    Teulon, Jean-Marie; Delcuze, Yannick; Odorico, Michael; Chen, Shu-wen W; Parot, Pierre; Pellequer, Jean-Luc

    2011-01-01

    Thanks to Dynamic Force Spectroscopy (DFS) and developments of massive data analysis tools, such as YieldFinder, Atomic Force Microscopy (AFM) becomes a powerful method for analyzing long lifetime ligand-receptor interactions. We have chosen the well-known system, (strept)avidin-biotin complex, as an experimental model due to the lack of consensus on interpretations of the rupture force spectrum (Walton et al., 2008). We present new measurements of force-displacement curves for the (strept)avidin-biotin complex. These data were analyzed using the YieldFinder software based on the Bell-Evans formalism. In addition, the Williams model was adopted to interpret the bonding state of the system. Our results indicate the presence of at least two energy barriers in two loading rate regimes. Combining with structural analysis, the energy barriers can be interpreted in a novel physico-chemical context as one inner barrier for H-bond ruptures ( <1 Å), and one outer barrier for escaping from the binding pocket which is blocked by the side chain of a symmetry-related Trp120 in the streptavidin tetramer. In each loading rate regime, the presence of multiple parallel bonds was implied by the Williams model. Interestingly, we found that in literature different terms created for addressing the apparent discrepancies in the results of avidin-biotin interactions can be reconciled by taking into account multiple parallel bonds.

  7. Topics in Ho Morphophonology and Morphosyntax

    ERIC Educational Resources Information Center

    Pucilowski, Anna

    2013-01-01

    Ho, an under-documented North Munda language of India, is known for its complex verb forms. This dissertation focuses on analysis of several features of those complex verbs, using data from original fieldwork undertaken by the author. By way of background, an analysis of the phonetics, phonology and morphophonology of Ho is first presented. Ho has…

  8. The Rhizobium etli bioMNY operon is involved in biotin transport.

    PubMed

    Guillén-Navarro, Karina; Araíza, Gisela; García-de los Santos, Alejandro; Mora, Yolanda; Dunn, Michael F

    2005-09-15

    Because Rhizobium etli CE3 is normally dependent on an external source of biotin and lacks orthodox biotin biosynthesis genes, we undertook an analysis of biotin uptake in this organism. By complementation of a Sinorhizobium meliloti bioM mutant we isolated an R. etli chromosomal region encoding homologs of the S. meliloti bioMNB genes, whose products have been implicated in intracellular biotin retention in that organism. Disruption of the R. etli bioM resulted in a mutant which took up biotin at a lower rate and accumulated significantly less biotin than the wild type. As in S. meliloti, the R. etli bioMN gene-products resemble the ATPase and permease components, respectively, of an ABC-type transporter. The bioB gene product is in fact similar to members of the BioY family, which has been postulated to function in biotin transport, and we refer to this gene as bioY. An R. etli bioY mutant exhibited lower biotin uptake than the wild-type, providing the first experimental evidence for a role of BioY in biotin transport. We show that the bioMNY operon is transcriptionally repressed by biotin. An analysis of the competitiveness of the wild-type strain versus the bioM mutant showed that the mutant had a diminished capacity to form nodules on bean plants.

  9. Identification and Characterization of a Novel Biotin Biosynthesis Gene in Saccharomyces cerevisiae

    PubMed Central

    Wu, Hong; Ito, Kiyoshi; Shimoi, Hitoshi

    2005-01-01

    Yeast Saccharomyces cerevisiae cells generally cannot synthesize biotin, a vitamin required for many carboxylation reactions. Although sake yeasts, which are used for Japanese sake brewing, are classified as S. cerevisiae, they do not require biotin for their growth. In this study, we identified a novel open reading frame (ORF) in the genome of one strain of sake yeast that we speculated to be involved in biotin synthesis. Homologs of this gene are widely distributed in the genomes of sake yeasts. However, they are not found in many laboratory strains and strains used for wine making and beer brewing. This ORF was named BIO6 because it has 52% identity with BIO3, a biotin biosynthesis gene of a laboratory strain. Further research showed that yeasts without the BIO6 gene are auxotrophic for biotin, whereas yeasts holding the BIO6 gene are prototrophic for biotin. The BIO6 gene was disrupted in strain A364A, which is a laboratory strain with one copy of the BIO6 gene. Although strain A364A is prototrophic for biotin, a BIO6 disrupted mutant was found to be auxotrophic for biotin. The BIO6 disruptant was able to grow in biotin-deficient medium supplemented with 7-keto-8-amino-pelargonic acid (KAPA), while the bio3 disruptant was not able to grow in this medium. These results suggest that Bio6p acts in an unknown step of biotin synthesis before KAPA synthesis. Furthermore, we demonstrated that expression of the BIO6 gene, like that of other biotin synthesis genes, was upregulated by depletion of biotin. We conclude that the BIO6 gene is a novel biotin biosynthesis gene of S. cerevisiae. PMID:16269718

  10. NdHO, a novel oxyhydride

    SciTech Connect

    Wideroe, Marius; Fjellvag, Helmer; Norby, Truls; Willy Poulsen, Finn; Willestofte Berg, Rolf

    2011-07-15

    A new metal oxyhydride; neodymium oxyhydride, NdHO, has been synthesized from a reactant mixture of metal hydride (CaH{sub 2} or NdH{sub 3}) and neodymium oxide (Nd{sub 2}O{sub 3}). The unit cell dimensions decrease smoothly in the series from LaHO, CeHO, PrHO to NdHO, in line with the lanthanide contraction. The crystal structure of NdHO is described on the basis of Rietveld refinement on neutron powder diffraction data: Space group: P4/nmm (no. 129, D{sub 4h}{sup 7}). Axis lengths: a=7.8480(5) A, c=5.5601(8) A. Volume: V=342.46(6) A{sup 3}. The tetragonal structure is derived from the fluorite structure, showing complete ordering of hydride and oxide ions over the anion sublatttice. The formation of NdHO was further substantiated by Raman spectroscopy. - Graphical Abstract: View of the NdHO structure. Highlights: > CaH{sub 2} or NdH{sub 3} react with Nd{sub 2}O{sub 3} in reducing atmospheres forming a new oxyhydride, NdHO. > NdHO crystalises in tetragonal space group P4/nmm with axes a=b=7.8480(5) A and c=5.5601(8) A. > The structure is similar to the fluorite structure with complete ordering of hydride and oxide ions. > Unit cell dimensions decrease smoothly in the series from LaHO, CeHO, PrHO to NdHO. > The formation of NdHO is substantiated by Raman spectroscopy.

  11. Covalent Immobilization of Biotin on Magnetic Nanoparticles: Synthesis, Characterization, and Cytotoxicity Studies.

    PubMed

    Islam, Md Rafiqul; Bach, Long Giang; Vo, Thanh-Sang; Lim, Kwon Taek

    2015-01-01

    A simple protocol for covalent immobilization of biotin onto the surface of Fe3O4 magnetic nanoparticles (MNPs) for improving the biocompatibility of original MNPs has been realized. MNPs were first prepared by co-precipitation method which was subsequently anchored with functionalized biotin. The as-synthesized MNPs were observed to be monocrystalline as evidenced from XRD and TEM images. The covalent grafting of biotin to MNPs was confirmed by FT-IR. The XPS analysis suggested the successful preparation of Biotin-f-MNPs. The as-synthesized Biotin-f-MNPs were found to be superparamagnetic character as recorded by SQUID. Cell viability studies revealed that the biocompatibility of MNPs was improved upon Biotin immobilization.

  12. Dietary biotin requirement for maximum growth of juvenile grass shrimp, Penaeus monodon.

    PubMed

    Shiau, S Y; Chin, Y H

    1998-12-01

    A feeding trial was conducted to estimate the minimal dietary biotin requirement for juvenile grass shrimp, Penaeus monodon. Purified diets with eight levels (0, 0.2, 0.5, 1.0, 3.0, 6.0, 10.0 and 20.0 mg/kg) of supplemental biotin were fed to P. monodon (mean weight 0. 26 +/- 0.01 g) for 8 wk. Each diet was fed to three replicate groups of shrimp. Shrimp fed diets supplemented with biotin (0.2-20.0 mg/kg) had significantly (P < 0.05) higher weight gain, feed efficiency and protein efficiency ratio than those fed the unsupplemented control diet. Weight gain was high in shrimp fed 3. 0-10.0 mg biotin/kg diet and lowest in shrimp fed biotin concentration in shrimp generally increased as dietary biotin supplementation increased. Highest hepatopancreatic pyruvate carboxylase and acetyl CoA carboxylase activity were in shrimp fed diets with 10 and 20 mg biotin/kg and 3. 0 mg biotin/kg, respectively. Weight gain percentage and protein efficiency ratio of the shrimp analyzed by broken-line regression indicated that the minimal dietary biotin concentration in growing P. monodon is 2.0-2.4 mg/kg.

  13. Epigenetic synergies between biotin and folate in the regulation of pro-inflammatory cytokines and repeats.

    PubMed

    Xue, J; Zempleni, J

    2013-11-01

    The protein biotin ligase, holocarboxylase synthetase (HLCS), is a chromatin protein that interacts physically with the DNA methyltransferase DNMT1, the methylated cytosine-binding protein MeCP2 and the histone H3 K9-methyltransferase EHMT1, all of which participate in folate-dependent gene repression. Here we tested the hypothesis that biotin and folate synergize in the repression of pro-inflammatory cytokines and long-terminal repeats (LTRs), mediated by interactions between HLCS and other chromatin proteins. Biotin and folate supplementation could compensate for each other's deficiency in the repression of LTRs in Jurkat and U937 cells. For example, when biotin-deficient Jurkat cells were supplemented with folate, the expression of LTRs decreased by >70%. Epigenetic synergies were more complex in the regulation of cytokines compared with LTRs. For example, the abundance of TNF-α was 100% greater in folate- and biotin-supplemented U937 cells compared with biotin-deficient and folate-supplemented cells. The NF-κB inhibitor curcumin abrogated the effects of folate and biotin in cytokine regulation, suggesting that transcription factor signalling adds an extra layer of complexity to the regulation of cytokine genes by epigenetic phenomena. We conclude that biotin and folate synergize in the repression of LTRs and that these interactions are probably mediated by HLCS-dependent epigenetic mechanisms. In contrast, synergies between biotin and folate in the regulation of cytokines need to be interpreted in the context of transcription factor signalling.

  14. Dietary Biotin Supplementation Modifies Hepatic Morphology without Changes in Liver Toxicity Markers.

    PubMed

    Riverón-Negrete, Leticia; Sicilia-Argumedo, Gloria; Álvarez-Delgado, Carolina; Coballase-Urrutia, Elvia; Alcántar-Fernández, Jonathan; Fernandez-Mejia, Cristina

    2016-01-01

    Pharmacological concentrations of biotin have pleiotropic effects. Several reports have documented that biotin supplementation decreases hyperglycemia. We have shown that a biotin-supplemented diet increased insulin secretion and the mRNA abundance of proteins regulating insulin transcription and secretion. We also found enlarged pancreatic islets and modified islet morphology. Other studies have shown that pharmacological concentrations of biotin modify tissue structure. Although biotin administration is considered safe, little attention has been given to its effect on tissue structure. In this study, we investigated the effect of biotin supplementation on hepatic morphology and liver toxicity markers. Male BALB/cAnN Hsd mice were fed a control or a biotin-supplemented diet for 8 weeks. Versus the control mice, biotin-supplemented mice had an altered portal triad with dilated sinusoids, increased vascularity, and bile conducts. Furthermore, we observed an increased proportion of nucleomegaly and binucleated hepatocytes. In spite of the liver morphological changes, no differences were observed in the serum liver damage indicators, oxidative stress markers, or antioxidant enzymes. Our data demonstrate for the first time that biotin supplementation affects liver morphology in normal mice, and that these modifications are not paralleled with damage markers.

  15. Deciphering a unique biotin scavenging pathway with redundant genes in the probiotic bacterium Lactococcus lactis

    PubMed Central

    Zhang, Huimin; Wang, Qingjing; Fisher, Derek J.; Cai, Mingzhu; Chakravartty, Vandana; Ye, Huiyan; Li, Ping; Solbiati, Jose O.; Feng, Youjun

    2016-01-01

    Biotin protein ligase (BPL) is widespread in the three domains of the life. The paradigm BPL is the Escherichia coli BirA protein, which also functions as a repressor for the biotin biosynthesis pathway. Here we report that Lactococcus lactis possesses two different orthologues of birA (birA1_LL and birA2_LL). Unlike the scenario in E. coli, L. lactis appears to be auxotrophic for biotin in that it lacks a full biotin biosynthesis pathway. In contrast, it retains two biotin transporter-encoding genes (bioY1_LL and bioY2_LL), suggesting the use of a scavenging strategy to obtain biotin from the environment. The in vivo function of the two L. lactis birA genes was judged by their abilities to complement the conditional lethal E. coli birA mutant. Thin-layer chromatography and mass spectroscopy assays demonstrated that these two recombinant BirA proteins catalyze the biotinylation reaction of the acceptor biotin carboxyl carrier protein (BCCP), through the expected biotinoyl-AMP intermediate. Gel shift assays were used to characterize bioY1_LL and BirA1_LL. We also determined the ability to uptake 3H-biotin by L. lactis. Taken together, our results deciphered a unique biotin scavenging pathway with redundant genes present in the probiotic bacterium L. lactis. PMID:27161258

  16. Dietary Biotin Supplementation Modifies Hepatic Morphology without Changes in Liver Toxicity Markers

    PubMed Central

    Riverón-Negrete, Leticia; Sicilia-Argumedo, Gloria; Álvarez-Delgado, Carolina; Alcántar-Fernández, Jonathan

    2016-01-01

    Pharmacological concentrations of biotin have pleiotropic effects. Several reports have documented that biotin supplementation decreases hyperglycemia. We have shown that a biotin-supplemented diet increased insulin secretion and the mRNA abundance of proteins regulating insulin transcription and secretion. We also found enlarged pancreatic islets and modified islet morphology. Other studies have shown that pharmacological concentrations of biotin modify tissue structure. Although biotin administration is considered safe, little attention has been given to its effect on tissue structure. In this study, we investigated the effect of biotin supplementation on hepatic morphology and liver toxicity markers. Male BALB/cAnN Hsd mice were fed a control or a biotin-supplemented diet for 8 weeks. Versus the control mice, biotin-supplemented mice had an altered portal triad with dilated sinusoids, increased vascularity, and bile conducts. Furthermore, we observed an increased proportion of nucleomegaly and binucleated hepatocytes. In spite of the liver morphological changes, no differences were observed in the serum liver damage indicators, oxidative stress markers, or antioxidant enzymes. Our data demonstrate for the first time that biotin supplementation affects liver morphology in normal mice, and that these modifications are not paralleled with damage markers. PMID:28105429

  17. Characterization of the cDNA and gene coding for the biotin synthase of Arabidopsis thaliana.

    PubMed Central

    Weaver, L M; Yu, F; Wurtele, E S; Nikolau, B J

    1996-01-01

    Biotin, an essential cofactor, is synthesized de novo only by plants and some microbes. An Arabidopsis thaliana expressed sequence tag that shows sequence similarity to the carboxyl end of biotin synthase from Escherichia coli was used to isolate a near-full-length cDNA. This cDNA was shown to code for the Arabidopsis biotin synthase by its ability to complement a bioB mutant of E. coli. Site-specific mutagenesis indicates that residue threonine-173, which is highly conserved in biotin synthases, is important for catalytic competence of the enzyme. The primary sequence of the Arabidopsis biotin synthase is most similar to biotin synthases from E. coli, Serratia marcescens, and Saccharomyces cerevisiae (about 50% sequence identity) and more distantly related to the Bacillus sphaericus enzyme (33% sequence identity). The primary sequence of the amino terminus of the Arabidopsis biotin synthase may represent an organelle-targeting transit peptide. The single Arabidopsis gene coding for biotin synthase, BIO2, was isolated and sequenced. The biotin synthase coding sequence is interrupted by five introns. The gene sequence upstream of the translation start site has several unusual features, including imperfect palindromes and polypyrimidine sequences, which may function in the transcriptional regulation of the BIO2 gene. PMID:8819873

  18. The Atypical Occurrence of Two Biotin Protein Ligases in Francisella novicida Is Due to Distinct Roles in Virulence and Biotin Metabolism

    PubMed Central

    Feng, Youjun; Chin, Chui-Yoke; Chakravartty, Vandana; Gao, Rongsui; Crispell, Emily K.

    2015-01-01

    ABSTRACT The physiological function of biotin requires biotin protein ligase activity in order to attach the coenzyme to its cognate proteins, which are enzymes involved in central metabolism. The model intracellular pathogen Francisella novicida is unusual in that it encodes two putative biotin protein ligases rather than the usual single enzyme. F. novicida BirA has a ligase domain as well as an N-terminal DNA-binding regulatory domain, similar to the prototypical BirA protein in E. coli. However, the second ligase, which we name BplA, lacks the N-terminal DNA binding motif. It has been unclear why a bacterium would encode these two disparate biotin protein ligases, since F. novicida contains only a single biotinylated protein. In vivo complementation and enzyme assays demonstrated that BirA and BplA are both functional biotin protein ligases, but BplA is a much more efficient enzyme. BirA, but not BplA, regulated transcription of the biotin synthetic operon. Expression of bplA (but not birA) increased significantly during F. novicida infection of macrophages. BplA (but not BirA) was required for bacterial replication within macrophages as well as in mice. These data demonstrate that F. novicida has evolved two distinct enzymes with specific roles; BplA possesses the major ligase activity, whereas BirA acts to regulate and thereby likely prevent wasteful synthesis of biotin. During infection BplA seems primarily employed to maximize the efficiency of biotin utilization without limiting the expression of biotin biosynthetic genes, representing a novel adaptation strategy that may also be used by other intracellular pathogens. PMID:26060274

  19. Shape coexistence in 153Ho

    NASA Astrophysics Data System (ADS)

    Pramanik, Dibyadyuti; Sarkar, S.; Saha Sarkar, M.; Bisoi, Abhijit; Ray, Sudatta; Dasgupta, Shinjinee; Chakraborty, A.; Krishichayan, Kshetri, Ritesh; Ray, Indrani; Ganguly, S.; Pradhan, M. K.; Ray Basu, M.; Raut, R.; Ganguly, G.; Ghugre, S. S.; Sinha, A. K.; Basu, S. K.; Bhattacharya, S.; Mukherjee, A.; Banerjee, P.; Goswami, A.

    2016-08-01

    The high-spin states in 153Ho have been studied by the La57(20Ne139,6 n ) reaction at a projectile energy of 139 MeV at the Variable Energy Cyclotron Centre (VECC), Kolkata, India, utilizing an earlier campaign of the Indian National Gamma Array (INGA) setup. Data from γ -γ coincidence, directional correlation, and polarization measurements have been analyzed to assign and confirm the spins and parities of the levels. We have suggested a few additions and revisions of the reported level scheme of 153Ho. The RF-γ time difference spectra have been useful to confirm the half-life of an isomer in this nucleus. From the comparison of experimental and theoretical results, it is found that there are definite indications of shape coexistence in this nucleus. The experimental and calculated lifetimes of several isomers have been compared to follow the coexistence and evolution of shape with increasing spin.

  20. Biotin protein ligase from Corynebacterium glutamicum: role for growth and L: -lysine production.

    PubMed

    Peters-Wendisch, P; Stansen, K C; Götker, S; Wendisch, V F

    2012-03-01

    Corynebacterium glutamicum is a biotin auxotrophic Gram-positive bacterium that is used for large-scale production of amino acids, especially of L-glutamate and L-lysine. It is known that biotin limitation triggers L-glutamate production and that L-lysine production can be increased by enhancing the activity of pyruvate carboxylase, one of two biotin-dependent proteins of C. glutamicum. The gene cg0814 (accession number YP_225000) has been annotated to code for putative biotin protein ligase BirA, but the protein has not yet been characterized. A discontinuous enzyme assay of biotin protein ligase activity was established using a 105aa peptide corresponding to the carboxyterminus of the biotin carboxylase/biotin carboxyl carrier protein subunit AccBC of the acetyl CoA carboxylase from C. glutamicum as acceptor substrate. Biotinylation of this biotin acceptor peptide was revealed with crude extracts of a strain overexpressing the birA gene and was shown to be ATP dependent. Thus, birA from C. glutamicum codes for a functional biotin protein ligase (EC 6.3.4.15). The gene birA from C. glutamicum was overexpressed and the transcriptome was compared with the control strain revealing no significant gene expression changes of the bio-genes. However, biotin protein ligase overproduction increased the level of the biotin-containing protein pyruvate carboxylase and entailed a significant growth advantage in glucose minimal medium. Moreover, birA overexpression resulted in a twofold higher L-lysine yield on glucose as compared with the control strain.

  1. Marginal biotin deficiency can be induced experimentally in humans using a cost-effective outpatient design.

    PubMed

    Stratton, Shawna L; Henrich, Cindy L; Matthews, Nell I; Bogusiewicz, Anna; Dawson, Amanda M; Horvath, Thomas D; Owen, Suzanne N; Boysen, Gunnar; Moran, Jeffery H; Mock, Donald M

    2012-01-01

    To date, marginal, asymptomatic biotin deficiency has been successfully induced experimentally by the use of labor-intensive inpatient designs requiring rigorous dietary control. We sought to determine if marginal biotin deficiency could be induced in humans in a less expensive outpatient design incorporating a self-selected, mixed general diet. We sought to examine the efficacy of three outpatient study designs: two based on oral avidin dosing and one based on a diet high in undenatured egg white for a period of 28 d. In study design 1, participants (n = 4; 3 women) received avidin in capsules with a biotin binding capacity of 7 times the estimated dietary biotin intake of a typical self-selected diet. In study design 2, participants (n = 2; 2 women) received double the amount of avidin capsules (14 times the estimated dietary biotin intake). In study design 3, participants (n = 5; 3 women) consumed egg-white beverages containing avidin with a biotin binding capacity of 7 times the estimated dietary biotin intake. Established indices of biotin status [lymphocyte propionyl-CoA carboxylase activity; urinary excretion of 3-hydroxyisovaleric acid, 3-hydroxyisovaleryl carnitine (3HIA-carnitine), and biotin; and plasma concentration of 3HIA-carnitine] indicated that study designs 1 and 2 were not effective in inducing marginal biotin deficiency, but study design 3 was as effective as previous inpatient study designs that induced deficiency by egg-white beverage. Marginal biotin deficiency can be induced experimentally by using a cost-effective outpatient design by avidin delivery in egg-white beverages. This design should be useful to the broader nutritional research community.

  2. Biotin limitation in Sinorhizobium meliloti strain 1021 alters transcription and translation.

    PubMed

    Heinz, Elke B; Streit, Wolfgang R

    2003-02-01

    Most Sinorhizobium meliloti strains lack several key genes involved in microbial biotin biosynthesis, and it is assumed that this may be a special adaptation which allows the microbe to down-regulate metabolic activities in the absence of a host plant. To further explore this hypothesis, we employed two different strategies. (i) Searches of the S. meliloti genome database in combination with the construction of nine different gusA reporter fusions identified three genes involved in a biotin starvation response in this microbe. A gene coding for a protein-methyl carboxyl transferase (pcm) exhibited 13.6-fold-higher transcription under biotin-limiting conditions than cells grown in the presence of 40 nM biotin. Consistent with this observation, biotin-limiting conditions resulted in a significantly decreased survival of pcm mutant cells compared to parental cells or cells grown in the presence of 40 nM biotin. Further studies indicated that the autoinducer synthase gene, sinI, was transcribed at a 4.5-fold-higher level in early stationary phase in biotin-starved cells than in biotin-supplemented cells. Lastly, we observed that open reading frame smc02283, which codes for a putative copper resistance protein (CopC), was 21-fold down-regulated in response to biotin starvation. (ii) In a second approach, proteome analysis identified 10 proteins which were significantly down-regulated under the biotin-limiting conditions. Among the proteins identified by using matrix-assisted laser desorption ionization-time of flight mass spectrometry were the pi subunit of the RNA polymerase and the 50S ribosomal protein L7/L12 (L8) subunit, indicating that biotin-limiting conditions generally affect transcription and translation in S. meliloti.

  3. In Vivo Biotinylation of Bacterial Magnetic Particles by a Truncated Form of Escherichia coli Biotin Ligase and Biotin Acceptor Peptide ▿

    PubMed Central

    Maeda, Yoshiaki; Yoshino, Tomoko; Matsunaga, Tadashi

    2010-01-01

    Escherichia coli biotin ligase can attach biotin molecules to a lysine residue of biotin acceptor peptide (BAP), and biotinylation of particular BAP-fused proteins in cells was carried out by coexpression of E. coli biotin ligase (in vivo biotinylation). This in vivo biotinylation technology has been applied for protein purification, analysis of protein localization, and protein-protein interaction in eukaryotic cells, while such studies have not been reported in bacterial cells. In this study, in vivo biotinylation of bacterial magnetic particles (BacMPs) synthesized by Magnetospirillum magneticum AMB-1 was attempted by heterologous expression of E. coli biotin ligase. To biotinylate BacMPs in vivo, BAP was fused to a BacMP surface protein, Mms13, and E. coli biotin ligase was simultaneously expressed in the truncated form lacking the DNA-binding domain. This truncation-based approach permitted the growth of AMB-1 transformants when biotin ligase was heterologously expressed. In vivo biotinylation of BAP on BacMPs was confirmed using an alkaline phosphatase-conjugated antibiotin antibody. The biotinylated BAP-displaying BacMPs were then exposed to streptavidin by simple mixing. The streptavidin-binding capacity of BacMPs biotinylated in vivo was 35-fold greater than that of BacMPs biotinylated in vitro, where BAP-displaying BacMPs purified from bacterial cells were biotinylated by being mixed with E. coli biotin ligase. This study describes not only a simple method to produce biotinylated nanomagnetic particles but also a possible expansion of in vivo biotinylation technology for bacterial investigation. PMID:20622127

  4. Oligonucleotide-stabilized fluorescent silver nanoclusters for the specific and sensitive detection of biotin.

    PubMed

    Xiong, Xiaoli; Tang, Yan; Zhao, Jingjin; Zhao, Shulin

    2016-02-21

    A novel biotin fluorescent probe based on oligonucleotide-stabilized silver nanoclusters (DNA-AgNCs) was synthesized by employing a biotinylated cytosine-rich sequence as a synthesized template. The fluorescence properties of the DNA-AgNCs are related to the modified position of the DNA. When biotin is linked to the middle thymine base of the DNA sequence, the DNA-AgNCs emit the strongest fluorescence. Moreover, the stability of the DNA-AgNCs was affected by avidin through biotin-avidin binding, quenching the fluorescence of the DNA-AgNCs. In contrast, if free biotin is further introduced into this system, the quenching is apparently weakened by competition, leading to the restoration of fluorescence. This phenomenon can be utilized for the detection of biotin. Under the optimal conditions, the fluorescence recovery is linearly proportional to the concentration of biotin in the range of 10 nM-1.0 μM with a detection limit of 6.0 nM. This DNA-AgNCs probe with excellent fluorescent properties is sensitive and selective for the detection of biotin and has been applied for the determination of biotin in wheat flour.

  5. The biotin repressor: thermodynamic coupling of corepressor binding, protein assembly, and sequence-specific DNA binding.

    PubMed

    Streaker, Emily D; Gupta, Aditi; Beckett, Dorothy

    2002-12-03

    The Escherichia coli biotin repressor, an allosteric transcriptional regulator, is activated for binding to the biotin operator by the small molecule biotinyl-5'-AMP. Results of combined thermodynamic, kinetic, and structural studies of the protein have revealed that corepressor binding results in disorder to order transitions in the protein monomer that facilitate tighter dimerization. The enhanced stability of the dimer leads to stabilization of the resulting biotin repressor-biotin operator complex. It is not clear, however, that the allosteric response in the system is transmitted solely through the protein-protein interface. In this work, the allosteric mechanism has been quantitatively probed by measuring the biotin operator binding and dimerization properties of three biotin repressor species: the apo or unliganded form, the biotin-bound form, and the holo or bio-5'-AMP-bound form. Comparisons of the pairwise differences in the bioO binding and dimerization energetics for the apo and holo species reveal that the enhanced DNA binding energetics resulting from adenylate binding track closely with the enhanced assembly energetics. However, when the results for repressor pairs that include the biotin-bound species are compared, no such equivalence is observed.

  6. Design and synthesis of metabolically stable chelate-biotin conjugates for pretargeted tumor radioimmunotherapy

    SciTech Connect

    Gustavson, L.M.; Su, F.M.; Reno, J.M.

    1995-12-01

    The use of radiolabeled chelate biotin conjugates for targeting antibody-avidin complexes prelocalized on tumors offers the advantage of delivering the radioactivity on a small molecule which exhibits fast tumor localization and rapid whole body clearance. To maximize efficacy, the radiolabeled biotin conjugate should exhibit high serum stability, rapid renal excretion, and uncompromised avidin binding capacity. we determined that the Y-90 labeled 2-(benzylamidocaproyl-biotin)-tetraatzacyclododecane-N, N`, N``, N```- tetraacetic acid conjugate, DOTA-LC-biotin, incubated in serum for 15 minutes, was 98% degraded to a fragment which no longer binds avidin. The synthesis of standards DOTA-benzylamine and 6- amninocaproamido benzyl-DOTA permitted the identification of the site of cleavage as the biotin carboxylamide. To prevent the enzymatic cleavage of the biotin-amide functionality, we designed four amide stabilized DOTA-biotin analogs. The analogs retained favorable biodistribution and avidin binding and showed excellent serum stability. The design of stable chelate biotin conjugates resulted in improved therapeutic efficacy in mice and a Phase I clinical trial has been initiated with a N-methyl biotinamide stabilized conjugate.

  7. Carrier-mediated system for transport of biotin in rat intestine in vitro

    SciTech Connect

    Said, H.M.; Redha, R.

    1987-01-01

    Transport of biotin was examined in rat intestine using the everted sac technique. Transport of 0.1 ..mu..M biotin was linear with time for at least 30 min of incubation and occurred at a rate 3.7 pmol g initial tissue wet wt/sup -1/ min/sup -1/. Transport of biotin was higher in the jejunum than the ileum and was minimum in the colon (85 +/- 6, 36 +/- 6, and 2.8 +/- 0.6 pmol x g initial tissue wet wt/sup -1/ x 25 min/sup -1/, respectively). In the jejunum, transport of biotin was saturable at low concentrations but linear at higher concentrations. The transport of low concentrations of biotin was 1) inhibited by structural analogues (desthiobiotin, biotin methyl ester, diaminobiotin, and biocytin), 2) Na/sup +/ dependent, 3) energy dependent, 4) temperature dependent, and 5) proceeded against a concentration gradient in the serosal compartment. No metabolic alteration occurs to the biotin molecule during transport. This study demonstrates that biotin transport in rat intestine occurs by a carrier-mediated process at low concentrations and by simple diffusion at high concentrations. Furthermore, the carrier-mediated process is Na/sup +/, energy, and temperature dependent.

  8. Biotin as a probe of the surface of Ascaris suum developmental stages.

    PubMed

    Hill, D E; Fetterer, R H; Urban, J F

    1990-06-01

    Sulfo-NHS-biotin (aqueous soluble) and NHS-biotin (organic soluble) labeled similar SDS-2ME (sodium dodecyl sulfate/beta-mercaptoethanol) soluble cuticular proteins of second stage larvae (L2) and third stage Ascaris suum larvae (L3). Comparable analysis of biotin-labeled fourth stage larvae (L4), young adults, and mature adult Ascaris suum revealed strong labeling of several SDS-2ME soluble cuticular proteins with NHS-biotin, while sulfo-NHS-biotin appeared to strongly label a single SDS-2ME soluble cuticular protein. Both biotin probes labeled only cuticular proteins, since no evidence of internal labeling was observed in any developmental stage examined by either electroblot analysis or by electron microscopy. Our data suggest a greater cuticular permeability to the organic soluble biotin reagent in the later developmental stages (greater than L3) of A. suum than to the aqueous soluble biotin reagent, and may indicate the presence of a hydrophobic barrier in the cuticle of the later stages of the parasite.

  9. A sandwich-type electrochemical immunosensor based on the biotin- streptavidin-biotin structure for detection of human immunoglobulin G

    PubMed Central

    Li, Yueyun; Zhang, Yihe; Jiang, Liping; Chu, Paul K.; Dong, Yunhui; Wei, Qin

    2016-01-01

    A sandwich-type immunosensor is designed and fabricated to detect the human immunoglobulin G (HIgG) using polyaniline and tin dioxide functionalized graphene (GS-SnO2-PAN) as the platform and biotin-functionalized amination magnetic nanoparticles composite (B-Fe3O4@APTES) as the label. GS-SnO2-PAN is used as the sensing agent to capture the primary anti-HIgG (Ab1) and SnO2 reduces the stack of GS. The B-Fe3O4@APTES with a large surface area and excellent biocompatibility captures second antibody (Ab2) efficiently based on the highly selective recognition of streptavidin to biotinylated antibody. The B-Fe3O4@APTES has better electro-catalytic activity in the reduction of hydrogen peroxide (H2O2) and the “biotin-streptavidin-biotin” (B-SA-B) strategy leads to signal amplification. Under optimal conditions, the immunosensor has a wide sensitivity range from 1 pg/L to 10 ng/L and low detection limit of 0.33 pg/L (S/N = 3) for HIgG. The immunosensor has high sensitivity, fast assay rate, as well as good reproducibility, specificity, and stability especially in the quantitative detection of biomolecules in serum samples. PMID:26948273

  10. Tm:YLF Pumped Ho:YAG and Ho:LuAG Lasers

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Reichle, Donald J.; Walsh, Brian M.; Axenson, Theresa J.

    2004-01-01

    Room temperature Ho:YAG and Ho:LuAG lasers pumped by a Tm:YLF laser demonstrated a 3.4 mJ threshold and 0.41 slope efficiency, incident optical to laser output energy. Results for numerous rod lengths, Ho concentrations, and output mirror reflectivities are presented.

  11. Enterohemorrhagic Escherichia coli senses low biotin status in the large intestine for colonization and infection.

    PubMed

    Yang, Bin; Feng, Lu; Wang, Fang; Wang, Lei

    2015-03-20

    Enterohemorrhagic Escherichia coli (EHEC) is an important foodborne pathogen that infects humans by colonizing the large intestine. Here we identify a virulence-regulating pathway in which the biotin protein ligase BirA signals to the global regulator Fur, which in turn activates LEE (locus of enterocyte effacement) genes to promote EHEC adherence in the low-biotin large intestine. LEE genes are repressed in the high-biotin small intestine, thus preventing adherence and ensuring selective colonization of the large intestine. The presence of this pathway in all nine EHEC serotypes tested indicates that it is an important evolutionary strategy for EHEC. The pathway is incomplete in closely related small-intestinal enteropathogenic E. coli due to the lack of the Fur response to BirA. Mice fed with a biotin-rich diet show significantly reduced EHEC adherence, indicating that biotin might be useful to prevent EHEC infection in humans.

  12. Enterohemorrhagic Escherichia coli senses low biotin status in the large intestine for colonization and infection

    PubMed Central

    Yang, Bin; Feng, Lu; Wang, Fang; Wang, Lei

    2015-01-01

    Enterohemorrhagic Escherichia coli (EHEC) is an important foodborne pathogen that infects humans by colonizing the large intestine. Here we identify a virulence-regulating pathway in which the biotin protein ligase BirA signals to the global regulator Fur, which in turn activates LEE (locus of enterocyte effacement) genes to promote EHEC adherence in the low-biotin large intestine. LEE genes are repressed in the high-biotin small intestine, thus preventing adherence and ensuring selective colonization of the large intestine. The presence of this pathway in all nine EHEC serotypes tested indicates that it is an important evolutionary strategy for EHEC. The pathway is incomplete in closely related small-intestinal enteropathogenic E. coli due to the lack of the Fur response to BirA. Mice fed with a biotin-rich diet show significantly reduced EHEC adherence, indicating that biotin might be useful to prevent EHEC infection in humans. PMID:25791315

  13. [Establishment of a novel biotin-inducible eukaryotic gene regulation system].

    PubMed

    Ye, Lingling; Hong, Liu; Li, Shichong; Wang, Qiwei; Lan, Sanchun; Chen, Zhaolie

    2014-08-01

    To establish a gene regulation system compatible with biopharmaceutical industry and gene therapy, we constructed a fusion protein of biotin ligase from Bacillus subtilis (BS-BirA) and the trans-activation domain, and used its expression vector as the regulatory vector. Meanwhile, BS-BirA-specific operators were ligated upstream of attenuated CMV promoter to obtain the response vector. In this way, a novel eukaryotic gene regulation system responsive to biotin was established and named BS-Biotin-On system. BS-Biotin-On system was further investigated with the enhancing green fluorescent protein (EGFP) as the reporter gene. The results showed that our system was superior to the current similar regulation system in its higher induction ratio, and that the expression of interest gene could be tuned in a rapid and efficient manner by changing the biotin concentrations in the cultures, Our results show that the established system may provide a new alternative for the exogenous gene modulation.

  14. Antioxidant status of serum, muscle, intestine and hepatopancreas for fish fed graded levels of biotin.

    PubMed

    Feng, Lin; Zhao, Shu; Chen, Gangfu; Jiang, Weidan; Liu, Yang; Jiang, Jun; Hu, Kai; Li, Shuhong; Zhou, Xiaoqiu

    2014-04-01

    Lipid peroxidation, protein oxidation and antioxidant activities of muscle, intestine, hepatopancreas and serum in juvenile Jian carp (Cyprinus carpio var. Jian) were investigated after feeding graded levels of biotin (0.010, 0.028, 0.054, 0.151, 0.330, 1.540 and 2.680 mg kg(-1) diet) for 63 days. Both malondialdehyde and protein carbonyl content in all studied tissues and serum were the lowest in fish fed diets containing 0.151-0.330 mg biotin kg(-1) diet and then increased in fish fed the diet with 2.680 mg biotin kg(-1) diet (P < 0.05). Similarly, glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase activities in serum significantly decreased with biotin levels up to 0.151 mg kg(-1) diet (P < 0.05). Conversely, capacities of anti-hydroxyl radical (AHR) and anti-superoxide anion (ASA) in the detected tissues and serum significantly improved with biotin levels up to 0.054-1.540 mg kg(-1) diet and then decreased in 2.680 mg biotin kg(-1) diet group for muscle and intestinal AHR as well as hepatopancreas ASA (P < 0.05). Activities of superoxide dismutase in all studied tissues and serum significantly elevated with biotin levels up to 0.330 mg kg(-1) diet and then decreased when fish fed the diet with 2.680 mg biotin kg(-1) diet, except intestine (P < 0.05). Meanwhile, activities of catalase, glutathione peroxidase, glutathione-S-transferase and glutathione reductase and total thiol content in all studied tissues and serum showed the upward trend with biotin supplementations (P < 0.05). These results indicated that biotin improved antioxidant status and depressed lipid peroxidation and protein oxidation in all studied tissues and serum.

  15. The hypotriglyceridemic effect of biotin supplementation involves increased levels of cGMP and AMPK activation.

    PubMed

    Aguilera-Méndez, Asdrúbal; Fernández-Mejía, Cristina

    2012-01-01

    In addition to its role as a carboxylase cofactor, biotin modifies gene expression and has manifold effects on systemic processes. Several studies have shown that biotin supplementation reduces hypertriglyceridemia. We have previously reported that this effect is related to decreased expression of lipogenic genes. In the present work, we analyzed signaling pathways and posttranscriptional mechanisms involved in the hypotriglyceridemic effects of biotin. Male BALB/cAnN Hsd mice were fed a control or a biotin-supplemented diet (1.76 or 97.7 mg of free biotin/kg diet, respectively for 8 weeks after weaning. The abundance of mature sterol regulatory element-binding protein (SREBP-1c), fatty-acid synthase (FAS), total acetyl-CoA carboxylase-1 (ACC-1) and its phosphorylated form, and AMP-activated protein kinase (AMPK) were evaluated in the liver. We also determined the serum triglyceride concentrations and the hepatic levels of triglycerides and cyclic GMP (cGMP). Compared to the control group, biotin-supplemented mice had lower serum and hepatic triglyceride concentrations. Biotin supplementation increased the levels of cGMP and the phosphorylated forms of AMPK and ACC-1 and decreased the abundance of the mature form of SREBP-1c and FAS. These data provide evidence that the mechanisms by which biotin supplementation reduces lipogenesis involve increased cGMP content and AMPK activation. In turn, these changes lead to augmented ACC-1 phosphorylation and decreased expression of both the mature form of SREBP-1c and FAS. Our results demonstrate for the first time that AMPK is involved in the effects of biotin supplementation and offer new insights into the mechanisms of biotin-mediated hypotriglyceridemic effects.

  16. Design and solid phase synthesis of new DOTA conjugated (+)-biotin dimers planned to develop molecular weight-tuned avidin oligomers.

    PubMed

    Pratesi, Alessandro; Ginanneschi, Mauro; Melani, Fabrizio; Chinol, Marco; Carollo, Angela; Paganelli, Giovanni; Lumini, Marco; Bartoli, Mattia; Frediani, Marco; Rosi, Luca; Petrucci, Giorgio; Messori, Luigi; Papini, Anna Maria

    2015-04-07

    Chemical modifications of the biotin carrier in pretargeted avidin–biotin radionuclide therapy may be of paramount importance for tuning the amount of the radioactivity delivered to cancer cells by labelled biotins. We report here the synthesis of a collection of new synthetic DOTA-constructs bearing two (+)-biotin molecules (bis-biotins), designed for the creation of multimeric Av units (tetramers) bonded to the antibody. All the syntheses were carried out following the solid phase strategy and growing the molecules on a Rink Amide resin. The biotin heads are connected through spacers containing PEG or non-PEG residues. Molecular modelling calculations suggested that the Av cross-linking ability of the bis-biotins depends mainly on the spacers length, with the best results being expected for arms affording distances in the range of 10–25 Å between the biotin carboxylate atoms, in the fully extended conformation. SEC-HPLC MALLS analysis of the products of our Av/bis-biotin reaction mixtures have confirmed this hypothesis. The bis-biotin 16, where the non-PEG linker ensured a distance of 26.7 Å between the biotin moieties, gave about 50% of Av oligomers while the shorter analogue 18 (19.5 Å) afforded 100% of an Av polymer containing about 21 protein units. Remarkably, the solubility of both the bis-biotins, i.e.16 and 18, in aqueous solutions was good and they showed excellent stability against the action of peptidases.

  17. Measurement by SPR of very low dissociation rates: oxidation-mediated loss of biotin-streptavidin affinity.

    PubMed

    Rebhan, Mario A E; Brunschweiger, Andreas; Hall, Jonathan

    2013-11-04

    Long-term relationship: biotin labels on RNAs, and possibly other biomacromolecules, are easily oxidized causing a dramatic loss of affinity for streptavidin and adversely affecting the measurement of high-affinity interactions. A new SPR method has been developed for measuring the very low rate-dissociation constants of biotin- and biotin oxide-conjugated RNAs with streptavidin.

  18. Ferroelectricity and competing interactions in Ho-deficient non-stoichiometric orthorhombic HoMnO3

    NASA Astrophysics Data System (ADS)

    Wang, J. X.; Yan, Z. B.; Xie, Y. L.; Zhou, X. H.; Liu, J.-M.

    2015-05-01

    We investigate the consequences of the Ho-deficient non-stoichiometry in orthorhombic HoMnO3 in terms of microscopic mechanisms for ferroelectricity modulation. It is suggested that the Ho-deficiency (then Mn excess) results in Ho-vacancies and then Mn occupation of the Ho-site with increasing non-stoichiometry. The Ho-deficiency enhances the Mn-Mn symmetric exchange striction by suppressing the independent Ho-Ho interaction, and thus benefits to the induced Ho spin ordering against the independent Ho spin ordering. The symmetric Ho-Mn exchange striction is thus enhanced by this induced Ho spin ordering, leading to remarkably enhanced ferroelectric polarization as observed. This work presents an alternative scheme to modulate the multiferroicity in rare-earth manganites of strong 4f-3d coupling.

  19. Ferroelectricity and competing interactions in Ho-deficient non-stoichiometric orthorhombic HoMnO{sub 3}

    SciTech Connect

    Wang, J. X.; Yan, Z. B.; Xie, Y. L.; Zhou, X. H.; Liu, J.-M.

    2015-05-07

    We investigate the consequences of the Ho-deficient non-stoichiometry in orthorhombic HoMnO{sub 3} in terms of microscopic mechanisms for ferroelectricity modulation. It is suggested that the Ho-deficiency (then Mn excess) results in Ho-vacancies and then Mn occupation of the Ho-site with increasing non-stoichiometry. The Ho-deficiency enhances the Mn-Mn symmetric exchange striction by suppressing the independent Ho-Ho interaction, and thus benefits to the induced Ho spin ordering against the independent Ho spin ordering. The symmetric Ho-Mn exchange striction is thus enhanced by this induced Ho spin ordering, leading to remarkably enhanced ferroelectric polarization as observed. This work presents an alternative scheme to modulate the multiferroicity in rare-earth manganites of strong 4f-3d coupling.

  20. Increasing Accuracy and Increasing Tension in Ho

    NASA Astrophysics Data System (ADS)

    Freedman, Wendy L.

    2017-01-01

    The Hubble Constant, Ho, provides a measure of the current expansion rate of the universe. In recent decades, there has been a huge increase in the accuracy with which extragalactic distances, and hence Ho, can be measured. While the historical factor-of-two uncertainty in Ho has been resolved, a new discrepancy has arisen between the values of Ho measured in the local universe, and that estimated from cosmic microwave background measurements, assuming a Lambda cold dark matter model. I will review the advances that have led to the increase in accuracy in measurements of Ho, as well as describe exciting future prospects with the James Webb Space Telescope (JWST) and Gaia, which will make it feasible to measure extragalactic distances at percent-level accuracy in the next decade.

  1. [Prospective study of biotin treatment in patients with erythema due to gefitinib or erlotinib].

    PubMed

    Ogawa, Yoshikazu; Kiba, Takayoshi; Nakano, Kikuo; Fujiwara, Keiichi; Taniguchi, Hitoshi; Hosokawa, Atsuko; Nakashima, Toshihisa; Kimoto, Shizue; Kajiume, Sayoko; Okada, Yuuko; Ichiba, Yasunori

    2014-04-01

    Gefitinib anderlotinib, which are epidermal growth factor receptor(EGFR)tyrosine kinase inhibitors(TKIs), have been usedfor the treatment of inoperable andrecurrent non-small cell lung cancer(NSCLC)patients. These drugs are known to cause a skin rash, one of the major side effects, at a high frequency. Biotin is a water-soluble vitamin, andit belongs to the vitamin B family. It is well known that biotin deficiency increases the risk of skin dermatitis. We administered biotin to four patients with skin rash, all of whom were treatedwith either gefitinib or erlotinib andwere unable to be treatedby a steroid ointment alone. In all patients, administration of biotin reduced the skin rash. Surprisingly, in 2 patients in whom EGFR-TKI therapy was discontinued because of the skin rash, the administration of biotin allowed for long-term gefitinib or erlotinib treatment. Biotin may be considereduseful for the treatment of skin rash causedby EGFR-TKIs. Further trials may be needed to confirm the value of biotin in this setting.

  2. Improving the performance of solventogenic clostridia by reinforcing the biotin synthetic pathway.

    PubMed

    Yang, Yunpeng; Lang, Nannan; Yang, Gaohua; Yang, Sheng; Jiang, Weihong; Gu, Yang

    2016-05-01

    An efficient production process is important for industrial microorganisms. The cellular efficiency of solventogenic clostridia, a group of anaerobes capable of producing a wealth of bulk chemicals and biofuels, must be improved for competitive commercialization. Here, using Clostridium acetobutylicum, a species of solventogenic clostridia, we revealed that the insufficient biosynthesis of biotin, a pivotal coenzyme for many important biological processes, is a major limiting bottleneck in this anaerobe's performance. To address this problem, we strengthened the biotin synthesis of C. acetobutylicum by overexpressing four relevant genes involved in biotin transport and biosynthesis. This strategy led to faster growth and improved the titer and productivity of acetone, butanol and ethanol (ABE solvents) of C. acetobutylicum in both biotin-containing and biotin-free media. Expressionally modulating these four genes by modifying the ribosome binding site further promoted cellular performance, achieving ABE solvent titer and productivity as high as 21.9g/L and 0.30g/L/h, respectively, in biotin-free medium; these values exceeded those of the wild-type strain by over 30%. More importantly, biotin synthesis reinforcement also conferred improved ability of C. acetobutylicum to use hexose and pentose sugars, further demonstrating the potential of this metabolic-engineering strategy in solventogenic clostridia.

  3. Medium composition influence on Biotin and Riboflavin production by newly isolated Candida sp

    PubMed Central

    Suzuki, Gaby Tiemi; Macedo, Juliana Alves; Macedo, Gabriela Alves

    2011-01-01

    Complex B vitamins as Biotin and Riboflavin are required by living organisms, not only for growth but also for metabolite production, and the feed market classifies them as growth promoters. Since Brazil will soon be one of the world’s biggest animal protein producers, feed production is a large consumer of vitamins and micronutrients. The industry requires 10 mg riboflavin/0.2 mg biotin per kilogram of feed; a ratio of 40 ~ 50:1. Although few studies have been conducted specifically on riboflavin production using factorial design and surface response method as an optimization strategy, it is a common practice in biotechnology with many research reports available. However, there are no reports on the use of statistical design for biotin production. This study set out to evaluate medium composition influence on biotin and riboflavin production using a statistical design. There are no studies relating biotin and riboflavin production by Candida sp LEB 130. In this preliminary study to improve the simultaneous production of biotin and riboflavin, the maximum riboflavin/biotin ratio of 8.3 μg/mL was achieved with medium component concentrations of: sucrose 30 g/L, KH2PO4 2 g/L, MgSO4 1 g/L and ZnSO4 0.5mL/L. PMID:24031727

  4. A Francisella virulence factor catalyses an essential reaction of biotin synthesis.

    PubMed

    Feng, Youjun; Napier, Brooke A; Manandhar, Miglena; Henke, Sarah K; Weiss, David S; Cronan, John E

    2014-01-01

    We recently identified a gene (FTN_0818) required for Francisella virulence that seemed likely involved in biotin metabolism. However, the molecular function of this virulence determinant was unclear. Here we show that this protein named BioJ is the enzyme of the biotin biosynthesis pathway that determines the chain length of the biotin valeryl side-chain. Expression of bioJ allows growth of an Escherichia coli bioH strain on biotin-free medium, indicating functional equivalence of BioJ to the paradigm pimeloyl-ACP methyl ester carboxyl-esterase, BioH. BioJ was purified to homogeneity, shown to be monomeric and capable of hydrolysis of its physiological substrate methyl pimeloyl-ACP to pimeloyl-ACP, the precursor required to begin formation of the fused heterocyclic rings of biotin. Phylogenetic analyses confirmed that distinct from BioH, BioJ represents a novel subclade of the α/β-hydrolase family. Structure-guided mapping combined with site-directed mutagenesis revealed that the BioJ catalytic triad consists of Ser151, Asp248 and His278, all of which are essential for activity and virulence. The biotin synthesis pathway was reconstituted reaction in vitro and the physiological role of BioJ directly assayed. To the best of our knowledge, these data represent further evidence linking biotin synthesis to bacterial virulence.

  5. Half-sandwich ruthenium(II) biotin conjugates as biological vectors to cancer cells.

    PubMed

    Babak, Maria V; Plażuk, Damian; Meier, Samuel M; Arabshahi, Homayon John; Reynisson, Jóhannes; Rychlik, Błażej; Błauż, Andrzej; Szulc, Katarzyna; Hanif, Muhammad; Strobl, Sebastian; Roller, Alexander; Keppler, Bernhard K; Hartinger, Christian G

    2015-03-23

    Ruthenium(II)-arene complexes with biotin-containing ligands were prepared so that a novel drug delivery system based on tumor-specific vitamin-receptor mediated endocytosis could be developed. The complexes were characterized by spectroscopic methods and their in vitro anticancer activity in cancer cell lines with various levels of major biotin receptor (COLO205, HCT116 and SW620 cells) was tested in comparison with the ligands. In all cases, coordination of ruthenium resulted in significantly enhanced cytotoxicity. The affinity of Ru(II) -biotin complexes to avidin was investigated and was lower than that of unmodified biotin. Hill coefficients in the range 2.012-2.851 suggest strong positive cooperation between the complexes and avidin. To estimate the likelihood of binding to the biotin receptor/transporter, docking studies with avidin and streptavidin were conducted. These explain, to some extent, the in vitro anticancer activity results and support the conclusion that these novel half-sandwich ruthenium(II)-biotin conjugates may act as biological vectors to cancer cells, although no clear relationship between the cellular Ru content, the cytotoxicity, and the presence of the biotin moiety was observed.

  6. Fatty liver and kidney syndrome in chicks. II. Biochemical role of biotin.

    PubMed

    Hood, R L; Johnson, A R; Fogerty, A C; Pearson, J A

    1976-12-01

    The role of biotin-dependent enzymes in the fatty liver and kidney syndrome of young chicks was studied. Under conditions of a marginal deficiency of dietary biotin, the level of biotin in the liver has differing effects on the activities of two biotin-dependent enzymes, pyruvate carboxylase and acetyl-CoA carboxylase. The activity of acetyl-CoA carboxylase is increased, but when the dietary deficiency of biotin produces biotin levels which are below 0-8 mug/g of liver, the activity of pyruvate carboxylase may be insufficient to completely metabolize pyruvate via gluconeogenesis. There is an increase in liver size and in the activities of enzymes involved in alternate pathways for the removal of pyruvate. Blood lactate accumulates and there is increased synthesis of fatty acids, and an accumulation of palmitoleic acid; these steps are accomplished by increased activities of at least the following enzymes: acetyl-CoA carboxylase, malate dehydrogenase (decarboxylating) (NADP+) and the desaturase enzyme. When the biotin level is below 0-35 mug/g of liver and the chick is subjected to a stress, physiological defence mechanisms of the chick may be inadequate to maintain homeostasis and they finally collapse, resulting in accumulation of triacylglycerol in the liver and blood; the chick is unable to maintain blood glucose levels and death occurs, often only a few hours after the imposition of the stress.

  7. Biotin deficiency and liver metabolism in relation to fatty liver and kidney syndrome.

    PubMed

    Pearce, J; Balnave, D

    1978-07-01

    Varying degrees of biotin deficiency were induced by adding freeze-dried, raw egg white to the diet of broiler chicks. Aspects of liver metabolism were studied with reference to fatty liver and kidney syndrome. Mortality was low with 11.8 g egg white/kg diet, or less, but with 17.7 g/kg or more, mortality was very high. High mortality was observed with less than 0.33 microgram biotin/g liver. Associated with low concentrations of liver biotin were substantial increases in liver weight and lipid content in starved birds. The increased liver lipid content was not observed in birds fed ad libitum. The increased liver lipid content in biotin-deficient, starved birds was not reflected in the specific activities of hepatic lipogenic enzymes or hepatic lipogenesis in vivo measured by the incorporation of tritium from 3H-labelled water into liver lipid. Biotin deficiency affected the specific activities of the biotin-requiring enzymes, pyruvate carboxylase and acetyl CoA carboxylase, differently; the latter was unaffected whereas the former decreased concomitantly with liver biotin concentration.

  8. Highly stabilized and photoluminescence enhancement of ZnS:Mn{sup 2+} nanoparticles in biotin matrix

    SciTech Connect

    Keshari, Ashish K.; Pandey, Avinash C.

    2009-03-15

    We synthesized the ZnS:Mn{sup 2+} nanoparticles passivated by biocompatible layer, namely, biotin by chemical precipitation route and studied their temporal evolution for size, structure, optical, and photoluminescence stability. To monitor the structural and optoelectronic properties of the nanoparticles with time, we have characterized the grown product by x-ray diffraction, small angle x-ray scattering, UV visible, and photoluminescence spectroscopic techniques at a regular interval for a period of three months. Results showed that the properties of nanophosphors capped with biotin are remaining the same even after 3 months. Energy dispersive x-ray analysis of 3 month aged sample shows long time compatibility between ZnS:Mn{sup 2+} nanoparticles and the biotin. This is also confirmed by electron microscopy that the growth of the nanoparticles is strongly arrested by the biotin. X-ray photoelectron spectra were also recorded to show the chemical state of the elements. Enhanced ratio of Zn 2p to Mn 2p peaks in the x-ray photoelectron spectra of ZnS:Mn{sup 2+} nanoparticles shows that the Mn{sup 2+} ions are incorporated within ZnS host matrix. We found that biotin capping will enhance the luminescence from ZnS:Mn{sup 2+} nanoparticles as compared to without capped particles. Absence of biotin will gradually degrade the luminescence upon aging while drastic degradation in luminescence intensity was observed after annealing. Properties show that biotin also protected the nanoparticles from any environmental attack.

  9. A Francisella Virulence Factor Catalyzes an Essential Reaction of Biotin Synthesis

    PubMed Central

    Feng, Youjun; Napier, Brooke A.; Manandhar, Miglena; Henke, Sarah K; Weiss, David S.; Cronan, John E.

    2014-01-01

    Summary We recently identified a gene (FTN_0818) required for Francisella virulence that seemed likely involved in biotin metabolism. However, the molecular function of this virulence determinant was unclear. Here we show that this protein named BioJ is the enzyme of the biotin biosynthesis pathway that determines the chain length of the biotin valeryl side chain. Expression of bioJ allows growth of an E. coli bioH strain on biotin-free medium, indicating functional equivalence of BioJ to the paradigm pimeloyl-ACP methyl ester carboxyl-esterase, BioH. BioJ was purified to homogeneity, shown to be monomeric and capable of hydrolysis of its physiological substrate methyl pimeloyl-ACP to pimeloyl-ACP, the precursor required to begin formation of the fused heterocyclic rings of biotin. Phylogenetic analyses confirmed that distinct from BioH, BioJ represents a novel sub-clade of the α/β-hydrolase family. Structure-guided mapping combined with site-directed mutagenesis revealed that the BioJ catalytic triad consists of Ser151, Asp248 and His278, all of which are essential for activity and virulence. The biotin synthesis pathway was reconstituted in vitro and the physiological role of BioJ directly assayed. To the best of our knowledge, these data represent further evidence linking biotin synthesis to bacterial virulence. PMID:24313380

  10. Dual functionalized graphene oxide serves as a carrier for delivering oligohistidine- and biotin-tagged biomolecules into cells.

    PubMed

    Jana, Batakrishna; Mondal, Goutam; Biswas, Atanu; Chakraborty, Indrani; Saha, Abhijit; Kurkute, Prashant; Ghosh, Surajit

    2013-11-01

    A versatile method of dual chemical functionalization of graphene oxide (GO) with Tris-[nitrilotris(acetic acid)] (Tris-NTA) and biotin for cellular delivery of oligohistidine- and biotin-tagged biomolecules is reported. Orthogonally functionalized GO surfaces with Tris-NTA and biotin to obtain a dual-functionalized GO (DFGO) are prepared and characterized by various spectroscopic and microscopic techniques. Fluorescence microscopic images reveal that DFGO surfaces are capable of binding oligohistidine-tagged biomolecules/proteins and avidin/biotin-tagged biomolecules/proteins orthogonally. The DFGO nanoparticles are non-cytotoxic in nature and can deliver oligohistidine- and biotin-tagged biomolecules simultaneously into the cell.

  11. Biotin-Streptavidin Affinity Purification of RNA-Protein Complexes Assembled In Vitro.

    PubMed

    Hou, Shuai; Shi, Lei; Lei, Haixin

    2016-01-01

    RNA-protein complexes are essential for the function of different RNAs, yet purification of specific RNA-protein complexes can be complicated and is a major obstacle in understanding the mechanism of regulatory RNAs. Here we present a protocol to purify RNA-protein complexes assembled in vitro based on biotin-streptavidin affinity. In vitro transcribed RNA is labeled with (32)P and biotin, ribonucleoprotein particles or RNPs are assembled by incubation of RNA in nuclear extract and fractionated using gel filtration, and RNP fractions are pooled for biotin-streptavidin affinity purification. The amount of RNA-protein complexes purified following this protocol is sufficient for mass spectrometry.

  12. Lactate administration and fatty liver and kidney syndrome development in biotin-deficient chicks.

    PubMed

    Balnave, D; Pearce, J

    1979-01-01

    Two experiments were carried out to determine whether administration of lactate to biotin-deficient chicks induced fatty liver and kidney syndrome (FLKS). 2. The results suggest that increased serum lactate concentrations are a consequence of the syndrome rather than a contributory factor in its incidence. 3. The increase in liver lipids of birds affected by FLKS was not associated with an increase in the specific activity of the hepatic lipogenic enzyme acetyl CoA carboxylase accept when birds developed FLKS spontaneously in experiment 2. 4. Some biotin-deficient chicks did not show physical symptoms of deficiency although mean liver biotin concentrations were low (0.31 microgram/g liver).

  13. Thermochemistry of HO2 + HO2 → H2O4: Does HO2 Dimerization Affect Laboratory Studies?

    PubMed

    Sprague, Matthew K; Irikura, Karl K

    2015-07-09

    Self-reaction is an important sink for the hydroperoxy radical (HO2) in the atmosphere. It has been suggested (Denis, P. A.; Ornellas, F. R. J. Phys. Chem. A, 2009, 113 (2), 499-506) that the minor product hydrogen tetroxide (HO4H) may act as a reservoir of HO2. Here, we compute the thermochemistry of HO2 self-reactions to determine if either HO4H or the cyclic hydrogen-bound dimer (HO2)2 can act as reservoirs. We computed electronic energies using coupled-cluster calculations in the complete basis set limit, CCSD(T)/CBS[45]//CCSD(T)/cc-pVTZ. Our model chemistry includes corrections for vibrational anharmonicity in the zero-point energy and vibrational partition functions, core-valence correlation, scalar relativistic effects, diagonal Born-Oppenheimer, spin-orbit splitting, and higher-order corrections. We compute the Gibbs energy of dimerization to be (-20.1 ± 1.6) kJ/mol at 298.15 K (2σ uncertainty), and (-32.3 ± 1.5) kJ/mol at 220 K. For atmospherically relevant [HO2] = 10(8) molecules per cm(3), our thermochemistry indicates that dimerization will be negligible, and thus H2O4 species are atmospherically unimportant. Under conditions used in laboratory experiments ([HO2] > 10(12) molecules per cm(3), 220 K), H2O4 formation may be significant. We compute two absorption spectra that could be used for laboratory detection of HO4H: the OH stretch overtone (near-IR) and electronic (UV) spectra.

  14. Theoretical Studies of the HO/HO2 Catalytic Cycle for Ozone Destruction

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Langhoff, Steve R. (Technical Monitor)

    1996-01-01

    Recently it has been determined that the HO/HO2 catalytic cycle accounts for nearly one-half of the total ozone depletion in the lower stratosphere. The catalytic cycle is: (1) HO + O3 yields HO2 + O2; (2) HO2 + O3 yields HO + O2 + O2. The net reaction is 2O3 yields 3O2. The rate limiting step in this process is the reaction of HO2 with ozone. There is a problem extending the experimental measurement of the rate of this reaction over the range 233-400 K down to stratospheric temperatures of 210-220 K. Therefore we have undertaken a project to determine the temperature dependence of the rate constant for this reaction in the low temperature region. The first step in this project, which is described in this poster, is the determination of the relevant potential energy surfaces. The calculations use CASSCF/derivative methods to define the pathways followed by CASSCF/ACPF to determine the energetics. The HO + O3 reaction is found to proceed through an HO4 complex, which is unstable with respect to HO2 + O2. The HO2 +O3 reaction is more complex. One pathway, which has been characterized, is the formation of an HO5 complex which decomposes to HO3 + O2 and subsequently to HO + O2 + O2. Another pathway, which is believed to also play a role, is hydrogen abstraction to give O2 + HO3 and subsequent decomposition of HO3 to HO + O2. Isotopic labeling experiments indicate that the later pathway is dominant. However, so far attempts to locate the saddle point for this pathway have not been successful. We have also characterized the potential energy surfaces for a number of species involved in these reactions, including HO3 and triplet O4. The triplet O4 species is probably involved in the reaction of vibrationally excited O2 with ground state O2 leading to O3 + O. The latter reaction is believed to be important as an additional source of stratospheric ozone.

  15. Ho:YLF pumped HBr laser.

    PubMed

    Botha, L R; Bollig, C; Esser, M J D; Campbell, R N; Jacobs, C; Preussler, D R

    2009-10-26

    A Ho:YLF laser pumped HBr molecular laser was developed that produced up to 2.5 mJ of energy in the 4 micron wavelength region. The Ho:YLF laser was fiber pumped using a commercial Tm:fibre laser. The Ho:YLF laser was operated in a single longitudinal mode via injection seeding with a narrow band diode laser which in turn was locked to one of the HBr transitions. The behavior of the HBr laser was described using a rate equation mathematical model and this was solved numerically. Good agreement both qualitatively and quantitatively between the model and experimental results was obtained.

  16. Registration of "HoCP 00-950" Sugarcane

    Technology Transfer Automated Retrieval System (TEKTRAN)

    HoCP 00-950 sugarcane was selected from progeny of the cross HoCP 93-750 x HoCP 92-676 made at Canal Point, Florida. HoCP 00-950 was developed through cooperative research by the Agricultural Research Service of the United States Department of Agriculture, the Louisiana Agricultural Experiment Stati...

  17. AN ELISA ASSAY FOR HEME OXYGENASE (HO-1)

    EPA Science Inventory

    An ELISA assay for heme oxygenase (HO-l )

    Abstract

    A double antibody capture ELISA for the HO-l protein has been developed to separately quantitate HO-I protein. The use of 2.5% NP40 detergent greatly assists in freeing HO-l protein from membranes and/or other cel...

  18. Biotin avidin amplified magnetic immunoassay for hepatitis B surface antigen detection using GoldMag nanoparticles

    NASA Astrophysics Data System (ADS)

    Yu, An; Geng, Tingting; Fu, Qiang; Chen, Chao; Cui, Yali

    2007-04-01

    Using GoldMag (Fe3O4/Au) nanoparticles as a carrier, a biotin-avidin amplified ELISA was developed to detect hepatitis B surface antigen (HBsAg). A specific antibody was labeled with biotin and then used to detect the antigen with an antibody coated on GoldMag nanoparticles by a sandwich ELISA assay. The results showed that 5 mol of biotin were surface bound per mole of antibody. The biotin-avidin amplified ELISA assay has a higher sensitivity than that of the direct ELISA assay. There is 5-fold difference between HBsAg positive and negative serum even at dilution of 1:10000, and the relative standard deviation of the parallel positive serum at dilution of 1:4000 is 5.98% (n=11).

  19. An improved smaller biotin ligase for BioID proximity labeling

    PubMed Central

    Kim, Dae In; Jensen, Samuel C.; Noble, Kyle A.; KC, Birendra; Roux, Kenneth H.; Motamedchaboki, Khatereh; Roux, Kyle J.

    2016-01-01

    The BioID method uses a promiscuous biotin ligase to detect protein–protein associations as well as proximate proteins in living cells. Here we report improvements to the BioID method centered on BioID2, a substantially smaller promiscuous biotin ligase. BioID2 enables more-selective targeting of fusion proteins, requires less biotin supplementation, and exhibits enhanced labeling of proximate proteins. Thus BioID2 improves the efficiency of screening for protein–protein associations. We also demonstrate that the biotinylation range of BioID2 can be considerably modulated using flexible linkers, thus enabling application-specific adjustment of the biotin-labeling radius. PMID:26912792

  20. Biotin and carnitine deficiency due to hypoallergenic formula nutrition in infants with milk allergy.

    PubMed

    Hayashi, Hisako; Tokuriki, Shuko; Okuno, Takashi; Shigematsu, Yosuke; Yasushi, Akiba; Matsuyama, Go; Sawada, Ken; Ohshima, Yusei

    2014-04-01

    Amino acid formulas and hydrolyzed formulas given to infants in Japan with milk allergies theoretically contain little, if any, biotin and carnitine. We assessed biotin and carnitine insufficiency in six infants with milk allergy who were fed amino acid formulas and/or hydrolyzed formulas, by measuring urine 3-hydroxyisovaleric acid (3-HIA) and serum free carnitine (C0), respectively. All patients presented with elevated urine 3-HIA and lowered serum C0 compared with post-menstrual age-matched infants who were fed breast milk or standard infant formulas. Supplementation with biotin and L-carnitine immediately improved the insufficiency. Care should be taken to avoid biotin and carnitine deficiency in allergic infants fed amino acid or hydrolyzed formulas.

  1. Biotin-conjugated fusogenic liposomes for high-quality cell purification.

    PubMed

    Hersch, Nils; Wolters, Benjamin; Ungvari, Zoltan; Gautam, Tripti; Deshpande, Dhruva; Merkel, Rudolf; Csiszar, Anna; Hoffmann, Bernd; Csiszár, Agnes

    2016-01-01

    Purification of defined cell populations from mixed primary cell sources is essential for many biomedical and biotechnological applications but often very difficult to accomplish due to missing specific surface markers. In this study, we developed a new approach for efficient cell population separation based on the specific membrane fusion characteristics of distinct cell types upon treatment with fusogenic liposomes. When such liposomes are conjugated with biotin, specific cell populations can be efficiently surface functionalized by biotin after liposomal treatment while other populations remain unlabeled. Due to the high affinity of biotin for avidin-like proteins, biotin functionalized cells are ideal targets for conjugation of e.g. avidin tagged magnetic beads, fluorophores or antibodies with bioanalytical relevance. Here, based on the differential biotinylation of distinct cell populations high quality separation of cardiac fibroblasts from myocytes, and cerebromicrovascular endothelial cells from fibroblasts was successfully established.

  2. A Rhizavidin Monomer with Nearly Multimeric Avidin-Like Binding Stability Against Biotin Conjugates.

    PubMed

    Lee, Jeong Min; Kim, Jung A; Yen, Tzu-Chi; Lee, In Hwan; Ahn, Byungjun; Lee, Younghoon; Hsieh, Chia-Lung; Kim, Ho Min; Jung, Yongwon

    2016-03-01

    Developing a monomeric form of an avidin-like protein with highly stable biotin binding properties has been a major challenge in biotin-avidin linking technology. Here we report a monomeric avidin-like protein-enhanced monoavidin-with off-rates almost comparable to those of multimeric avidin proteins against various biotin conjugates. Enhanced monoavidin (eMA) was developed from naturally dimeric rhizavidin by optimally maintaining protein rigidity during monomerization and additionally shielding the bound biotin by diverse engineering of the surface residues. eMA allowed the monovalent and nonperturbing labeling of head-group-biotinylated lipids in bilayer membranes. In addition, we fabricated an unprecedented 24-meric avidin probe by fusing eMA to a multimeric cage protein. The 24-meric avidin and eMA were utilized to demonstrate how artificial clustering of cell-surface proteins greatly enhances the internalization rates of assembled proteins on live cells.

  3. [Adaptation of the avidin-biotin system for identifying and quantifying Sendai virus antigens].

    PubMed

    Popa, L M; Marcheş, F; Repanovici, R; Iliescu, R; Muţiu, A; Cajal, N

    1989-01-01

    The avidin-biotin system was adapted in view of the identification and dosage of the Sendai parainfluenza virus and of its antigens, using the method of double antibodies (biotinylated and nonbiotinylated) in ELISA type tests.

  4. The Binding of Biotin to Sepharose-Avidin Column: Demonstration of the Affinity Chromatography Technique

    ERIC Educational Resources Information Center

    Landman, A. D.; Landman, N. N.

    1976-01-01

    Describes a biochemistry experiment that illustrates the methodology of affinity chromatography by attaching avidin, a glycoprotein in egg white, to a Sepharose matrix in order to bind biotin-containing proteins. (MLH)

  5. Homogeneous assay for biotin based on Aequorea victoria bioluminescence resonance energy transfer system.

    PubMed

    Gorokhovatsky, Andrey Yu; Rudenko, Natalia V; Marchenkov, Victor V; Skosyrev, Vitaly S; Arzhanov, Maxim A; Burkhardt, Nils; Zakharov, Mikhail V; Semisotnov, Gennady V; Vinokurov, Leonid M; Alakhov, Yuli B

    2003-02-01

    Here we describe a homogeneous assay for biotin based on bioluminescence resonance energy transfer (BRET) between aequorin and enhanced green fluorescent protein (EGFP). The fusions of aequorin with streptavidin (SAV) and EGFP with biotin carboxyl carrier protein (BCCP) were purified after expression of the corresponding genes in Escherichia coli cells. Association of SAV-aequorin and BCCP-EGFP fusions was followed by BRET between aequorin (donor) and EGFP (acceptor), resulting in significantly increasing 510 nm and decreasing 470 nm bioluminescence intensity. It was shown that free biotin inhibited BRET due to its competition with BCCP-EGFP for binding to SAV-aequorin. These properties were exploited to demonstrate competitive homogeneous BRET assay for biotin.

  6. A fluorescence polarization assay to quantify biotin and biotin-binding proteins in whole plant extracts using Alexa-Fluor 594 biocytin.

    PubMed

    Martin, Harry; Murray, Colleen; Christeller, John; McGhie, Tony

    2008-10-01

    A high-throughput fluorescence polarization assay has been developed for the detection of biotin and biotin-binding proteins in whole leaf extracts. Various groups are investigating the insecticidal properties of avidin and other biotin-binding proteins expressed in leaves of transgenic plants. The methods commonly used to quantify biotin and avidin in leaf extracts are enzyme-linked immunosorbent assay (ELISA) and Western blotting. Here we describe a homogeneous fluorescence polarization (FP) method that quantifies transgenic avidin in whole leaf extract by the simple addition of the fluorescent avidin ligand Alexa-Fluor 594 biocytin (AFB). The FP assay exploits the fact that AFB excites and emits in regions of the spectrum that are relatively free of background fluorescence in leaf extract. Transgenic leaf avidin can be quantified within 1-2 h by the FP method, in comparison with 1-2 days for ELISA and Western blotting. The FP method can also measure the amount of biotin in control leaves, not expressing avidin. Functional avidin levels of 1.54 microM (26.1 microg/g leaf tissue) were detected in tobacco leaves expressing vacuole-targeted avidin. Control leaves had biotin levels of around 0.74 microM (approximately 0.18 microg/g leaf tissue). Reagent costs are minimal: typically AFB is used at concentrations of 1-10 nM, avidin is used at 1-100 nM, and sample volumes are 20 microL in 384-well microplates.

  7. [Biotidinase deficiency: a disease with neurologic and cutaneous expression susceptible to biotin].

    PubMed

    de Parscau, L; Beaufrère, B; Vianey-Liaud, C; Rolland, M O; Langue, J; Divry, P; Guibaud, P

    1989-01-01

    The authors report 2 familial cases of biotin deficiency. The first neurological signs appeared at the age of 2 years in a boy. The diagnosis was established in his sister in the neonatal period. A review of 41 published cases summarizes the neurologic signs (seizures, ataxia, hypotonia and later, developmental delay and deafness) and the cutaneous signs (rash, alopecia). An early treatment with biotin cures or prevents the clinical signs of the disease in most cases.

  8. Thermodynamic analysis of small ligand binding to the Escherichia coli repressor of biotin biosynthesis.

    PubMed

    Xu, Y; Johnson, C R; Beckett, D

    1996-04-30

    BirA is the transcriptional repressor of biotin biosynthesis and a biotin holoenzyme synthetase. It catalyzes synthesis of biotinyl-5'-AMP from the substrates biotin and ATP. The adenylate is the activated intermediate in the biotin transfer reaction as well as the positive allosteric effector for site-specific DNA binding. The affinity of BirA for the adenylate is considerably greater than its affinity for biotin, and both binding reactions are coupled to changes in the conformation of the protein. The temperature dependencies of the two binding interactions have been determined using kinetic techniques. Van't Hoff analysis of the equilibrium dissociation constants derived from the kinetic data indicate that while the two binding processes are characterized by large negative enthalpies, the entropic contributions are small for both. Binding enthalpies have also been determined by isothermal titration calorimetry. Consistent with the results of the van't Hoff analyses, the calorimetric enthalpies are large and negative. The greater precision of the calorimetric measurements allowed more accurate estimation of the entropic contributions to the binding processes, which are of opposite sign for the two ligands. In addition, the heat capacity changes associated with the two binding reactions are small. The measured thermodynamic parameters for binding of biotin and bio-5'-AMP to BirA have been utilized to dissect out structural contributions to the binding energetics. Results of these calculations indicate equivalent contributions of burial of polar and apolar surface area to both binding processes. The total loss of solvent accessible surface area is, however, greater for biotin binding. The analysis indicates furthermore that although both binding reactions are coupled to losses in configurational entropy, the magnitude of the conformational change is significantly larger for biotin binding.

  9. Carbon nanofiber-based luminol-biotin probe for sensitive chemiluminescence detection of protein.

    PubMed

    Baj, Stefan; Krawczyk, Tomasz; Pradel, Natalia; Azam, Md Golam; Shibata, Takayuki; Dragusha, Shpend; Skutil, Krzysztof; Pawlyta, Miroslawa; Kai, Masaaki

    2014-01-01

    A carbon nanofiber-based luminol-biotin probe was synthesized for the sensitive chemiluminescence (CL) detection of a target protein by grafting luminol and biotin onto an oxidized carbon nanofiber. This carbon nanofiber was prepared by chemical vapor-deposition with methane in the presence of the Ni-Cu-MgO catalyst, which was followed by oxidization with HNO3-H2SO4 to produce a carboxyl group on the surface of the nanofiber. The material was grafted with luminol and biotin by means of a standard carbodiimide activation of COOH groups to produce corresponding amides. The substance was water-soluble and thus could be utilized as a sensitive CL probe for a protein assay. The probe showed highly specific affinity towards the biotin-labeled antibody via a streptavidin-biotin interaction. The detection limit for this model assay was approximately 0.2 pmol of the biotinized IgG spotted on a polyvinylidene fluoride (PVDF) membrane. Nonspecific binding to other proteins was not observed. Therefore, the synthesized carbon nanofiber-based CL probe may be useful for a sensitive and specific analysis of the target protein.

  10. Biotin-Streptavidin Competition Mediates Sensitive Detection of Biomolecules in Enzyme Linked Immunosorbent Assay.

    PubMed

    Lakshmipriya, Thangavel; Gopinath, Subash C B; Tang, Thean-Hock

    2016-01-01

    Enzyme Linked Immunosorbent Assay (ELISA) is the gold standard assay for detecting and identifying biomolecules using antibodies as the probe. Improving ELISA is crucial for detecting disease-causing agents and facilitating diagnosis at the early stages of disease. Biotinylated antibody and streptavidin-conjugated horse radish peroxide (streptavidin-HRP) often are used with ELISA to enhance the detection of various kinds of targets. In the present study, we used a competition-based strategy in which we pre-mixed free biotin with streptavidin-HRP to generate high-performance system, as free biotin occupies some of the biotin binding sites on streptavidin, thereby providing more chances for streptavidin-HRP to bind with biotinylated antibody. ESAT-6, which is a protein secreted early during tuberculosis infection, was used as the model target. We found that 8 fM of free biotin mixed with streptavidin-HRP anchored the higher detection level of ESAT-6 by four-fold compared with detection without free biotin (only streptavidin-HRP), and the limit of detection of the new method was 250 pM. These results suggest that biotin-streptavidin competition can be used to improve the diagnosis of analytes in other types of sensors.

  11. Time-resolved homo-FRET studies of biotin-streptavidin complexes.

    PubMed

    Andreoni, Alessandra; Nardo, Luca; Rigler, Rudolf

    2016-09-01

    Förster resonance energy transfer is a mechanism of fluorescence quenching that is notably useful for characterizing properties of biomolecules and/or their interactions. Here we study water-solutions of Biotin-Streptavidin complexes, in which Biotin is labeled with a rigidly-bound fluorophore that can interact by Förster resonance energy transfer with the fluorophores labeling the other, up to three, Biotins of the same complex. The fluorophore, Atto550, is a Rhodamine analogue. We detect the time-resolved fluorescence decay of the fluorophores with an apparatus endowed with single-photon sensitivity and temporal resolution of ~30ps. The decay profiles we observe for samples containing constant Biotin-Atto550 conjugates and varying Streptavidin concentrations are multi-exponential. Each decay component can be associated with the rate of quenching exerted on each donor by each of the acceptors that label the other Biotin molecules, depending on the binding site they occupy. The main features that lead to this result are that (i) the transition dipole moments of the up-to-four Atto550 fluorophores that label the complexes are fixed as to both relative positions and mutual orientations; (ii) the fluorophores are identical and the role of donor in each Biotin-Streptavidin complex is randomly attributed to the one that has absorbed the excitation light (homo-FRET). Obviously the high-temporal resolution of the excitation-detection apparatus is necessary to discriminate among the fluorescence decay components.

  12. Biotin-Streptavidin Competition Mediates Sensitive Detection of Biomolecules in Enzyme Linked Immunosorbent Assay

    PubMed Central

    Lakshmipriya, Thangavel; Gopinath, Subash C. B.; Tang, Thean-Hock

    2016-01-01

    Enzyme Linked Immunosorbent Assay (ELISA) is the gold standard assay for detecting and identifying biomolecules using antibodies as the probe. Improving ELISA is crucial for detecting disease-causing agents and facilitating diagnosis at the early stages of disease. Biotinylated antibody and streptavidin-conjugated horse radish peroxide (streptavidin-HRP) often are used with ELISA to enhance the detection of various kinds of targets. In the present study, we used a competition-based strategy in which we pre-mixed free biotin with streptavidin-HRP to generate high-performance system, as free biotin occupies some of the biotin binding sites on streptavidin, thereby providing more chances for streptavidin-HRP to bind with biotinylated antibody. ESAT-6, which is a protein secreted early during tuberculosis infection, was used as the model target. We found that 8 fM of free biotin mixed with streptavidin-HRP anchored the higher detection level of ESAT-6 by four-fold compared with detection without free biotin (only streptavidin-HRP), and the limit of detection of the new method was 250 pM. These results suggest that biotin-streptavidin competition can be used to improve the diagnosis of analytes in other types of sensors. PMID:26954237

  13. Contribution of Cysteine Desulfurase (NifS Protein) to the Biotin Synthase Reaction of Escherichia coli

    PubMed Central

    Kiyasu, Tatsuya; Asakura, Akira; Nagahashi, Yoshie; Hoshino, Tatsuo

    2000-01-01

    The contribution of cysteine desulfurase, the NifS protein of Klebsiella pneumoniae and the IscS protein of Escherichia coli, to the biotin synthase reaction was investigated in in vitro and in vivo reaction systems with E. coli. When the nifS and nifU genes of K. pneumoniae were coexpressed in E. coli, NifS and NifU proteins in complex (NifU/S complex) and NifU monomer forms were observed. Both the NifU/S complex and the NifU monomer stimulated the biotin synthase reaction in the presence of l-cysteine in an in vitro reaction system. The NifU/S complex enhanced the production of biotin from dethiobiotin by the cells growing in an in vivo reaction system. Moreover, the IscS protein of E. coli stimulated the biotin synthase reaction in the presence of l-cysteine in the cell-free system. These results strongly suggest that cysteine desulfurase participates in the biotin synthase reaction, probably by supplying sulfur to the iron-sulfur cluster of biotin synthase. PMID:10781558

  14. Local Measurement of Tropospheric HO(x)

    NASA Technical Reports Server (NTRS)

    Crosley, David R.

    1994-01-01

    In March of 1992 a workshop sponsored by NASA and NSF was held at SRI International to assess the current ability to measure atmospheric OH and HO2. The measurement techniques reviewed during the workshop for detection of OH included five laser-induced fluorescence schemes, five laser-based adsorption techniques, and four non-laser methods. Six instruments or instrument concepts for HO2 detection, including chemical amplification, conversion to OH with subsequent OH detection, or direct spectroscopic detection of the HO2 were also discussed. The conclusions from the workshop identify several measurement techniques for OH and HO2 that are ready for field tests. These have the ability to measure the radicals with sufficient sensitivity and accuracy to form meaningful comparison with atmospheric model predictions. The workshop conclusions also include recommendations for informal and formal intercomparison protocols.

  15. LiHo(PO3)4

    PubMed Central

    Ben Zarkouna, Emna; Driss, Ahmed; Férid, Mokhtar

    2009-01-01

    Lithium holmium(III) polyphosphate(V), LiHo(PO3)4, belongs to the type I of polyphosphates with general formula ALn(PO3)4, where A is a monovalent cation and Ln is a trivalent rare earth cation. In the crystal structure, the polyphosphate chains spread along the b-axis direction, with a repeat period of four tetra­hedra and 21 inter­nal symmetry. The Li and Ho atoms are both located on twofold rotation axes and are surrounded by four and eight O atoms, leading to a distorted tetra­hedral and dodeca­hedral coordination, respectively. The HoO8 polyhedra are isolated from each other, the closest Ho⋯Ho distance being 5.570 (1) Å. PMID:21581738

  16. [The effects of biotin on the metabolism of ammonia and amino acids in urease-induced hyperammonemic rats].

    PubMed

    Nagamine, T; Saito, S; Yamada, S; Sekiguchi, T; Kobayashi, S; Nakano, M

    1989-07-01

    The effects of oral and intraperitoneal administration of biotin in urease-induced hyperammonemic rats, as well as the influence of biotin deficiency, have been studied. Biotin deficiency was produced by feeding standard diet MF (Oriental Yeast Co.) supplemented with dry egg-white (egg-white group). Egg-white + biotin group had free access to 0.0014% of biotin solution at all time. Following an intraperitoneal injection of urease, 25 U/kg (B.W.), plasma ammonia levels in egg-white + biotin group were lower than in egg-white group, especially there was significance (p less than 0.05) at 8 hours after the urease injection. Similarly, plasma ammonia levels in biotin-injected rats, in which 1 mg of biotin had been injected intraperitoneally prior to the experiment, were significantly low compared with saline-injected controls at 4 and 6 hours after urease administration. Results of plasma amino acid analysis, 9 hours after the urease injection indicated that Fischer's molar ratio (Leu + Ileu + Val/Tyr + Phe) was significantly higher in the biotin-injected rats than the saline-injected control. It suggests that biotin might decrease blood ammonia by facilitating the detoxification mechanism as follow: L-glutamate + NH3----L-glutamine.

  17. Intramitochondrial accumulation of cationic Atto520-biotin proceeds via voltage-dependent slow permeation through lipid membrane.

    PubMed

    Antonenko, Yuri N; Nechaeva, Natalya L; Baksheeva, Victoria E; Rokitskaya, Tatyana I; Plotnikov, Egor Y; Kotova, Elena A; Zorov, Dmitry B

    2015-06-01

    Conjugation to penetrating cations is a general approach for intramitochondrial delivery of physiologically active compounds, supported by a high membrane potential of mitochondria having negative sign on the matrix side. By using fluorescence correlation spectroscopy, we found here that Atto520-biotin, a conjugate of a fluorescent cationic rhodamine-based dye with the membrane-impermeable vitamin biotin, accumulated in energized mitochondria in contrast to biotin-rhodamine 110. The energy-dependent uptake of Atto520-biotin by mitochondria, being slower than that of the conventional mitochondrial dye tetramethyl-rhodamine ethyl ester, was enhanced by the hydrophobic anion tetraphenylborate (TPB). Atto520-biotin also exhibited accumulation in liposomes driven by membrane potential resulting from potassium ion gradient in the presence valinomycin. The induction of electrical current across planar bilayer lipid membrane by Atto520-biotin proved the ability of the compound to permeate through lipid membrane in a cationic form. Atto520-biotin stained mitochondria in a culture of L929 cells, and the staining was enhanced in the presence of TPB. Therefore, the fluorescent Atto520 moiety can serve as a vehicle for intramitochondrial delivery of hydrophilic drugs. Of importance for biotin-streptavidin technology, binding of Atto520-biotin to streptavidin was found to cause quenching of its fluorescence similar to the case of fluorescein-4-biotin.

  18. Novel Insights into the Biotin Carboxylase Domain Reactions of Pyruvate Carboxylase from Rhizobium etli†

    PubMed Central

    Zeczycki, Tonya N.; Menefee, Ann L.; Adina-Zada, Abdussalam; Jitrapakdee, Sarawut; Surinya, Kathy H.; Wallace, John C.; Attwood, Paul V.; St. Maurice, Martin; Cleland, W. Wallace

    2011-01-01

    The catalytic mechanism of the MgATP-dependent carboxylation of biotin in the biotin carboxylase domain of pyruvate carboxylase from R. etli (RePC) is common to the biotin-dependent carboxylases. The current site-directed mutagenesis study has clarified the catalytic functions of several residues proposed to be pivotal in MgATP-binding and cleavage (Glu218 and Lys245), HCO3− deprotonation (Glu305 and Arg301) and biotin enolization (Arg353). The E218A mutant was inactive for any reaction involving the BC domain and the E218Q mutant exhibited a 75-fold decrease in kcat for both pyruvate carboxylation and the full reverse reaction. The E305A mutant also showed a 75- and 80-fold decrease in kcat for both pyruvate carboxylation and the full reverse reaction, respectively. While Glu305 appears to be the active site base which deprotonates HCO3−, Lys245, Glu218 and Arg301 are proposed to contribute to catalysis through substrate binding interactions. The reactions of the biotin carboxylase and carboxyl transferase domains were uncoupled in the R353M-catalyzed reactions, indicating that Arg353 may not only facilitate the formation of the biotin enolate, but also assist in coordinating catalysis between the two spatially distinct active sites. The 2.5 and 4-fold increase in kcat for the full reverse reaction with the R353K and R353M mutants, respectively, suggests that mutation of Arg353 allows carboxybiotin increased access to the biotin carboxylase domain active site. The proposed chemical mechanism is initiated by the deprotonation of HCO3− by Glu305 and concurrent nucleophilic attack on the γ-phosphate of MgATP. The trianionic carboxyphosphate intermediate formed reversibly decomposes in the active site to CO2 and PO43−. PO43− then acts as the base to deprotonate the tethered biotin at the N1-position. Stabilized by interactions between the ureido oxygen and Arg353, the biotin-enolate reacts with CO2 to give carboxybiotin. The formation of a distinct salt

  19. The Unimolecular Decomposition and H Abstraction Reactions by HO and HO2 from n-Butanol

    NASA Astrophysics Data System (ADS)

    Moc, Jerzy; Black, Gráinne; Simmie, John M.; Curran, Henry J.

    2009-08-01

    By using correlated ab initio (MP2, CCSD(T)) and multi-level (G3, CBS-QB3) methods we have studied unimolecular and bimolecular reactions of n-butanol in the gas phase. The specific processes investigated include H2O elimination and hydrogen abstraction by the hydroxy (HO) and hydroperoxy (HO2) radicals from this alcohol.

  20. Biotin-conjugated tumour-targeting photocytotoxic iron(III) complexes.

    PubMed

    Saha, Sounik; Majumdar, Ritankar; Hussain, Akhtar; Dighe, Rajan R; Chakravarty, Akhil R

    2013-07-28

    Iron(III) complexes [FeL(B)] (1-4) of a tetradentate phenolate-based ligand (H3L) and biotin-conjugated dipyridophenazine bases (B), viz. 7-aminodipyrido [3,2-a:2',3'-c]-phenazine (dppza in 1), (N-dipyrido[3,2-a:2',3'-c]-phenazino)amidobiotin (dppzNB in 2), dipyrido [3,2-a:2',3'-c]-phenazine-11-carboxylic acid (dppzc in 3) and 2-((2-biotinamido)ethyl) amido-dipyrido[3,2-a:2',3'-c]-phenazine (dppzCB in 4) are prepared, characterized and their interaction with streptavidin and DNA and their photocytotoxicity and cellular uptake in various cells studied. The high-spin iron(III) complexes display Fe(III)/Fe(II) redox couple near -0.7 V versus saturated calomel electrode in dimethyl sulfoxide-0.1 M tetrabutylammonium perchlorate. The complexes show non-specific interaction with DNA as determined from the binding studies. Complexes with appended biotin moiety show similar binding to streptavidin as that of free biotin, suggesting biotin conjugation to dppz does not cause any loss in its binding affinity to streptavidin. The photocytotoxicity of the complexes is tested in HepG2, HeLa and HEK293 cell lines. Complex 2 shows higher photocytotoxicity in HepG2 cells than in HeLa or HEK293, forming reactive oxygen species. This effect is attributed to the presence of overexpressed sodium-dependent multi-vitamin transporters in HepG2 cells. Microscopic studies in HepG2 cells show internalization of the biotin complexes 2 and 4 essentially occurring by receptor-mediated endocytosis, which is similar to that of native biotin and biotin fluorescein isothiocyanate conjugate.

  1. Measurement of acylcarnitine substrate to product ratios specific to biotin-dependent carboxylases offers a combination of indicators of biotin status in humans.

    PubMed

    Bogusiewicz, Anna; Horvath, Thomas D; Stratton, Shawna L; Mock, Donald M; Boysen, Gunnar

    2012-09-01

    This work describes a novel liquid chromatography tandem MS (LC-MS/MS) method for the determination of ratios of acylcarnitines arising from acyl-CoA substrates and products that reflect metabolic disturbances caused by marginal biotin deficiency. The urinary ratios reflecting reduced activities of biotin-dependent enzymes include the following: 1) the ratio of 3-hydroxyisovalerylcarnitine : 3-methylglutarylcarnitine (3HIAc : MGc) for methylcrotonyl-CoA carboxylase; 2) the ratio of propionylcarnitine:methylmalonylcarnitine (Pc : MMc) for propionyl-CoA carboxylase (PCC); and 3) the ratio of acetylcarnitine : malonylcarnitine (Ac : Mc) for acetyl-CoA carboxylase. To demonstrate the suitability of the LC-MS/MS method for biomonitoring, we measured the 3 ratios for 7 healthy adults at various time points (d 0, 14, and 28) during the induction of marginal biotin through the consumption of egg white. The mean change in the Pc : MMc ratio relative to d 0 was 5.3-fold by d 14 (P = 0.0049) and 8.5-fold by d 28 (P = 0.0042). The mean change in the 3HIAc : MGc ratio was 2.8-fold by d 14 (P = 0.0022) and 3.8-fold by d 28 (P = 0.0001). The mean change in the Ac : Mc ratio was 2.9-fold by d 14 (P = 0.03) and 4.7-fold by d 28 (P = 0.02). The results suggest that simultaneous assessment of ratios of multiple biotin-dependent pathways offers insight into the complex metabolic disturbances caused by marginal biotin deficiency. We hypothesize that one or a combination of the ratios might be more sensitive or robust with respect to other nutrient deficiencies or confounding metabolic processes.

  2. Synthesis of fluorine-18-labeled biotin derivatives: Biodistribution and infection localization

    SciTech Connect

    Shoup, T.M.; Fischman, A.J.; Jaywook, S.

    1994-10-01

    Recently there has been much interest in the exploitation of the high binding affinity of avidin/biotin as a means of targeting drugs and radionuclides for in vivo applications. We are interested in broadening the application of the avidin/biotin complex to PET. To this end we set out to prepare {sup 18}F-labeled biotin analogs. Two {sup 18}F biotin derivatives, [3aS-(3a{alpha},4{beta},6a{alpha})]-hexa-hydro-2-oxo-1H-thieno[3,4-d]imidazole-4-(N-3-(1-[{sup 18F}]fluoropropyl))pentanamide (1) and [3aS-(3a{alpha},4{beta},6a{alpha})]-tetrahydro - 4 - 5-(1-[{sup 18}F]fluoropentyl)-1H-thieno[3,4-d]imidazol-2(3H)-F(2) were prepared with high specific activity (NCA) and evaluated for their potential in infection localization. Compound 1 binds to avidin and the biodistribution of these derivatives were studied in Escherichia coli infected rats. Half of the infected rats were treated with avidin 24 hr prior to intravenous injection of the {sup 18}F-labeled biotin analogs. Biotin 1, without avidin pretreatment, showed a selectivity of 6.08 {plus_minus} 1.12 for infection compared to normal muscle. With avidin pretreatment, selectivity increased slightly, giving an infection to normal muscle ratio of 6.39 {plus_minus} 0.96. In contrast, the biodistribution of biotin 2 indicated more binding to normal muscle with an infection to normal muscle ratio of 0.58 {plus_minus} 0.07. This lack of selectivity illustrates the importance of the side-chain amide group in infection localization. There was some defluorination of 1 and 2, as evidenced by increased {sup 18}F bone uptake after 60 min: 2.94 {plus_minus} 0.37 and 1.17 {plus_minus} 0.21%IG/g {plus_minus}s.d., respectively. Biotin derivatives could be radiofluorinated with high specific activity. Biotin 1, is a potential positron tomography tracer for infection imaging. 16 refs., 2 figs., 6 tabs.

  3. A replaceable liposomal aptamer for the ultrasensitive and rapid detection of biotin

    PubMed Central

    Sung, Tzu-Cheng; Chen, Wen-Yih; Shah, Pramod; Chen, Chien-Sheng

    2016-01-01

    Biotin is an essential vitamin which plays an important role for maintaining normal physiological function. A rapid, sensitive, and simple method is necessary to monitor the biotin level. Here, we reported a replacement assay for the detection of biotin using a replaceable liposomal aptamer. Replacement assay is a competitive assay where a sample analyte replaces the labeled competitor of analyte out of its biorecognition element on a surface. It is user friendly and time-saving because of washing free. We used aptamer as a competitor, not a biorecognition element as tradition. To label aptamers, we used cholesterol-conjugated aptamers to tag signal-amplifying-liposomes. Without the need of conjugation procedure, aptamers can be easily incorporated into the surface of dye-encapsulating liposomes. Two aptamers as competitors of biotin, ST-21 and ST-21M with different affinities to streptavidin, were studied in parallel for the detection of biotin using replacement assays. ST-21 and ST-21M aptamers reached to limits of detection of 1.32 pg/80 μl and 0.47 pg/80 μl, respectively. The dynamic ranges of our assays using ST-21 and ST-21M aptamers were seven and four orders of magnitude, respectively. This assay can be completed in 20 minutes without washing steps. These results were overall better than previous reported assays. PMID:26903199

  4. Target-based identification of whole-cell active inhibitors of biotin biosynthesis in Mycobacterium tuberculosis.

    PubMed

    Park, Sae Woong; Casalena, Dominick E; Wilson, Daniel J; Dai, Ran; Nag, Partha P; Liu, Feng; Boyce, Jim P; Bittker, Joshua A; Schreiber, Stuart L; Finzel, Barry C; Schnappinger, Dirk; Aldrich, Courtney C

    2015-01-22

    Biotin biosynthesis is essential for survival and persistence of Mycobacterium tuberculosis (Mtb) in vivo. The aminotransferase BioA, which catalyzes the antepenultimate step in the biotin pathway, has been established as a promising target due to its vulnerability to chemical inhibition. We performed high-throughput screening (HTS) employing a fluorescence displacement assay and identified a diverse set of potent inhibitors including many diversity-oriented synthesis (DOS) scaffolds. To efficiently select only hits targeting biotin biosynthesis, we then deployed a whole-cell counterscreen in biotin-free and biotin-containing medium against wild-type Mtb and in parallel with isogenic bioA Mtb strains that possess differential levels of BioA expression. This counterscreen proved crucial to filter out compounds whose whole-cell activity was off target as well as identify hits with weak, but measurable whole-cell activity in BioA-depleted strains. Several of the most promising hits were cocrystallized with BioA to provide a framework for future structure-based drug design efforts.

  5. A replaceable liposomal aptamer for the ultrasensitive and rapid detection of biotin.

    PubMed

    Sung, Tzu-Cheng; Chen, Wen-Yih; Shah, Pramod; Chen, Chien-Sheng

    2016-02-23

    Biotin is an essential vitamin which plays an important role for maintaining normal physiological function. A rapid, sensitive, and simple method is necessary to monitor the biotin level. Here, we reported a replacement assay for the detection of biotin using a replaceable liposomal aptamer. Replacement assay is a competitive assay where a sample analyte replaces the labeled competitor of analyte out of its biorecognition element on a surface. It is user friendly and time-saving because of washing free. We used aptamer as a competitor, not a biorecognition element as tradition. To label aptamers, we used cholesterol-conjugated aptamers to tag signal-amplifying-liposomes. Without the need of conjugation procedure, aptamers can be easily incorporated into the surface of dye-encapsulating liposomes. Two aptamers as competitors of biotin, ST-21 and ST-21M with different affinities to streptavidin, were studied in parallel for the detection of biotin using replacement assays. ST-21 and ST-21M aptamers reached to limits of detection of 1.32 pg/80 μl and 0.47 pg/80 μl, respectively. The dynamic ranges of our assays using ST-21 and ST-21M aptamers were seven and four orders of magnitude, respectively. This assay can be completed in 20 minutes without washing steps. These results were overall better than previous reported assays.

  6. [Construction of biotin-modified polymeric micelles for pancreatic cancer targeted photodynamic therapy].

    PubMed

    Deng, Chun-yue; Long, Ying-ying; Liu, Sha; Chen, Zhang-bao; Li, Chong

    2015-08-01

    In this study, we explored the feasibility of biotin-mediated modified polymeric micelles for pancreatic cancer targeted photodynamic therapy. Poly (ethylene glycol)-distearoyl phosphatidyl ethanolamine (mPEG2000-DSPE) served as the drug-loaded material, biotin-poly(ethylene glycol)-distearoyl phosphatidyl ethanolamine (Biotin-PEG3400-DSPE) as the functional material and the polymeric micelles were prepared by a thin-film hydration method. The targeting capability of micelles was investigated by cell uptake assay in vitro and fluorescence imaging in vivo and the amounts of Biotin-PEG-DSPE were optimized accordingly. Hypocrellin B (HB), a novel photosensitizer was then encapsulated in biotinylated polymeric micelles and the anti-tumor efficacy was evaluated systemically in vitro and in vivo. The results showed that micelles with 5 mol % Biotin-PEG-DSPE demonstrated the best targeting capability than those with 20 mol % or 0.5 mol % of corresponding materials. This formulation has a small particle size [mean diameter of (36.74 ± 2.16) nm] with a homogeneous distribution and high encapsulation efficiency (80.06 ± 0.19) %. The following pharmacodynamics assays showed that the biotinylated micelles significantly enhanced the cytotoxicity of HB against tumor cells in vitro and inhibited tumor growth in vivo, suggesting a promising potential of this formulation for treatment of pancreatic cancer, especially those poorly permeable, or insensitive to radiotherapy and chemotherapy.

  7. The role of biotin and oxamate in the carboxyltransferase reaction of pyruvate carboxylase.

    PubMed

    Lietzan, Adam D; Lin, Yi; St Maurice, Martin

    2014-11-15

    Pyruvate carboxylase (PC) is a biotin-dependent enzyme that catalyzes the MgATP-dependent carboxylation of pyruvate to oxaloacetate, an important anaplerotic reaction in central metabolism. During catalysis, carboxybiotin is translocated to the carboxyltransferase domain where the carboxyl group is transferred to the acceptor substrate, pyruvate. Many studies on the carboxyltransferase domain of PC have demonstrated an enhanced oxaloacetate decarboxylation activity in the presence of oxamate and it has been shown that oxamate accepts a carboxyl group from carboxybiotin during oxaloacetate decarboxylation. The X-ray crystal structure of the carboxyltransferase domain from Rhizobium etli PC reveals that oxamate is positioned in the active site in an identical manner to the substrate, pyruvate, and kinetic data are consistent with the oxamate-stimulated decarboxylation of oxaloacetate proceeding through a simple ping-pong bi bi mechanism in the absence of the biotin carboxylase domain. Additionally, analysis of truncated PC enzymes indicates that the BCCP domain devoid of biotin does not contribute directly to the enzymatic reaction and conclusively demonstrates a biotin-independent oxaloacetate decarboxylation activity in PC. These findings advance the description of catalysis in PC and can be extended to the study of related biotin-dependent enzymes.

  8. Terahertz spectra of biotin based on first principle, molecular mechanical, and hybrid simulations.

    PubMed

    Bykhovski, Alexei; Woolard, Dwight

    2013-07-01

    Terahertz (THz) absorption of biotin was simulated using the first principle and the density functional theory (DFT) both in the harmonic approximation and with corrections for the anharmonicity. Anharmonicity corrections were calculated using two different approaches. First, the perturbation theory-based first principle calculations were performed to include third- and fourth-order anharmonicity corrections in atomic displacements to harmonic vibrational states. Second, the atom-centered density matrix propagation molecular dynamics model that provides a good energy conservation was used to calculate the atomic trajectories, velocities, and a dipole moment time history of biotin at low and room temperatures. Predicted low-THz lines agree well with the experimental spectra. The influence of the polyethylene (PE) matrix embedment on the THz spectra of biotin at the nanoscale was studied using the developed hybrid DFT/molecular mechanical approach. While PE is almost transparent at THz frequencies, additional low-THz lines are predicted in the biotin/PE system, which reflects a dynamic interaction between biotin and a surrounding PE cavity.

  9. A replaceable liposomal aptamer for the ultrasensitive and rapid detection of biotin

    NASA Astrophysics Data System (ADS)

    Sung, Tzu-Cheng; Chen, Wen-Yih; Shah, Pramod; Chen, Chien-Sheng

    2016-02-01

    Biotin is an essential vitamin which plays an important role for maintaining normal physiological function. A rapid, sensitive, and simple method is necessary to monitor the biotin level. Here, we reported a replacement assay for the detection of biotin using a replaceable liposomal aptamer. Replacement assay is a competitive assay where a sample analyte replaces the labeled competitor of analyte out of its biorecognition element on a surface. It is user friendly and time-saving because of washing free. We used aptamer as a competitor, not a biorecognition element as tradition. To label aptamers, we used cholesterol-conjugated aptamers to tag signal-amplifying-liposomes. Without the need of conjugation procedure, aptamers can be easily incorporated into the surface of dye-encapsulating liposomes. Two aptamers as competitors of biotin, ST-21 and ST-21M with different affinities to streptavidin, were studied in parallel for the detection of biotin using replacement assays. ST-21 and ST-21M aptamers reached to limits of detection of 1.32 pg/80 μl and 0.47 pg/80 μl, respectively. The dynamic ranges of our assays using ST-21 and ST-21M aptamers were seven and four orders of magnitude, respectively. This assay can be completed in 20 minutes without washing steps. These results were overall better than previous reported assays.

  10. Target-Based Identification of Whole-Cell Active Inhibitors of Biotin Biosynthesis in Mycobacterium tuberculosis

    PubMed Central

    Park, Sae Woong; Casalena, Dominick; Wilson, Daniel; Dai, Ran; Nag, Partha; Liu, Feng; Boyce, Jim P.; Bittker, Joshua; Schreiber, Stuart; Finzel, Barry C.; Schnappinger, Dirk; Aldrich, Courtney C.

    2014-01-01

    SUMMARY Biotin biosynthesis is essential for survival and persistence of Mycobacterium tuberculosis (Mtb) in vivo. The aminotransferase BioA, which catalyzes the antepenultimate step in the biotin pathway, has been established as a promising target due to its vulnerability to chemical inhibition. We performed high-throughput screening (HTS) employing a fluorescence displacement assay and identified a diverse set of potent inhibitors including many diversity-oriented synthesis (DOS) scaffolds. To efficiently select only hits targeting biotin biosynthesis, we then deployed a whole-cell counter-screen in either biotin-free and biotin-containing medium against wild-type Mtb and in parallel with isogenic bioA Mtb strains that possess differential levels of BioA expression. This counter-screen proved crucial to filter out compounds whose whole-cell activity was off-target as well as identify hits with weak, but measurable whole-cell activity in BioA-depleted strains. Several of the most promising hits were co-crystallized with BioA to provide a framework for future structure-based drug design efforts. PMID:25556942

  11. Conditional knockout of the Slc5a6 gene in mouse intestine impairs biotin absorption.

    PubMed

    Ghosal, Abhisek; Lambrecht, Nils; Subramanya, Sandeep B; Kapadia, Rubina; Said, Hamid M

    2013-01-01

    The Slc5a6 gene expresses a plasma membrane protein involved in the transport of the water-soluble vitamin biotin; the transporter is commonly referred to as the sodium-dependent multivitamin transporter (SMVT) because it also transports pantothenic acid and lipoic acid. The relative contribution of the SMVT system toward carrier-mediated biotin uptake in the native intestine in vivo has not been established. We used a Cre/lox technology to generate an intestine-specific (conditional) SMVT knockout (KO) mouse model to address this issue. The KO mice exhibited absence of expression of SMVT in the intestine compared with sex-matched littermates as well as the expected normal SMVT expression in other tissues. About two-thirds of the KO mice died prematurely between the age of 6 and 10 wk. Growth retardation, decreased bone density, decreased bone length, and decreased biotin status were observed in the KO mice. Microscopic analysis showed histological abnormalities in the small bowel (shortened villi, dysplasia) and cecum (chronic active inflammation, dysplasia) of the KO mice. In vivo (and in vitro) transport studies showed complete inhibition in carrier-mediated biotin uptake in the intestine of the KO mice compared with their control littermates. These studies provide the first in vivo confirmation in native intestine that SMVT is solely responsible for intestinal biotin uptake. These studies also provide evidence for a casual association between SMVT function and normal intestinal health.

  12. Semi-synthetic biotin imprinting onto avidin crosslinked gold-silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Atılır Özcan, Ayça; Ersöz, Arzu; Hür, Deniz; Yılmaz, Filiz; Gültekin, Aytaç; Denizli, Adil; Say, Rıdvan

    2012-06-01

    This study is a different and new application of molecular imprinted polymers (MIPs) based on sensor technologies. In this study, semi-synthetic biotin imprinted polymeric shell has been decorated onto the surface of avidin crosslinked Au/Ag nanoclusters using bis (2-2'-bipyridyl) MATyr-MATrp-ruthenium(II) (MATyr-Ru-MATrp) as photosensitive monomer. The synthesized nanoclusters have been used the recognition of biotin by flourometric method. Synthesis of the photosensitive monomers has been realized by AmiNoAcid (monomer) Decorated and Light Underpinning Conjugation Approach (ANADOLUCA) method. This method provides a strategy for the preparation of photosensitive ruthenium based aminoacid monomers and oligomers, aminoacid monomer-protein crosslinking using photosensitation and conjugation approach on micro and nano-structures by ruthenium-chelate based monomers. The affinity constant ( K a) of biotin imprinted Au/Ag nanoclusters has been determined using the Scatchard method and found to be 3.89 × 105 M-1. The obtained calibration graph is linear for the range of 0.051 and 2.50 μM of biotin. The detection limit of biotin has been found to be 15 nM. Also, the reusability of these nanoclusters has been investigated and it has been observed that the same clusters could be used 10 times during a long period without any binding capacity decreasing.

  13. Detection of Protein Carbonyls by Means of Biotin Hydrazide-Streptavidin Affinity Methods.

    PubMed

    Hensley, Kenneth

    2015-01-01

    Oxidative posttranslational protein modifications occur as a normal process of cell biology and to a greater extent during pathogenic conditions. The detection and quantitation of protein oxidation has posed a continuing challenge to bioanalytical chemists because of the following reasons: The products of oxidative protein damage are chemically diverse; protein oxidation generally occurs at low background levels; and the complexity of biological samples introduces high background noise when standard techniques such as immunolabeling are applied to "dirty" tissue extracts containing endogenous immunoglobulins or small molecular weight, chemically reactive compounds has been developed which circumvents these difficulties by incorporating a biotin label at sites of protein carbonylation. Biotin hydrazide-labeled proteins are detectable using standard streptavidin-coupled detection techniques such as peroxidase-catalyzed chemiluminescence of immunoblots. Advantages of the biotin hydrazide-labeling technique are its sensitivity and its lack of reliance upon antibodies that inevitably suffer from nonspecific background noise and contaminating endogenous immunoglobulins.

  14. Construction of heparinylated multilayer films on Tisbnd O via streptavidin/biotin interaction

    NASA Astrophysics Data System (ADS)

    Weng, Y. J.; Jing, F. J.; Chen, J. Y.; Huang, N.

    2012-06-01

    Construction of heparinylated multilayer films on Tisbnd O via streptavidin/biotin interaction was conducted in the present study. An organic layer of 3-aminopropylphosphonic acid (APP) was first introduced on Tisbnd O by self-assembling, and then biotin was immobilized by photochemical methods. So streptavidin and biotinylated heparin were assembling through biorecognition, and a desired 6-layer heparinylated multilayer was obtained through layer-by-layer driven by streptavidin/biotin interaction. The in vitro platelet adhesion and activation were investigated by a static platelet adhesion test. The clotting time was examined by activated partial thromboplastin time (APTT). Results show that the heparinylated multilayer coated Tisbnd O can significantly decrease platelet adhesion and activation, and prolong clotting time of APTT compared to untreated Tisbnd O, which indicates the heparinylated multilayer coated Tisbnd O displays more excellent anticoagulation performance than that of the bare Tisbnd O.

  15. Imaging proteins in live mammalian cells with biotin ligase and monovalent streptavidin

    PubMed Central

    Howarth, Mark; Ting, Alice Y

    2009-01-01

    This protocol describes a simple and efficient way to label specific cell surface proteins with biophysical probes on mammalian cells. Cell surface proteins tagged with a 15-amino acid peptide are biotinylated by Escherichia coli biotin ligase (BirA), whereas endogenous proteins are not modified. The biotin group then allows sensitive and stable binding by streptavidin conjugates. This protocol describes the optimal use of BirA and streptavidin for site-specific labeling and also how to produce BirA and monovalent streptavidin. Streptavidin is tetravalent and the cross-linking of biotinylated targets disrupts many of streptavidin’s applications. Monovalent streptavidin has only a single functional biotin-binding site, but retains the femtomolar affinity, low off-rate and high thermostability of wild-type streptavidin. Site-specific biotinylation and streptavidin staining take only a few minutes, while expression of BirA takes 4 d and expression of monovalent streptavidin takes 8 d. PMID:18323822

  16. A cleavable biotin tagging reagent that enables the enrichment and identification of carbonylation sites in proteins.

    PubMed

    Coffey, Chelsea M; Gronert, Scott

    2016-01-01

    The utility of a new, cleavable tag for identifying and enriching protein carbonyls is examined. Using a model system, human serum albumin modified with acrolein, the EZ-Link alkoxyamine-PEG4-SS-PEG4-biotin affinity tag, was tested for its ability to label protein carbonyls in proteomic analyses of protein carbonylation. The efficiency of the labeling was assayed and compared to standard biotin hydrazide reagents. The label was also tested in liquid chromatography-tandem mass spectrometry (LC/MS/MS) experiments. The quality of the fragmentation spectra was assessed and the relative detection efficiency of various modification sites was compared to standard biotin hydrazide reagents. Finally, the viability of using the label with streptavidin bead enrichment protocols in a standard proteomics workflow was probed.

  17. Immobilization of sugar-non-specific nucleases by utilizing the streptavidin--biotin interaction.

    PubMed

    Gast, F U; Franke, I; Meiss, G; Pingoud, A

    2001-05-04

    Due to their high enzymatic activity, the sugar-non-specific endonucleases from Serratia marcescens and Anabaena can be used for a number of applications, such as the removal of contaminating genetic material from biological preparations, footprinting studies, and the determination of nucleic acids in biochemical samples. These methods would benefit from immobilized nucleases. For this purpose, a single cysteine residue was added at the N-terminus of the Serratia and Anabaena nucleases and subsequently modified with a maleimide-biotin conjugate. Alternatively, a biotin acceptor domain was fused to the Anabaena nuclease, allowing biotinylation during expression in E. coli without a further chemical step. The attachment of biotin-modified nucleases to streptavidin-coated paramagnetic beads and to streptavidin-coated surface plasmon resonance sensor chips (to study interactions with substrate and inhibitor) worked well when aggregates present in the protein preparations were removed by ultrafiltration. These methods should be of general use for similar enzyme systems.

  18. Familial Uncombable Hair Syndrome: Ultrastructural Hair Study and Response to Biotin.

    PubMed

    Boccaletti, V; Zendri, E; Giordano, G; Gnetti, L; De Panfilis, G

    2007-01-01

    We report a family affected to the fourth generation by uncombable hair syndrome. This syndrome is characterized by unruly, dry, blond hair with a tangled appearance. The family pedigree strongly supports the hypothesis of autosomal dominant inheritance; some members of the family had, apart from uncombable hair, minor signs of atopy and ectodermal dysplasia, such as abnormalities of the nails. The diagnosis was confirmed by means of extensive scanning electron microscopy. A trial with oral biotin 5 mg/day was started on two young patients with excellent results as regards the hair appearance, although scanning electron microscopy did not show structural changes in the hair. After a 2-year-period of follow-up, hair normality was maintained without biotin, while nail fragility still required biotin supplementation for control.

  19. 75 FR 52534 - Su Van Ho: Debarment Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-26

    ... Salmonella bacteria, with verification of such exportation or destruction by FDA. Mr. Ho concealed and... with Salmonella bacteria. As a result of his conviction, on June 10, 2010, FDA sent Mr. Ho a notice...

  20. Molecular cloning and chromosomal localization of human holocarboxylase synthetase, a gene responsible for biotin dependency

    SciTech Connect

    Suzuki, Y.; Aoki, Y.; Ishida, Y.

    1994-09-01

    Holocarboxylase synthetase (HCS) catalyzes biotin incorporation into various carboxylases that require biotin as a prosthetic group. They are acetyl-CoA carboxylase, a rate-limiting enzyme of fatty acid synthesis; pyruvate carboxylase, a key enzyme of gluconeogenesis; propionyl-CoA carboxylase and 3-methylcrotonyl-CoA carboxylase, enzymes involved in amino acid catabolism. HCS is therefore involved in various metabolic processes and is a key enzyme for biotin utilization by mammalian cells. Deficiency of HCS in man is known to cause biotin-responsive multiple carboxylase deficiency. Isolation of cDNA clones for the enzyme is essential to understand HCS and its deficiency at the molecular level. We purified bovine liver HCS and sequenced its proteolytic peptides. Degenerative oligonucleotide primers were synthesized from the two peptide sequences and used to amplify a putative HCS cDNA fragment from human liver by PCR. Using the amplified DNA fragment as a probe, we screened {lambda}gt10 human liver cDNA library and isolated 12 positive clones. The isolated cDNAs encoded a protein of 726 amino acids with molecular mass of 80,759. The protein contained several sequences identical or similar to those of peptides derived from the bovine liver HCS. The predicted protein had a homologous region with BirA which acts as both a biotin-[acetyl-CoA-carboxylase] ligase and a biotin repressor in E. coli, suggesting a functional relationship between the two proteins. We expressed the protein using pET3 a vector in E. coli (BL21 strain) and raised antiserum against the expressed protein. The antiserum immunoprecipitated HCS activities of human lymphoblasts and bovine liver. A one-base deletion and a missense mutation were found in cells from siblings with HCS deficiency. The human HCS gene was assigned to chromosome 21, region 21q22.1 by fluorescence in situ hybridization analysis.

  1. Crystal Structure of Biotin Carboxylase in Complex with Substrates and Implications for Its Catalytic Mechanism

    SciTech Connect

    Chou, C.; Yu, L; Tong, L

    2009-01-01

    Biotin-dependent carboxylases are widely distributed in nature and have important functions in many cellular processes. These enzymes share a conserved biotin carboxylase (BC) component, which catalyzes the ATP-dependent carboxylation of biotin using bicarbonate as the donor. Despite the availability of a large amount of biochemical and structural information on BC, the molecular basis for its catalysis is currently still poorly understood. We report here the crystal structure at 2.0 {angstrom} resolution of wild-type Escherichia coli BC in complex with its substrates biotin, bicarbonate, and Mg-ADP. The structure suggests that Glu{sup 296} is the general base that extracts the proton from bicarbonate, and Arg{sup 338} is the residue that stabilizes the enolate biotin intermediate in the carboxylation reaction. The B domain of BC is positioned closer to the active site, leading to a 2-{angstrom} shift in the bound position of the adenine nucleotide and bringing it near the bicarbonate for catalysis. One of the oxygen atoms of bicarbonate is located in the correct position to initiate the nucleophilic attack on ATP to form the carboxyphosphate intermediate. This oxygen is also located close to the N1' atom of biotin, providing strong evidence that the phosphate group, derived from decomposition of carboxyphosphate, is the general base that extracts the proton on this N1' atom. The structural observations are supported by mutagenesis and kinetic studies. Overall, this first structure of BC in complex with substrates offers unprecedented insights into the molecular mechanism for the catalysis by this family of enzymes.

  2. Adding Biotin to Parenteral Nutrition Solutions Without Lipid Accelerates the Growth of Candida albicans

    PubMed Central

    Kuwahara, Takashi; Kaneda, Shinya; Shimono, Kazuyuki

    2016-01-01

    Background: We have previously demonstrated that Candida albicans requires multivitamins (MVs) or lipid to increase rapidly in parenteral nutrition (PN) solutions. In this study, in detail, the effects of vitamins on the growth of C. albicans in PN solutions without lipid were investigated. Methods: In the 1st experiment, a commercial PN solution without lipid was supplemented with water-soluble vitamins (SVs: vitamins B1, B2, B6, B12 and C, folic acid, nicotinamide, biotin and panthenol), water-insoluble vitamins (IVs: vitamins A, D, E and K) or both (MVs). In the 2nd experiment, the test solutions were prepared by supplementing the PN solution with one of each or all of the SVs. In the 3rd experiment, another commercial peripheral PN (PPN) solution without lipid was supplemented with SVs, nicotinic acid, biotin or both nicotinic acid and biotin. In each of the experiments, a specified number of C. albicans organisms was added to each test solution, and all of the test solutions were allowed to stand at room temperature (23-26ºC). The number of C. albicans was counted at 0, 24, 48 and 72 hours after the addition of the organism. Results: In the 1st experiment, the C. albicans increased rapidly in the PN solution supplemented with the SVs, but increased slowly without the SVs, regardless of the addition of the IVs. In the 2nd experiment, the C. albicans increased rapidly in the PN solution supplemented with the SVs or biotin, but increased slowly with each of the other water-soluble vitamins. In the 3rd experiment, the C. albicans increased rapidly in the PPN solution supplemented with the SVs or biotin, but increased slowly with the addition of nicotinic acid. Conclusions: These results suggested that adding MVs or SVs to PN solutions without lipid promotes the growth of C. albicans, and that this effect is mostly attributable to biotin. PMID:27648003

  3. Chemistry of HO x radicals in the upper troposphere

    NASA Astrophysics Data System (ADS)

    Jaeglé, Lyatt; Jacob, Daniel J.; Brune, William H.; Wennberg, Paul O.

    Aircraft observations from three recent missions (STRAT, SUCCESS, SONEX) are synthesized into a theoretical analysis of the factors controlling the concentrations of HO x radicals (HO x=OH+peroxy) and the larger reservoir family HO y (HO y=HO x+2H 2O 2+2CH 3OOH+HNO 2+HNO 4) in the upper troposphere. Photochemical model calculations capture 66% of the variance of observed HO x concentrations. Two master variables are found to determine the variance of the 24 h average HO x concentrations: the primary HO x production rate, P(HO x), and the concentration of nitrogen oxide radicals (NO x=NO+NO 2). We use these two variables as a coordinate system to diagnose the photochemistry of the upper troposphere and map the different chemical regimes. Primary HO x production is dominated by the O( 1D)+H 2O reaction when [H 2O]>100 ppmv, and by photolysis of acetone (and possibly other convected HO x precursors) under drier conditions. For the principally northern midlatitude conditions sampled by the aircraft missions, the HO x yield from acetone photolysis ranges from 2 to 3. Methane oxidation amplifies the primary HO x source by a factor of 1.1-1.9. Chemical cycling within the HO x family has a chain length of 2.5-7, while cycling between the HO x family and its HO y reservoirs has a chain length of 1.6-2.2. The number of ozone molecules produced per HO y molecule consumed ranges from 4 to 12, such that ozone production rates vary between 0.3 and 5 ppbv d -1 in the upper troposphere. Three chemical regimes (NO x-limited, transition, NO x-saturated) are identified to describe the dependence of HO x concentrations and ozone production rates on the two master variables P(HO x) and [NO x]. Simplified analytical expressions are derived to express these dependences as power laws for each regime. By applying an eigenlifetime analysis to the HO x-NO x-O 3 chemical system, we find that the decay of a perturbation to HO y in the upper troposphere (as from deep convection) is represented

  4. Ho:YAG Single Crystal Fiber: Fabrication and Optical Characterization

    DTIC Science & Technology

    2014-06-16

    optical characterization 0.5% Holmium (Ho) doped YAG single crystal fiber (SCF) was fabricated using Laser Heated Pedestal Growth (LHPG) method and...ABSTRACT Ho:YAG single crystal fiber: fabrication and optical characterization Report Title 0.5% Holmium (Ho) doped YAG single crystal fiber (SCF) was...0.5% Holmium (Ho) doped YAG single crystal fiber (SCF) was fabricated using Laser Heated Pedestal Growth (LHPG) method and characterized for its

  5. Paracoccus denitrificans possesses two BioR homologs having a role in regulation of biotin metabolism.

    PubMed

    Feng, Youjun; Kumar, Ritesh; Ravcheev, Dmitry A; Zhang, Huimin

    2015-08-01

    Recently, we determined that BioR, the GntR family of transcription factor, acts as a repressor for biotin metabolism exclusively distributed in certain species of α-proteobacteria, including the zoonotic agent Brucella melitensis and the plant pathogen Agrobacterium tumefaciens. However, the scenario is unusual in Paracoccus denitrificans, another closely related member of the same phylum α-proteobacteria featuring with denitrification. Not only does it encode two BioR homologs Pden_1431 and Pden_2922 (designated as BioR1 and BioR2, respectively), but also has six predictive BioR-recognizable sites (the two bioR homolog each has one site, whereas the two bio operons (bioBFDAGC and bioYB) each contains two tandem BioR boxes). It raised the possibility that unexpected complexity is present in BioR-mediated biotin regulation. Here we report that this is the case. The identity of the purified BioR proteins (BioR1 and BioR2) was confirmed with LC-QToF-MS. Phylogenetic analyses combined with GC percentage raised a possibility that the bioR2 gene might be acquired by horizontal gene transfer. Gel shift assays revealed that the predicted BioR-binding sites are functional for the two BioR homologs, in much similarity to the scenario seen with the BioR site of A. tumefaciens bioBFDAZ. Using the A. tumefaciens reporter system carrying a plasmid-borne LacZ fusion, we revealed that the two homologs of P. denitrificans BioR are functional repressors for biotin metabolism. As anticipated, not only does the addition of exogenous biotin stimulate efficiently the expression of bioYB operon encoding biotin transport/uptake system BioY, but also inhibits the transcription of the bioBFDAGC operon resembling the de novo biotin synthetic pathway. EMSA-based screening failed to demonstrate that the biotin-related metabolite is involved in BioR-DNA interplay, which is consistent with our former observation with Brucella BioR. Our finding defined a complex regulatory network for biotin

  6. Genetic Analysis of the System that Reduces Biotin-d-Sulfoxide in Escherichia coli

    PubMed Central

    Dykhuizen, Daniel

    1973-01-01

    Four genes of Escherichia coli whose products are needed to reduce biotin-d-sulfoxide to biotin have been mapped: bisA next to chlA, bisB next to chlE, bisC linked to xyl, and bisD next to chlG. A defective λ transducing phage, λdbis5, which carries all the bacterial genes between the λ attachment site and chlE, was isolated and shown to have lost the phage genes from int through Q. PMID:4579877

  7. Copper dependence of the biotin switch assay: modified assay for measuring cellular and blood nitrosated proteins.

    PubMed

    Wang, Xunde; Kettenhofen, Nicholas J; Shiva, Sruti; Hogg, Neil; Gladwin, Mark T

    2008-04-01

    Studies have shown that modification of critical cysteine residues in proteins leads to the regulation of protein function. These modifications include disulfide bond formation, glutathionylation, sulfenic and sulfinic acid formation, and S-nitrosation. The biotin switch assay was developed to specifically detect protein S-nitrosation (S. R. Jaffrey et al., Nat. Cell Biol. 3:193-197; 2001). In this assay, proteins are denatured with SDS in the presence of methyl methane thiosulfonate (MMTS) to block free thiols. After acetone precipitation or Sephadex G25 separation to remove excess MMTS, HPDP-biotin and 1 mM ascorbate are added to reduce the S-nitrosothiol bonds and label the reduced thiols with biotin. The proteins are then separated by nonreducing SDS PAGE and detected using either streptavidin-HRP or anti-biotin-HRP conjugate. Our examination of this labeling scheme has revealed that the extent of labeling depends on the buffer composition and, importantly, on the choice of metal-ion chelator (DTPA vs EDTA). Unexpectedly, using purified S-nitrosated albumin, we have found that "contaminating" copper is required for the ascorbate-dependent degradation of S-nitrosothiol; this is consistent with the fact that ascorbate itself does not rapidly reduce S-nitrosothiols. Removal of copper from buffers by DTPA and other copper chelators preserves approximately 90% of the S-nitrosothiol, whereas the inclusion of copper and ascorbate completely eliminates the S-nitrosothiol in the preparation and increases the specific biotin labeling. These biotin switch experiments were confirmed using triiodide-based and copper-based reductive chemiluminescence. Additional modifications of the assay using N-ethylmaleimide for thiol blockade, ferricyanide pretreatment to stabilize S-nitrosated hemoglobin, and cyanine dye labeling instead of biotin are presented for the measurement of cellular and blood S-nitrosothiols. These results indicate that degradation of S-nitrosothiol in the

  8. Some biochemical observations on gluconeogenesis from propionate in hepatocytes isolated from normal and biotin-deficients rats.

    PubMed

    Djabal, A; Mangeot, M; Cherruau, B; Lemonnier, A

    1985-01-01

    Propionate and pyruvate added to isolated normal and biotin-deficient adult rat hepatocytes increase the production of glucose. This production decreases about 30% on biotin deficiency. Malonate inhibits gluconeogenesis from propionate showing the metabolic transformation of propionyl-CoA via the Krebs cycle. Neither glucagon nor dibutyryl-cyclic AMP significantly stimulate gluconeogenesis.

  9. Kinetics of the reaction HO2 + NO2 + M yields HO2NO2 + M

    NASA Technical Reports Server (NTRS)

    Sander, S. P.; Peterson, M. E.

    1984-01-01

    The flash photolysis/ultraviolet absorption technique was used to measure the rate constants for the reaction HO2 + NO2 + M yields HO2NO2 + M over the pressure range 50-700 torr and temperature range 229-362 K using He, O2, and N2 as diluent gases. The data were fit to the expression derived by Troe (1979) and co-workers for describing the pressure and temperature dependence of reactions in the falloff region. By combining these data with recent measurements of the rate constant for HO2NO2 thermal decomposition values of 73.8 + or - 2 eu for the standard entropy and -12.6 + or - kcal/mol for the standard enthalpy of formation of HO2NO2 were obtained. A significant enhancement in the rate constant was observed when water vapor was added to the system.

  10. Infrared Identification of HO2 and HO3 Radicals in Irradiated Ices

    NASA Astrophysics Data System (ADS)

    Cooper, P. D.; Moore, M. H.; Hudson, R. L.

    2006-05-01

    Absorption bands at 1259 and 1142 cm-1 in H2O-O2 ice mixtures irradiated with 0.8 MeV protons at 9 K, have been assigned to the HO3 and HO2 radicals respectively. The assignment of these bands is based upon isotopic shift measurements when 18O2 is used. These bands are also observed in irradiated H2O-O3 and pure H2O2 ices. In each case, they are formed by the following reactions: H + O3 → HO3 H + O2 → HO2 While neither radical has been observed in ice using infrared spectroscopy before, the HO2 radical is known to form in irradiated water ice, but remarkably, the lesser known HO3 is the more prominent spectral feature. These species are probably formed in the surfaces of icy outer solar system bodies where O2 and O3 have already been observed. Their ability to remain trapped in ice is unknown and their reactivity at typical surface temperatures may prevent signficant concentrations being produced. However, even as intermediate species, due to their reactivity they may constitute an important component of the oxidant population in such ices. If they can remain trapped, they may provide a potential energy source for organic reactions or even microbial life in places such as Europa's sub-surface ocean.

  11. Crystallization and preliminary X-ray crystallographic studies of the biotin carboxyl carrier protein and biotin protein ligase complex from Pyrococcus horikoshii OT3

    SciTech Connect

    Bagautdinov, Bagautdin; Matsuura, Yoshinori; Bagautdinova, Svetlana; Kunishima, Naoki

    2007-04-01

    A truncated form of biotin carboxyl carrier protein containing the C-terminal half fragment (BCCPΔN76) and the biotin protein ligase (BPL) with the mutation R48A (BPL*) or the double mutation R48A K111A (BPL**) were successfully cocrystallized in the presence of ATP and biotin. The BPL*–BCCPΔN76 and BPL**–BCCPΔN76 crystals belong to space group P2{sub 1} and diffract X-rays to 2.7 and 2.0 Å resolution, respectively. Biotin protein ligase (BPL) catalyses the biotinylation of the biotin carboxyl carrier protein (BCCP) subunit of acetyl-CoA carboxylase. To elucidate the exact details of the protein–protein interactions in the biotinylation function, the C-terminal half fragment of BCCP (BCCPΔN76), the R48A mutant of BPL (BPL*) and the R48A K111A double mutant of BPL (BPL**), all of which are from Pyrococcus horikoshii OT3, have been expressed, purified and successfully cocrystallized. Cocrystals of the BPL*–BCCPΔN76 and BPL**–BCCPΔN76 complexes as well as crystals of BPL*, BPL** and BCCPΔN76 were obtained by the oil-microbatch method using PEG 20 000 as a precipitant at 295 K. Complete X-ray diffraction data sets for BPL*–BCCPΔN76 and BPL**–BCCPΔN76 crystals were collected at 100 K to 2.7 and 2.0 Å resolution, respectively, using synchrotron radiation. They belong to the monoclinic space group P2{sub 1}, with similar unit-cell parameters a = 69.85, b = 63.12, c = 75.64 Å, β = 95.9°. Assuming two subunits of the complex per asymmetric unit gives a V{sub M} value of 2.45 Å{sup 3} Da{sup −1} and a solvent content of 50%.

  12. Distributed biotin-streptavidin transcription roadblocks for mapping cotranscriptional RNA folding.

    PubMed

    Strobel, Eric J; Watters, Kyle E; Nedialkov, Yuri; Artsimovitch, Irina; Lucks, Julius B

    2017-04-08

    RNA folding during transcription directs an order of folding that can determine RNA structure and function. However, the experimental study of cotranscriptional RNA folding has been limited by the lack of easily approachable methods that can interrogate nascent RNA structure at nucleotide resolution. To address this, we previously developed cotranscriptional selective 2΄-hydroxyl acylation analyzed by primer extension sequencing (SHAPE-Seq) to simultaneously probe all intermediate RNA transcripts during transcription by stalling elongation complexes at catalytically dead EcoRIE111Q roadblocks. While effective, the distribution of elongation complexes using EcoRIE111Q requires laborious PCR using many different oligonucleotides for each sequence analyzed. Here, we improve the broad applicability of cotranscriptional SHAPE-Seq by developing a sequence-independent biotin-streptavidin (SAv) roadblocking strategy that simplifies the preparation of roadblocking DNA templates. We first determine the properties of biotin-SAv roadblocks. We then show that randomly distributed biotin-SAv roadblocks can be used in cotranscriptional SHAPE-Seq experiments to identify the same RNA structural transitions related to a riboswitch decision-making process that we previously identified using EcoRIE111Q. Lastly, we find that EcoRIE111Q maps nascent RNA structure to specific transcript lengths more precisely than biotin-SAv and propose guidelines to leverage the complementary strengths of each transcription roadblock in cotranscriptional SHAPE-Seq.

  13. Integrin-Generated Forces Lead to Streptavidin-Biotin Unbinding in Cellular Adhesions

    PubMed Central

    Jurchenko, Carol; Chang, Yuan; Narui, Yoshie; Zhang, Yun; Salaita, Khalid S.

    2014-01-01

    The interplay between chemical and mechanical signals plays an important role in cell biology, and integrin receptors are the primary molecules involved in sensing and transducing external mechanical cues. We used integrin-specific probes in molecular tension fluorescence microscopy to investigate the pN forces exerted by integrin receptors in living cells. The molecular tension fluorescence microscopy probe consisted of a cyclic Arg-Gly-Asp-D-Phe-Lys(Cys) (cRGDfK(C)) peptide tethered to the terminus of a polyethylene glycol polymer that was attached to a surface through streptavidin-biotin linkage. A fluorescence resonance energy transfer mechanism was used to visualize tension-driven extension of the polymer. Surprisingly, we found that integrin receptors dissociate streptavidin-biotin tethered ligands in focal adhesions within 60 min of cell seeding. Although streptavidin-biotin binding affinity is described as the strongest noncovalent bond in nature, and is ∼106 - 108 times larger than that of integrin-RGD affinity, our results suggest that individual integrin-ligand complexes undergo a marked enhancement in stability when the receptor assembles in the cell membrane. Based on the observation of streptavidin-biotin unbinding, we also conclude that the magnitude of integrin-ligand tension in focal adhesions can reach values that are at least 10 fold larger than was previously estimated using traction force microscopy-based methods. PMID:24703305

  14. The Use of Biotin to Demonstrate Immunohistochemistry, Western Blotting, and Dot Blots in University Practical Classes

    ERIC Educational Resources Information Center

    Millar, Thomas James; Knighton, Ronald; Chuck, Jo-Anne

    2012-01-01

    Immunological detection of proteins is an essential method to demonstrate to undergraduate biology students, however, is often difficult in resource and time poor student laboratory sessions. This method describes a failsafe method to rapidly and economically demonstrate this technique using biotinylated proteins or biotin itself as targets for…

  15. Nonenzymatic biotinylation of a biotin carboxyl carrier protein: unusual reactivity of the physiological target lysine.

    PubMed

    Streaker, Emily D; Beckett, Dorothy

    2006-08-01

    Enzyme-catalyzed addition of biotin to proteins is highly specific. In any single organism one or a small number of proteins are biotinylated and only a single lysine on each of these proteins is modified. A detailed understanding of the structural basis for the selective biotinylation process has not yet been elucidated. Recently certain mutants of the Escherichia coli biotin protein ligase have been shown to mediate "promiscuous" biotinylation of proteins. It was suggested that the reaction involved diffusion of a reactive activated biotin intermediate, biotinoyl-5'-AMP, with nonspecific proteins. In this work the reactivity of this chemically synthesized intermediate toward the natural target of enzymatic biotinylation, the biotin carboxyl carrier protein, was investigated. The results indicate that the intermediate does, indeed, react with target protein, albeit at a significantly slower rate than the enzyme-catalyzed process. Surprisingly, analysis of the products of nonenzymatic biotinylation indicates that of five lysine residues in the protein only the physiological target side chain is modified. These results indicate that either the environment of this lysine residue or its intrinsic properties render it highly reactive to nonenzymatic biotinylation mediated by biotinoyl-5'-AMP. This reactivity may be important for its selective biotinylation in vivo.

  16. Specific detection of avidin-biotin binding using liquid crystal droplets.

    PubMed

    Khan, Mashooq; Park, Soo-Young

    2015-03-01

    Poly(acrylicacid-b-4-cynobiphenyl-4'-undecylacrylate) (PAA-b-LCP)-functionalized 4-cyano-4'-pentylbiphenyl (5CB) droplets were made by using microfluidic technique. The PAA chains on the 5CB droplets, were biotinylated, and used to specifically detect avidin-biotin binding at the 5CB/aqueous interface. The avidin-biotin binding was characterized by the configurational change (from radial to bipolar) of the 5CB droplets, as observed through a polarized optical microscope. The maximum biotinylation was obtained by injecting a >100 μg/mL biotin aqueous solution, which enabled a limit of detection of 0.5 μg/mL avidin. This droplet biosensor could specifically detect avidin against other proteins such as bovine serum albumin, lysozyme, hemoglobin, and chymotrypsinogen solutions. Avidin detection with 5CBPAA-biotin droplets having high sensitivity, specificity, and stability demonstrates new applications of the functionalized liquid crystal droplets that can detect specific proteins or other analytes through a ligand/receptor model.

  17. Magnetically separable polymer (Mag-MIP) for selective analysis of biotin in food samples.

    PubMed

    Uzuriaga-Sánchez, Rosario Josefina; Khan, Sabir; Wong, Ademar; Picasso, Gino; Pividori, Maria Isabel; Sotomayor, Maria Del Pilar Taboada

    2016-01-01

    This work presents an efficient method for the preparation of magnetic nanoparticles modified with molecularly imprinted polymers (Mag-MIP) through core-shell method for the determination of biotin in milk food samples. The functional monomer acrylic acid was selected from molecular modeling, EGDMA was used as cross-linking monomer and AIBN as radical initiator. The Mag-MIP and Mag-NIP were characterized by FTIR, magnetic hysteresis, XRD, SEM and N2-sorption measurements. The capacity of Mag-MIP for biotin adsorption, its kinetics and selectivity were studied in detail. The adsorption data was well described by Freundlich isotherm model with adsorption equilibrium constant (KF) of 1.46 mL g(-1). The selectivity experiments revealed that prepared Mag-MIP had higher selectivity toward biotin compared to other molecules with different chemical structure. The material was successfully applied for the determination of biotin in diverse milk samples using HPLC for quantification of the analyte, obtaining the mean value of 87.4% recovery.

  18. Virus immobilization on biomaterial scaffolds through biotin-avidin interaction for improving bone regeneration.

    PubMed

    Hu, Wei-Wen; Wang, Zhuo; Krebsbach, Paul H

    2016-02-01

    To spatially control therapeutic gene delivery for potential tissue engineering applications, a biotin-avidin interaction strategy was applied to immobilize viral vectors on biomaterial scaffolds. Both adenoviral vectors and gelatin sponges were biotinylated and avidin was applied to link them in a virus-biotin-avidin-biotin-material (VBABM) arrangement. The tethered viral particles were stably maintained within scaffolds and SEM images illustrated that viral particles were evenly distributed in three-dimensional (3D) gelatin sponges. An in vivo study demonstrated that transgene expression was restricted to the implant sites only and transduction efficiency was improved using this conjugation method. For an orthotopic bone regeneration model, adenovirus encoding BMP-2 (AdBMP2) was immobilized to gelatin sponges before implanting into critical-sized bone defects in rat calvaria. Compared to gelatin sponges with AdBMP2 loaded in a freely suspended form, the VBABM method enhanced gene transfer and bone regeneration was significantly improved. These results suggest that biotin-avidin immobilization of viral vectors to biomaterial scaffolds may be an effective strategy to facilitate tissue regeneration.

  19. Biotin-Binding Proteins in the Defense of Mushrooms against Predators and Parasites

    PubMed Central

    Bleuler-Martinez, Silvia; Schmieder, Stefanie; Aebi, Markus

    2012-01-01

    Tamavidins are fungal biotin-binding proteins (BBPs) displaying antifungal activity against phytopathogens. Here we show high toxicity of tamavidins toward nematodes, insects, and amoebae. As these organisms represent important phyla of fungal predators and parasites, we propose that BBPs are part of the chemical defense system of fungi. PMID:23001676

  20. Identification of total reversible cysteine oxidation in an atherosclerosis model using a modified biotin switch assay.

    PubMed

    Li, Ru; Huang, Jiqing; Kast, Juergen

    2015-05-01

    Oxidative stress due to the imbalance of reactive oxygen species (ROS) and the resulting reversible cysteine oxidation (CysOX) are involved in the early proatherogenic aspect of atherosclerosis. Given that the corresponding redox signaling pathways are still unclear, a modified biotin switch assay was developed to quantify the reversible CysOX in an atherosclerosis model established by using a monocytic cell line treated with platelet releasate. The accumulation of ROS was observed in the model system and validated in human primary monocytes. Through the application of the modified biotin switch assay, we obtained the first reversible CysOX proteome for this model. A total of 75 peptides, corresponding to 53 proteins, were quantified with oxidative modification. The bioinformatics analysis of these CysOX-containing proteins highlighted biological processes including glycolysis, cytoskeleton arrangement, and redox regulation. Moreover, the reversible oxidation of three glycolysis enzymes was observed using this method, and the regulation influence was verified by an enzyme activity assay. NADPH oxidase (NOX) inhibition treatment, in conjunction with the modified biotin switch method, was used to evaluate the global CysOX status. In conclusion, this versatile modified biotin switch assay provides an approach for the quantification of all reversible CysOX and for the study of redox signaling in atherosclerosis as well as in diseases in other biological systems.

  1. Evaluating the Sensitivity of Mycobacterium tuberculosis to Biotin Deprivation Using Regulated Gene Expression

    PubMed Central

    Woong Park, Sae; Klotzsche, Marcus; Wilson, Daniel J.; Boshoff, Helena I.; Eoh, Hyungjin; Manjunatha, Ujjini; Blumenthal, Antje; Rhee, Kyu; Barry, Clifton E.; Aldrich, Courtney C.; Ehrt, Sabine; Schnappinger, Dirk

    2011-01-01

    In the search for new drug targets, we evaluated the biotin synthetic pathway of Mycobacterium tuberculosis (Mtb) and constructed an Mtb mutant lacking the biotin biosynthetic enzyme 7,8-diaminopelargonic acid synthase, BioA. In biotin-free synthetic media, ΔbioA did not produce wild-type levels of biotinylated proteins, and therefore did not grow and lost viability. ΔbioA was also unable to establish infection in mice. Conditionally-regulated knockdown strains of Mtb similarly exhibited impaired bacterial growth and viability in vitro and in mice, irrespective of the timing of transcriptional silencing. Biochemical studies further showed that BioA activity has to be reduced by approximately 99% to prevent growth. These studies thus establish that de novo biotin synthesis is essential for Mtb to establish and maintain a chronic infection in a murine model of TB. Moreover, these studies provide an experimental strategy to systematically rank the in vivo value of potential drug targets in Mtb and other pathogens. PMID:21980288

  2. Aspects of lipid and carbohydrate metabolism, dietary biotin and fatty liver and kidney syndrome in broilers.

    PubMed

    Balnave, D; Pearce, J

    1976-11-01

    Two experiments were performed to investigate the biochemical changes associated with FLKS. A diet reported to induce FLKS was fed with or without supplementary biotin to broilers. In experiment 1 various stresses were applied to the birds. 2. In experiment 1 mortality from FLKS was 6% and in experiment 2 nil. Stress had little effect on the induction of the syndrome. 3. There were no significant differences due to diet in any of the variables examined in apparently normal birds. 4. Birds affected by FLKS showed the typical changes of increased liver and kidney weights and lipid contents but hepatic enzyme activities did not differ significantly from those of normal birds except that malate dehydrogenase (decarboxylating) (NADP) activity was significantly decreased. 5. Despite the low content of biotin in the unsupplemented diet (57 mug/kg) liver biotin content was not low in birds fed on this diet. 6. The results suggest that the incidence of FLKS is not related solely to dietary biotin content.

  3. Fatty liver and kidney syndrome in chicks. I. Effect of biotin in diet.

    PubMed

    Pearson, J A; Johnson, A R; Hood, R L; Fogerty, A C

    1976-12-01

    Fatty liver and kidney syndrome, a disorder of young chicks, was studied under laboratory conditions. Affected chicks had enlarged livers (hepatomegaly), an increased content of lipid in the liver, and an increased level of palmitoleic acid in the liver lipids. The disorder was observed mainly in chicks from young parent flocks, and was associated either with commerical diets which were subsequently found to be low in biotin, or with specially formulated low-biotin diets. A third factor, imposition of stress, was required to initiate the disorder. There was evidence of increased lipogenesis causing an increase of triacylglycerols in the liver lipids and an increased production of saturated fatty acids, particularly palmitic acid. Increased levels of palmitoleic acid resulted from an increased desaturation of palmitic acid. Under stress, affected chicks had low blood glucose levels, suggesting that gluconeogenesis was impaired. Since biotin-dependent enzymes are involved in both gluconeogenesis and lipogenesis, it would appear that the relevant enzymes respond differently to a deficiency of biotin.

  4. Chronic alcohol exposure inhibits biotin uptake by pancreatic acinar cells: possible involvement of epigenetic mechanisms.

    PubMed

    Srinivasan, Padmanabhan; Kapadia, Rubina; Biswas, Arundhati; Said, Hamid M

    2014-11-01

    Chronic exposure to alcohol affects different physiological aspects of pancreatic acinar cells (PAC), but its effect on the uptake process of biotin is not known. We addressed this issue using mouse-derived pancreatic acinar 266-6 cells chronically exposed to alcohol and wild-type and transgenic mice (carrying the human SLC5A6 5'-promoter) fed alcohol chronically. First we established that biotin uptake by PAC is Na(+) dependent and carrier mediated and involves sodium-dependent multivitamin transporter (SMVT). Chronic exposure of 266-6 cells to alcohol led to a significant inhibition in biotin uptake, expression of SMVT protein, and mRNA as well as in the activity of the SLC5A6 promoter. Similarly, chronic alcohol feeding of wild-type and transgenic mice carrying the SLC5A6 promoter led to a significant inhibition in biotin uptake by PAC, as well as in the expression of SMVT protein and mRNA and the activity of the SLC5A6 promoters expressed in the transgenic mice. We also found that chronic alcohol feeding of mice is associated with a significant increase in the methylation status of CpG islands predicted to be in the mouse Slc5a6 promoters and a decrease in the level of expression of transcription factor KLF-4, which plays an important role in regulating SLC5A6 promoter activity. These results demonstrate, for the first time, that chronic alcohol exposure negatively impacts biotin uptake in PAC and that this effect is exerted (at least in part) at the level of transcription of the SLC5A6 gene and may involve epigenetic/molecular mechanisms.

  5. Contributions of the Peroxisome and β-Oxidation Cycle to Biotin Synthesis in Fungi*

    PubMed Central

    Magliano, Pasqualina; Flipphi, Michel; Arpat, Bulak A.; Delessert, Syndie; Poirier, Yves

    2011-01-01

    The first step in the synthesis of the bicyclic rings of d-biotin is mediated by 8-amino-7-oxononanoate (AON) synthase, which catalyzes the decarboxylative condensation of l-alanine and pimelate thioester. We found that the Aspergillus nidulans AON synthase, encoded by the bioF gene, is a peroxisomal enzyme with a type 1 peroxisomal targeting sequence (PTS1). Localization of AON to the peroxisome was essential for biotin synthesis because expression of a cytosolic AON variant or deletion of pexE, encoding the PTS1 receptor, rendered A. nidulans a biotin auxotroph. AON synthases with PTS1 are found throughout the fungal kingdom, in ascomycetes, basidiomycetes, and members of basal fungal lineages but not in representatives of the Saccharomyces species complex, including Saccharomyces cerevisiae. A. nidulans mutants defective in the peroxisomal acyl-CoA oxidase AoxA or the multifunctional protein FoxA showed a strong decrease in colonial growth rate in biotin-deficient medium, whereas partial growth recovery occurred with pimelic acid supplementation. These results indicate that pimeloyl-CoA is the in vivo substrate of AON synthase and that it is generated in the peroxisome via the β-oxidation cycle in A. nidulans and probably in a broad range of fungi. However, the β-oxidation cycle is not essential for biotin synthesis in S. cerevisiae or Escherichia coli. These results suggest that alternative pathways for synthesis of the pimelate intermediate exist in bacteria and eukaryotes and that Saccharomyces species use a pathway different from that used by the majority of fungi. PMID:21998305

  6. Peptide nucleic acid probe for protein affinity purification based on biotin-streptavidin interaction and peptide nucleic acid strand hybridization.

    PubMed

    Tse, Jenny; Wang, Yuanyuan; Zengeya, Thomas; Rozners, Eriks; Tan-Wilson, Anna

    2015-02-01

    We describe a new method for protein affinity purification that capitalizes on the high affinity of streptavidin for biotin but does not require dissociation of the biotin-streptavidin complex for protein retrieval. Conventional reagents place both the selectively reacting group (the "warhead") and the biotin on the same molecule. We place the warhead and the biotin on separate molecules, each linked to a short strand of peptide nucleic acid (PNA), synthetic polymers that use the same bases as DNA but attached to a backbone that is resistant to attack by proteases and nucleases. As in DNA, PNA strands with complementary base sequences hybridize. In conditions that favor PNA duplex formation, the warhead strand (carrying the tagged protein) and the biotin strand form a complex that is held onto immobilized streptavidin. As in DNA, the PNA duplex dissociates at moderately elevated temperature; therefore, retrieval of the tagged protein is accomplished by a brief exposure to heat. Using iodoacetate as the warhead, 8-base PNA strands, biotin, and streptavidin-coated magnetic beads, we demonstrate retrieval of the cysteine protease papain. We were also able to use our iodoacetyl-PNA:PNA-biotin probe for retrieval and identification of a thiol reductase and a glutathione transferase from soybean seedling cotyledons.

  7. Biotin starvation causes mitochondrial protein hyperacetylation and partial rescue by the SIRT3-like deacetylase Hst4p.

    PubMed

    Madsen, Christian T; Sylvestersen, Kathrine B; Young, Clifford; Larsen, Sara C; Poulsen, Jon W; Andersen, Marianne A; Palmqvist, Eva A; Hey-Mogensen, Martin; Jensen, Per B; Treebak, Jonas T; Lisby, Michael; Nielsen, Michael L

    2015-07-09

    The essential vitamin biotin is a covalent and tenaciously attached prosthetic group in several carboxylases that play important roles in the regulation of energy metabolism. Here we describe increased acetyl-CoA levels and mitochondrial hyperacetylation as downstream metabolic effects of biotin deficiency. Upregulated mitochondrial acetylation sites correlate with the cellular deficiency of the Hst4p deacetylase, and a biotin-starvation-induced accumulation of Hst4p in mitochondria supports a role for Hst4p in lowering mitochondrial acetylation. We show that biotin starvation and knockout of Hst4p cause alterations in cellular respiration and an increase in reactive oxygen species (ROS). These results suggest that Hst4p plays a pivotal role in biotin metabolism and cellular energy homeostasis, and supports that Hst4p is a functional yeast homologue of the sirtuin deacetylase SIRT3. With biotin deficiency being involved in various metabolic disorders, this study provides valuable insight into the metabolic effects biotin exerts on eukaryotic cells.

  8. Biotin starvation causes mitochondrial protein hyperacetylation and partial rescue by the SIRT3-like deacetylase Hst4p

    PubMed Central

    Madsen, Christian T.; Sylvestersen, Kathrine B.; Young, Clifford; Larsen, Sara C.; Poulsen, Jon W.; Andersen, Marianne A.; Palmqvist, Eva A.; Hey-Mogensen, Martin; Jensen, Per B.; Treebak, Jonas T.; Lisby, Michael; Nielsen, Michael L.

    2015-01-01

    The essential vitamin biotin is a covalent and tenaciously attached prosthetic group in several carboxylases that play important roles in the regulation of energy metabolism. Here we describe increased acetyl-CoA levels and mitochondrial hyperacetylation as downstream metabolic effects of biotin deficiency. Upregulated mitochondrial acetylation sites correlate with the cellular deficiency of the Hst4p deacetylase, and a biotin-starvation-induced accumulation of Hst4p in mitochondria supports a role for Hst4p in lowering mitochondrial acetylation. We show that biotin starvation and knockout of Hst4p cause alterations in cellular respiration and an increase in reactive oxygen species (ROS). These results suggest that Hst4p plays a pivotal role in biotin metabolism and cellular energy homeostasis, and supports that Hst4p is a functional yeast homologue of the sirtuin deacetylase SIRT3. With biotin deficiency being involved in various metabolic disorders, this study provides valuable insight into the metabolic effects biotin exerts on eukaryotic cells. PMID:26158509

  9. Synthesis and evaluation of 99mTc/99Tc-MAG3-biotin conjugates for antibody pretargeting strategies.

    PubMed

    van Gog, F B; Visser, G W; Gowrising, R W; Snow, G B; van Dongen, G A

    1998-10-01

    Four 99mTc-MAG3-biotin conjugates were synthesized to determine their potential use in antibody pretargeting strategies for radioimmunoscintigraphy (RIS). To use these 99mTc-MAG3-biotin conjugates as model compounds for 186Re-MAG3-biotin conjugates for radioimmunotherapy (RIT), nanomolar amounts of 99Tc were added as carrier to 99mTc. The biotin derivatives used for the preparation of the conjugates-biocytin, biotin hydrazide, biotinyl-piperazine, and biotinyl-diaminosuccinic acid-differed at the site that is regarded to be susceptible to hydrolysis by biotinidase present in human plasma. All four conjugates were produced with high radiochemical purity, were stable in PBS, and demonstrated full binding capacity to streptavidin. The 99mTc/99Tc-MAG3-labeled biotinyl-piperazine and biotinyl-diaminosuccinic acid conjugates were stable in mouse as well as human plasma, whereas the corresponding biocytin and biotin hydrazide conjugates were rapidly degraded. The biodistribution in nude mice at 30 min after injection was similar for all conjugates, and a rapid blood clearance and high intestinal excretion were both observed. It is concluded that the metabolic routing of a conjugate containing biotin and MAG3 is dominated by these two moieties. For this reason, MAG3-biotin conjugates do not seem suited for pretargeted RIT, for which quantitative and fast renal excretion is a prerequisite to minimize radiation toxicity. However, in a pretargeted RIS approach the 99mTc-MAG3-biotin conjugates might have potential.

  10. Effect of biotin on transcription levels of key enzymes and glutamate efflux in glutamate fermentation by Corynebacterium glutamicum.

    PubMed

    Cao, Yan; Duan, Zuoying; Shi, Zhongping

    2014-02-01

    Biotin is an important factor affecting the performance of glutamate fermentation by biotin auxotrophic Corynebacterium glutamicum and glutamate is over-produced only when initial biotin content is controlled at suitable levels or initial biotin is excessive but with Tween 40 addition during fermentation. The transcription levels of key enzymes at pyruvate, isocitrate and α-ketoglutarate metabolic nodes, as well as transport protein (TP) of glutamate were investigated under the conditions of varied biotin contents and Tween 40 supplementation. When biotin was insufficient, the genes encoding key enzymes and TP were down-regulated in the early production phase, in particular, the transcription level of isocitrate dehydrogenase (ICDH) which was only 2% of that of control. Although the cells' morphology transformation and TP level were not affected, low transcription level of ICDH led to lower final glutamate concentration (64 g/L). When biotin was excessive, the transcription levels of key enzymes were at comparable levels as those of control with ICDH as an exception, which was only 3-22% of control level throughout production phase. In this case, little intracellular glutamate accumulation (1.5 mg/g DCW) and impermeable membrane resulted in non glutamate secretion into broth, even though the quantity of TP was more than 10-folds of control level. Addition of Tween 40 when biotin was excessive stimulated the expression of all key enzymes and TP, intracellular glutamate content was much higher (10-12 mg/g DCW), and final glutamate concentration reached control level (75-80 g/L). Hence, the membrane alteration and TP were indispensable in glutamate secretion. Biotin and Tween 40 influenced the expression level of ICDH and glutamate efflux, thereby influencing glutamate production.

  11. NeutrAvidin Functionalization of CdSe/CdS Quantum Nanorods and Quantification of Biotin Binding Sites using Biotin-4-Fluorescein Fluorescence Quenching.

    PubMed

    Lippert, Lisa G; Hallock, Jeffrey T; Dadosh, Tali; Diroll, Benjamin T; Murray, Christopher B; Goldman, Yale E

    2016-03-16

    We developed methods to solubilize, coat, and functionalize with NeutrAvidin elongated semiconductor nanocrystals (quantum nanorods, QRs) for use in single molecule polarized fluorescence microscopy. Three different ligands were compared with regard to efficacy for attaching NeutrAvidin using the "zero-length cross-linker" 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC). Biotin-4-fluorescene (B4F), a fluorophore that is quenched when bound to avidin proteins, was used to quantify biotin binding activity of the NeutrAvidin coated QRs and biotin binding activity of commercially available streptavidin coated quantum dots (QDs). All three coating methods produced QRs with NeutrAvidin coating density comparable to the streptavidin coating density of the commercially available quantum dots (QDs) in the B4F assay. One type of QD available from the supplier (ITK QDs) exhibited ∼5-fold higher streptavidin surface density compared to our QRs, whereas the other type of QD (PEG QDs) had 5-fold lower density. The number of streptavidins per QD increased from ∼7 streptavidin tetramers for the smallest QDs emitting fluorescence at 525 nm (QD525) to ∼20 tetramers for larger, longer wavelength QDs (QD655, QD705, and QD800). QRs coated with NeutrAvidin using mercaptoundecanoicacid (MUA) and QDs coated with streptavidin bound to biotinylated cytoplasmic dynein in single molecule TIRF microscopy assays, whereas Poly(maleic anhydride-alt-1-ocatdecene) (PMAOD) or glutathione (GSH) QRs did not bind cytoplasmic dynein. The coating methods require optimization of conditions and concentrations to balance between substantial NeutrAvidin binding vs tendency of QRs to aggregate and degrade over time.

  12. Computational redesign of bacterial biotin carboxylase inhibitors using structure-based virtual screening of combinatorial libraries.

    PubMed

    Brylinski, Michal; Waldrop, Grover L

    2014-04-02

    As the spread of antibiotic resistant bacteria steadily increases, there is an urgent need for new antibacterial agents. Because fatty acid synthesis is only used for membrane biogenesis in bacteria, the enzymes in this pathway are attractive targets for antibacterial agent development. Acetyl-CoA carboxylase catalyzes the committed and regulated step in fatty acid synthesis. In bacteria, the enzyme is composed of three distinct protein components: biotin carboxylase, biotin carboxyl carrier protein, and carboxyltransferase. Fragment-based screening revealed that amino-oxazole inhibits biotin carboxylase activity and also exhibits antibacterial activity against Gram-negative organisms. In this report, we redesigned previously identified lead inhibitors to expand the spectrum of bacteria sensitive to the amino-oxazole derivatives by including Gram-positive species. Using 9,411 small organic building blocks, we constructed a diverse combinatorial library of 1.2×10⁸ amino-oxazole derivatives. A subset of 9×10⁶ of these compounds were subjected to structure-based virtual screening against seven biotin carboxylase isoforms using similarity-based docking by eSimDock. Potentially broad-spectrum antibiotic candidates were selected based on the consensus ranking by several scoring functions including non-linear statistical models implemented in eSimDock and traditional molecular mechanics force fields. The analysis of binding poses of the top-ranked compounds docked to biotin carboxylase isoforms suggests that: (1) binding of the amino-oxazole anchor is stabilized by a network of hydrogen bonds to residues 201, 202 and 204; (2) halogenated aromatic moieties attached to the amino-oxazole scaffold enhance interactions with a hydrophobic pocket formed by residues 157, 169, 171 and 203; and (3) larger substituents reach deeper into the binding pocket to form additional hydrogen bonds with the side chains of residues 209 and 233. These structural insights into drug-biotin

  13. Low noise, tunable Ho:fiber soliton oscillator for Ho:YLF amplifier seeding

    NASA Astrophysics Data System (ADS)

    Li, Peng; Ruehl, Axel; Bransley, Colleen; Hartl, Ingmar

    2016-06-01

    We present a passively mode-locked, tunable soliton Ho:fiber ring oscillator, optimized for seeding of holmium-doped yttrium lithium flouride (Ho:YLF) amplifiers. The oscillator is independently tunable in central wavelength and spectral width from 2040 to 2070 nm and from 5 to 10 nm, respectively. At all settings the pulse energy within the soliton is around 800 pJ. The soliton oscillator was optimized to fully meet the spectral requirements for seeding Ho:YLF amplifiers. Its Kelly sidebands are located outside the amplifier gain spectrum, resulting in a train of about 1 ps long pedestal-free pulses with relative intensity noise of only 0.13% RMS when integrated from 1 Hz to Nyquist frequency.

  14. Hydration and mobility of HO-(aq)

    PubMed Central

    Asthagiri, D.; Pratt, Lawrence R.; Kress, J. D.; Gomez, Maria A.

    2004-01-01

    The hydroxide anion plays an essential role in many chemical and biochemical reactions. But a molecular-scale description of its hydration state, and hence also its transport, in water is currently controversial. The statistical mechanical quasichemical theory of solutions suggests that \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\mathrm{HO}}{\\cdot}[{\\mathrm{H}}_{2}{\\mathrm{O}}]_{3}^{-}\\end{equation*}\\end{document} is the predominant species in the aqueous phase under standard conditions. This result agrees with recent spectroscopic studies on hydroxide water clusters and with the available thermodynamic hydration free energies. In contrast, a recent ab initio molecular dynamics simulation has suggested that \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\mathrm{HO}}{\\cdot}[{\\mathrm{H}}_{2}{\\mathrm{O}}]_{4}^{-}\\end{equation*}\\end{document} is the only dominant aqueous solution species. We apply adiabatic ab initio molecular dynamics simulations and find good agreement with both the quasichemical theoretical predictions and experimental results. The present results suggest a picture that is simpler, more traditional, but with additional subtlety. These coordination structures are labile but the tricoordinate species is the prominent case. This conclusion is unaltered with changes in the electronic density functional. No evidence is found for rate-determining activated interconversion of a \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength

  15. AN ENZYME LINKED IMMUNOSORBENT ASSAY FOR THE HO-1 ISOFORM OF HEME OXYGENASE

    EPA Science Inventory

    AN ENZYME LINKED IMMUNOSORBENT ASSAY FOR THE HO-1 ISOFORM OF HEME OXYGENASE

    Heme oxygenase (HO) occurs in biological tissues as two major isoforms HO-1 and HO-2. HO-1 is inducible by many treatments, particularly oxidative stress-related conditions such as depletion of gl...

  16. High Energy Directly Pumped Ho:YLF Laser

    NASA Technical Reports Server (NTRS)

    Petros, Mulugeta; Yu, Ji-Rong; Singh, Upendra N.; Barnes, Norman P.

    2000-01-01

    The most commonly used crystal architecture to produce 2 micrometer laser is co-doping Ho and Tm into a single host crystal. In this method, the stored energy transfer from the Tm (3)F4 to the Ho (5)I7 manifold is not fast enough to warrant high efficiency for short pulse applications. By separating the Ho and the Tm ions and doping the Tm in YALO3 and the Ho in YLF, we were able to directly pump the Ho (5)I7 manifold with 1.94 micrometers. The Ho:YLF laser has produced 33 mJ at 2.062 micrometers with a quantum efficiency of 0.88. The performance of each laser will be presented.

  17. Spectroscopic and lasing properties of Ho:Tm:LuAG

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Filer, Elizabeth D.; Naranjo, Felipe L.; Rodriguez, Waldo J.; Kokta, Milan R.

    1993-01-01

    Ho:Tm:LuAG has been grown, examined spectroscopically, and lased at 2.1 microns. Ho:Tm:LuAG was selected for this experimental investigation when quantum-mechanical modeling predicted that it would be a good laser material for Ho laser operation on one of the 5I7 to 5I8 transitions. Lasing was achieved at 2.100 microns, one of the three wavelengths predicted to be most probable for laser action.

  18. Determination of biotin in Antarctic krill (Euphausia superba) by high-performance TLC with different post-chromatographic derivatizations.

    PubMed

    Teo, Peishan; Liu, Daicheng

    2013-08-01

    A new efficient method was developed to detect biotin in Antarctic krill by Vis-absorbance detection. DMF was used after chloroform pretreatment to extract biotin and two chromogenic methods were developed. The development system consisted of dichloromethane/dimethylcarbinol/methanol/glacial acetic acid (3:3:2:0.015, v/v/v/v). Samples were separated on precoated silica gel GF254 high-performance TLC plates. Densitometric analysis of biotin was carried out in the absorbance mode at 400 and 530 nm. The biotin content was determined to be 1.0948 ± 0.0097 and 1.1212 ± 0.0155 mg/g in Antarctic krill with the two chromogenic methods, which had no significant difference.

  19. Thiol- and biotin-labeled probes for oligonucleotide quartz crystal microbalance biosensors of microalga alexandrium minutum.

    PubMed

    Lazerges, Mathieu; Perrot, Hubert; Rabehagasoa, Niriniony; Compère, Chantal

    2012-07-04

    Two quartz crystal microbalance oligonucleotide biosensors of a toxic microalga gene sequence (Alexandrium Minutum) have been designed. Grafting on a gold surface of 20-base thiol- or biotin-labeled probe, and selective hybridization with the complementary 20-base target, have been monitored in situ with a 27 MHz quartz crystal microbalance under controlled hydrodynamic conditions. The frequency of the set up is stable to within a few hertz, corresponding to the nanogram scale, for three hour experiments. DNA recognition by the two biosensors is efficient and selective. Hybridization kinetic curves indicate that the biosensor designed with the thiol-labeled probe is more sensitive, and that the biosensor designed with the biotin-labeled probe has a shorter time response and a higher hybridization efficiency.

  20. Proximity-Dependent Biotin Identification (BioID) in Dictyostelium Amoebae.

    PubMed

    Batsios, Petros; Meyer, Irene; Gräf, Ralph

    2016-01-01

    The identification of a bona fide lamin-like protein in Dictyostelium made this lower eukaryote an attractive model organism to study evolutionarily conserved nuclear envelope (NE) proteins important for nuclear organization and human laminopathies. Proximity-dependent biotin identification (BioID), reported by Roux and colleagues, is a powerful discovery tool for lamin-associated proteins. In this method, living cells express a bait protein (e.g., lamin) fused to an R118G-mutated version of BirA, an Escherichia coli biotinylase. In the presence of biotin, BirA-R118G biotinylates target proteins in close proximity in vivo, which are purified using streptavidin and identified by immunoblotting or mass spectrometry. We adapted the BioID method for use in Dictyostelium amoebae. The protocols described here successfully revealed Dictyostelium lamin-like protein NE81 proximity to Sun1, a conserved inner nuclear membrane protein.

  1. Electrochemical DNA biosensor based on avidin-biotin conjugation for influenza virus (type A) detection

    NASA Astrophysics Data System (ADS)

    Chung, Da-Jung; Kim, Ki-Chul; Choi, Seong-Ho

    2011-09-01

    An electrochemical DNA biosensor (E-DNA biosensor) was fabricated by avidin-biotin conjugation of a biotinylated probe DNA, 5'-biotin-ATG AGT CTT CTA ACC GAG GTC GAA-3', and an avidin-modified glassy carbon electrode (GCE) to detect the influenza virus (type A). An avidin-modified GCE was prepared by the reaction of avidin and a carboxylic acid-modified GCE, which was synthesized by the electrochemical reduction of 4-carboxyphenyl diazonium salt. The current value of the E-DNA biosensor was evaluated after hybridization of the probe DNA and target DNA using cyclic voltammetry (CV). The current value decreased after the hybridization of the probe DNA and target DNA. The DNA that was used follows: complementary target DNA, 5'-TTC GAC CTC GGT TAG AAG ACT CAT-3' and two-base mismatched DNA, 5'-TTC GAC AGC GGT TAT AAG ACT CAT-3'.

  2. Thiol- and Biotin-Labeled Probes for Oligonucleotide Quartz Crystal Microbalance Biosensors of Microalga Alexandrium Minutum

    PubMed Central

    Lazerges, Mathieu; Perrot, Hubert; Rabehagasoa, Niriniony; Compère, Chantal

    2012-01-01

    Two quartz crystal microbalance oligonucleotide biosensors of a toxic microalga gene sequence (Alexandrium Minutum) have been designed. Grafting on a gold surface of 20-base thiol- or biotin-labeled probe, and selective hybridization with the complementary 20-base target, have been monitored in situ with a 27 MHz quartz crystal microbalance under controlled hydrodynamic conditions. The frequency of the set up is stable to within a few hertz, corresponding to the nanogram scale, for three hour experiments. DNA recognition by the two biosensors is efficient and selective. Hybridization kinetic curves indicate that the biosensor designed with the thiol-labeled probe is more sensitive, and that the biosensor designed with the biotin-labeled probe has a shorter time response and a higher hybridization efficiency. PMID:25585927

  3. Avidin-biotin-immunoglucose oxidase: use in single and double labeling procedures.

    PubMed

    Gown, A M; Garcia, R; Ferguson, M; Yamanaka, E; Tippens, D

    1986-03-01

    We have investigated the use of an avidin-biotin-immunoglucose oxidase (AB-GO) technique for single and double antigen localization in conjunction with the avidin-biotin-immunoperoxidase (AB-P) technique in fixed, embedded specimens, using sequential monoclonal and polyclonal antibodies of the same species. The optimal technique for double labeling requires the first antibody to be applied and localized with the AB-P technique using 3,3'-diaminobenzidine (DAB) as the chromogen, followed by an optional elution step and/or incubation with mild detergent (0.01% Triton). The second antigen is localized with the AB-GO technique with nitro blue tetrazolium (NBT) as a chromogen. Effects of antigen concentration, intermediate elution steps, and the relative efficiency of the two methodologies are described.

  4. Biotin-mediated epigenetic modifications: Potential defense against the carcinogenicity of benzo[a]pyrene.

    PubMed

    Xia, Bo; Pang, Li; Zhuang, Zhi-xiong; Liu, Jian-jun

    2016-01-22

    Environmental pollution and an unhealthy lifestyle result in direct exposure to dangerous chemicals that can modify endogenous pathways and induce malignant transformation of human cells. Although the molecular mechanisms of tumorigenesis are still not well understood, epigenetic alteration may be associated with exogenous chemical-induced carcinogenicity. Given the association between nutrition and cancer, nutrient supplementation may reduce aberrant epigenetic modifications induced by chemicals, thus decreasing carcinogenesis. This paper provides an overview of the epigenetic events caused by benzo[a]pyrene, a procarcinogenic and environmental pollutant, and biotin, an essential water-soluble vitamin, and investigates potential connections between them. This paper also discusses the potential inhibitory effect of biotin-related epigenetic modifications on the carcinogenicity of benzo[a]pyrene. The effect of nutritional supplementation on tumorigenesis involving epigenetic modifications is also discussed.

  5. Structural evidence for substrate-induced synergism and half-sites reactivity in biotin carboxylase

    SciTech Connect

    Mochalkin, Igor; Miller, J. Richard; Evdokimov, Artem; Lightle, Sandra; Yan, Chunhong; Stover, Charles Ken; Waldrop, Grover L.

    2008-10-24

    Bacterial acetyl-CoA carboxylase is a multifunctional biotin-dependent enzyme that consists of three separate proteins: biotin carboxylase (BC), biotin carboxyl carrier protein (BCCP), and carboxyltransferase (CT). Acetyl-CoA carboxylase is a potentially attractive target for novel antibiotics because it catalyzes the first committed step in fatty acid biosynthesis. In the first half-reaction, BC catalyzes the ATP-dependent carboxylation of BCCP. In the second half-reaction, the carboxyl group is transferred from carboxybiotinylated BCCP to acetyl-CoA to produce malonyl-CoA. A series of structures of BC from several bacteria crystallized in the presence of various ATP analogs is described that addresses three major questions concerning the catalytic mechanism. The structure of BC bound to AMPPNP and the two catalytically essential magnesium ions resolves inconsistencies between the kinetics of active-site BC mutants and previously reported BC structures. Another structure of AMPPNP bound to BC shows the polyphosphate chain folded back on itself, and not in the correct (i.e., extended) conformation for catalysis. This provides the first structural evidence for the hypothesis of substrate-induced synergism, which posits that ATP binds nonproductively to BC in the absence of biotin. The BC homodimer has been proposed to exhibit half-sites reactivity where the active sites alternate or 'flip-flop' their catalytic cycles. A crystal structure of BC showed the ATP analog AMPPCF{sub 2}P bound to one subunit while the other subunit was unliganded. The liganded subunit was in the closed or catalytic conformation while the unliganded subunit was in the open conformation. This provides the first structural evidence for half-sites reactivity in BC.

  6. Structural and Biochemical Studies on the Regulation of Biotin Carboxylase by Substrate Inhibition and Dimerization

    SciTech Connect

    Chou, Chi-Yuan; Tong, Liang

    2012-06-19

    Biotin carboxylase (BC) activity is shared among biotin-dependent carboxylases and catalyzes the Mg-ATP-dependent carboxylation of biotin using bicarbonate as the CO{sub 2} donor. BC has been studied extensively over the years by structural, kinetic, and mutagenesis analyses. Here we report three new crystal structures of Escherichia coli BC at up to 1.9 {angstrom} resolution, complexed with different ligands. Two structures are wild-type BC in complex with two ADP molecules and two Ca{sup 2+} ions or two ADP molecules and one Mg{sup 2+} ion. One ADP molecule is in the position normally taken by the ATP substrate, whereas the other ADP molecule occupies the binding sites of bicarbonate and biotin. One Ca{sup 2+} ion and the Mg{sup 2+} ion are associated with the ADP molecule in the active site, and the other Ca{sup 2+} ion is coordinated by Glu-87, Glu-288, and Asn-290. Our kinetic studies confirm that ATP shows substrate inhibition and that this inhibition is competitive against bicarbonate. The third structure is on the R16E mutant in complex with bicarbonate and Mg-ADP. Arg-16 is located near the dimer interface. The R16E mutant has only a 2-fold loss in catalytic activity compared with the wild-type enzyme. Analytical ultracentrifugation experiments showed that the mutation significantly destabilized the dimer, although the presence of substrates can induce dimer formation. The binding modes of bicarbonate and Mg-ADP are essentially the same as those to the wild-type enzyme. However, the mutation greatly disrupted the dimer interface and caused a large re-organization of the dimer. The structures of these new complexes have implications for the catalysis by BC.

  7. Structural and Biochemical Studies on the Regulation of Biotin Carboxylase by Substrate Inhibition and Dimerization

    SciTech Connect

    C Chou; L Tong

    2011-12-31

    Biotin carboxylase (BC) activity is shared among biotin-dependent carboxylases and catalyzes the Mg-ATP-dependent carboxylation of biotin using bicarbonate as the CO{sub 2} donor. BC has been studied extensively over the years by structural, kinetic, and mutagenesis analyses. Here we report three new crystal structures of Escherichia coli BC at up to 1.9 {angstrom} resolution, complexed with different ligands. Two structures are wild-type BC in complex with two ADP molecules and two Ca{sup 2+} ions or two ADP molecules and one Mg{sup 2+} ion. One ADP molecule is in the position normally taken by the ATP substrate, whereas the other ADP molecule occupies the binding sites of bicarbonate and biotin. One Ca{sup 2+} ion and the Mg{sup 2+} ion are associated with the ADP molecule in the active site, and the other Ca{sup 2+} ion is coordinated by Glu-87, Glu-288, and Asn-290. Our kinetic studies confirm that ATP shows substrate inhibition and that this inhibition is competitive against bicarbonate. The third structure is on the R16E mutant in complex with bicarbonate and Mg-ADP. Arg-16 is located near the dimer interface. The R16E mutant has only a 2-fold loss in catalytic activity compared with the wild-type enzyme. Analytical ultracentrifugation experiments showed that the mutation significantly destabilized the dimer, although the presence of substrates can induce dimer formation. The binding modes of bicarbonate and Mg-ADP are essentially the same as those to the wild-type enzyme. However, the mutation greatly disrupted the dimer interface and caused a large re-organization of the dimer. The structures of these new complexes have implications for the catalysis by BC.

  8. Introduction of biotin or folic acid into polypyrrole magnetite core-shell nanoparticles

    SciTech Connect

    Nan, Alexandrina; Turcu, Rodica; Liebscher, Jürgen

    2013-11-13

    In order to contribute to the trend in contemporary research to develop magnetic core shell nanoparticles with better properties (reduced toxicity, high colloidal and chemical stability, wide scope of application) in straightforward and reproducible methods new core shell magnetic nanoparticles were developed based on polypyrrole shells functionalized with biotin and folic acid. Magnetite nanoparticles stabilized by sebacic acid were used as magnetic cores. The morphology of magnetite was determined by transmission electron microscopy TEM, while the chemical structure investigated by FT-IR.

  9. Structural evidence for substrate-induced synergism and half-sites reactivity in biotin carboxylase

    PubMed Central

    Mochalkin, Igor; Miller, J. Richard; Evdokimov, Artem; Lightle, Sandra; Yan, Chunhong; Stover, Charles Ken; Waldrop, Grover L.

    2008-01-01

    Bacterial acetyl-CoA carboxylase is a multifunctional biotin-dependent enzyme that consists of three separate proteins: biotin carboxylase (BC), biotin carboxyl carrier protein (BCCP), and carboxyltransferase (CT). Acetyl-CoA carboxylase is a potentially attractive target for novel antibiotics because it catalyzes the first committed step in fatty acid biosynthesis. In the first half-reaction, BC catalyzes the ATP-dependent carboxylation of BCCP. In the second half-reaction, the carboxyl group is transferred from carboxybiotinylated BCCP to acetyl-CoA to produce malonyl-CoA. A series of structures of BC from several bacteria crystallized in the presence of various ATP analogs is described that addresses three major questions concerning the catalytic mechanism. The structure of BC bound to AMPPNP and the two catalytically essential magnesium ions resolves inconsistencies between the kinetics of active-site BC mutants and previously reported BC structures. Another structure of AMPPNP bound to BC shows the polyphosphate chain folded back on itself, and not in the correct (i.e., extended) conformation for catalysis. This provides the first structural evidence for the hypothesis of substrate-induced synergism, which posits that ATP binds nonproductively to BC in the absence of biotin. The BC homodimer has been proposed to exhibit half-sites reactivity where the active sites alternate or “flip-flop” their catalytic cycles. A crystal structure of BC showed the ATP analog AMPPCF2P bound to one subunit while the other subunit was unliganded. The liganded subunit was in the closed or catalytic conformation while the unliganded subunit was in the open conformation. This provides the first structural evidence for half-sites reactivity in BC. PMID:18725455

  10. Revisiting the streptavidin-biotin binding by using an aptamer and displacement isothermal calorimetry titration.

    PubMed

    Kuo, Tai-Chih; Tsai, Ching-Wei; Lee, Peng-Chen; Chen, Wen-Yih

    2015-03-01

    The association constant of a well-known streptavidin-biotin binding has only been inferred from separately measured kinetic parameters. In a single experiment, we obtained Ka 1 × 10(12)  M(-1) by using a streptavidin-binding aptamer and ligand-displacement isothermal titration calorimetry. This study explores the challenges of determining thermodynamic parameters and the derived equilibrium binding affinity of tight ligand-receptor binding.

  11. Biotin uptake by mouse and human pancreatic beta cells/islets: a regulated, lipopolysaccharide-sensitive carrier-mediated process.

    PubMed

    Ghosal, Abhisek; Sekar, Thillai V; Said, Hamid M

    2014-08-01

    Biotin is essential for the normal function of pancreatic beta cells. These cells obtain biotin from their surroundings via transport across their cell membrane. Little is known about the uptake mechanism involved, how it is regulated, and how it is affected by internal and external factors. We addressed these issues using the mouse-derived pancreatic beta-TC-6 cells and freshly isolated mouse and human primary pancreatic beta cells as models. The results showed biotin uptake by pancreatic beta-TC-6 cells occurs via a Na(+)-dependent, carrier-mediated process, that is sensitive to desthiobiotin, as well as to pantothenic acid and lipoate; the process is also saturable as a function of concentration (apparent Km = 22.24 ± 5.5 μM). These cells express the sodium-dependent multivitamin transporter (SMVT), whose knockdown (with doxycycline-inducible shRNA) led to a sever inhibition in biotin uptake. Similarly, uptake of biotin by mouse and human primary pancreatic islets is Na(+)-dependent and carrier-mediated, and both cell types express SMVT. Biotin uptake by pancreatic beta-TC-6 cells is also adaptively regulated (via transcriptional mechanism) by extracellular substrate level. Chronic treatment of pancreatic beta-TC-6 cells with bacterial lipopolysaccharides (LPS) leads to inhibition in biotin uptake. This inhibition is mediated via a Toll-Like receptor 4-mediated process and involves a decrease in membrane expression of SMVT. These findings show, for the first time, that pancreatic beta cells/islets take up biotin via a specific and regulated carrier-mediated process, and that the process is sensitive to the effect of LPS.

  12. Biotin deprivation impairs mitochondrial structure and function and has implications for inherited metabolic disorders.

    PubMed

    Ochoa-Ruiz, Estefanía; Díaz-Ruiz, Rodrigo; Hernández-Vázquez, Alaín de J; Ibarra-González, Isabel; Ortiz-Plata, Alma; Rembao, Daniel; Ortega-Cuéllar, Daniel; Viollet, Benoit; Uribe-Carvajal, Salvador; Corella, José Ahmed; Velázquez-Arellano, Antonio

    2015-11-01

    Certain inborn errors of metabolism result from deficiencies in biotin containing enzymes. These disorders are mimicked by dietary absence or insufficiency of biotin, ATP deficit being a major effect,whose responsible mechanisms have not been thoroughly studied. Here we show that in rats and cultured cells it is the result of reduced TCA cycle flow, partly due to deficient anaplerotic biotin-dependent pyruvate carboxylase. This is accompanied by diminished flow through the electron transport chain, augmented by deficient cytochrome c oxidase (complex IV) activity with decreased cytochromes and reduced oxidative phosphorylation. There was also severe mitochondrial damage accompanied by decrease of mitochondria, associated with toxic levels of propionyl CoA as shown by carnitine supplementation studies, which explains the apparently paradoxical mitochondrial diminution in the face of the energy sensor AMPK activation, known to induce mitochondria biogenesis. This idea was supported by experiments on AMPK knockout mouse embryonic fibroblasts (MEFs). The multifactorial ATP deficit also provides a plausible basis for the cardiomyopathy in patients with propionic acidemia, and other diseases.Additionally, systemic inflammation concomitant to the toxic state might explain our findings of enhanced IL-6, STAT3 and HIF-1α, associated with an increase of mitophagic BNIP3 and PINK proteins, which may further increase mitophagy. Together our results imply core mechanisms of energy deficit in several inherited metabolic disorders.

  13. Magnetic molecularly imprinted polymer for the isolation and detection of biotin and biotinylated biomolecules.

    PubMed

    Ben Aissa, A; Herrera-Chacon, A; Pupin, R R; Sotomayor, M D P T; Pividori, M I

    2017-02-15

    Magnetic separation based on biologically-modified magnetic particles is a preconcentration procedure commonly integrated in magneto actuated platforms for the detection of a huge range of targets. However, the main drawback of this material is the low stability and high cost. In this work, a novel hybrid molecularly-imprinted polymer with magnetic properties is presented with affinity towards biotin and biotinylated biomolecules. During the synthesis of the magneto core-shell particles, biotin was used as a template. The characterization of this material by microscopy techniques including SEM, TEM and confocal microscopy is presented. The application of the magnetic-MIPs for the detection of biotin and biotinylated DNA in magneto-actuated platforms is also described for the first time. The magnetic-MIP showed a significant immobilization capacity of biotinylated molecules, giving rise to a cheaper and a robust method (it is not required to be stored at 4°C) with high binding capacity for the separation and purification under magnetic actuation of a wide range of biotinylated molecules, and their downstream application including determination of their specific targets.

  14. Biotin-Avidin Based Universal Cell-Matrix Interaction for Promoting Three-Dimensional Cell Adhesion.

    PubMed

    Dou, Xiao-Qiu; Zhang, Jia; Feng, Chuanliang

    2015-09-23

    To promote cell adhesion in three-dimensional (3D) extracellular matrix (ECM) is crucial for avoiding cell anoikis, which is one of the most important issues for fundamental cell biology. Herein, a biotin-avidin based universal cell-matrix interaction for different types of cells is developed in order to achieve the promoted adhesion in 3D ECM. For the purpose, biotinylated nanofibrous hydrogels are constructed by coassembling 1,4-benzyldicarboxamide (C2) based non-biotinylated and biotinylated supramolecular gelators. The used cells are modified by avidin (AV-cells) through biotinylating cells and then interacting with avidin. After in situ encapsulating AV-cells in the hydrogels, the adhered amount can be increased by tens of percent even with adding several percentages of the biotinylated C2 gelators in the coassembly due to the specific biotin-avidin interaction. Reverse transcription polymerase chain reaction (RT-PCR) confirms that AV-cells can proliferate without varying gene expression and denaturation. Compared with the interaction between RGD and cells, this avidin-biotin interaction should be much more universal and it is feasible to be employed to promote cell adhesion for most types of cells in 3D matrix.

  15. Isolation of the Arabidopsis phosphoproteome using a biotin-tagging approach.

    PubMed

    Kwon, Sun Jae; Choi, Eun Young; Seo, Jong Bok; Park, Ohkmae K

    2007-10-31

    Protein phosphorylation plays a key role in signal transduction in cells. Since phosphoproteins are present in low abundance, enrichment methods are required for their purification and analysis. Chemical derivatization strategies have been devised for enriching phosphoproteins and phosphopeptides. In this report, we employed a strategy that replaces the phosphate moieties on serine and threonine residues with a biotin-containing tag via a series of chemical reactions. Ribulose 1,5-bis-phosphate carboxylase/oxygenase (RUBISCO)-depleted protein extracts prepared from Arabidopsis seedlings were chemically modified for 'biotin-tagging'. The biotinylated (previously phosphorylated) proteins were then selectively isolated by avidin-biotin affinity chromatography, followed by two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). This led to the identification of 31 protein spots, representing 18 different proteins, which are implicated in a variety of cellular processes. Despite its current technical limitations, with further improvements in tools and techniques this strategy may be developed into a useful approach.

  16. Antibody immobilization using pneumatic spray: comparison with the avidin-biotin bridge immobilization method.

    PubMed

    Figueroa, Jhon; Magaña, Sonia; Lim, Daniel V; Schlaf, Rudy

    2012-12-14

    The formation of a thin antibody film on a glass surface using pneumatic spray was investigated as a potential immobilization technique for capturing pathogenic targets. Goat-Escherichia coli O157:H7 IgG films were made by pneumatic spray and compared against the avidin-biotin bridge immobilized films by assaying with green fluorescent protein (GFP) transformed E. coli O157:H7 cells and fluorescent reporter antibodies. Functionality, stability, and immobilization of the films were tested. The pneumatic spray films had lower fluorescence intensity values than the avidin-biotin bridge films but resulted in similar detection for E. coli O157:H7 at 10(5)-10(7)cells/ml sample concentrations with no detection of non-E. coli O157:H7 strains. Both methods also resulted in similar percent capture efficiencies. The results demonstrated that immobilization of antibody via pneumatic spray did not render the antibody non-functional and produced stable antibody films. The amount of time necessary for immobilization of the antibody was reduced significantly from 24h for the avidin-biotin bridge to 7 min using the pneumatic spray technique, with additional benefits of greatly reduced use of materials and chemicals. The pneumatic spray technique promises to be an alternative for the immobilization of antibodies on glass slides for capturing pathogenic targets and use in biosensor type devices.

  17. Re-evaluation of biotin-streptavidin conjugation in Förster resonance energy transfer applications

    PubMed Central

    Saremi, Bahar; Wei, Ming-Yuan; Liu, Yuan; Cheng, Bingbing; Yuan, Baohong

    2014-01-01

    Abstract. Bioaffinity conjugation between streptavidin (SA) and biotin has been widely used to link donors and acceptors for investigating the distance-dependent Förster resonance energy transfer (FRET). When studying a commonly used FRET system of (QD-SA)-(biotin-DNA-dye) [donor: quantum dot (QD); acceptor: small organic fluorescent dye; and linker: deoxyribose nucleic acid (DNA) molecule via SA-biotin conjugation], however, a contradictory finding was recently reported in the literature. It was found that the FRET lost its dependence on the number of DNA base pairs when using a phosphate-buffered saline (PBS) solution. We found that the conflicted results were caused by the ionic strength of the adopted buffer solutions. Our results suggest that the dependent FRET on the number of DNA bases is favorable in a low-ionic-strength buffer, whereas in relatively high-ionic-strength buffers, the FRET loses the DNA length dependence. We propose that the independence is mainly caused by the conformational change of DNA molecules from a stretched to a coiled mode when the cations in the high-ionic-strength buffer neutralize the negatively charged backbone of DNA molecules, thereby bringing the acceptors close to the donors. PMID:25162908

  18. Biotin synthase: insights into radical-mediated carbon-sulfur bond formation.

    PubMed

    Fugate, Corey J; Jarrett, Joseph T

    2012-11-01

    The enzyme cofactor and essential vitamin biotin is biosynthesized in bacteria, fungi, and plants through a pathway that culminates with the addition of a sulfur atom to generate the five-membered thiophane ring. The immediate precursor, dethiobiotin, has methylene and methyl groups at the C6 and C9 positions, respectively, and formation of a thioether bridging these carbon atoms requires cleavage of unactivated CH bonds. Biotin synthase is an S-adenosyl-l-methionine (SAM or AdoMet) radical enzyme that catalyzes reduction of the AdoMet sulfonium to produce 5'-deoxyadenosyl radicals, high-energy carbon radicals that can directly abstract hydrogen atoms from dethiobiotin. The available experimental and structural data suggest that a [2Fe-2S](2+) cluster bound deep within biotin synthase provides a sulfur atom that is added to dethiobiotin in a stepwise reaction, first at the C9 position to generate 9-mercaptodethiobiotin, and then at the C6 position to close the thiophane ring. The formation of sulfur-containing biomolecules through a radical reaction involving an iron-sulfur cluster is an unprecedented reaction in biochemistry; however, recent enzyme discoveries suggest that radical sulfur insertion reactions may be a distinct subgroup within the burgeoning Radical SAM superfamily. This article is part of a Special Issue entitled: Radical SAM enzymes and Radical Enzymology.

  19. A biotin enrichment strategy identifies novel carbonylated amino acids in proteins from human plasma.

    PubMed

    Havelund, Jesper F; Wojdyla, Katarzyna; Davies, Michael J; Jensen, Ole N; Møller, Ian Max; Rogowska-Wrzesinska, Adelina

    2017-03-06

    Protein carbonylation is an irreversible protein oxidation correlated with oxidative stress, various diseases and ageing. Here we describe a peptide-centric approach for identification and characterisation of up to 14 different types of carbonylated amino acids in proteins. The modified residues are derivatised with biotin-hydrazide, enriched and characterised by tandem mass spectrometry. The strength of the method lies in an improved elution of biotinylated peptides from monomeric avidin resin using hot water (95°C) and increased sensitivity achieved by reduction of analyte losses during sample preparation and chromatography. For the first time MS/MS data analysis utilising diagnostic biotin fragment ions is used to pinpoint sites of biotin labelling and improve the confidence of carbonyl peptide assignments. We identified a total of 125 carbonylated residues in bovine serum albumin after extensive in vitro metal ion-catalysed oxidation. Furthermore, we assigned 133 carbonylated sites in 36 proteins in native human plasma protein samples. The optimised workflow enabled detection of 10 hitherto undetected types of carbonylated amino acids in proteins: aldehyde and ketone modifications of leucine, valine, alanine, isoleucine, glutamine, lysine and glutamic acid (+14Da), an oxidised form of methionine - aspartate semialdehyde (-32Da) - and decarboxylated glutamic acid and aspartic acid (-30Da).

  20. Functional definition of BirA suggests a biotin utilization pathway in the zoonotic pathogen Streptococcus suis

    PubMed Central

    Ye, Huiyan; Cai, Mingzhu; Zhang, Huimin; Li, Zhencui; Wen, Ronghui; Feng, Youjun

    2016-01-01

    Biotin protein ligase is universal in three domains of life. The paradigm version of BPL is the Escherichia coli BirA that is also a repressor for the biotin biosynthesis pathway. Streptococcus suis, a leading bacterial agent for swine diseases, seems to be an increasingly-important opportunistic human pathogen. Unlike the scenario in E. coli, S. suis lacks the de novo biotin biosynthesis pathway. In contrast, it retains a bioY, a biotin transporter-encoding gene, indicating an alternative survival strategy for S. suis to scavenge biotin from its inhabiting niche. Here we report functional definition of S. suis birA homologue. The in vivo functions of the birA paralogue with only 23.6% identity to the counterpart of E. coli, was judged by its ability to complement the conditional lethal mutants of E. coli birA. The recombinant BirA protein of S. suis was overexpressed in E. coli, purified to homogeneity and verified with MS. Both cellulose TLC and MALDI-TOFF-MS assays demonstrated that the S. suis BirA protein catalyzed the biotinylation reaction of its acceptor biotin carboxyl carrier protein. EMSA assays confirmed binding of the bioY gene to the S. suis BirA. The data defined the first example of the bifunctional BirA ligase/repressor in Streptococcus. PMID:27217336

  1. A small-molecule-linked DNA-graphene oxide-based fluorescence-sensing system for detection of biotin.

    PubMed

    Zhang, Hao; Li, Yan; Su, Xingguang

    2013-11-15

    In this paper, we establish a novel fluorescence-sensing system for the detection of biotin based on the interaction between DNA and graphene oxide and on protection of the terminal of the biotinylated single-stranded DNA fluorescent probe by streptavidin. In this system, streptavidin binds to the biotinylated DNA, which protects the DNA from hydrolysis by exonuclease I. The streptavidin-DNA conjugate is then adsorbed to the graphene oxide resulting in the fluorescence being quenched. Upon the addition of free biotin, it competes with the labeled biotin for the binding sites of streptavidin and then the exonuclease I digests the unbound DNA probe from the 3' to the 5' terminal, releasing the fluorophore from the DNA. Because of the weak affinity between the fluorophore and graphene oxide, the fluorescence is recovered. Under optimal conditions, the fluorescence intensity is proportional to the concentration of biotin in the concentration range of 0.5-20nmol/L. The detection limit for biotin is 0.44nmol/L. The proposed fluorescence-sensing system was applied to the determination of biotin in some real samples with satisfactory reproducibility and accuracy. This work could provide a common platform for detecting small biomolecules based on protein-small molecule ligand binding.

  2. Effect of dietary palm kernel oil and biotin on the fatty liver and kidney syndrome in broiler chicken.

    PubMed

    Oloyo, R A; Ogunmodede, B K

    1989-01-01

    The effect of feeding biotin and palm kernel oil to broiler chicks on the appearance of Fatty Liver and Kidney Syndrome (FLKS) was investigated. A total of 480 broiler chicks was divided into two equal batches each of which was divided into 6 groups of 40 chicks per group. Each group was further subdivided into equal units of 20 chicks. Six dietary levels of biotin (40, 80, 120, 160, 200, and 240 mcg/kg feed) were given to the first batch of chicks, while the second batch had 2% palm kernel oil added to the six dietarybiotin levels. These two basic rations were supplemented with biotin in order to obtain six levels of the vitamin in the rations. The results showed that the 2% palm kernel oil forage affected FLKS mortality and the minimum biotin requirement. FLKS mortality was significantly reduced in case of palm kernel oil supplement. A lower amount of biotin (120 mcg/kg feed) was needed in case of palm kernel oil supplement-as compared with the necessary biotin (160 mcg/kg feed)-in order to prevent FLKS mortality when palm kernel oil was not contained in the rations. The biochemical analysis of the liver and kidney syndrome-coupled with the correlation and regression analysis of the data collected-showed that a minimum of 120 mcg/kg feed was needed by broiler chicks for the prevention of FLKS.

  3. Structural Characterization of the Mycobacterium tuberculosis Biotin Biosynthesis Enzymes 7,8-Diaminopelargonic Acid Synthase and Dethiobiotin Synthetase†,‡

    PubMed Central

    Dey, Sanghamitra; Lane, James M.; Lee, Richard E.; Rubin, Eric J.; Sacchettini, James C.

    2010-01-01

    Mycobacterium tuberculosis (Mtb) depends on biotin synthesis for survival during infection. In the absence of biotin, disruption of the biotin biosynthesis pathway results in cell death rather than growth arrest, an unusual phenotype for an Mtb auxotroph. Humans lack the enzymes for biotin production, making the proteins of this essential Mtb pathway promising drug targets. To this end, we have determined the crystal structures of the second and third enzymes of the Mtb biotin biosynthetic pathway, 7,8-diaminopelargonic acid synthase (DAPAS) and dethiobiotin synthetase (DTBS), at respective resolutions of 2.2 Å and 1.85 Å. Superimposition of the DAPAS structures bound either to the SAM analog sinefungin or to 7-keto-8-aminopelargonic acid (KAPA) allowed us to map the putative binding site for the substrates and to propose a mechanism by which the enzyme accommodates their disparate structures. Comparison of the DTBS structures bound to the substrate 7,8-diaminopelargonic acid (DAPA) or to ADP and the product dethiobiotin (DTB) permitted derivation of an enzyme mechanism. There are significant differences between the Mtb enzymes and those of other organisms; the Bacillus subtilis DAPAS, presented here at a high resolution of 2.2 Å, has active site variations and the Escherichia coli and Helicobacter pylori DTBS have alterations in their overall folds. We have begun to exploit the unique characteristics of the Mtb structures to design specific inhibitors against the biotin biosynthesis pathway in Mtb. PMID:20565114

  4. Synthesis of a Biotin Derivative of Iberiotoxin: Binding Interactions with Streptavidin and the BK Ca2+-activated K+ Channel Expressed in a Human Cell Line

    PubMed Central

    Bingham, Jon-Paul; Bian, Shumin; Tan, Zhi-Yong; Takacs, Zoltan; Moczydlowski, Edward

    2008-01-01

    Iberiotoxin (IbTx) is a scorpion venom peptide that inhibits BK Ca2+-activated K+ channels with high affinity and specificity. Automated solid phase synthesis was used to prepare a biotin-labeled derivative (IbTx-LC-biotin) of IbTx by substitution of Asp19 of the native 37-residue peptide with N-ε-(d-biotin-6-amidocaproate)-l-lysine. Both IbTx-LC-biotin and its complex with streptavidin (StrAv) block single BK channels from rat skeletal muscle with nanomolar affinity, indicating that the biotin-labeled residue, either alone or in complex with StrAv, does not obstruct the toxin binding interaction with the BK channel. IbTx-LC-biotin exhibits high affinity (KD = 26 nM) and a slow dissociation rate (koff = 5.4 × 10-4 s-1) in a macroscopic blocking assay of whole-cell current of the cloned human BK channel. Titration of IbTx-LC-biotin with StrAv monitored by high performance size exclusion chromatography is consistent with a stoichiometry of two binding sites for IbTx-LC-biotin per StrAv tetramer, indicating that steric interference hinders simultaneous binding of two toxin molecules on each of the two biotin-binding faces of StrAv. In combination with fluorescent conjugates of StrAv or anti-biotin antibody, IbTx-LC-biotin was used to image the surface distribution of BK channels on a transfected cell line. Fluorescence microscopy revealed a patch-like surface distribution of BK channel protein. The results support the feasibility of using IbTx-LC-biotin and similar biotin-tagged K+ channel toxins for diverse applications in cellular neurobiology. PMID:16704206

  5. Brucella BioR regulator defines a complex regulatory mechanism for bacterial biotin metabolism.

    PubMed

    Feng, Youjun; Xu, Jie; Zhang, Huimin; Chen, Zeliang; Srinivas, Swaminath

    2013-08-01

    The enzyme cofactor biotin (vitamin H or B7) is an energetically expensive molecule whose de novo biosynthesis requires 20 ATP equivalents. It seems quite likely that diverse mechanisms have evolved to tightly regulate its biosynthesis. Unlike the model regulator BirA, a bifunctional biotin protein ligase with the capability of repressing the biotin biosynthetic pathway, BioR has been recently reported by us as an alternative machinery and a new type of GntR family transcriptional factor that can repress the expression of the bioBFDAZ operon in the plant pathogen Agrobacterium tumefaciens. However, quite unusually, a closely related human pathogen, Brucella melitensis, has four putative BioR-binding sites (both bioR and bioY possess one site in the promoter region, whereas the bioBFDAZ [bio] operon contains two tandem BioR boxes). This raised the question of whether BioR mediates the complex regulatory network of biotin metabolism. Here, we report that this is the case. The B. melitensis BioR ortholog was overexpressed and purified to homogeneity, and its solution structure was found to be dimeric. Functional complementation in a bioR isogenic mutant of A. tumefaciens elucidated that Brucella BioR is a functional repressor. Electrophoretic mobility shift assays demonstrated that the four predicted BioR sites of Brucella plus the BioR site of A. tumefaciens can all interact with the Brucella BioR protein. In a reporter strain that we developed on the basis of a double mutant of A. tumefaciens (the ΔbioR ΔbioBFDA mutant), the β-galactosidase (β-Gal) activity of three plasmid-borne transcriptional fusions (bioBbme-lacZ, bioYbme-lacZ, and bioRbme-lacZ) was dramatically decreased upon overexpression of Brucella bioR. Real-time quantitative PCR analyses showed that the expression of bioBFDA and bioY is significantly elevated upon removal of bioR from B. melitensis. Together, we conclude that Brucella BioR is not only a negative autoregulator but also a repressor of

  6. Role of HO-1 in protective effect of electro-acupuncture against endotoxin shock-induced acute lung injury in rabbits.

    PubMed

    Yu, Jian-Bo; Jianbo, Yu; Dong, Shu-An; Shuan, Dong; Luo, Xiao-Qing; Xiaoqing, Luo; Gong, Li-Rong; Lirong, Gong; Zhang, Yuan; Yuan, Zhang; Wang, Man; Man, Wang; Cao, Xin-Shun; Xinshun, Cao; Liu, Da-Quan; Daquan, Liu

    2013-06-01

    Heme oxygenase (HO)-1 has been reported to play a great role in attenuating lung injury during endotoxic shock in our previous research. Although electro-acupuncture has been explored to reduce oxidative stress and decrease inflammatory reaction in animals with endotoxic shock, the mechanism of this effect is still unclear. The aim of this study was to determine whether HO-1 is involved in the effect of electro-acupuncture on the injured lung during endotoxic shock in rabbits. Sixty New England white rabbits were randomly divided into groups C, Z, ES, EA, AP, and EAZ. Before inducing endotoxic shock, group ES received no electro-acupuncture, while group EA received electro-acupuncture at ST36 (zusanli) and BL13 (feishu) acupoints on both sides for five days and group AP received electro-acupuncture (EA) stimulation at a non-acupoint. Groups ES, AP, EA, and EAZ received LPS to replicate the experimental model of injured lung induced by endotoxic shock, and electro-acupuncture was performed throughout the procedure with the same parameter. Groups EAZ and Z received the HO-1 inhibitor, ZnPP-IX, intraperitoneally. The animals were sacrificed by blood-letting at 6 h after LPS administration. The blood samples were collected for serum examination, and the lungs were removed for pathology examination, detection of alveolaer epithelial cell apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay (TUNEL assay), determination of wet to dry ratio, measurement of Evans blue (EB) contents, and determination of HO-1protein and mRNA expression. According to the results, EA at ST36 and BL13 could increase the expression of HO-1. At the same time, index of quantitative assessment (IQA) score and the number of TUNEL-positive cells decreased, while electro-acupuncture at the other points did not exert this effect, and pretreatment with ZnPP-IX in group EAZ suppressed the efficacy of electro-acupuncture preconditioning. In summary, electro

  7. EGR-1 regulates Ho-1 expression induced by cigarette smoke

    SciTech Connect

    Chen, Huaqun; Wang, Lijuan; Gong, Tao; Yu, Yang; Zhu, Chunhua; Li, Fen; Wang, Li; Li, Chaojun

    2010-05-28

    As an anti-oxidant molecule, heme oxygenase-1 (HO-1) has been implicated in the protection of lung injury by cigarette smoke (CS). The mechanisms regulating its expression have not been defined. In this report, the role of early growth response 1 (EGR-1) in the regulation of Ho-1 expression was investigated. In C57BL/6 mice with CS exposure, HO-1 was greatly increased in bronchial epithelial cells and alveolar inflammatory cells. In primary cultured mouse lung fibroblasts and RAW264.7 cells exposed to cigarette smoke water extract (CSE), an increase in HO-1 protein level was detected. In addition, CSE induced HO-1 expression was decreased in Egr-1 deficient mouse embryo fibroblasts (Egr-1{sup -/-} MEFs). Nuclear localization of EGR-1 was examined in mouse lung fibroblasts after exposure to CSE. Luciferase reporter activity assays showed that the enhancer region of the Ho-1 gene containing a proposed EGR-1 binding site was responsible for the induction of HO-1. A higher increase of alveolar mean linear intercept (Lm) was observed in lung tissues, and a larger increase in the number of total cells and monocytes/macrophages from bronchial alveolar lavage fluid was found in CS-exposed mice by loss of function of EGR-1 treatment. In summary, the present data demonstrate that EGR-1 plays a critical role in HO-1 production induced by CS.

  8. Monitoring DNA recombination initiated by HO endonuclease.

    PubMed

    Sugawara, Neal; Haber, James E

    2012-01-01

    DNA double-strand breaks (DSBs) have proven to be very potent initiators of recombination in yeast and other organisms. A single, site-specific DSB initiates homologous DNA repair events such as gene conversion, break-induced replication, and single-strand annealing, as well as nonhomologous end joining, microhomology-mediated end joining, and new telomere addition. When repair is either delayed or prevented, a single DSB can trigger checkpoint-mediated cell cycle arrest. In budding yeast, expressing the HO endonuclease under the control of a galactose-inducible promoter has been instrumental in the study of these processes by providing us a way to synchronously induce a DSB at a unique site in vivo. We describe how the HO endonuclease has been used to study the recombination events in mating-type (MAT) switching. Southern blots provide an overview of the process by allowing one to examine the formation of the DSB, DNA degradation at the break, and formation of the product. Denaturing gels and slot blots as well as PCR have provided important tools to follow the progression of resection in wild-type and mutant cells. PCR has also been important in allowing us to follow the kinetics of certain recombination intermediates such as the initiation of repair DNA synthesis or the removal of nonhomologous Y sequences during MAT switching. Finally chromatin immunoprecipitation has been used to follow the recruitment of key proteins to the DSB and in subsequent steps in DSB repair.

  9. Towards Performance Portability with GungHo

    NASA Astrophysics Data System (ADS)

    Ford, Rupert; Glover, Matthew; Ham, David; Hobson, Mike; Maynard, Chris; Mitchell, Lawrence; Mullerworth, Steve; Pickles, Stephen; Rezny, Mike; Riley, Graham; Wood, Nigel; Ashworth, Mike

    2014-05-01

    The Met Office's numerical weather prediction and climate model code, the Unified Model (UM), is almost 25 years old. Up to the present day the UM has been able to be run efficiently on many of the worlds most powerful computers, helping to keep the Met Office at the forefront of climate prediction and weather forecasting. However, with performance increases from each new generation of computers now being primarily provided by an increase in the amount of parallelism rather than an increase in the clock-speed of the processors themselves, running higher resolutions of the UM now faces the double challenge of code scalability and numerical accuracy. The UM's atmospheric dynamical core makes use of a finite-difference scheme on a regular latitude-longitude grid. The regular latitude-longitude mesh results in an increasingly disparate grid resolution as the mesh resolution increases due to lines of longitude converging at the poles. For example, a 10km resolution at mid-latitudes would result in a 12m resolution at the poles. The difference in resolution leads to increased communication at the poles and load balance issues which are known to impair scalability; it also leads to issues with numerical accuracy and smaller time-steps due to the difference in scale. To address this problem the Met Office, NERC and STFC initiated the GungHo project. The primary aim of this project is to deliver a scalable, numerically accurate dynamical core. This dynamical core is scheduled to become operational around the year 2022. The project is currently investigating the use of quasi-uniform meshes, such as triangular, icosahedral and cubed-sphere meshes, using finite element methods. The associated GungHo software infrastructure is being developed to support multiple meshes and element types thus allowing for future model development. GungHo is also proposing a novel separation of concerns for the software implementation of the dynamical core. This approach distinguishes between

  10. Transcarboxylase (TC): demonstration by site-directed mutagenesis that methionines at the biotin site are essential for catalysis

    SciTech Connect

    Wood, H.G.; Shenoy, B.C.; Kumar, G.K.; Paranjape, S.; Murtif, V.; Samols, D.

    1987-05-01

    All biotin enzymes that have thus far been sequenced contain a conserved region ALA MET BCT MET. Two possible roles of the conserved region are (i) for recognition of the specific lysine of the enzyme that is to be biotinated posttranslationally by the synthetase or (ii) for activation of the biotin to function as a carboxyl carrier. The BCT of TC is at residue 89 of the 1.3S subunit. By site-directed mutagenesis, single amino acid substitutions have been made giving LEU 88, THR 88 and LEU 90 and these mutant subunits have been expressed in E. coli and isolated. Catalysis by TC involves Partial Reactions: (1) /sup -/00/sup 14/CCH/sub 2/COCOO/sup -/ + 1.3S biotin pyruvate + 1.3S biotin-COO/sup -/ catalyzed by the 5S subunit (2) /sub 14/CH/sub 3/CH(/sup 14/COO/sup -/)COSCoA + 1.3S biotin CH/sub 3/CH/sub 2/COSCoA + 1.3S biotin-/sup 14/COO/sup -/, catalyzed by the 12S subunit. The mutant subunits LEU 88 and THR 88 are inactive in Reaction 1. In Reaction 2, they are 8% as active as the 1.3S wild type. At 10 times the concentration of the wild type, they are 40% as active. The LEU 90 subunit is about 40% as active as wild type in both Reactions 1 and 2. Thus, the two METS are functionally not equivalent. What their catalytic roles are remains to be determined. Shenoy et al. have shown these modifications do not effect the synthetase reaction.

  11. Biotin deficiency and fatty liver and kidney syndrome in chicks given purified diets containing different fat and protein levels.

    PubMed

    Whitehead, C C; Bannister, D W; Evans, A J; Siller, W G; Wight, P A

    1976-01-01

    1. The occurence of biotin deficiency and fatty liver and kidney syndrome (FLKS) in chicks was studied using a 2x2x2x2 factorial-design experiment in which the variables were dietary biotin, fat and protein, and starvation. 2. The severity of biotin deficiency, using growth retardation and severity of dermal lesions as criteria, was least when the low-biotin diet also contained low levels of fat and protein. Addition of fat or protein increased the severity of the deficiency. Tissue fatty acid composition was affected by biotin deficiency only in those birds given the low-protein, low-fat diet. The main change was an increase in the ratio, 16:1 fatty acids :18:0 fatty acids. Plasma glucose and free fatty acid levels in non-fasted birds were unaffected by the dietary variables. 3. Mortality from FLKS with the diet containing low biotin, fat and protein levels was 52% at 28d, but was reduced or eliminated when the dietary level of any of these ingredients was increased. 4. Starvation considerably increased the incidnece of FLKS in the period immediately after fasting, and also affected plasma glucose and free fatty acid concentrations. Liver fatty acid composition, indicated an increase in the proportion of 18:0 at the expense of 16:1 and concentrations increased in proportion, at the expense of 18:0. 5. The relationship between biotin deficiency and FLKS, and a possible mechanism for the induction of FLKS by starvation are discussed.

  12. Heterogeneous Reaction of HO2 Radical with Dicarboxylic Acid Particles

    NASA Astrophysics Data System (ADS)

    Taketani, F.; Kanaya, Y.

    2010-12-01

    HOx(OH+ HO2) radical plays a central role in the tropospheric chemistry. Recently, the heterogeneous loss of HO2 by aerosol particles is a potentially important HOx sink in the troposphere suggested from observation study. However, there have been few studies for loss of HO2 by aerosols. In this study, we measured the HO2 uptake coefficients for four dicarboxylic acids (succinic acid, glutaric acid, adipic acid, and pimelic acid) aerosol particles under ambient conditions (760Torr and 296K) using an aerosol flow tube(AFT) coupled with a chemical conversion /laser-induced fluorescence(CC/LIF) technique. The CC/LIF technique enabled experiments to be performed at almost the same HO2 radical concentration as that in the atmosphere(-10^8 molecules/cm^3). In this system, the effect of the self-reaction of HO2 in the gas phase can be neglected. HO2 radicals were injected into the AFT through a vertically movable Pyrex tube. Injector position dependent profiles of LIF intensity were measured as a function of aerosol concentration at 30% and 70% of relative humilities (RH). Determined HO2 uptake coefficients by succinic acid, glutaric acid, adipic acid, and pimelic acid aerosol particles at 30% RH were 0.05 +/- 0.02, 0.07 +/- 0.03, 0.02 +/- 0.01, and 0.06 +/- 0.03, respectively, while the uptake coefficients by those particles at 70% RH were 0.13 +/- 0.05, 0.13 +/- 0.03, 0.06 +/- 0.01, and 0.11 +/- 0.03, respectively. These results suggest that compositions and relative humidity are significant to the HO2 uptake. We will discuss the potential HO2 loss processes.

  13. Heterogeneous Uptake of HO2 Radicals onto Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    George, I. J.; Matthews, P. S.; Brooks, B.; Goddard, A.; Whalley, L. K.; Baeza-Romero, M. T.; Heard, D. E.

    2011-12-01

    The hydroxyl (OH) and hydroperoxyl (HO2) radicals, together known as HOx, play a vital role in atmospheric chemistry by controlling the oxidative capacity of the troposphere. The atmospheric lifetime and concentrations of many trace reactive species, such as volatile organic compounds (VOCs), are determined by HOx radical levels. Therefore, the ability to accurately predict atmospheric HOx concentrations from a detailed knowledge of their sources and sinks is a very useful diagnostic tool to assess our current understanding of atmospheric chemistry. Several recent field studies have observed significantly lower concentrations of HO2 radicals than predicted using box models, where HO2 loss onto aerosols was suggested as a possible missing sink [1, 2]. However, the mechanism on HO2 uptake onto aerosols and its impact on ambient HOx levels are currently not well understood. To improve our understanding of this process, we have conducted laboratory experiments to measure HO2 uptake coefficients onto submicron aerosol particles. The FAGE (Fluorescence Assay by Gas Expansion) technique, a highly sensitive laser induced fluorescence based detection method, was used to monitor HO2 uptake kinetics onto aerosol particles in an aerosol flow tube. The application of the FAGE technique allowed for kinetic experiments to be performed under low HO2 concentrations, i.e. [HO2] < 109 molecules cm-3. HO2 radicals were produced by the photolysis of water vapour in the presence of O2 and aerosol particles were produced either by atomizing dilute salt solutions or by homogeneous nucleation. HO2 uptake coefficients (γ) have been measured for single-component solid and aqueous inorganic salt and organic aerosol particles with a wide range of hygroscopicities. HO2 uptake coefficients on solid particles were below the detection limit (γ < 0.001), whereas on aqueous aerosols uptake coefficients were somewhat larger (γ = 0.001 - 0.008). HO2 uptake coefficients were highest on aerosols

  14. Molecular dynamics investigations of BioH protein substrate specificity for biotin synthesis.

    PubMed

    Xue, Qiao; Cui, Ying-Lu; Zheng, Qing-Chuan; Zhang, Hong-Xing

    2016-05-01

    BioH, an enzyme of biotin synthesis, plays an important role in fatty acid synthesis which assembles the pimelate moiety. Pimeloyl-acyl carrier protein (ACP) methyl ester, which is long known to be a biotin precursor, is the physiological substrate of BioH. Azelayl methyl ester, which has a longer chain than pimeloyl methyl ester, conjugated to ACP is also indeed accepted by BioH with very low rate of hydrolysis. To date, the substrate specificity for BioH and the molecular origin for the experimentally observed rate changes of hydrolysis by the chain elongation have remained elusive. To this end, we have investigated chain elongation effects on the structures by using the fully atomistic molecular dynamics simulations combined with binding free energy calculations. The results indicate that the substrate specificity is determined by BioH together with ACP. The added two methylenes would increase the structural flexibility by protein motions at the interface of ACP and BioH, instead of making steric clashes with the side chains of the BioH hydrophobic cavity. On the other hand, the slower hydrolysis of azelayl substrate is suggested to be associated with the loose of contacts between BioH and ACP, and with the lost electrostatic interactions of two ionic/hydrogen bonding networks at the interface of the two proteins. The present study provides important insights into the structure-function relationships of the complex of BioH with pimeloyl-ACP methyl ester, which could contribute to further understanding about the mechanism of the biotin synthetic pathway, including the catalytic role of BioH.

  15. Electrochemical biotin detection based on magnetic beads and a new magnetic flow cell for screen printed electrode.

    PubMed

    Biscay, Julien; González García, María Begoña; Costa García, Agustín

    2015-01-01

    The use of the first flow-cell for magnetic assays with an integrated magnet is reported here. The flow injection analysis system (FIA) is used for biotin determination. The reaction scheme is based on a one step competitive assay between free biotin and biotin labeled with horseradish peroxidase (B-HRP). The mixture of magnetic beads modified with streptavidin (Strep-MB), biotin and B-HRP is left 15 min under stirring and then a washing step is performed. After that, 100 μL of the mixture is injected and after 30s 100 μL of 3,3',5,5'-Tetramethylbenzidine (TMB) is injected and the FIAgram is recorded applying a potential of -0.2V. The linear range obtained is from 0.01 to 1 nM of biotin and the sensitivity is 758 nA/nM. The modification and cleaning of the electrode are performed in an easy way due to the internal magnet of the flow cell.

  16. Biotin deficiency and the development of the fatty liver and kidney syndrome in chickens: an ultrastructural study.

    PubMed

    Bain, J M

    1977-04-01

    The structure of the tissue from the liver, kidneys, pancreas and adrenal glands of 4-week-old chickens showing symptoms of the fatty liver and kidney syndrome (FLKS) was compared with that of normal tissue and related to the amount of biotin present in the liver tissue. These birds were reared with different levels of dietary biotin and were stressed by removal of food before being killed. Birds with less than 1-5 microgram biotin/g liver were considered to be deficient in biotin. In the stressed birds the severity of FLKS increased with decreasing levels of biotin. No lesions were found in the liver and kidney tissue of the birds with severe FLKS. Large quantities of fat were accumulated in the hepatocytes and intercellular spaces of the liver tissue, but the cell contents were not disorganized. In the kidney, conspicuous fat accumulation occurred in the proximal convoluted tubule cells and some ultrastructural disorganization of the cell contents was evident. No structural changes were found in the tissue of the pancreas or the adrenal glands of chickens suffering from severe FLKS.

  17. Structural analysis, plastid localization, and expression of the biotin carboxylase subunit of acetyl-coenzyme A carboxylase from tobacco.

    PubMed Central

    Shorrosh, B S; Roesler, K R; Shintani, D; van de Loo, F J; Ohlrogge, J B

    1995-01-01

    Acetyl-coenzyme A carboxylase (ACCase, EC 6.4.1.2) catalyzes the synthesis of malonyl-coenzyme A, which is utilized in the plastid for de novo fatty acid synthesis and outside the plastid for a variety of reactions, including the synthesis of very long chain fatty acids and flavonoids. Recent evidence for both multifunctional and multisubunit ACCase isozymes in dicot plants has been obtained. We describe here the isolation of a tobacco (Nicotiana tabacum L. cv bright yellow 2 [NT1]) cDNA clone (E3) that encodes a 58.4-kD protein that shares 80% sequence similarity and 65% identity with the Anabaena biotin carboxylase subunit of ACCase. Similar to other biotin carboxylase subunits of acetyl-CoA carboxylase, the E3-encoded protein contains a putative ATP-binding motif but lacks a biotin-binding site (methionine-lysine-methionine or methionine-lysine-leucine). The deduced protein sequence contains a putative transit peptide whose function was confirmed by its ability to direct in vitro chloroplast uptake. The subcellular localization of this biotin carboxylase has also been confirmed to be plastidial by western blot analysis of pea (Pisum sativum), alfalfa (Medicago sativa L.), and castor (Ricinus communis L.) plastid preparations. Northern blot analysis indicates that the plastid biotin carboxylase transcripts are expressed at severalfold higher levels in castor seeds than in leaves. PMID:7610168

  18. Two-dimensional gel electrophoretic detection of protein carbonyls derivatized with biotin-hydrazide.

    PubMed

    Wu, Jinzi; Luo, Xiaoting; Jing, Siqun; Yan, Liang-Jun

    2016-04-15

    Protein carbonyls are protein oxidation products that are often used to measure the magnitude of protein oxidative damage induced by reactive oxygen or reactive nitrogen species. Protein carbonyls have been found to be elevated during aging and in age-related diseases such as stroke, diabetes, and neurodegenerative diseases. In the present article, we provide detailed protocols for detection of mitochondrial protein carbonyls labeled with biotin-hydrazide followed by 2-dimensional isoelectric focusing (IEF)/SDS-PAGE and Western blotting probed with horse-radish peroxidase-conjugated streptavidin. The presented procedures can also be modified for detection of carbonylation of non-mitochondrial proteins.

  19. Chiral one- and two-dimensional silver(I)-biotin coordination polymers.

    PubMed

    Altaf, Muhammad; Stoeckli-Evans, Helen

    2013-02-01

    Reaction of biotin {C(10)H(16)N(2)O(3)S, HL; systematic name: 5-[(3aS,4S,6aR)-2-oxohexahydro-1H-thieno[3,4-d]imidazol-4-yl]pentanoic acid} with silver acetate and a few drops of aqueous ammonia leads to the deprotonation of the carboxylic acid group and the formation of a neutral chiral two-dimensional polymer network, poly[[{μ(3)-5-[(3aS,4S,6aR)-2-oxohexahydro-1H-thieno[3,4-d]imidazol-4-yl]pentanoato}silver(I)] trihydrate], {[Ag(C(10)H(15)N(2)O(3)S)]·3H(2)O}(n) or {[Ag(L)]·3H(2)O}(n), (I). Here, the Ag(I) cations are pentacoordinate, coordinated by four biotin anions via two S atoms and a ureido O atom, and by two carboxylate O atoms of the same molecule. The reaction of biotin with silver salts of potentially coordinating anions, viz. nitrate and perchlorate, leads to the formation of the chiral one-dimensional coordination polymers catena-poly[[bis[nitratosilver(I)]-bis{μ(3)-5-[(3aS,4S,6aR)-2-oxohexahydro-1H-thieno[3,4-d]imidazol-4-yl]pentanoato}] monohydrate], {[Ag(2)(NO(3))(2)(C(10)H(16)N(2)O(3)S)(2)]·H(2)O}(n) or {[Ag(2)(NO(3))(2)(HL)(2)]·H(2)O}(n), (II), and catena-poly[bis[perchloratosilver(I)]-bis{μ(3)-5-[(3aS,4S,6aR)-2-oxohexahydro-1H-thieno[3,4-d]imidazol-4-yl]pentanoato}], [Ag(2)(ClO(4))(2)(C(10)H(16)N(2)O(3)S)(2)](n) or [Ag(2)(ClO(4))(2)(HL)(2)](n), (III), respectively. In (II), the Ag(I) cations are again pentacoordinated by three biotin molecules via two S atoms and a ureido O atom, and by two O atoms of a nitrate anion. In (I), (II) and (III), the Ag(I) cations are bridged by an S atom and are coordinated by the ureido O atom and the O atoms of the anions. The reaction of biotin with silver salts of noncoordinating anions, viz. hexafluoridophosphate (PF(6)(-)) and hexafluoridoantimonate (SbF(6)(-)), gave the chiral double-stranded helical structures catena-poly[[silver(I)-bis{μ(2)-5-[(3aS,4S,6aR)-2-oxohexahydro-1H-thieno[3,4-d]imidazol-4-yl]pentanoato}] hexafluoridophosphate], {[Ag(C(10)H(16)N(2)O(3)S)(2)](PF(6))}(n) or {[Ag(HL)(2)](PF(6

  20. Optical Characterization of the Ho^3+ Complex in HEMA

    NASA Astrophysics Data System (ADS)

    Rodriguez, Manuel, III; Sardar, Dhiraj; Nash, Kelly; Yow, Raylon; Gruber, John

    2007-10-01

    The spectroscopic properties of the Ho^3+ complex embedded in 2-hydroxyethyl methacrylate (HEMA) are investigated. The intensities of the room temperature absorption spectra of the Ho^3+(4f^10) transitions in Ho(NO3)3.5H2O:HEMA have been analyzed using the Judd-Ofelt (J-O) model to obtain the phenomenological intensity parameters, φ2, φ4, and φ6. These parameters are used to calculate the spontaneous emission probabilities, radiative lifetimes, and branching ratios of the Ho^3+ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds of ^2S+1LJ Ho^3+(4f^10), which include ^5G4+^3K7^(2), ^5G5, ^5G6+^5F1, ^5F2+^3K8^(2), ^5F3, ^5F4+^5S2, and ^5F5. The predicted room temperature fluorescence lifetime of ^5I7 to ^5I8 is about 0.5 ms, suggesting a reasonably strong interaction between the complex and the polymer. A comparative study of Ho^3+(4f^10) ions in different host materials suggests that Ho(NO3)3.5H2O:HEMA could be an excellent candidate for certain applications such as narrow band pass filters, especially in the visible-to-near infrared region of the spectrum.

  1. HoBi-like viruses: an emerging group of pestiviruses.

    PubMed

    Bauermann, Fernando V; Ridpath, Julia F; Weiblen, Rudi; Flores, Eduardo F

    2013-01-01

    The genus Pestivirus is composed of 4 important pathogens of livestock: Bovine viral diarrhea virus 1 and 2 (BVDV-1 and BVDV-2), Classical swine fever virus (CSFV), and Border disease virus of sheep (BDV). BVDV are major pathogens of cattle, and infection results in significant economic loss worldwide. A new putative pestivirus species, tentatively called "HoBi-like," "BVDV-3," or "atypical pestiviruses," was first identified in Europe in fetal bovine serum (FBS) imported from Brazil. HoBi-like viruses are related to BVDV at the genetic and antigenic levels. Further, the disease caused by these new viruses resembles clinical presentations historically associated with BVDV infection, including growth retardation, reduced milk production, respiratory disease, reduced reproductive performance, and increased mortality among young stock. Current BVDV diagnostic tests may fail to detect HoBi-like viruses or to differentiate between BVDV and HoBi-like viruses. Further, commercial tests for BVDV exposure, based on serological response, do not reliably detect HoBi-like virus exposure, and cross protection against HoBi-like viruses conferred by current BVDV vaccines is likely limited. As many HoBi-like viruses, characterized to date, were isolated from FBS originating from Brazil, it is assumed that the agent is probably widespread in Brazilian herds. Nevertheless, reports of natural infection in Southeast Asia and Europe demonstrate that these viruses are not restricted to South America. Increased demand for FBS has led to widespread distribution of FBS originating in HoBi-like virus endemic regions. The contamination of such FBS with HoBi-like viruses may lead to spread of this virus to other regions.

  2. Review of Tm and Ho Materials; Spectroscopy and Lasers

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.

    2008-01-01

    A review of Tm and Ho materials is presented, covering some fundamental aspects on the spectroscopy and laser dynamics in both single and co-doped systems. Following an introduction to 2- m lasers, applications and historical development, the physics of quasi-four level lasers, energy transfer and modeling are discussed in some detail. Recent developments in using Tm lasers to pump Ho lasers are discussed, and seen to offer some advantages over conventional Tm:Ho lasers. This article is not intended as a complete review, but as a primer for introducing concepts and a resource for further study.

  3. Effects of defaunation on fermentation characteristics and biotin balance in an artificial rumen-simulation system (RUSITEC) receiving diets with different amounts and types of cereal.

    PubMed

    Abel, H; Schröder, B; Lebzien, P; Flachowsky, G

    2006-01-01

    Biotin is required by rumen microbes for efficient fermentation. To evaluate the role of protozoa in ruminal biotin metabolism, five diets composed of grass hay or of grass hay/cereal grain mixtures were supplied to faunated or defaunated RUSITEC fermenters. In the mixed diets, hay was replaced to 33:67 or 67:33 w/w on an air-dried basis by either wheat or maize grain in order to simulate different cellulolytic and amylolytic fermentation conditions. Defaunation increased SCFA production, whereas NH4 concentration and the release of CH4 were reduced. Biotin input declined when cereal grain was used to replace the hay. With the exception of the high-wheat treatment, defaunated fermenters yielded higher biotin outputs than faunated fermenters. The biotin balance, calculated as the difference between the total biotin output (biotin in the solid residue contained in the nylon bags after fermentation plus the biotin in the effluent) and the biotin input with the feed, was negative for all the dietary treatments apart from fermenters supplied with the high-maize diet. It was less negative or, in the case of the high-maize diets, more positive for defaunated compared with faunated fermenters. It was concluded that, under normal faunated conditions, protozoa directly utilise or indirectly affect the bacterial synthesis and/or utilisation of biotin. With diets of a high fermentation potential, as realised with the high-wheat diet, protozoa prevent the development of a bacterial population that would utilise high or synthesise low amounts of biotin.

  4. Studies on the biotin flow at the duodenum of dairy cows fed diets with different concentrate levels and types of forages.

    PubMed

    Lebzien, Peter; Abel, Hansjörg; Schröder, Benjamin; Flachowsky, Gerhard

    2006-02-01

    Biotin is involved in many vital metabolic pathways and must be provided for an efficient fermentation in the rumen, as well as for the intermediary metabolism of the host animal. Factors influencing ruminal biotin metabolism and output are widely unknown at present. Therefore, dairy cows fitted with permanent cannulas in the dorsal rumen and in the proximal duodenum were fed differently composed diets, and the biotin flow at the proximal duodenum was measured. The diets (on DM basis) consisted of 8.9 kg grass hay (Diet 1), 8.9 kg corn silage plus 2.0 kg concentrate (Diet 2), or 7.3 and 7.4 kg grass silage plus 10.0kg concentrate (Diets 3 and 4). The concentrate in Diets 3 and 4 contained 87% wheat and corn grain, respectively. The cows were pre-fed the rations for 21 days. Thereafter duodenal digesta was sampled every two h for 5 days. Cr2O3 served as a flow marker and the microbial proportion of total nitrogen at the duodenum was estimated by near infrared spectroscopy (NIRS). The duodenal flow of biotin was not related to biotin intake, but to the amount of fermented organic matter (FOM) and the amount of microbial protein (Biotin [mg/d] = 0.518 kg FOM - 0.300; r=0.85 and biotin [mg/d] = 0.012 x g microbial protein + 1.478; r = 0.84), irrespective of the composition of the diet fed. Mean daily biotin flow was 0.48 +/- 0.11 mg/kg FOM without any systematic effect of diet composition. The ruminal biotin balance, calculated as the difference between biotin flow at the duodenum and biotin intake, was positive (1.4 - 2.0 mg/d) in cows fed the mixed roughage/concentrate diets and negative (-0.71 mg/d) when the pure hay diet was fed.

  5. Enhanced hypoglycemic effect of biotin-modified liposomes loading insulin: effect of formulation variables, intracellular trafficking, and cytotoxicity

    NASA Astrophysics Data System (ADS)

    Zhang, Xingwang; Qi, Jianping; Lu, Yi; Hu, Xiongwei; He, Wei; Wu, Wei

    2014-04-01

    Peroral protein/peptide delivery has been one of the most challenging, but encouraging topics in pharmaceutics. This article was intended to explore the potential of biotin-modified liposomes (BLPs) as oral insulin delivery carriers. By incorporating biotin-DSPE into the lipid bilayer, we prepared BLPs using reverse evaporation/sonication method. We investigated hypoglycemic effects in normal rats after oral administration of BLPs, and the possible absorption mechanism by a series of in vitro tests. The relative pharmacological bioavailability of BLPs was up to 11.04% that was as much as 5.28 folds of conventional liposomes (CLPs). The results showed that the enhanced oral absorption of insulin mainly attributed to biotin ligand-mediated endocytosis. The results provided proof of BLPs as effective carriers for oral insulin delivery.

  6. A promiscuous biotin ligase fusion protein identifies proximal and interacting proteins in mammalian cells

    PubMed Central

    Kim, Dae In; Raida, Manfred; Burke, Brian

    2012-01-01

    We have developed a new technique for proximity-dependent labeling of proteins in eukaryotic cells. Named BioID for proximity-dependent biotin identification, this approach is based on fusion of a promiscuous Escherichia coli biotin protein ligase to a targeting protein. BioID features proximity-dependent biotinylation of proteins that are near-neighbors of the fusion protein. Biotinylated proteins may be isolated by affinity capture and identified by mass spectrometry. We apply BioID to lamin-A (LaA), a well-characterized intermediate filament protein that is a constituent of the nuclear lamina, an important structural element of the nuclear envelope (NE). We identify multiple proteins that associate with and/or are proximate to LaA in vivo. The most abundant of these include known interactors of LaA that are localized to the NE, as well as a new NE-associated protein named SLAP75. Our results suggest BioID is a useful and generally applicable method to screen for both interacting and neighboring proteins in their native cellular environment. PMID:22412018

  7. Biotin-functionalized semiconducting polymer in an organic field effect transistor and application as a biosensor.

    PubMed

    Kim, Zin-Sig; Lim, Sang Chul; Kim, Seong Hyun; Yang, Yong Suk; Hwang, Do-Hoon

    2012-01-01

    This report presents biotin-functionalized semiconducting polymers that are based on fluorene and bithiophene co-polymers (F8T2). Also presented is the application of these polymers to an organic thin film transistor used as a biosensor. The side chains of fluorene were partially biotinylated after the esterification of the biotin with corresponding alcohol-groups at the side chain in F8T2. Their properties as an organic semiconductor were tested using an organic thin film transistor (OTFT) and were found to show typical p-type semiconductor curves. The functionality of this biosensor in the sensing of biologically active molecules such as avidin in comparison with bovine serum albumin (BSA) was established through a selective decrease in the conductivity of the transistor, as measured with a device that was developed by the authors. Changes to the optical properties of this polymer were also measured through the change in the color of the UV-fluorescence before and after a reaction with avidin or BSA.

  8. Manual immunohistochemistry staining of mouse tissues using the avidin-biotin complex (ABC) technique.

    PubMed

    Cardiff, Robert D; Miller, Claramae H; Munn, Robert J

    2014-06-02

    There are many variations on the immunohistochemistry (IHC) procedure, but all are based on attachment of a primary antibody to a unique epitope on or within the cell. This step is followed by incubation of the cell/primary antibody complex with another, secondary antibody that recognizes the species in which the primary antibody was produced. The secondary antibody has an indicator molecule attached to it. The indicator produces a colored reaction product at the site of original epitope, allowing visualization. This basic two-antibody "sandwich" procedure has many modifications that include other layers of antibodies and numerous indicators, but all variations depend upon the unique ability of antibodies to recognize specific epitopes or antigenic determinants. The procedure described here is called the ABC (avidin-biotin complex) technique. The method utilizes the high avidity of biotin for avidin, which allows formation of a strong bond. The reagents described in this technique produce a gold/brown reaction product that identifies the epitope of interest.

  9. Discovery of Antibacterial Biotin Carboxylase Inhibitors by Virtual Screening and Fragment-Based Approaches

    SciTech Connect

    Mochalkin, Igor; Miller, J. Richard; Narasimhan, Lakshmi; Thanabal, Venkataraman; Erdman, Paul; Cox, Philip B.; Prasad, J.V.N. Vara; Lightle, Sandra; Huband, Michael D.; Stover, C. Kendall; Pfizer

    2009-07-24

    As part of our effort to inhibit bacterial fatty acid biosynthesis through the recently validated target biotin carboxylase, we employed a unique combination of two emergent lead discovery strategies. We used both de novo fragment-based drug discovery and virtual screening, which employs 3D shape and electrostatic property similarity searching. We screened a collection of unbiased low-molecular-weight molecules and identified a structurally diverse collection of weak-binding but ligand-efficient fragments as potential building blocks for biotin carboxylase ATP-competitive inhibitors. Through iterative cycles of structure-based drug design relying on successive fragment costructures, we improved the potency of the initial hits by up to 3000-fold while maintaining their ligand-efficiency and desirable physicochemical properties. In one example, hit-expansion efforts resulted in a series of amino-oxazoles with antibacterial activity. These results successfully demonstrate that virtual screening approaches can substantially augment fragment-based screening approaches to identify novel antibacterial agents.

  10. A Label-Free Biosensing Platform Using a PLL Circuit and Biotin-Streptavidin Binding System.

    PubMed

    Yunseog Hong; Hee-Jo Lee; Sang-Gyu Kim; Byung-Hyun Kim; Gi-Ho Yun; Jong-Gwan Yook

    2015-06-01

    This paper proposes a novel RF biosensor that utilizes a frequency synthesizer associated with a microstrip open-loop resonator for label-free biomolecular detection. The RF biosensor consists mainly of a resonance-assisted transducer and a phase locked loop (PLL) circuit. In this work, the performance of the RF biosensor is validated using the well-known biotin-streptavidin binding system. When biotin is bound to streptavidin, the input impedance of the resonator is varied, resulting in a change in the oscillation frequency. The concentration of the streptavidin is ultimately detected by a voltage signal of the PLL's loop filter with simple measurement equipment. According to the experimental results, the RF biosensor has revealed excellent sensitivity ( ~ 61 kHz/ngml(-1)) and a low detection limit ( ~ 1 ng/ml), as well as a rapid response. These results demonstrate that the RF biosensor can be an effective sensing platform for label-free detection in a biomolecular binding system.

  11. Location of Promoter and Operator Sites in the Biotin Gene Cluster of Escherichia coli

    PubMed Central

    Cleary, Paul P.; Campbell, Allan; Chang, Robin

    1972-01-01

    Biotin independence in E. coli requires five closely linked genes, bioA, bioB, bioF, bioC, and bioD. The residual gene activity of deletion mutants has been studied by complementation and enzyme assays. Deletion of the left end of the bioA gene does not impair expression of the remaining genes, but deletions from the left extending into bioB abolish all gene expression. Nonsense mutations in bioB reduce expression of bioC, bioF, and bioD. Therefore, the four genes, bioB, bioF, bioC, and bioD, are transcribed as a unit from left to right, from a promotor located between bioA and bioB. Expression of the bio genes is repressible by added biotin. Deletions removing the left end of bioA do not affect repressibility of bioD. Therefore the operator, as well as the promoter, lie to the right of bioA. One deletion that removes bioA, bioB, and bioF renders the bioD gene constitutive, presumably by fusion to an unknown operon. Therefore, the operator lies to the left of bioC. PMID:4559599

  12. Enhanced biosensor performance using an avidin-biotin bridge for antibody immobilization

    NASA Astrophysics Data System (ADS)

    Narang, Upvan; Anderson, George P.; King, Keeley D.; Liss, Heidi S.; Ligler, Frances S.

    1997-05-01

    Maintaining antibody function after immobilization is critical to the performance of a biosensor. The conventional methods to immobilize antibodies onto surfaces are via covalent attachment using a crosslinker or by adsorption. Often, these methods of immobilization result in partial denaturation of the antibody and conformational changes leading to a reduced activity of the antibody. In this paper, we report on the immobilization of antibodies onto the surface of an optical fiber through an avidin-biotin bridge for the detection of ricin, ovalbumin, and Bacillus globigii (Bg). The assays are performed in a sandwich format. First, a capture antibody is immobilized, followed by the addition of the analyte. Finally, a fluorophore- labeled antibody is added for the specific detection of the analyte. The evanescent wave-induced fluorescence is coupled back through the same fiber to be detected using a photodiode. In all cases, we observe an improved performance of the biosensor, i.e., lower limit of detection and wide linear dynamic range, for the assays in which the antibody is immobilized via avidin-biotin bridges compared to covalent attachment method.

  13. A hypersensitive biotin-avidin-TRFIA for quantitative detection of ANA-Ig(GAM) and its clinical application.

    PubMed

    Liu, Jie; Ye, Yan; Hu, Zhigang; Zou, Yaohong; Chen, Guoqian; Yu, Lei

    2013-01-01

    We demonstrate herein a novel time-resolved fluoroimmunoassay (TRFIA) with high sensitivity and wide range for quantitative detection of ANA-Ig(GAM) antibodies using a biotin-avidin amplification system. The immunoassay was conducted by following procedures for a typical sandwich immunoreactions with cell nucleus form Hela and the Eu(3+)-labeled biotin combined with biotinylated mouse anti-human Ig(GAM) served as the solid nuclear antigen for ANA and the tracer, respectively. The sensitivity, specificity, and stability of the kit were evaluated and comparison with the classical enzyme-linked immunosorbent assay (ELISA) kit was also made. The average intra-assay and interassay CVs detected by the established ANA-Ig(GAM) biotin-avidin-TRFIA were 4.21% and 6.34%, respectively. The lower detection limit was 2.24 U/mL, and the mean recovery rate was 100.74%. The good measurable range of the established biotin-avidin-TRFIA was within 1.95-64,000 U/mL, while it was only within 32.5-4000 U/mL using an ELISA kit. The values determined by the biotin-avidin-TRFIA and ELISA correlated well (R2 = 0.989). The positive rate of healthy volunteers and patients with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), primary biliary cirrhosis (PBC), Sjögren's syndrome (SS), scleroderma, and mixed connective tissue disease (MCTD) was 0, 100%, 18.5%, 100%, 37.9%, 90.9%, and 92%, respectively. We conclude that the biotin-avidin-TRFIA we developed gives promise for greater sensitivity and accurate detection for ANA-Ig(GAM) in diagnosing and monitoring autoimmune disorders.

  14. Road to Victory: Building the Ho Chi Minh Trail.

    ERIC Educational Resources Information Center

    Kenney, Marianne

    1993-01-01

    Presents a secondary school lesson on the building of the Ho Chi Minh Trail during the Vietnam War. Helps students link history and geographical skills through cooperative group learning. Includes maps, diagrams, and three student readings. (CFR)

  15. Kinetics and mechanism of HO2 and DO2 disproportionations

    NASA Technical Reports Server (NTRS)

    Kircher, C. C.; Sander, S. P.

    1984-01-01

    A flash photolysis/UV abosrption technique was used to study the HO2 + HO2 and DO2 + DO2 reactions in the gas phase. Rate constants were measured at pressures between 100 and 700 torr of Ar and N2, and at temperatures between 230 and 420 K with up to 10 torr of added water vapor. The overall disproportionation rate constants for the reaction is given as the sum of pressure-independent and pressure-dependent terms. A kinetic analysis shows that both reactions have a zero-pressure bimolecular component and a termolecular component which is linearly dependent on pressure up to 700 torr. A priori estimates of the vibrational frequencies of the product of the HO2 + HO2 reaction suggest binding energies of 12-20 kcal per mol (for the initial association).

  16. High-spin yrast structure of {sup 159}Ho

    SciTech Connect

    Ollier, J.; Simpson, J.; Riley, M. A.; Wang, X.; Aguilar, A.; Teal, C.; Paul, E. S.; Nolan, P. J.; Petri, M.; Rigby, S. V.; Thomson, J.; Unsworth, C.; Carpenter, M. P.; Janssens, R. V. F.; Lauritsen, T.; Zhu, S.; Darby, I. G.; Hartley, D. J.; Kondev, F. G.

    2011-08-15

    An investigation of the yrast structure of the odd-Z {sup 159}Ho nucleus to high spin has been performed. The {sup 159}Ho nucleus was populated by the reaction {sup 116}Cd({sup 48}Ca,p4n{gamma}) at a beam energy of 215 MeV, and resulting {gamma} decays were detected by the Gammasphere spectrometer. The h{sub 11/2} yrast band has been significantly extended up to I{sup {pi}=}75/2{sup -} (tentatively 79/2{sup -}). A lower frequency limit for the second (h{sub 11/2}){sup 2} proton alignment was extracted consistent with the systematics of this alignment frequency, indicating an increased deformation with neutron number in the Ho isotopes. The energy-level splitting between the signature partners in the h{sub 11/2} structures of the Ho isotopes and the neighboring N=92 isotones is discussed.

  17. HoCaMA: Home Care Hybrid Multiagent Architecture

    NASA Astrophysics Data System (ADS)

    Fraile, Juan A.; Bajo, Javier; Abraham, Ajith; Corchado, Juan M.

    Home Care is one of the main objectives of Ambient Intelligence. Nowadays, the disabled and elderly population, which represents a significant part of our society, requires novel solutions for providing home care in an effective way. In this chapter, we present HoCaMA, a hybrid multiagent architecture that facilitates remote monitoring and care services for disabled patients at their homes. HoCaMA combines multiagent systems and Web services to facilitate the communication and integration with multiple health care systems. In addition, HoCaMA focuses on the design of reactive agents capable of interacting with different sensors present in the environment, and incorporates a system of alerts through SMS and MMS mobile technologies. Finally, it uses Radio Frequency IDentification and JavaCard technologies to provide advanced location and identification systems, as well as automatic access control facilities. HoCaMA has been implemented in a real environment and the results obtained are presented within this chapter.

  18. Biotin/Folate-decorated Human Serum Albumin Nanoparticles of Docetaxel: Comparison of Chemically Conjugated Nanostructures and Physically Loaded Nanoparticles for Targeting of Breast Cancer.

    PubMed

    Nateghian, Navid; Goodarzi, Navid; Amini, Mohsen; Atyabi, Fatemeh; Khorramizadeh, Mohammad Reza; Dinarvand, Rassoul

    2016-01-01

    Docetaxel (DTX) is a widely used chemotherapeutic agent with very low water solubility. Conjugation of DTX to human serum albumin (HSA) is an effective way to increase its water solubility. Attachment of folic acid (FA) or biotin as targeting moieties to DTX-HSA conjugates may lead to active targeting and specific uptake by cancer cells with overexpressed FA or biotin receptors. In this study, FA or biotin molecules were attached to DTX-HSA conjugates by two different methods. In one method, FA or biotin molecules were attached to remaining NH2 residues of HSA in DTX-HSA conjugate by covalent bonds. In the second method, HSA-FA or HSA-biotin conjugates were synthesized separately and then combined by DTX-HSA conjugate in proper ratio to prepare nanoparticles containing DTX-HSA plus HSA-FA or HSA-biotin. Cell viability of different nanoparticle was evaluated on MDA-MB-231 (folate receptor positive), A549 (folate receptor negative), and 4T1 (biotin receptor positive) and showed superior cytotoxicity compared with free docetaxel (Taxotere). In vivo studies of DTX-HSA-FA and DTX-HSA-biotin conjugates in BULB/c mice, tumorized by 4T1 cell line, showed the conjugates prepared in this study were more powerful in the reduction in tumor size and increasing the survival rate when compared to free docetaxel.

  19. Genes encoding biotin carboxylase subunit of acetyl-CoA carboxylase from Brassica napus and parental species: cloning, expression patterns, and evolution

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Comparative genomics is a useful tool to investigate gene and genome evolution. Biotin carboxylase (BC), an important subunit of heteromeric ACCase that is a rate-limiting enzyme in fatty acid biosynthesis in dicots, catalyzes ATP, biotin-carboxyl-carrier protein and CO2 to form carboxybiotin-carbo...

  20. Uptake of HO2 Radicals Onto Dust Aerosols

    NASA Astrophysics Data System (ADS)

    Matthews, P. S.; Whalley, L. K.; Baeza-Romero, M. T.; Heard, D. E.

    2013-12-01

    OH and HO2 radicals play an important role in the troposphere by controlling its oxidative capacity and therefore the concentration of many trace species. Several field studies have observed significantly lower concentrations of HO2 radicals than predicted using box models (1,2). HO2 loss onto aerosols has been suggested as a possible sink. Mineral dust has an estimated annual flux of 2000 Tg year-1 (3). However, there has only been one study of HO2 uptake onto Arizona Test Dust (ATD) surfaces (4) and there are currently no published studies for dust aerosols. Therefore, the aim of this study was to measure the HO2 uptake coefficient onto ATD aerosols over a range of humidities and for different HO2 concentrations, as well as investigating the uptake as a function of the exposure time to the aerosol, for which a dependence had been observed for aqueous salt aerosols (5). Uptake coefficients were measured for ATD aerosols at atmospheric pressure and at 291 K using a Fluorescence Assay by Gas Expansion (FAGE) detector combined with a flow tube. HO2 was formed from the photolysis of water vapour and was injected into the flow tube using a moveable injector, which was placed in six different positions along the flow tube. The non stable aerosol output was produced by stirring ATD in a bottle producing a dust cloud which was entrained into a flow. The aerosol number concentration was measured using a Condensation Particle Counter (CPC) and was converted into a surface area using the average radius of one aerosol. The uptake coefficient was then able to be calculated by assuming first order kinetics. The HO2 uptake coefficient was measured at a relative humidity of between 6 and 75% and at initial HO2 concentrations of ~ 0.3 - 1 × 10^9 molecule cm-3. Average uptake coefficients of 0.018 × 0.006 and 0.031 × 0.008 were measured for the higher and lower HO2 concentrations respectively, and the impact investigated using a constrained box model. A time dependence was also

  1. The role of equilibrium and kinetic properties in the dissociation of Gd[DTPA-bis(methylamide)] (Omniscan) at near to physiological conditions.

    PubMed

    Baranyai, Zsolt; Brücher, Ernő; Uggeri, Fulvio; Maiocchi, Alessandro; Tóth, Imre; Andrási, Melinda; Gáspár, Attila; Zékány, László; Aime, Silvio

    2015-03-16

    [Gd(DTPA-BMA)] is the principal constituent of Omniscan, a magnetic resonance imaging (MRI) contrast agent. In body fluids, endogenous ions (Zn(2+), Cu(2+), and Ca(2+)) may displace the Gd(3+). To assess the extent of displacement at equilibrium, the stability constants of DTPA-BMA(3-) complexes of Gd(3+), Ca(2+), Zn(2+), and Cu(2+) have been determined at 37 °C in 0.15 M NaCl. The order of these stability constants is as follows: GdL≈CuL>ZnL≫CaL. Applying a simplified blood plasma model, the extent of dissociation of Omniscan (0.35 mM [Gd(DTPA-BMA)]) was found to be 17% by the formation of Gd(PO4), [Zn(DTPA-BMA)](-) (2.4%), [Cu(DTPA-BMA)](-) (0.2%), and [Ca(DTPA-BMA)](-) (17.7%). By capillary electrophoresis, the formation of [Ca(DTPA-BMA)](-) has been detected in human serum spiked with [Gd(DTPA-BMA)] (2.0 mM) at pH 7.4. Transmetallation reactions between [Gd(DTPA-BMA)] and Cu(2+) at 37 °C in the presence of citrate, phosphate, and bicarbonate ions occur by dissociation of the complex assisted by the endogenous ligands. At physiological concentrations of citrate, phosphate, and bicarbonate ions, the half-life of dissociation of [Gd(DTPA-BMA)] was calculated to be 9.3 h at pH 7.4. Considering the rates of distribution and dissociation of [Gd(DTPA-BMA)] in the extracellular space of the body, an open two-compartment model has been developed, which allows prediction of the extent of dissociation of the Gd(III) complex in body fluids depending on the rate of elimination of the contrast agent.

  2. Registration of 'HoCP 91-552' sugarcane

    Technology Transfer Automated Retrieval System (TEKTRAN)

    HoCP 91-552’ sugarcane was selected from progeny of the cross ‘LCP 81-10’ x ‘CP 72-356’ made at Canal Point, Florida. HoCP 91-552 was developed through cooperative research by the Agricultural Research Service of the United States Department of Agriculture’s Sugarcane Research Unit, the Louisiana A...

  3. Flashlamp-pumped Ho:Tm:Cr:LuAG laser

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G. (Inventor); Barnes, Norman P. (Inventor); Murray, Keith E. (Inventor); Kokta, Milan R. (Inventor)

    1997-01-01

    A room temperature solid-state laser is provided. A laser crystal is disposed in a laser cavity. The laser crystal has a LuAG host material doped with a concentration of about 0.35% Ho ions, about 5.57% Tm ions and at least about 1.01% Cr ions. A broadband energizing source such as a flashlamp is disposed transversely to the laser crystal to energize the Ho ions, Tm ions and Cr ions.

  4. Line Identification of Atomic and Ionic Spectra of Holmium in the Near-UV. II. Spectra of Ho II and Ho III

    NASA Astrophysics Data System (ADS)

    Başar, Gö.; Al-Labady, N.; Özdalgiç, B.; Güzelçimen, F.; Er, A.; Öztürk, I. K.; Ak, T.; Bİlİr, S.; Tamanis, M.; Ferber, R.; Kröger, S.

    2017-02-01

    Fourier Transform spectra of holmium (Ho) in the UV spectral range from 31,530 to 25,000 cm‑1 (317 to 400 nm) have been investigated, particularly focusing on the ionic lines. The distinction between the different degrees of ionization (I, II, and III) is based on differences in signal-to-noise ratios from two Ho spectra, which have been measured with different buffer gases, i.e., neon and argon. Based on 106 known Ho ii and 126 known Ho iii energy levels, 97 lines could be classified as transitions of singly ionized Ho and 9 lines could be classified as transitions of doubly ionized Ho. Of the 97 Ho ii lines, 6 have not been listed in the extant literature. Another 215 lines have been assigned to Ho ii, though they could not be classified on the basis of the known energy levels.

  5. The role of neutrophils in corneal wound healing in HO-2 null mice.

    PubMed

    Marrazzo, Giuseppina; Bellner, Lars; Halilovic, Adna; Li Volti, Giovanni; Drago, Filippo; Dunn, Michael W; Schwartzman, Michal Laniado

    2011-01-01

    Our studies demonstrated that Heme oxygenase (HO), in particular, the constitutive HO-2, is critical for a self-resolving inflammatory and repair response in the cornea. Epithelial injury in HO-2 null mice leads to impaired wound closure and chronic inflammation in the cornea. This study was undertaken to examine the possible relationship between HO-2 and the recruitment of neutrophils following a corneal surface injury in wild type (WT) and HO-2 knockout (HO-2(-/-)) mice treated with Gr-1 monoclonal antibody to deplete peripheral neutrophils. Epithelial injury was performed by removing the entire corneal epithelium. Infiltration of inflammatory cell into the cornea in response to injury was higher in HO-2(-/-) than in WT. However, the rate of corneal wound closure following neutrophil depletion was markedly inhibited in both WT and HO-2(-/-) mice by 60% and 85%, respectively. Neutropenia induced HO-1 expression in WT but not in HO-2(-/-) mice. Moreover, endothelial cells lacking HO-2 expressed higher levels of the Midkine and VE-cadherin and displayed strong adhesion to neutrophils suggesting that perturbation in endothelial cell function caused by HO-2 depletion underlies the increased infiltration of neutrophils into the HO-2(-/-) cornea. Moreover, the fact that neutropenia worsened epithelial healing of the injured cornea in both WT and HO-2(-/-) mice suggest that cells other than neutrophils contribute to the exaggerated inflammation and impaired wound healing seen in the HO-2 null cornea.

  6. Effect of biotin and pantothenic acid on performance and concentrations of avidin-binding substances in blood and milk of lactating dairy cows.

    PubMed

    Ferreira, Gonzalo; Brown, Alston N; Teets, Christy L

    2015-09-01

    We hypothesized that pantothenic acid reduces the absorption of biotin in lactating dairy cows. Therefore, the objective of this study was to evaluate the plausible interaction between biotin and pantothenic acid on production performance and concentration of avidin-binding substances (ABS), an indicator of biotin concentration, in blood and milk of lactating dairy cows. Eight primiparous and 16 multiparous Holstein cows were assigned to 1 of 4 diet sequences in a replicated 4×4 Latin square design with 18-d periods. Cows were housed in a freestall barn and fed once daily (0730 h) by means of a Calan gate system (American Calan Inc., Northwood, NH). Treatments consisted of a control diet that contained no B-vitamins, a biotin diet that contained 0.87 mg of biotin per kilogram of dry matter (DM), a pantothenic acid diet that contained 21 mg of pantothenic acid per kilogram of DM, and a biotin plus pantothenic acid diet that contained 0.87 mg of biotin and 21 mg of calcium pantothenic acid per kilogram of DM. Four different concentrates were prepared in a commercial feed mill. These concentrates were mixed with corn silage and grass hay and delivered ad libitum as a total mixed ration. Biotin supplementation did not affect DM intake, milk yield, or milk fat, protein, lactose, and milk-urea-nitrogen concentrations. Fat, protein, and lactose yields were not affected by treatments. The fat-to-protein ratio was <1 and similar among all treatments. Biotin supplementation did not increase the concentration of ABS in plasma. The supplementation of pantothenic acid did not affect the concentration of ABS in plasma when either supplemented alone or in combination with biotin. Biotin supplementation increased the concentration of ABS in milk relative to control. Contrary to our hypothesis, the supplementation of pantothenic acid did not decrease the concentration of ABS in milk relative to the control. When cows were supplemented with both biotin and pantothenic acid, the

  7. The effect of an acute dose of biotin at a post-implantation stage and its relation with female sex steriods in the rat.

    PubMed

    Paul, P K; Duttagupta, P N

    1976-01-01

    An acute dose (10 mg/100 g body weight) of biotin at the post-implantation stage (day 14 and 15) inhibited the fetal and placental growth, and in few rats it also caused resorption of fetuses and placentae. The maintenance of pregnancy with normal fetal and placental growth was effected with estrogen therapy, but progesterone failed to correct the biotin-induced effect. The uterine and placental glycogen, RNA and protein levels, as well as, glucose-6-phosphate dehydrogenase activity in the ovary, liver and uterus showed a reduction following biotin treatment. Estrogen therapy under such conditions corrected these adverse effects of biotin overdose, while progesterone had no significant effects. The study suggests that the acute dose of biotin at an advance stage of pregnancy may cause adverse effects on the physiological regulation of gestation, possibly by creating deficiency of estrogen and gestagen. The possible role of estrogen in the fetal and placental growth and regulation of gestagen secretion is discussed.

  8. Reaction of HO2 with O3 and the effect of water vapor on HO2 kinetics

    NASA Technical Reports Server (NTRS)

    Demore, W. B.

    1979-01-01

    The effects of temperature and water vapor concentration on the ratio of the rate constant of the reaction HO2 + O3 yields OH + 2(O2) to the square root of the rate constant for the reaction HO2 + HO2 yields H2O2 + O2 are determined. Photolysis of H2-O2-O3 mixtures at 253.7 nm was carried out with H2O pressures in the range 0 to 15 torr at a temperature range of -42.5 to 61 C along with 184.9 nm photolysis of H2O-O2-O3 mixtures. It is shown that the rate of O3 photolysis is suppressed by the addition of water vapor and it is suggested that this effect is realized in the HO2 + HO2 yields H2O2 + O2 reaction. The calculated expression for the temperature dependence of the rate constant ratio is found to be in good agreement with that calculated from separate rate constants. Rate constants determined for the reaction OH + HO2 yields H2O + O2 are found to be higher than those previously determined, presumably due to increased pressure, indicating that atmospheric models should take into account the possible pressure dependences of the reactions considered.

  9. Attenuation of hepatotoxicity and oxidative stress in diabetes STZ-induced type 1 by biotin in Swiss albino mice

    PubMed Central

    Aldahmash, Badr Abdullah; El-Nagar, Doaa Mohamed; Ibrahim, Khalid Elfakki

    2015-01-01

    Diabetes mellitus is one of the major health problems. This study was designed to investigate the effect of biotin to regulate blood glucose level, reduced toxicity and oxidative stress in liver of diabetic mice STZ-induced type 1. Male mice were divided into three groups, the first one served as the control group, the second and the third groups received single ip dose of 150 mg/kg of STZ, the second group served as the untreated diabetic group, the third group received daily oral dose of 15 mg/kg of biotin, livers and liver index showed insignificant difference among groups. Blood glucose level showed a significant decrease in treated diabetic mice compared to untreated diabetic mice. Biochemical analysis showed a significant decrease in liver enzymes AST and ALT compared to the control group. Histopathological examination showed severe changes in untreated diabetic liver tissue manifested by dilated portal vein, leukocytic infiltration, fatty degeneration and moderate to severe histopathological score, whereas, treated diabetic mice with biotin showed reduction in hepatotoxicity represented by appearance of relative healthy hepatocytes and normal histopathological score. Immunohistochemistry of acrolein showed intense immunoreactions in liver section of untreated diabetic mice and faint immunoreactions in treated diabetic mice with biotin as evidence to oxidative stress reduction. PMID:26981014

  10. Biotin-conjugated anti-CD44 antibody-avidin binding system for the improvement of chondrocyte adhesion to scaffolds.

    PubMed

    Lin, Hong; Zhou, Jian; Shen, Longxiang; Ruan, Yuhui; Dong, Jian; Guo, Changan; Chen, Zhengrong

    2014-04-01

    The clinical need for improved treatment options for patients with cartilage injuries has motivated tissue-engineering studies aimed at the in vitro generation of cell-based implants with functional properties. The success of tissue-engineered repair of cartilage may depend on the rapid and efficient adhesion of transplanted cells to the scaffold. In the present study, chondrocyte-scaffold constructs were engineered by planting porcine chondrocytes into nonporous chitosan membranes and 3D porous chitosan scaffolds that were treated with or without biotin-conjugated anti-CD44 antibody-avidin binding system and avidin-biotin binding system. The spreading area, cell exfoliation rates, cell proliferation rates, histological analysis, DNA and glycosaminoglycan (GAG) content, and mRNA expression were investigated to evaluate the efficiency of biotin-conjugated anti-CD44 antibody-avidin binding system for the improvement of cell adhesion to scaffolds in the cartilage tissue. The results showed that the biotin-conjugated anti-CD44 antibody-avidin binding system improved cell adhesion to scaffolds effectively. These studies suggest that this binding system has the potential to provide improved tissue-engineered cartilage for clinical applications.

  11. Effect of biotin supplementation on meat quality of F1 Wagyu/Black Angus feedlot steers of known genotype.

    PubMed

    Lawrence, R J; Doyle, J C; Elliott, R; Norton, B W; Loxton, I

    2007-10-01

    Biotin (D-biotin) was supplemented to F1 Wagyu/Black Angus steers fed a wheat-based ration to evaluate the effect on meat quality. One hundred and eight steers of known Wagyu sire lines were assigned to three biotin treatments (0, 10 and 20mg/head/day) with each treatment replicated four times using an unfasted liveweight of 410.5kg (±24.42 SD). Biotin supplementation had no effect (P>0.05) on beef marbling standard at either the 5/6th or 10/11th rib quartering site, 10/11th rib intra-muscular fat percentage, intra-muscular fat fatty acid composition or adipose melting points. Wagyu genotype had an effect (P<0.05) on beef marbling standard and intra-muscular fat percentage at the 10/11th rib, inter-muscular and intra-muscular melting point and fatty acid composition of intra-muscular fat. A significant (P<0.001) but poor correlation existed between beef marbling standard and intra-muscular fat percentage (R(2)=0.198). Total conjugated linoleic acid had a highly significantly (P<0.0001) positive correlation to intra-muscular fat percentage (R(2)=0.446).

  12. Collaborative Student Laboratory Exercise Using FT-IR Spectroscopy for the Kinetics Study of a Biotin Analogue

    ERIC Educational Resources Information Center

    Leong, Jhaque; Ackroyd, Nathan C.; Ho, Karen

    2014-01-01

    The synthesis of N-methoxycarbonyl-2-imidazolidone, an analogue of biotin, was conducted by organic chemistry students and confirmed using FT-IR and H NMR. Spectroscopy students used FT-IR to measure the rate of hydrolysis of the product and determined the rate constant for the reaction using the integrated rate law. From the magnitude of the rate…

  13. Biotin-streptavidin binding interactions of dielectric filled silicon bulk acoustic resonators for smart label-free biochemical sensor applications.

    PubMed

    Heidari, Amir; Yoon, Yong-Jin; Park, Woo-Tae; Su, Pei-Chen; Miao, Jianmin; Lin, Julius Tsai Ming; Park, Mi Kyoung

    2014-03-07

    Sensor performance of a dielectric filled silicon bulk acoustic resonator type label-free biosensor is verified with biotin-streptavidin binding interactions as a model system. The mass sensor is a micromachined silicon square plate with a dielectric filled capacitive excitation mechanism. The resonance frequency of the biotin modified resonator decreased 315 ppm when exposed to streptavidin solution for 15 min with a concentration of 10(-7) M, corresponding to an added mass of 3.43 ng on the resonator surface. An additional control is added by exposing a bovine serum albumin (BSA)-covered device to streptavidin in the absence of the attached biotin. No resonance frequency shift was observed in the control experiment, which confirms the specificity of the detection. The sensor-to-sensor variability is also measured to be 4.3%. Consequently, the developed sensor can be used to observe in biotin-streptavidin interaction without the use of labelling or molecular tags. In addition, biosensor can be used in a variety of different immunoassay tests.

  14. Dual roles of F123 in protein homodimerization and inhibitor binding to biotin protein ligase from Staphylococcus aureus.

    PubMed

    Soares da Costa, Tatiana P; Yap, Min Y; Perugini, Matthew A; Wallace, John C; Abell, Andrew D; Wilce, Matthew C J; Polyak, Steven W; Booker, Grant W

    2014-01-01

    Protein biotinylation is catalysed by biotin protein ligase (BPL). The most characterized BPL is from Escherichia coli where it functions as both a biotin ligase and a homodimeric transcriptional repressor. Here we investigated another bifunctional BPL from the clinically important Staphylococcus aureus (SaBPL). Unliganded SaBPL (apo) exists in a dimer-monomer equilibrium at low micromolar concentrations - a stark contrast to E. coli BPL (EcBPL) that is monomeric under the same conditions. EMSA and SAXS analysis demonstrated that dimeric apo SaBPL adopted a conformation that was competent to bind DNA and necessary for it to function as a transcription factor. The SaBPL dimer-monomer dissociation constant was 5.8-fold tighter when binding the inhibitor biotin acetylene, but unchanged with biotin. F123, located in the dimer interface, was critical for homodimerization. Inhibition studies together with surface plasmon resonance analyses revealed a strong correlation between inhibitor potency and slow dissociation kinetics. A 24-fold difference in Ki values for these two enzymes was explained by differences in enzyme:inhibitor dissociation rates. Substitution of F123 in SaBPL and its equivalent in EcBPL altered both inhibitor potency and dissociation. Hence, F123 in SaBPL has novel roles in both protein dimerization and ligand-binding that have not been reported in EcBPL.

  15. Quantum dot-fluorescence in situ hybridisation for Ectromelia virus detection based on biotin-streptavidin interactions.

    PubMed

    Wang, Ting; Zheng, Zhenhua; Zhang, Xian-En; Wang, Hanzhong

    2016-09-01

    Ectromelia virus (ECTV) is an pathogen that can lead to a lethal, acute toxic disease known as mousepox in mice. Prevention and control of ECTV infection requires the establishment of a rapid and sensitive diagnostic system for detecting the virus. In the present study, we developed a method of quantum-dot-fluorescence based in situ hybridisation for detecting ECTV genome DNA. Using biotin-dUTP to replace dTTP, biotin was incorporated into a DNA probe during polymerase chain reaction. High sensitivity and specificity of ECTV DNA detection were displayed by fluorescent quantum dots based on biotin-streptavidin interactions. ECTV DNA was then detected by streptavidin-conjugated quantum dots that bound the biotin-labelled probe. Results indicated that the established method can visualise ECTV genomic DNA in both infected cells and mouse tissues. To our knowledge, this is the first study reporting quantum-dot-fluorescence based in situ hybridisation for the detection of viral nucleic acids, providing a reference for the identification and detection of other viruses.

  16. Biotin-Streptavidin Binding Interactions of Dielectric Filled Silicon Bulk Acoustic Resonators for Smart Label-Free Biochemical Sensor Applications

    PubMed Central

    Heidari, Amir; Yoon, Yong-Jin; Park, Woo-Tae; Su, Pei-Chen; Miao, Jianmin; Lin, Julius Tsai Ming; Park, Mi Kyoung

    2014-01-01

    Sensor performance of a dielectric filled silicon bulk acoustic resonator type label-free biosensor is verified with biotin-streptavidin binding interactions as a model system. The mass sensor is a micromachined silicon square plate with a dielectric filled capacitive excitation mechanism. The resonance frequency of the biotin modified resonator decreased 315 ppm when exposed to streptavidin solution for 15 min with a concentration of 10−7 M, corresponding to an added mass of 3.43 ng on the resonator surface. An additional control is added by exposing a bovine serum albumin (BSA)-covered device to streptavidin in the absence of the attached biotin. No resonance frequency shift was observed in the control experiment, which confirms the specificity of the detection. The sensor-to-sensor variability is also measured to be 4.3%. Consequently, the developed sensor can be used to observe in biotin-streptavidin interaction without the use of labelling or molecular tags. In addition, biosensor can be used in a variety of different immunoassay tests. PMID:24608003

  17. [A novel and practical synthesis of (+)-biotin via Fukuyama coupling reaction].

    PubMed

    Shimizu, Toshiaki

    2003-02-01

    (+)-Biotin (1) was synthesized from readily accessible L-aspartic acid (4). The contiguous asymmetric centers at C-3a and C-6a were formed through a diastereoselective aldol reaction of N-Cbz-3-amino-4-butanolide 5 to provide trans-disubstituted lactone 6 with high stereoselectivity (trans/cis = 12:1). The imidazolidin-2-one moiety of 1 was constructed by a stereoselective Hofmann rearrangement of beta-substituted asparagine derivative 7 to provide cyclic urea 8. This reaction proceeds with complete retention of stereochemistry. Removal of the protective groups of 8 and subsequent dibenzylation and thionation provided thiolactone 2. The installation of the C-4 side chain of 1 was performed through a Pd/C-catalyzed coupling reaction of 2 with ethoxycarbonylbutylzinc iodide 14a (Fukuyama coupling reaction), which permitted the synthesis of 1 from 2 under industrially applicable mild conditions in three steps.

  18. Astatine-211-labeled biotin conjugates resistant to biotinidase for use in pretargeted radioimmunotherapy.

    PubMed

    Foulon, C F; Alston, K L; Zalutsky, M R

    1998-02-01

    We report herein the preparation and biological evaluation of two radioastatinated biotin conjugates, (3-[211At]astatobenzoyl)norbiotinamide and ((5-[211At]astato-3-pyridinyl)carbonyl)norbiotinamide. Both conjugates were stable in the presence of human serum and cerebrospinal fluid as well as murine serum, indicating a resistance to degradation to biotinidase. The normal tissue clearance of (3-[211At]astatobenzoyl)norbiotinamide and ((5-[211At]astato-3-pyridinyl)carbonyl)norbiotinamide was rapid, as observed previously with their iodo analogues. Also reported are the first syntheses of N-succinimidyl 5-[211At]astato-3-pyridinecarboxylate and 3-[211At]astatoaniline, two reagents of potential utility for labeling proteins and peptides with 211At.

  19. Diagnosis of intestinal acariasis with avidin-biotin system enzyme-linked immunosorbent assay

    PubMed Central

    Zhang, Rong-Bo; Huang, Yong; Li, Chao-Pin; Cui, Yu-Bao

    2004-01-01

    AIM: To explore the value of avidin-biotin system enzyme-linked immunosorbent assay (ABC-ELISA) in diagnosis of intestinal acariasis. METHODS: Mite-specific IgG levels in serum of 48 patients with intestinal acariasis were measured with ABC-ELISA. The sensitivity of this method was compared with that of staphylococcal protein A enzyme-linked immunosorbent assay (SPA-ELISA). RESULTS: The positive rate of mite-specific IgG detected with ABC-ELISA and SPA-ELISA was 89.58% (43/48) and 56.25% (27/48), respectively. The positive rate with ABC-ELISA was statistically higher than that with SPA-ELISA (χ2 = 13.50, P < 0.01). CONCLUSION: ABC-ELISA is an effective method for the diagnosis of intestinal acariasis. PMID:15112362

  20. Is Dimerization Required for the Catalytic Activity of Bacterial Biotin Carboxylase?

    SciTech Connect

    Shen,Y.; Chou, C.; Chang, G.; Tong, L.

    2006-01-01

    Acetyl-coenzyme A carboxylases (ACCs) have crucial roles in fatty acid metabolism. The biotin carboxylase (BC) subunit of Escherichia coli ACC is believed to be active only as a dimer, although the crystal structure shows that the active site of each monomer is 25 Angstroms from the dimer interface. We report here biochemical, biophysical, and structural characterizations of BC carrying single-site mutations in the dimer interface. Our studies demonstrate that two of the mutants, R19E and E23R, are monomeric in solution but have only a 3-fold loss in catalytic activity. The crystal structures of the E23R and F363A mutants show that they can still form the correct dimer at high concentrations. Our data suggest that dimerization is not an absolute requirement for the catalytic activity of the E. coli BC subunit, and we propose a new model for the molecular mechanism of action for BC in multisubunit and multidomain ACCs.

  1. A continuous fluorescence displacement assay for BioA: An enzyme involved in biotin biosynthesis

    PubMed Central

    Wilson, Daniel J.; Shi, Ce; Duckworth, Benjamin P.; Muretta, Joseph M.; Manjunatha, Ujjini; Sham, Yuk Y.; Thomas, David D.; Aldrich, Courtney C.

    2011-01-01

    Cofactor biosynthetic pathways represent a rich source of potential antibiotic targets. The second step in biotin biosynthesis is performed by BioA, a pyridoxal 5′-phosphate (PLP) dependent enzyme. This enzyme has been confirmed as a candidate target in Mycobacterium tuberculosis; however, the current bioassay used to measure BioA activity is cumbersome and low-throughput. Here we describe the design, development and optimization of a continuous coupled fluorescence displacement assay to measure BioA activity. In this coupled assay, BioD converts the product of the BioA–catalyzed reaction into dethiobiotin, which is subsequently detected by displacement of a fluorescently labeled dethiobiotin probe from streptavidin. The assay was further adapted to a high-throughput screening format and validated against the LOPAC library. PMID:21621502

  2. Heterogeneous Uptake of HO2 Radicals onto Submicron Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Matthews, P. S.; George, I. J.; Brooks, B.; Whalley, L. K.; Baeza-Romero, M. T.; Heard, D. E.

    2012-12-01

    OH and HO2 (HOx) radicals are closely coupled and OH is responsible for the majority of the oxidation in the troposphere and controls the concentrations of many trace species. Therefore, it is important to be able to accurately predict HOx concentrations. However, some field measurement studies have reported significantly lower HO2 radical concentrations than calculated by constrained box models using detailed chemical mechanisms. Although the inclusion of halogen chemistry into the mechanisms can explain much of the differences in the marine boundary layer (MBL) (1,2), HO2 uptake by aerosols has been suggested as a possible sink in the MBL (2), the Arctic troposphere (3) and the upper troposphere (4). There have been very few laboratory studies (5,6) on HO2 uptake by aerosols and the rates and mechanism is still uncertain. The HO2 uptake coefficients were measured for a variety of atmospherically relevant inorganic and organic aerosols. The measurements were performed using an aerosol flow tube combined with a Fluorescence Assay by Gas Expansion (FAGE) detector. The sensitive FAGE cell allowed low HO2 concentrations (108-109 molecule cm-3) to be injected into the flow tube using a moveable injector. By moving the injector along the flow tube, position dependent HO2 decays were able to be recorded which when plotted against the total aerosol surface area allowed an uptake coefficient to be obtained. The aerosols were generated using an atomiser or by homogeneous nucleation and the total aerosol surface area was measured using a Scanning Mobility Particle Sizer. The HO2 uptake coefficient (γ) was measured at room temperature for dry inorganic salts and dry organics (γ< 0.004), wet inorganic salts and wet organics (γ= 0.002-0.005), wet copper doped ammonium sulfate aerosols (γ= 0.28± 0.05) and ammonium sulfate aerosols doped with different molar amounts of iron (γ= 0.003-0.06). The pH dependence of the HO2 uptake coefficient was investigated, however no

  3. Peptide labeling with photoactivatable trifunctional cadaverine derivative and identification of interacting partners by biotin transfer.

    PubMed

    App, Christine; Knop, Jana; Huff, Thomas; Seebahn, Angela; Becker, Cord-Michael; Iavarone, Federica; Castagnola, Massimo; Hannappel, Ewald

    2014-07-01

    A new photoactivatable trifunctional cross-linker, cBED (cadaverine-2-[6-(biotinamido)-2-(p-azidobenzamido) hexanoamido]ethyl-1,3'-dithiopropionate), was synthesized by chemical conversion of sulfo-SBED (sulfosuccinimidyl-2-[6-(biotinamido)-2-(p-azidobenzamido) hexanoamido]ethyl-1,3'-dithiopropionate) with cadaverine. This cross-linker was purified by reversed-phase high-performance liquid chromatography (RP-HPLC) and characterized using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis. cBED is based on sulfo-SBED that has a photoactivatable azido group, a cleavable disulfide bond for label transfer methods, and a biotin moiety for highly sensitive biotin/avidin detection. By ultraviolet (UV) light, the azido group is converted to a reactive nitrene, transforming transient bindings of interacting structures to covalent bonds. In contrast to the sulfo-N-hydroxysuccinimide (sulfo-NHS) moiety of sulfo-SBED, which attaches quite unspecifically to amino groups, cBED includes a cadaverine moiety that can be attached by transglutaminase more specifically to certain glutamine residues. For instance, thymosin β4 can be labeled with cBED using tissue transglutaminase. By high-resolution HPLC/ESI-MS (electrospray ionization-mass spectrometry) and tandem MS (MS/MS) of the trypsin digest, it was established that glutamine residues at positions 23 and 36 were labeled, whereas Q39 showed no reactivity. The covalent binding of cBED to thymosin β4 did not influence its G-actin sequestering activity, and the complex could be used to identify new interaction partners. Therefore, cBED can be used to better understand the multifunctional role of thymosin β4 as well as of other proteins and peptides.

  4. SPECT/NIRF Dual Modality Imaging for Detection of Intraperitoneal Colon Tumor with an Avidin/Biotin Pretargeting System.

    PubMed

    Dong, Chengyan; Yang, Sujuan; Shi, Jiyun; Zhao, Huiyun; Zhong, Lijun; Liu, Zhaofei; Jia, Bing; Wang, Fan

    2016-01-06

    We describe herein dual-modality imaging of intraperitoneal colon tumor using an avidin/biotin pretargeting system. A novel dual-modality probe, (99m)Tc-HYNIC-lys(Cy5.5)-PEG4-biotin, was designed, synthesized and characterized. Single-photon emission computed tomography/ computed tomography (SPECT/CT) imaging and near infrared fluorescence (NIRF) imaging were developed using intraperitoneal LS180 human colon adenocarcinoma xenografts. Following avidin preinjection for 4 hours, (99m)Tc-HYNIC-lys(Cy5.5)-PEG4-biotin could successfully detect colon tumors of different sizes inside the abdominal region using both modalities, and the imaging results showed no differences. Biodistribution studies demonstrated that the tumors had a very high uptake of the probe (99m)Tc-HYNIC-lys(Cy5.5)-PEG4-biotin (12.74 ± 1.89% ID/g at 2 h p.i.), and the clearance from blood and other normal tissues occured very fast. The low tumor uptake in the non-pretargeted mice (1.63 ± 0.50% ID/g at 2 h p.i.) and tumor cell staining results showed excellent tumor binding specificity of the pretargeting system. The ability of the novel probe to show excellent imaging quality with high tumor-to-background contrast, a high degree of binding specificity with tumors and excellent in vivo biodistribution pharmacokinetics should prove that the avidin/biotin based dual-modality pretargeting probe is a promising imaging tool during the entire period of tumor diagnosis and treatment.

  5. Avidin-biotin interactions at vesicle surfaces: adsorption and binding, cross-bridge formation, and lateral interactions.

    PubMed

    Noppl-Simson, D A; Needham, D

    1996-03-01

    Densely packed domains of membrane proteins are important structures in cellular processes that involve ligand-receptor binding, receptor-mediated adhesion, and macromolecule aggregation. We have used the biotin-avidin interaction at lipid vesicle surfaces to mimic these processes, including the influence of a surface grafted polymer, polyethyleneglycol (PEG). Single vesicles were manipulated by micropipette in solutions of fluorescently labeled avidin to measure the rate and give an estimate of the amount of avidin binding to a biotinylated vesicle as a function of surface biotin concentration and surface-grafted PEG as PEG-lipid. The rate of avidin adsorption was found to be four times less with 2 mol% PEG750 than for the unmodified surface, and 10 mol% PEG completely inhibited binding of avidin to biotin for a 2-min incubation. Using two micropipettes, an avidin-coated vesicle was presented to a biotinylated vesicle. In this vesicle-vesicle adhesion test, the accumulation of avidin in the contact zone was observed, again by using fluorescent avidin. More importantly, by controlling the vesicle membrane tension, this adhesion test provided a direct measure of the spreading pressure of the biotin-avidin-biotin cross-bridges confined in the contact zone. Assuming ideality, this spreading pressure gives the concentration of avidin cross-bridges in the contact zone. The rate of cross-bridge accumulation was consistent with the diffusion of the lipid-linked "receptors" into the contact zone. Once adherent, the membranes failed in tension before they could be peeled apart. PEG750 did not influence the mechanical equilibrium because it was not compressed in the contact zone, but it did perform an important function by eliminating all nonspecific adhesion. This vesicle-vesicle adhesion experiment, with a lower tension limit of 0.01 dyn/cm, now provides a new and useful method with which to measure the spreading pressures and therefore colligative properties of a range of

  6. Theoretical characterization of the potential energy surface for H + O2 yields HO2(asterisk) yields HO + O. II - The potential for H atom exchange in HO2

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Rohlfing, Celeste Mcmichael

    1989-01-01

    The results of CASSCF multireference contracted CI calculations with large ANO basis sets are presented for the exchange region of the HO2 potential-energy surface. The saddle point for H atom exchange is about 13 kcal/mol below the energy of H + O2; therefore, this region of the surface should be accessible during H + O2 recombination and methathesis reactions.

  7. Heterogeneous Uptake of HO2 Radicals onto Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    George, I. J.; Brooks, B.; Goddard, A.; Whalley, L. K.; Baeza-Romero, M. T.; Heard, D. E.

    2010-12-01

    The hydroxyl (OH) and hydroperoxyl (HO2) radicals, known collectively as HOx radicals, are the key reactants that control the oxidative capacity of the troposphere and the atmospheric lifetimes and concentrations of most trace reactive species, i.e. NOx, O3 and volatile organic compounds. Therefore, in order to gain an overall understanding of atmospheric chemistry and to predict the fate of atmospheric pollutants, a detailed knowledge of the sources and sinks of HOx species and their steady-state atmospheric concentrations is crucial. To this end, field measurements of atmospheric HOx concentrations have been recently compared to model predictions to gauge our level of understanding of atmospheric chemistry of trace reactive species. Box models incorporating known gas-phase chemistry have significantly overpredicted steady-state HO2 levels in comparison to field observations, suggesting heterogeneous uptake onto aerosols as a possible missing atmospheric sink for HO2 radicals [1-2]. However, relatively few laboratory studies have been performed to determine the kinetic parameters for HO2 loss onto aerosols, and thus the ability to assess the impact of this mechanism on HOx levels is limited. The goal of this laboratory study is to improve our understanding of the tropospheric HOx budget by measuring HO2 uptake kinetics onto aerosol particles. In this work, HO2 radicals were produced by the photolysis of water vapour and the FAGE (Fluorescence Assay by Gas Expansion) technique was used to monitor HO2 loss kinetics onto aerosol particles in an aerosol flow tube setup. FAGE is a highly sensitive laser-induced fluorescence based detection method for HOx radicals that has allowed for kinetic measurements to be performed under low HO2 concentrations minimizing gas-phase HO2 self reaction, i.e. for [HO2] < 109 molecules cm-3. The mass accommodation coefficient was determined by measuring HO2 uptake onto Cu(II)-doped ammonium sulfate aerosols. Reactive uptake coefficients

  8. Quantum yields of OH, HO2 and NO3 in the UV photolysis of HO2NO2.

    PubMed

    Jiménez, Elena; Gierczak, Tomasz; Stark, Harald; Burkholder, James B; Ravishankara, A R

    2005-01-21

    Quantum yields, phi, of OH and HO2 in the ultraviolet photolysis of HO2NO2 (peroxynitric acid, PNA) at 193 and 248 nm and that of NO3 at 193, 248 and 308 nm are reported. Quantum yields were measured using pulsed excimer laser photolysis combined with pulsed laser induced fluorescence (PLIF) detection of OH radicals and cavity ring-down (CRD) detection of NO3 radicals. HO2 radicals were quantified by converting them to OH via the HO2 + NO --> OH + NO2 reaction and detecting OH. The quantum yields obtained at 296 K are: phi193 nm(OH) = 0.21 +/- 0.12, phi248 nm(OH) = 0.085 +/- 0.08, phi193 nm(HO2) = 0.56 +/- 0.09, phi248 nm(HO2) = 0.89 +/- 0.26, phi193 nm(NO3) = 0.35 +/- 0.09, phi248 nm(NO3) = 0.08 +/- 0.04 and phi308 nm(NO3) = 0.05 +/- 0.02. The quoted uncertainties are 2sigma (95% confidence level) and include estimated systematic errors. Our results are compared with the previous quantum yield measurements of OH (MacLeod et al., J. Geophys. Res., 1988, 93, 3813) and NO2 (Roehl et al., 2001, J. Phys. Chem., 105, 1592) at 248 nm and the discrepancies are discussed. The rate coefficients at 298 K for reactions of OH with HO2NO2, H2O2, HNO3 and NO are also reported.

  9. 1.88 Micrometers InGaAsP Pumped, Room Temperature Ho: LuAG Laser

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Amzajerdian, Farzin; Reichle, Donald J.; Busch, George; Leisher, Paul

    2009-01-01

    A room temperature, directly diode pumped Ho:LuAG laser oscillated for the first time. Direct pumping of the Ho upper laser manifold maximizes efficiency, minimizes heating, and eliminates Ho:Tm energy sharing. Design and performance are presented.

  10. Evaluation of the avidin/biotin-liposome system injected in pleural space and peritoneum for drug delivery to mediastinal lymph nodes

    NASA Astrophysics Data System (ADS)

    Medina-Velazquez, Luis Alberto

    The avidin/biotin-liposome system is a new modality recently developed for targeting lymph nodes through the lymphatic system after local injection in a cavity as the route of delivery. In this dissertation we show that the avidin/biotin-liposome system has potential advantages over the injection of only liposomes for targeting lymph nodes. A goal of this dissertation was to evaluate the potential of pleural space as a route of transport for the targeting of mediastinal nodes. Another objective was to study the role of the injected dose of the avidin/biotin-liposome system for targeting mediastinal nodes. Dose, volume, site and sequence of injection of the agents were studied as factors that play an important role in the lymphatic targeting and in the organ distribution of liposomes after intracavitary injection of the avidin/biotin-liposome system. The hypothesis tested in this dissertation was that intracavitary injection of the avidin/biotin-liposome system in pleural space and/or peritoneum results in high levels of mediastinal node targeting with a significant reduction of unfavorable organ distribution when compared with the injection of only liposomes. The specific aims of this dissertation were: (1) to determine the pharmacokinetics, mediastinal node targeting, and biodistribution of avidin and biotin-liposomes injected individually in pleural and peritoneal space, (2) to determine the effect of injected dose and volume on the targeting of mediastinal nodes after intrapleural injection of the avidin/biotin-liposome system, and (3) to evaluate the dose effect of the avidin/biotin-liposome system on the targeting of mediastinal nodes and the lymphatics that drain the peritoneum and pleural space by injecting one agent in peritoneum and the corresponding agent in pleural space, and vice versa. To perform these studies, scintigraphic images were acquired with a gamma camera to non-invasively follow the pharmacokinetics and organ uptake of the avidin/biotin

  11. Development of a streptavidin-anti-carcinoembryonic antigen antibody, radiolabeled biotin pretargeting method for radioimmunotherapy of colorectal cancer. Reagent development.

    PubMed

    Karacay, H; Sharkey, R M; Govindan, S V; McBride, W J; Goldenberg, D M; Hansen, H J; Griffiths, G L

    1997-01-01

    With pretargeting, radioisotope delivery to tumor is decoupled from the long antibody localization process, and this can increase tumor:blood ratios dramatically. Several reagents were prepared for each step of a "two-step" pretargeting method, and their properties were investigated. For pretargeting tumor, streptavidin-monoclonal antibody (StAv-mab) conjugates were prepared by cross-linking sulfo-SMCC-derivatized streptavidin to a free thiol (SH) group on MN-14 [a high-affinity anti-carcinoembryonic antigen (CEA) mab]. Thiolated mabs were generated either by reaction of 2-iminothiolane (2-IT) with mab lysine residues or by reduction of mab disulfide bonds with (2-mercaptoethyl)amine (MEA). Both procedures gave protein-protein conjugates isolated in relatively low yields (20-25%) after preparative size-exclusion (SE) chromatography purification with conservative peak collection. Both StAv-MN-14 conjugates retained their ability to bind to CEA, to an anti-idiotypic antibody to MN-14 (WI2), and to biotin, as demonstrated by SE-HPLC. Two clearing agents, WI2 mab and a biotin-human serum albumin (biotin-HSA) conjugate, were developed to remove excess circulating StAv-MN-14 conjugates in animals. Both clearing proteins were also modified with galactose residues, introduced using an activated thioimidate derivative, to produce clearing agents which would clear rapidly and clear primary mab rapidly. At least 14 galactose residues on WI2 were required to reduce blood levels to 5.9 +/- 0.7% ID/g in 1 h. Faster blood clearance (0.7 +/- 0.2% ID/g) was observed in 1 h using 44 galactose units per WI2. For the delivery of radioisotope to tumor, several biotinylated conjugates consisting of biotin, a linker, and a chelate were prepared. Conjugates showed good in vitro and in vivo stability when D-amino acid peptides were used as linkers, biotin-peptide-DOTA-indium-111 had a slightly longer blood circulation time (0.09 +/- 0.02% ID/g in 1 h) than biotin-peptide-DTPA-indium-111 (0

  12. Magnetic properties of HoMn2O5

    NASA Astrophysics Data System (ADS)

    Radulov, I.; Lovchinov, V.; Dimitrov, D.; Apostolov, A.; Nizhankovskii, V.; Daszkiewicz, M.

    2007-04-01

    We have investigated the detailed field and temperature dependence of the dielectric constant, dielectric losses, electric polarization, magnetization and magnetostriction (MS) in orthorhombic HoMn2O5 single crystals. HoMn2O5 displays incommensurate antiferromagnetic ordering below 39 K, becoming commensurate on further cooling. The commensurate-incommensurate transition takes place at low temperatures. The inherent magnetic frustration in this material is lifted by a small lattice distortion, primarily involving shifts of the Mn3+ cations and giving rise to a canted antiferroelectric phase. Colossal magnetostriction (CMS) effect was observed and a novel phase transition diagram was build.

  13. Asymptotic Freedom in Hořava-Lifshitz Gravity

    NASA Astrophysics Data System (ADS)

    D'Odorico, Giulio; Saueressig, Frank; Schutten, Marrit

    2014-10-01

    We use the Wetterich equation for foliated spacetimes to study the renormalization group flow of projectable Hořava-Lifshitz gravity coupled to n Lifshitz scalars. Using novel results for anisotropic heat kernels, the matter-induced beta functions for the gravitational couplings are computed explicitly. The renormalization group flow exhibits an UV attractive anisotropic Gaussian fixed point where Newton's constant vanishes and the extra scalar mode decouples. This fixed point ensures that the theory is asymptotically free in the large-n expansion, indicating that projectable Hořava-Lifshitz gravity is perturbatively renormalizable. Notably, the fundamental fixed point action does not obey detailed balance.

  14. Behavior of OH and HO 2 in the winter atmosphere in New York City

    NASA Astrophysics Data System (ADS)

    Ren, Xinrong; Brune, William H.; Mao, Jingqiu; Mitchell, Michael J.; Lesher, Robert L.; Simpas, James B.; Metcalf, Andrew R.; Schwab, James J.; Cai, Chenxia; Li, Yongquan; Demerjian, Kenneth L.; Felton, Henry D.; Boynton, Garry; Adams, Allen; Perry, Jacqueline; He, Yi; Zhou, Xianliang; Hou, Jian

    Hydroxyl (OH) and hydroperxy (HO 2) radicals, collectively known as HO x, were measured during an intensive field study in January and February 2004 in New York City. Much less OH and HO 2 levels were observed than in the summer of 2001 at the same site. On average, the maximum daytime mixing ratios were 0.05 pptv (1.4×10 6 cm -3) for OH and 0.7 pptv for HO 2, which were about one fifth of the levels in the summer of 2001. A zero-dimensional chemical model, based on the regional atmospheric chemical mechanism (RACM) and constrained by the measured concentrations of O 3, NO, NO 2, CO, SO 2, speciated volatile organic compounds (VOCs) and meteorological parameters, was used to study the HO x chemistry in this environment. The model generally reproduced the daytime OH well, with a median measured-to-model ratio of 0.98. However, HO 2 was significantly under-predicted both at day and at night, with a median measured-to-model ratio of 6.0 during daytime. The discrepancy is pronounced when NO concentrations were high, a result that is consistent with some previous studies in urban environments. Photolysis of HONO was the dominant calculated HO x source during daytime; O 3 reactions with alkenes became the main calculated HO x source at night. The main calculated HO x sink was the OH reaction with NO 2. The discrepancy between measured and modeled HO 2 may be caused by significant HO x production that is missing in the model. An additional HO 2 production of up to 3×10 7 cm -3 s -1 (1.1 pptv s -1), which is three times the calculated HO x production, is needed. This HO 2 production can come either from unknown new HO x production or from unknown HO 2 recycling that does not go through OH.

  15. [Skin changes in chronic alcoholism with special reference to the zinc and biotin content of the serum].

    PubMed

    Bahmer, F A; Bader, M

    1987-05-01

    We report on 52 dermatologic patients suffering from chronic alcoholism. The skin changes observed mainly consisted of erythrosis interfollicularis colli, icterus of the sclerae, teleangiectatic reddening of the face, and diminished secondary hair. In 29 out of 44 sera investigated, we found elevation of the gamma-glutamyl transferase. In 17 patients, serum samples were analyzed for zinc. In 16 cases, the zinc levels were slightly decreased but still within the normal range, i.e. below 100 micrograms/dl. The biotin levels in the 48 serum samples examined varied very much. In 6 patients, however, we found definitely lowered values. Our results support the view that routine investigation of serum zinc and biotin levels might be valuable in patients suffering from chronic alcoholism associated with cutaneous changes. If lowered values are found, a substitution therapy might be of benefit at least in some patients.

  16. Biotin-decorated silica coated PbS nanocrystals emitting in the second biological near infrared window for bioimaging

    NASA Astrophysics Data System (ADS)

    Corricelli, M.; Depalo, N.; di Carlo, E.; Fanizza, E.; Laquintana, V.; Denora, N.; Agostiano, A.; Striccoli, M.; Curri, M. L.

    2014-06-01

    Nanoparticles (NPs) emitting in the second biological near infrared (NIR) window of the electromagnetic spectrum have been successfully synthesized by growing a silica shell on the hydrophobic surface of OLEA/TOP PbS nanocrystals (NCs), by means of a reverse microemulsion approach, and subsequently decorated with biotin molecules. The fabrication of very uniform and monodisperse NPs, formed of SiO2 shell coated single core PbS NCs, has been demonstrated by means of a set of complementary optical and structural techniques (Vis-NIR absorption and photoluminescence spectroscopy, transmission electron microscopy) that have highlighted how experimental parameters, such as PbS NC and silica precursor concentration, are crucial to direct the morphology and optical properties of silica coated PbS NPs. Subsequently, the silica surface of the core-shell NPs has been grafted with amino groups, in order to achieve covalent binding of biotin to NIR emitting silica coated NPs. Finally the successful reaction with a green-fluorescent labelled streptavidin has verified the molecular recognition response of the biotin molecules decorating the PbS@SiO2 NP surface. Dynamic light scattering (DLS) and ζ-potential techniques have been used to monitor the hydrodynamic diameter and colloidal stability of both PbS@SiO2 and biotin decorated NPs, showing their high colloidal stability in physiological media, as needed for biomedical applications. Remarkably the obtained biotinylated PbS@SiO2 NPs have been found to retain emission properties in the `second optical window' of the NIR region of the electromagnetic spectrum, thus representing attractive receptor-targeted NIR fluorescent probes for in vivo tumour imaging.Nanoparticles (NPs) emitting in the second biological near infrared (NIR) window of the electromagnetic spectrum have been successfully synthesized by growing a silica shell on the hydrophobic surface of OLEA/TOP PbS nanocrystals (NCs), by means of a reverse microemulsion

  17. Theoretical characterization of the minimum energy path for the reaction H + O2 to HO2(asterisk) to HO + O

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Rohlfing, Celeste Mcmichael; Melius, Carl F.; Bauschlicher, Charles W., Jr.

    1988-01-01

    The potential energy surface for the H + O2 to HO2(asterisk) to HO + O reaction has been investigated in the region of the minimum energy path using CASSCF/contracted CI (CCI) calculations with a large basis set. The results show no barrier for the addition of an H atom to O2, in agreement with previous studies. A crossing between the surface for electrostatic (OH dipole-O quadrupole) interaction and that for the formation of an O-O chemical bond, at r(infinity) of about 5.5 a(0), results in a small (about 0.5 kcal/mol) barrier.

  18. Microscopic insight into the study of band spectra of 158Ho and 159,161,163Ho isotopes

    NASA Astrophysics Data System (ADS)

    Slathia, Barun; Devi, Rani; Khosa, S. K.

    2016-11-01

    The nuclear structure properties of the low-lying and excited states of Holmium isotopes have been studied within the framework of Projected Shell Model. The theoretical results are found to be in the reasonable agreement with the observed ones. The theoretical B (M 1) / B (E 2) estimates of 158Ho are seen to reproduce the same systematics as shown by the observed ones. However, for 159,161,163Ho, the B (E 2) transition probabilities for the ground state band have been predicted for transitions for which the experimental values are not available.

  19. ATP-dependent Conformational Changes Trigger Substrate Capture and Release by an ECF-type Biotin Transporter.

    PubMed

    Finkenwirth, Friedrich; Sippach, Michael; Landmesser, Heidi; Kirsch, Franziska; Ogienko, Anastasia; Grunzel, Miriam; Kiesler, Cornelia; Steinhoff, Heinz-Jürgen; Schneider, Erwin; Eitinger, Thomas

    2015-07-03

    Energy-coupling factor (ECF) transporters for vitamins and metal ions in prokaryotes consist of two ATP-binding cassette-type ATPases, a substrate-specific transmembrane protein (S component) and a transmembrane protein (T component) that physically interacts with the ATPases and the S component. The mechanism of ECF transporters was analyzed upon reconstitution of a bacterial biotin transporter into phospholipid bilayer nanodiscs. ATPase activity was not stimulated by biotin and was only moderately reduced by vanadate. A non-hydrolyzable ATP analog was a competitive inhibitor. As evidenced by cross-linking of monocysteine variants and by site-specific spin labeling of the Q-helix followed by EPR-based interspin distance analyses, closure and reopening of the ATPase dimer (BioM2) was a consequence of ATP binding and hydrolysis, respectively. A previously suggested role of a stretch of small hydrophobic amino acid residues within the first transmembrane segment of the S units for S unit/T unit interactions was structurally and functionally confirmed for the biotin transporter. Cross-linking of this segment in BioY (S) using homobifunctional thiol-reactive reagents to a coupling helix of BioN (T) indicated a reorientation rather than a disruption of the BioY/BioN interface during catalysis. Fluorescence emission of BioY labeled with an environmentally sensitive fluorophore was compatible with an ATP-induced reorientation and consistent with a hypothesized toppling mechanism. As demonstrated by [(3)H]biotin capture assays, ATP binding stimulated substrate capture by the transporter, and subsequent ATP hydrolysis led to substrate release. Our study represents the first experimental insight into the individual steps during the catalytic cycle of an ECF transporter in a lipid environment.

  20. ATP-dependent Conformational Changes Trigger Substrate Capture and Release by an ECF-type Biotin Transporter*

    PubMed Central

    Finkenwirth, Friedrich; Sippach, Michael; Landmesser, Heidi; Kirsch, Franziska; Ogienko, Anastasia; Grunzel, Miriam; Kiesler, Cornelia; Steinhoff, Heinz-Jürgen; Schneider, Erwin; Eitinger, Thomas

    2015-01-01

    Energy-coupling factor (ECF) transporters for vitamins and metal ions in prokaryotes consist of two ATP-binding cassette-type ATPases, a substrate-specific transmembrane protein (S component) and a transmembrane protein (T component) that physically interacts with the ATPases and the S component. The mechanism of ECF transporters was analyzed upon reconstitution of a bacterial biotin transporter into phospholipid bilayer nanodiscs. ATPase activity was not stimulated by biotin and was only moderately reduced by vanadate. A non-hydrolyzable ATP analog was a competitive inhibitor. As evidenced by cross-linking of monocysteine variants and by site-specific spin labeling of the Q-helix followed by EPR-based interspin distance analyses, closure and reopening of the ATPase dimer (BioM2) was a consequence of ATP binding and hydrolysis, respectively. A previously suggested role of a stretch of small hydrophobic amino acid residues within the first transmembrane segment of the S units for S unit/T unit interactions was structurally and functionally confirmed for the biotin transporter. Cross-linking of this segment in BioY (S) using homobifunctional thiol-reactive reagents to a coupling helix of BioN (T) indicated a reorientation rather than a disruption of the BioY/BioN interface during catalysis. Fluorescence emission of BioY labeled with an environmentally sensitive fluorophore was compatible with an ATP-induced reorientation and consistent with a hypothesized toppling mechanism. As demonstrated by [3H]biotin capture assays, ATP binding stimulated substrate capture by the transporter, and subsequent ATP hydrolysis led to substrate release. Our study represents the first experimental insight into the individual steps during the catalytic cycle of an ECF transporter in a lipid environment. PMID:25991724

  1. Electron-induced damage of biotin studied in the gas phase and in the condensed phase at a single-molecule level

    NASA Astrophysics Data System (ADS)

    Keller, Adrian; Kopyra, Janina; Gothelf, Kurt V.; Bald, Ilko

    2013-08-01

    Biotin is an essential vitamin that is, on the one hand, relevant for the metabolism, gene expression and in the cellular response to DNA damage and, on the other hand, finds numerous applications in biotechnology. The functionality of biotin is due to two particular sub-structures, the ring structure and the side chain with carboxyl group. The heterocyclic ring structure results in the capability of biotin to form strong intermolecular hydrogen and van der Waals bonds with proteins such as streptavidin, whereas the carboxyl group can be employed to covalently bind biotin to other complex molecules. Dissociative electron attachment (DEA) to biotin results in a decomposition of the ring structure and the carboxyl group, respectively, within resonant features in the energy range 0-12 eV, thereby preventing the capability of biotin for intermolecular binding and covalent coupling to other molecules. Specifically, the fragment anions (M-H)-, (M-O)-, C3N2O-, CH2O2-, OCN-, CN-, OH- and O- are observed, and exemplarily the DEA cross section of OCN- formation is determined to be 3 × 10-19 cm2. To study the response of biotin to electrons within a complex condensed environment, we use the DNA origami technique and determine a dissociation yield of (1.1 ± 0.2) × 10-14 cm2 at 18 eV electron energy, which represents the most relevant energy for biomolecular damage induced by secondary electrons. The present results thus have important implications for the use of biotin as a label in radiation experiments.

  2. The origin of the cooperativity in the streptavidin-biotin system: A computational investigation through molecular dynamics simulations.

    PubMed

    Liu, Fengjiao; Zhang, John Z H; Mei, Ye

    2016-06-01

    Previous experimental study measuring the binding affinities of biotin to the wild type streptavidin (WT) and three mutants (S45A, D128A and S45A/D128A double mutant) has shown that the loss of binding affinity from the double mutation is larger than the direct sum of those from two single mutations. The origin of this cooperativity has been investigated in this work through molecular dynamics simulations and the end-state free energy method using the polarized protein-specific charge. The results show that this cooperativity comes from both the enthalpy and entropy contributions. The former contribution mainly comes from the alternations of solvation free energy. Decomposition analysis shows that the mutated residues nearly have no contributions to the cooperativity. Instead, N49 and S88, which are located at the entry of the binding pocket and interact with the carboxyl group of biotin, make the dominant contribution among all the residues in the first binding shell around biotin.

  3. The origin of the cooperativity in the streptavidin-biotin system: A computational investigation through molecular dynamics simulations

    PubMed Central

    Liu, Fengjiao; Zhang, John Z. H.; Mei, Ye

    2016-01-01

    Previous experimental study measuring the binding affinities of biotin to the wild type streptavidin (WT) and three mutants (S45A, D128A and S45A/D128A double mutant) has shown that the loss of binding affinity from the double mutation is larger than the direct sum of those from two single mutations. The origin of this cooperativity has been investigated in this work through molecular dynamics simulations and the end-state free energy method using the polarized protein-specific charge. The results show that this cooperativity comes from both the enthalpy and entropy contributions. The former contribution mainly comes from the alternations of solvation free energy. Decomposition analysis shows that the mutated residues nearly have no contributions to the cooperativity. Instead, N49 and S88, which are located at the entry of the binding pocket and interact with the carboxyl group of biotin, make the dominant contribution among all the residues in the first binding shell around biotin. PMID:27249234

  4. A simple and efficient design to improve the detection of biotin-streptavidin interaction with plasmonic nanobiosensors.

    PubMed

    Focsan, Monica; Campu, Andreea; Craciun, Ana-Maria; Potara, Monica; Leordean, Cosmin; Maniu, Dana; Astilean, Simion

    2016-12-15

    In this manuscript we propose a simple and efficient strategy to improve the sensitivity of localized surface plasmon resonance (LSPR) shift-based biosensors using biotin-streptavidin recognition interaction as a proof-of-concept. Specifically, biotin molecules are immobilized on a low-cost plasmonic LSPR biosensor based on annealed self-assembled spherical gold nanoparticles (AuNSs) and successively incubated with increasing concentrations of streptavidin, achieving a limit of detection (LOD) of 5nM. Interestingly, when the detection is performed by the same biotin-functionalized plasmonic AuNSs substrate but against streptavidin previously conjugated to gold nanorods, the LSPR shift is 26-fold enhanced. Moreover, we confirm these results through numerical simulations and demonstrate that the proposed sensing architecture can operate as transducer not only to confirm the adsorption of bioanalyte but also to provide the chemical identity of the capture and targeted molecules from their vibrational Raman fingerprints. Therefore, we are confident that the development of such plasmonic biosensors that use metallic labels for improving the sensitivity of detection could become highly promising for future point-of-care diagnostic assays, pushing sensitivity towards single-molecule detection limit.

  5. Bimetallic gold-silver nanoplate array as a highly active SERS substrate for detection of streptavidin/biotin assemblies.

    PubMed

    Bi, Liyan; Dong, Jian; Xie, Wei; Lu, Wenbo; Tong, Wei; Tao, Lin; Qian, Weiping

    2013-12-17

    The silver-modified gold nanoplate arrays as bimetallic surface-enhanced Raman scattering (SERS) substrates were optimized for the surface-enhanced Raman detection of streptavidin/biotin monolayer assemblies. The bimetallic gold-silver nanoplate arrays were fabricated by coating silver nanoparticles uniformly on the gold nanoplate arrays. Depending on silver nanoparticle coating, the localized surface plasmon resonance (LSPR) peak of the bimetallic gold-silver nanoplate arrays blue-shifted and broadened significantly. The common probe molecule, Niel Blue A sulfate (NBA) was used for testing the SERS activity of the bimetallic gold-silver nanoplate arrays. The SERS intensity increased with the silver nanoparticle coating, due to a large number of hot spots and nanoparticle interfaces. The platforms were tested against a monolayer of streptavidin functionalized over the bimetallic gold-silver nanoplate arrays showing that good quality spectra could be acquired with a short acquisition time. The supramolecular interaction between streptavidin (strep) and biotin showed subsequent modification of Raman spectra that implied a change of the secondary structure of the host biomolecule. And the detection concentration for biotin by this method was as low as 1.0 nM. The enhanced SERS performance of such bimetallic gold-silver nanoplate arrays could spur further interest in the integration of highly sensitive biosensors for rapid, nondestructive, and quantitative bioanalysis, particularly in microfluidics.

  6. Periodic protein adsorption at the gold/biotin aqueous solution interface: evidence of kinetics with time delay

    PubMed Central

    Neff, H.; Laborde, H. M.; Lima, A. M. N.

    2016-01-01

    An oscillatory molecular adsorption pattern of the protein neutravidin from aqueous solution onto gold, in presence of a pre-deposited self assembled mono-molecular biotin film, is reported. Real time surface Plasmon resonance sensing was utilized for evaluation of the adsorption kinetics. Two different fractions were identified: in the initial phase, protein molecules attach irreversibly onto the Biotin ligands beneath towards the jamming limit, forming a neutravidin-biotin fraction. Afterwards, the growth rate exhibits distinct, albeit damped adsorption-desorption oscillations over an extended time span, assigned to a quasi reversibly bound fraction. These findings agree with, and firstly confirm a previously published model, proposing macro-molecular adsorption with time delay. The non-linear dynamic model is applicable to and also resembles non-damped oscillatory binding features of the hetero-catalytic oxidation of carbon monoxide molecules on platinum in the gas phase. An associated surface residence time can be linked to the dynamics and time scale required for self-organization. PMID:27808155

  7. The origin of the cooperativity in the streptavidin-biotin system: A computational investigation through molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Liu, Fengjiao; Zhang, John Z. H.; Mei, Ye

    2016-06-01

    Previous experimental study measuring the binding affinities of biotin to the wild type streptavidin (WT) and three mutants (S45A, D128A and S45A/D128A double mutant) has shown that the loss of binding affinity from the double mutation is larger than the direct sum of those from two single mutations. The origin of this cooperativity has been investigated in this work through molecular dynamics simulations and the end-state free energy method using the polarized protein-specific charge. The results show that this cooperativity comes from both the enthalpy and entropy contributions. The former contribution mainly comes from the alternations of solvation free energy. Decomposition analysis shows that the mutated residues nearly have no contributions to the cooperativity. Instead, N49 and S88, which are located at the entry of the binding pocket and interact with the carboxyl group of biotin, make the dominant contribution among all the residues in the first binding shell around biotin.

  8. Periodic protein adsorption at the gold/biotin aqueous solution interface: evidence of kinetics with time delay

    NASA Astrophysics Data System (ADS)

    Neff, H.; Laborde, H. M.; Lima, A. M. N.

    2016-11-01

    An oscillatory molecular adsorption pattern of the protein neutravidin from aqueous solution onto gold, in presence of a pre-deposited self assembled mono-molecular biotin film, is reported. Real time surface Plasmon resonance sensing was utilized for evaluation of the adsorption kinetics. Two different fractions were identified: in the initial phase, protein molecules attach irreversibly onto the Biotin ligands beneath towards the jamming limit, forming a neutravidin-biotin fraction. Afterwards, the growth rate exhibits distinct, albeit damped adsorption-desorption oscillations over an extended time span, assigned to a quasi reversibly bound fraction. These findings agree with, and firstly confirm a previously published model, proposing macro-molecular adsorption with time delay. The non-linear dynamic model is applicable to and also resembles non-damped oscillatory binding features of the hetero-catalytic oxidation of carbon monoxide molecules on platinum in the gas phase. An associated surface residence time can be linked to the dynamics and time scale required for self-organization.

  9. Direct immobilization of biotin on the micro-patterned PEN foil treated by excimer laser.

    PubMed

    Štofik, Marcel; Semerádtová, Alena; Malý, Jan; Kolská, Zdeňka; Neděla, Oldřich; Wrobel, Dominika; Slepička, Petr

    2015-04-01

    Polymers with functionalized surfaces have attracted a lot of attention in the last few years. Due to the progress in the techniques of polymer micro-patterning, miniaturized bioanalytical assays and biocompatible devices can be developed. In the presented work, we performed surface modification of polyethylene naphthalate (PEN) foil by an excimer laser beam through a photolithographic contact mask. The aim was to fabricate micro-patterned areas with surface functional groups available for localized covalent immobilization of biotin. It was found out that depending on the properties of the laser scans, a polymer surface exhibits different degrees of modification and as a consequence, different degrees of surface biotinylation can be achieved. Several affinity tests with optical detection of fluorescently labeled streptavidin were successfully performed on biotinylated micro-patterns of a PEN foil. The polymer surface properties were also evaluated by electrokinetic analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results have shown that PEN foils can be considered suitable substrates for construction of micro-patterned bioanalytical affinity assays.

  10. Comparative genomics provides a timeframe for Wolbachia evolution and exposes a recent biotin synthesis operon transfer.

    PubMed

    Gerth, Michael; Bleidorn, Christoph

    2016-12-22

    The genus Wolbachia (Alphaproteobacteria) comprises the most abundant inherited intracellular bacteria(1). Despite their relevance as manipulators of human pathogen transmission(2) and arthropod reproduction(3), many aspects of their evolutionary history are not well understood(4). In arthropods, Wolbachia infections are typically transient on evolutionary timescales(5,6) and co-divergence between hosts and Wolbachia is supposedly rare. Consequently, much of our knowledge of Wolbachia genome evolution derives from very recently diverged strains, and a timescale for Wolbachia is lacking. Here, we investigated the genomes of four Wolbachia strains that have persisted within and co-diverged with their host lineage for ∼2 million years. Although the genomes showed very little evolutionary change on a nucleotide level, we found evidence for a recent lateral transfer of a complete biotin synthesis operon that has the potential to transform Wolbachia-host relationships(7). Furthermore, this evolutionary snapshot enabled us to calibrate the divergence times of the supergroup A and B Wolbachia lineages using genome-wide data sets and relaxed molecular clock models. We estimated the origin of Wolbachia supergroups A and B to be ∼200 million years ago (Ma), which is considerably older than previously appreciated. This age coincides with the diversification of many insect lineages(8) that represent most of Wolbachia's host spectrum.

  11. Rapid colchicine competition-binding scintillation proximity assay using biotin-labeled tubulin.

    PubMed

    Tahir, S K; Kovar, P; Rosenberg, S H; Ng, S C

    2000-07-01

    We have developed a rapid [3H]colchicine competition-binding scintillation proximity assay (SPA) to evaluate antimitotic compounds that bind to the colchicine-binding site on tubulin. The premise of our assay is that compounds will compete with radiolabeled colchicine for the tubulin-binding domain. Biotin-labeled tubulin is incubated first with unlabeled compound and radiolabeled ligand. Streptavidin-labeled SPA beads are added, and the radiolabel associated with tubulin is directly counted with no separation steps. Under our experimental conditions, the dissociation constant of binding (Kd) for colchicine to tubulin was determined to be 1.4 microM, which was consistent with previously reported values. Assay validation was performed by competitively inhibiting [3H]colchicine binding to tubulin with known microtubule inhibitors and comparing their inhibition constants (Ki). Our SPA bead method is a powerful tool since it overcomes the disadvantage of traditional filtration techniques, as there are no separation steps. It is extremely easy to set up, multiple samples can be assayed and supply and labor costs are reduced because of the minimal volume and test reagents used.

  12. Reconsideration of dynamic force spectroscopy analysis of streptavidin-biotin interactions.

    PubMed

    Taninaka, Atsushi; Takeuchi, Osamu; Shigekawa, Hidemi

    2010-05-13

    To understand and design molecular functions on the basis of molecular recognition processes, the microscopic probing of the energy landscapes of individual interactions in a molecular complex and their dependence on the surrounding conditions is of great importance. Dynamic force spectroscopy (DFS) is a technique that enables us to study the interaction between molecules at the single-molecule level. However, the obtained results differ among previous studies, which is considered to be caused by the differences in the measurement conditions. We have developed an atomic force microscopy technique that enables the precise analysis of molecular interactions on the basis of DFS. After verifying the performance of this technique, we carried out measurements to determine the landscapes of streptavidin-biotin interactions. The obtained results showed good agreement with theoretical predictions. Lifetimes were also well analyzed. Using a combination of cross-linkers and the atomic force microscope that we developed, site-selective measurement was carried out, and the steps involved in bonding due to microscopic interactions are discussed using the results obtained by site-selective analysis.

  13. Force Dependent Biotinylation of Myosin IIA by α-Catenin Tagged with a Promiscuous Biotin Ligase

    PubMed Central

    Ueda, Shuji; Blee, Alexandra M.; Macway, Katherine G.; Renner, Derrick J.; Yamada, Soichiro

    2015-01-01

    Tissues and organs undergo constant physical perturbations and individual cells must respond to mechanical forces to maintain tissue integrity. However, molecular interactions underlying mechano-transduction are not fully defined at cell-cell junctions. This is in part due to weak and transient interactions that are likely prevalent in force-induced protein complexes. Using in situ proximal biotinylation by the promiscuous biotin ligase BirA tagged to α-catenin and a substrate stretch cell chamber, we sought to identify force-dependent molecular interactions surrounding α-catenin, an actin regulator at the sites of cadherin mediated cell-cell adhesion. While E-cadherin, β-catenin, vinculin and actin localize with α-catenin at cell-cell contacts in immuno-fluorescent staining, only β-catenin and plakoglobin were biotinylated, suggesting that this proximal biotinylation is limited to the molecules that are in the immediate vicinity of α-catenin. In mechanically stretched samples, increased biotinylation of non-muscle myosin IIA, but not myosin IIB, suggests close spatial proximity between α-catenin and myosin IIA during substrate stretching. This force-induced biotinylation diminished as myosin II activity was inhibited by blebbistatin. Taken together, this promising technique enables us to identify force sensitive complexes that may be essential for mechano-responses in force bearing cell adhesion. PMID:25806963

  14. Vitamin-responsive disorders: cobalamin, folate, biotin, vitamins B1 and E.

    PubMed

    Baumgartner, Matthias R

    2013-01-01

    The catalytic properties of many enzymes depend on the participation of vitamins as obligatory cofactors. Vitamin B12 (cobalamin) and folic acid (folate) deficiencies in infants and children classically present with megaloblastic anemia and are often accompanied by neurological signs. A number of rare inborn errors of cobalamin and folate absorption, transport, cellular uptake, and intracellular metabolism have been delineated and identification of disease-causing mutations has improved our ability to diagnose and treat many of these conditions. Two inherited defects in biotin metabolism are known, holocarboxylase synthetase and biotinidase deficiency. Both lead to multiple carboxylase deficiency manifesting with metabolic acidosis, neurological abnormalities, and skin rash. Thiamine-responsive megaloblastic anemia is characterized by megaloblastic anemia, non-type I diabetes, and sensorineural deafness that responds to pharmacological doses of thiamine (vitamin B1). Individuals affected with inherited vitamin E deficiencies including ataxia with isolated vitamin E deficiency and abetalipoproteinemia present with a spinocerebellar syndrome similar to patients with Friedreich's ataxia. If started early, treatment of these defects by oral or parenteral administration of the relevant vitamin often results in correction of the metabolic defect and reversal of the signs of disease, stressing the importance of early and correct diagnosis in these treatable conditions.

  15. Bone Tissue Engineering by Using Calcium Phosphate Glass Scaffolds and the Avidin-Biotin Binding System.

    PubMed

    Kim, Min-Chul; Hong, Min-Ho; Lee, Byung-Hyun; Choi, Heon-Jin; Ko, Yeong-Mu; Lee, Yong-Keun

    2015-12-01

    Highly porous and interconnected scaffolds were fabricated using calcium phosphate glass (CPG) for bone tissue engineering. An avidin-biotin binding system was used to improve osteoblast-like cell adhesion to the scaffold. The scaffolds had open macro- and micro-scale pores, and continuous struts without cracks or defects. Scaffolds prepared using a mixture (amorphous and crystalline CPG) were stronger than amorphous group and crystalline group. Cell adhesion assays showed that more cells adhered, with increasing cell seeding efficiency to the avidin-adsorbed scaffolds, and that cell attachment to the highly porous scaffolds significantly differed between avidin-adsorbed scaffolds and other scaffolds. Proliferation was also significantly higher for avidin-adsorbed scaffolds. Osteoblastic differentiation of MG-63 cells was observed at 3 days, and MG-63 cells in direct contact with avidin-adsorbed scaffolds were positive for type I collagen, osteopontin, and alkaline phosphatase gene expression. Osteocalcin expression was observed in the avidin-adsorbed scaffolds at 7 days, indicating that cell differentiation in avidin-adsorbed scaffolds occurred faster than the other scaffolds. Thus, these CPG scaffolds have excellent biological properties suitable for use in bone tissue engineering.

  16. Biotin-Avidin ELISA Detection of Grapevine Fanleaf Virus in the Vector Nematode Xiphinema index

    PubMed Central

    Esmenjaud, D.; Walter, B.; Minot, J. C.; Voisin, R.; Cornuet, P.

    1993-01-01

    The value of biotin-avidin (B-A) ELISA for the detection of grapevine fanleaf virus (GFLV) in Xiphinema was estimated with field populations and greenhouse subpopulations. Samples consisted of increasing numbers of adults ranging from 1 to 64 in multiples of two. Tests with virus-free X. index populations reared on grapevine and fig plants as negative controls did not reveal a noticeable effect of the host plant. ELISA absorbances of virus-free X. index samples were greater than corresponding absorbances of X. pachtaicum samples. Differences occurred between two X. index field populations from GFLV-infected grapevines in Champagne and Languedoc. In most tests, 1-, 2-, 4-, and 8-nematode samples of virus-free and virus-infected populations, respectively, could not be separated. Consequently, B-A ELISA was not a reliable method for GFLV detection in samples of less than 10 X. index adults, but comparison of the absorbances obtained with increasing numbers may allow differentiation of the viral infectious potential of several populations. PMID:19279786

  17. Targeting Mycobacterium tuberculosis Biotin Protein Ligase (MtBPL) with Nucleoside-Based Bisubstrate Adenylation Inhibitors

    PubMed Central

    Petrelli, Riccardo; De la Mora-Rey, Teresa; Tiwari, Divya; Liu, Feng; Dawadi, Surrendra; Nandakumar, Madhumitha; Rhee, Kyu Y.; Schnappinger, Dirk; Finzel, Barry C.; Aldrich, Courtney C.

    2015-01-01

    Mycobacterium tuberculosis (Mtb) responsible for both latent and symptomatic tuberculosis (TB) remains the second leading cause of mortality among infectious diseases worldwide. Mycobacterial biotin protein ligase (MtBPL) is an essential enzyme in Mtb and regulates lipid metabolism through the post-translational biotinylation of acyl coenzyme A carboxylases. We report the synthesis and evaluation of a systematic series of potent nucleoside-based inhibitors of MtBPL that contain modifications to the ribofuranosyl ring of the nucleoside. All compounds were characterized by isothermal titration calorimetry (ITC) and shown to bind potently with KD's below 2 nM. Additionally, we obtained high-resolution co-crystal structures for a majority of the compounds. Despite fairly uniform biochemical potency, the whole-cell Mtb activity varied greatly with minimum inhibitory concentrations (MIC) ranging from 0.78 to >100 μM. Cellular accumulation studies showed a nearly 10-fold enhanced accumulation of a C-2′-α analog over the corresponding C-2′-β analog, consistent with their differential whole-cell activity. PMID:26299766

  18. Cleavable Biotin Probes for Labeling of Biomolecules via the Azide – Alkyne Cycloaddition

    PubMed Central

    Szychowski, Janek; Mahdavi, Alborz; Hodas, Jennifer J. L.; Bagert, John D.; Ngo, John T.; Landgraf, Peter; Dieterich, Daniela C.; Schuman, Erin M.; Tirrell, David A.

    2010-01-01

    The azide-alkyne cycloaddition provides a powerful tool for bio-orthogonal labeling of proteins, nucleic acids, glycans, and lipids. In some labeling experiments, e.g., in proteomic studies involving affinity purification and mass spectrometry, it is convenient to use cleavable probes that allow release of labeled biomolecules under mild conditions. Five cleavable biotin probes are described for use in labeling of proteins and other biomolecules via the azide – alkyne cycloaddition. Subsequent to conjugation with metabolically labeled protein, these probes are subject to cleavage with either 50 mM Na2S2O4, 2% HOCH2CH2SH, 10% HCO2H, 95% CF3CO2H, or irradiation at 365 nm. Most strikingly, a probe constructed around a dialkoxydiphenylsilane (DADPS) linker was found to be cleaved efficiently when treated with 10% HCO2H for 0.5 h. A model GFP protein was used to demonstrate that the DADPS probe undergoes highly selective conjugation and leaves a small (143 Da) mass tag on the labeled protein after cleavage. These features make the DADPS probe especially attractive for use in biomolecular labeling and proteomic studies. PMID:21141861

  19. Living with ghosts in Hořava-Lifshitz gravity

    NASA Astrophysics Data System (ADS)

    Ramazanov, S.; Arroja, F.; Celoria, M.; Matarrese, S.; Pilo, L.

    2016-06-01

    We consider the branch of the projectable Hořava-Lifshitz model which exhibits ghost instabilities in the low energy limit. It turns out that, due to the Lorentz violating structure of the model and to the presence of a finite strong coupling scale, the vacuum decay rate into photons is tiny in a wide range of phenomenologically acceptable parameters. The strong coupling scale, understood as a cutoff on ghosts' spatial momenta, can be raised up to Λ ˜ 10 TeV. At lower momenta, the projectable Hořava-Lifshitz gravity is equivalent to General Relativity supplemented by a fluid with a small positive sound speed squared (10-42 ≲) c s 2 ≲ 10-20, that could be a promising candidate for the Dark Matter. Despite these advantages, the unavoidable presence of the strong coupling obscures the implementation of the original Hořava's proposal on quantum gravity. Apart from the Hořava-Lifshitz model, conclusions of the present work hold also for the mimetic matter scenario, where the analogue of the projectability condition is achieved by a non-invertible conformal transformation of the metric.

  20. Conductively Cooled Ho:Tm:LuLiF Laser Amplifier

    NASA Technical Reports Server (NTRS)

    Bai, Yingxin; Yu, Jirong; Trieu, Bo; Petros, M.; Petzar, Paul; Lee, Hyung; Singh, U.

    2008-01-01

    A conductively-cooled Ho:Tm:LuLiF laser head can amplify 80mJ/340ns probe pulses into 400mJ when the pump pulse energy is close to amplified spontaneous emission (ASE) threshold, 5.6J. For a small signal, the double-pass amplification exceeds 25.

  1. Registration of ‘Ho 00-961’ sugarcane

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ho 00-961’ (Reg. No., PI) sugarcane (a complex hybrid of Saccharum officinarum L., S. spontaneum L., S. barberi Jeswiet, and S. sinense Roxb. amend. Jeswiet) was selected by the USDA-ARS Sugarcane Research Unit, and evaluated cooperatively with the Louisiana State University Agricultural Center, an...

  2. Programme Note: Realities and Opportunities in Ho Chi Minh City.

    ERIC Educational Resources Information Center

    Franchet, Chi Nguyen

    1996-01-01

    The current status of street children in Ho Chi Minh City, Vietnam, is characterized by marginalization from society through street vending, begging, theft, and prostitution. Evaluation of a drop-in center serving children without family linkages indicates need for needs assessments, follow-up activities, measurement of individual child progress,…

  3. Performance of Ho:YAG as a function of temperature

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Gettemy, Donald J.

    1990-01-01

    The performance of two multiply doped Ho:YAG lasers has been characterized as a function of the laser rod temperature. From the experimental results, the dependence of the slope efficiency and threshold on temperature has been extracted. Threshold can be correlated with the occupation of the lower laser level. Implications on the optimum operating temperature are discussed.

  4. Atomic transition rates for neutral holmium (Ho I)

    NASA Astrophysics Data System (ADS)

    Nave, Gillian

    2003-10-01

    Transition rates for 321 lines between 345 and 1080 nm from 73 levels of Ho I are presented. They have been measured by combining branching fractions obtained by Fourier transform spectrometry with lifetimes of Den Hartog et al. [J. Opt. Soc. Am. B 6, 2278 (1999)]. The uncertainty of the transition rates is 5%-10%.

  5. 2012 Louisiana "Ho" nursery and infield variety trials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three years after selection in the seedling stage of the USDA variety program, superior experimental varieties are assigned permanent “HoCP” or “Ho” numbers. These varieties are then planted in replicated yield trials at SRU’s Ardoyne Farm in Schriever and at the LSU AgCenter’s Iberia Research Stati...

  6. Temperature Dependence of the O + HO2 Rate Coefficient

    NASA Technical Reports Server (NTRS)

    Nicovich, J. M.; Wine, P. H.

    1997-01-01

    A pulsed laser photolysis technique has been employed to investigate the kinetics of the radical-radical reaction O((sup 3)P) + HO2 OH + O2 over the temperature range 266-391 K in 80 Torr of N2 diluent gas. O((sup 3)P) was produced by 248.5-nm KrF laser photolysis of O3 followed by rapid quenching of O(1D) to O((sup 3)P) while HO2 was produced by simultaneous photolysis of H2O2 to create OH radicals which, in turn, reacted with H2O2 to yield HO2. The O((sup 3)P) temporal profile was monitored by using time-resolved resonance fluorescence spectroscopy. The HO2 concentration was calculated based on experimentally measured parameters. The following Arrhenius expression describes our experimental results: k(sub 1)(T) equals (2.91 +/- 0.70) x 10(exp -11) exp[(228 +/- 75)/T] where the errors are 2 sigma and represent precision only. The absolute uncertainty in k, at any temperature within the range 266-391 K is estimated to be +/- 22 percent. Our results are in excellent agreement with a discharge flow study of the temperature dependence of k(sub 1) in 1 Torr of He diluent reported by Keyser, and significantly reduce the uncertainty in the rate of this important stratospheric reaction at subambient temperatures.

  7. Single-frequency lasing of monolithic Ho,Tm:YLF

    NASA Technical Reports Server (NTRS)

    Koch, Grady J.; Deyst, John P.; Storm, Mark E.

    1993-01-01

    Single-frequency lasing in monolithic crystals of holmium-thulium-doped YLF (Ho,Tm:YLF) is reported. A maximum single-frequency output power of 6 mW at a wavelength of 2.05 microns is demonstrated. Frequency tuning is also described.

  8. Low temperature magnetic transitions of single crystal HoBi

    SciTech Connect

    Fente, A.; Suderow, H.; Vieira, S.; Nemes, N. M.; García-Hernández, M.; Bud'ko, S. L.; Canfield, P. C.

    2013-10-01

    We present resistivity, specific heat and magnetization measurements in high quality single crystals of HoBi, with a residual resistivity ratio of 126. We find, from the temperature and field dependence of the magnetization, an antiferromagnetic transition at 5.7 K, which evolves, under magnetic fields, into a series of up to five metamagnetic phases.

  9. 2014 Louisiana "Ho" nursery and infield variety trials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the USDA sugarcane variety program, superior experimental varieties are assigned permanent “HoCP” or “Ho” numbers three years after selection in the seedling stage. These varieties are then planted in replicated yield trials at the Sugarcane Research Unit's (SRU) Ardoyne Farm in Schriever and at ...

  10. Flash-lamp-pumped Ho:Tm:Cr:YAG and Ho:Tm:Er:YLF lasers: experimental results of a single, long pulse length comparison.

    PubMed

    Jani, M G; Barnes, N P; Murray, K E

    1997-05-20

    Flash-lamp-pumped, room-temperature Ho:Tm:Cr:YAG and Ho:Tm:Er:YLF are compared for single but long pulse operation, with pulse lengths of approximately 1.0 mus. Under similar operating conditions in normal-mode operation, a slope efficiency of 0.0331 was observed for Ho:Tm:Er:YLF compared with 0.0047 for Ho:Tm:Cr:YAG. For Q-switched operation, Ho:Tm:Er:YLF yielded a slope efficiency of 0.0075. In comparison, a slope efficiency of 0.0012 was obtained for Ho:Tm:Cr:YAG. Two methods of producing long pulse lengths are compared: pulse selection of normal-mode relaxation oscillations and Q-switching in a long resonator. Theoretical models developed in a companion paper for normal-mode relaxation oscillations and Q-switching in quasi-four-level solid-state lasers are in agreement with the experimental results.

  11. Growth hormone-releasing peptide-biotin conjugate stimulates myocytes differentiation through insulin-like growth factor-1 and collagen type I

    PubMed Central

    Lim, Chae Jin; Jeon, Jung Eun; Jeong, Se Kyoo; Yoon, Seok Jeong; Kwon, Seon Deok; Lim, Jina; Park, Keedon; Kim, Dae Yong; Ahn, Jeong Keun; Kim, Bong-Woo

    2015-01-01

    Based on the potential beneficial effects of growth hormone releasing peptide (GHRP)-6 on muscle functions, a newly synthesized GHRP-6-biotin conjugate was tested on cultured myoblast cells. Increased expression of myogenic marker proteins was observed in GHRP-6-biotin conjugate-treated cells. Additionally, increased expression levels of insulin-like growth factor-1 and collagen type I were observed. Furthermore, GHRP-6-biotin conjugate-treated cells showed increased metabolic activity, as indicated by increased concentrations of energy metabolites, such as ATP and lactate, and increased enzymatic activity of lactate dehydrogenase and creatine kinase. Finally, binding protein analysis suggested few candidate proteins, including desmin, actin, and zinc finger protein 691 as potential targets for GHRP6-biotin conjugate action. These results suggest that the newly synthesized GHRP-6-biotin conjugate has myogenic stimulating activity through, at least in part, by stimulating collagen type I synthesis and several key proteins. Practical applications of the GHRP-6-biotin conjugate could include improving muscle condition. [BMB Reports 2015; 48(9): 501-506] PMID:25644636

  12. Growth hormone-releasing peptide-biotin conjugate stimulates myocytes differentiation through insulin-like growth factor-1 and collagen type I.

    PubMed

    Lim, Chae Jin; Jeon, Jung Eun; Jeong, Se Kyoo; Yoon, Seok Jeong; Kwon, Seon Deok; Lim, Jina; Park, Keedon; Kim, Dae Yong; Ahn, Jeong Keun; Kim, Bong-Woo

    2015-09-01

    Based on the potential beneficial effects of growth hormone releasing peptide (GHRP)-6 on muscle functions, a newly synthesized GHRP-6-biotin conjugate was tested on cultured myoblast cells. Increased expression of myogenic marker proteins was observed in GHRP-6-biotin conjugate-treated cells. Additionally, increased expression levels of insulin-like growth factor-1 and collagen type I were observed. Furthermore, GHRP-6-biotin conjugate-treated cells showed increased metabolic activity, as indicated by increased concentrations of energy metabolites, such as ATP and lactate, and increased enzymatic activity of lactate dehydrogenase and creatine kinase. Finally, binding protein analysis suggested few candidate proteins, including desmin, actin, and zinc finger protein 691 as potential targets for GHRP6-biotin conjugate action. These results suggest that the newly synthesized GHRP-6-biotin conjugate has myogenic stimulating activity through, at least in part, by stimulating collagen type I synthesis and several key proteins. Practical applications of the GHRP-6-biotin conjugate could include improving muscle condition.

  13. Synthesis of a beta-estradiol-biotin chimera that potently heterodimerizes estrogen receptor and streptavidin proteins in a yeast three-hybrid system.

    PubMed

    Hussey, Stephen L; Muddana, Smita S; Peterson, Blake R

    2003-04-02

    Small molecules that dimerize proteins in living cells provide powerful probes of biological processes and have potential as tools for the identification of protein targets of natural products. We synthesized 7-alpha-substituted derivatives of beta-estradiol tethered to the natural product biotin to regulate heterodimerization of estrogen receptor (ER) and streptavidin (SA) proteins expressed as components of a yeast three-hybrid system. Addition of an estradiol-biotin chimera bearing a 19-atom linker to yeast expressing DNA-bound ER-alpha or ER-beta LexA fusion proteins and wild-type SA protein fused to the B42 activation domain activated reporter gene expression by as much as 450-fold in vivo (10 muM ligand). Comparative analysis of lower affinity Y43A (biotin Kd approximately 100 pM) and W120A (biotin Kd approximately 100 nM) mutants of SA indicated that moderate affinity interactions can be readily detected with this system. Comparison of a 7-alpha-substituted estradiol-biotin chimera with a structurally similar dexamethasone-biotin chimera revealed that yeast expressing ER proteins can detect cognate ligands with up to 5-fold greater potency and 70-fold higher activity than yeast expressing analogous glucocorticoid receptor (GR) proteins. This approach may facilitate the identification of protein targets of biologically active small molecules screened against genetically encoded libraries of proteins expressed in yeast three-hybrid systems.

  14. Quantitative measurement of urinary excretion of 3-hydroxyisovaleryl carnitine by LC-MS/MS as an indicator of biotin status in humans.

    PubMed

    Horvath, Thomas D; Stratton, Shawna L; Bogusiewicz, Anna; Owen, Suzanne N; Mock, Donald M; Moran, Jeffery H

    2010-11-15

    Abnormally increased urinary excretion of 3-hydroxyisovaleryl carnitine (3HIA-carnitine) results from impairment in leucine catabolism caused by reduced activity of the biotin-dependent enzyme 3-methylcrotonyl-CoA carboxylase. Accordingly, urinary 3HIA-carnitine might reflect biotin status. Here, we describe an LC-MS/MS method for accurately quantitating the urinary concentration of 3HIA-carnitine at concentrations that are typical for excretion rates that are normal or only modestly increased. This method allows for high sample throughput and does not require solid-phase extraction. We used this method to provide evidence validating urinary 3HIA-carnitine as a biomarker of biotin deficiency in humans. Four healthy adult subjects were successfully made marginally biotin deficient by feeding a 30% egg white diet for 28 days. From study day 0 to 28, the mean urinary excretion of 3HIA-carnitine increased 3.5-fold (p = 0.026). These preliminary results indicate that urinary excretion of 3HIA-carnitine increases with marginal biotin deficiency. If these results are confirmed in studies involving larger numbers of subjects, urinary excretion of 3HIA-carnitine may potentially be a clinically useful indicator of biotin status.

  15. Derivation of hydroperoxyl radical (HO2) levels at an urban site via measurement of pernitric acid (HO2NO2) by iodide chemical ionization mass spectrometry (I(-)-CIMS).

    PubMed

    Chen, Dexian; Huey, L Gregory; Tanner, David J; Li, Jianfeng; Ng, Nga Lee; Wang, Yuhang

    2017-02-17

    Hydroperoxyl radical (HO2) is a key species to atmospheric chemistry. At warm temperatures, the hydroperoxyl radical (HO2) and NO2 come to a rapid steady state with pernitric acid (HO2NO2). This paper presents the derivation of HO2 from observations of HO2NO2 and NO2 in metropolitan Atlanta, US in winter 2014 and summer 2015. HO2 was observed to have a diurnal cycle with morning concentrations suppressed by high NO from the traffic. At night, derived HO2 levels were nonzero and exhibited correlations with O3 and NO3, consistent with previous studies that ozonolysis and oxidation by NO3 are sources of nighttime HO2. Measured and model calculated HO2 were in reasonable agreement: Without the constraint of measured HO2NO2 , the model reproduced HO2 with a model-to-observed ratio (M/O) 1.27 (r = 0.54) for winter, 2014, and 0.70 (r = 0.80) for summer, 2015. Adding measured HO2NO2 as a constraint, the model predicted HO2 with M/O = 1.13 ((r = 0.77) for winter 2014, and 0.90 ((r = 0.97) for summer 2015. These results demonstrate the feasibility of deriving HO2 from HO2NO2 measurements in warm regions where HO2NO2 has a short lifetime.

  16. Relationships between NOS2 and HO-1 in liver of rats with chronic bile duct ligation.

    PubMed

    Flores, Olga; Criado, Manuela; Sánchez-Rodríguez, Angel; Hidalgo, Froilán; Collía, Francisco; López-Novoa, José Miguel; Esteller, Alejandro

    2005-05-01

    An increased expression and activity of the heme oxygenase-1 (HO-1) in the liver has been observed in models of hepatic damage. Nitric oxide (NO) seems to be involved in HO-1 regulation. The aim of this work is to assess HO-1 induction and heme oxygenase (HO) activity in rats with bile duct ligation (BDL). We have assessed the effect of chronic inhibition of the NO synthesis by N(G)-nitro-l-arginine methyl ester (l-NAME) on HO-1 induction and HO activity. In the BDL animals, compared with sham-operated ones, we found an increased plasma nitrite and bilirubin concentration, and a marked liver expression of inducible nitric oxide synthase and HO-1, assessed by both Western blot and immunohistochemistry. Chronic l-NAME treatment prevented plasma nitrite increase in animals subjected to BDL. BDL animals treated with l-NAME, compared with untreated BDL rats, showed an important decrease in HO-1 expression and in HO activity (assessed as a decreased plasma bilirubin and bilirubin excretion). In conclusion, our experiments show parallel changes in expression and activity of HO-1 and NOS2 activity in the BDL model of liver damage and suggest that increased NO production is involved in HO-1 overexpression.

  17. HO(x) Measurements in PEM Tropics B with the Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS)

    NASA Technical Reports Server (NTRS)

    Brune, William H.

    2001-01-01

    The primary objective of PEM Tropics B was to study the processes responsible for the production and loss of tropospheric ozone over the tropical Pacific. This region of the globe contains very clean air as well as aged, polluted air that was advected from both the Asian and American continents. Understanding ozone requires understanding of HO(x) (HO(x) = OH + HO2) chemistry, since the reaction between H02 and NO leads to ozone production and the production of OH often requires ozone loss. In addition, OH is the atmosphere's primary oxidant. Since most atmospheric oxidation is thought to occur in the tropical lower troposphere, measurements during PEM Tropics B should provide an important test of the OH abundances and distributions. Thus, understanding and thoroughly testing HO(x) processes was an important objective of PEM Tropics B. Several issues need to be tested, One is HO, production rates and sources, since HO,, production directly affects ozone production and loss. Another is HO(x) behavior in and around clouds, since HO(x) is lost to cloud particles, but convection may bring HO(x) precursors from near the surface to the upper troposphere. A third is the rise and fall of HO(x) at sunrise and sunset, since these variations give strong indications of the important sources and sinks of HO(x). Making and interpreting high-quality OH and H02 measurements from the NASA DC-8 during PEM Tropics B is the objective of this research effort.

  18. Reproductive performance and oviductal expression of avidin and avidin-related protein-2 in young and old broiler breeder hens orally exposed to supplementary biotin.

    PubMed

    Daryabari, H; Akhlaghi, A; Zamiri, M J; Mianji, G Rahimi; Pirsaraei, Z Ansari; Deldar, H; Eghbalian, A N

    2014-09-01

    Published data on the probable involvement of avidin and avidin-related protein-2 (AVR2) in sustaining sperm viability in sperm storage tubules in 38-wk-old turkeys, and the high affinity of avidin or its analogs to biotin suggest that supplementary biotin may increase oviductal avidin and AVR2 expression, thereby attenuating the adverse effect of aging on hen reproductive performance. Broiler breeder hens (n = 120) were randomly assigned to receive 0 (T0), 0.30 (T1), or 0.45 (T2) mg of biotin/L of drinking water from 30 to 33 (young) and 53 to 56 (old) wk of age, and artificially inseminated to determine their reproductive performance. At the end of each period of biotin administration, 8 hens from each treatment group were killed for RNA extraction from the uterovaginal junction. Egg production was lower in the old hens (44%) compared with the young ones (82%), and biotin supplementation increased egg production only in the latter. Administering supplementary biotin to young hens increased their oviductal expression of AVR2, which was much higher in the old hens (1.0 and 4.6 for young and old groups, respectively). Fertility rate was not different between young and old hens, and was increased (4.4%) at the higher level of biotin supplementation. Hatchability and hatchling quality were not affected by biotin supplementation. Embryonic mortality between 17 to 21 d of incubation was higher in young (5.2%) compared with old (1.4%) birds. Egg fertility rate showed a moderate correlation (P < 0.05) with avidin (r = 0.59) and AVR2 (r = 0.55) expression in the young-age group, and very low correlations in old-age group (0.04 and 0.17). Regardless of the hen's age, the correlation coefficient of hatchability with avidin or AVR2 expression was very low (-0.16 and 0.18). Overall, the effect of biotin supplementation on AVR2 expression, and the relationship between biotin administration and oviductal expression of avidin and AVR2 was dependent on the hen's age, being higher

  19. Nuclear spectroscopy above isomers in {sub 67}{sup 148}Ho{sub 81} and {sub 67}{sup 149}Ho{sub 82} nuclei: Search for core-excited states in {sup 149}Ho

    SciTech Connect

    Kownacki, J.; Napiorkowski, P. J.; Zielinska, M.; Kordyasz, A.; Srebrny, J.; Droste, Ch.; Morek, T.; Grodner, E.; Ruchowska, E.; Korman, A.; Czarnacki, W.; Kisielinski, M.; Kowalczyk, M.; Wrzosek-Lipska, K.; Hadynska-KlePk, K.; Mierzejewski, J.; Lieder, R. M.; Perkowski, J.; Andrzejewski, J.; Krol, A.

    2010-04-15

    The excited states of {sup 148}Ho and {sup 149}Ho isotopes are studied using gamma-ray and electron spectroscopy in off-beam and in-beam modes following {sup 112,114}Sn({sup 40}Ar,xnyp) reactions. Experiments include measurements of single gamma-rays and conversion electron spectra as well as gamma-gamma, electron-gamma, gamma-t, and gamma-gamma-t coincidences with the use of the OSIRIS-II 12-HPGe array and conversion electron spectrometer. Based on the present results, the level schemes of {sup 148}Ho and {sup 149}Ho are revised and significantly extended, up to about 4 and 5 MeV of excitation energy, respectively. Spin and parity of 5{sup -} are assigned to the 9.59-s isomer in {sup 148}Ho based on conversion electron results. Previously unobserved gamma rays feeding the 10{sup +} isomer in {sup 148}Ho and the 27/2{sup -} isomer in {sup 149}Ho nuclei are proposed. Shell-model calculations are performed. Possible core-excited states in {sup 149}Ho are discussed.

  20. Cluster-size dependent internal dynamics and magnetic anisotropy of Ho ions in HoM2N@C80 and Ho2MN@C80 families (M = Sc, Lu, Y)

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Krylov, D.; Schiemenz, S.; Rosenkranz, M.; Westerström, R.; Dreiser, J.; Greber, T.; Büchner, B.; Popov, A. A.

    2014-09-01

    The paramagnetic NMR study of HoM2N@C80-Ih and Ho2MN@C80-Ih nitride cluster fullerenes (M = Sc, Lu, Y) reveals strong dependence of Ho-induced paramagnetic shifts (δpara) in 13C NMR spectra on the size of the diamagnetic metal in the cluster. In particular, the δpara value in HoY2N@C80 is almost doubled in comparison to that in HoSc2N@C80. X-ray magnetic circular dichroism studies show that all Ho-nitride cluster fullerenes have the same magnetic ground state of Ho3+. Point-charge ligand-field splitting calculations show that the increase of the M3+ radius in going from Sc to Y results in a considerable increase of the energy splitting between different Jz states. This leads to a 19% higher magnetic anisotropy of Ho3+ in HoY2N@C80 than in HoSc2N@C80 at 300 K. Variations of the molecular geometry and cluster dynamics with the size of the cluster are found to have even greater influence on δpara values. This work shows that the magnetic properties of the species confined inside the fullerene cages can be tuned using the geometrical factors such as the cluster and the cage size.The paramagnetic NMR study of HoM2N@C80-Ih and Ho2MN@C80-Ih nitride cluster fullerenes (M = Sc, Lu, Y) reveals strong dependence of Ho-induced paramagnetic shifts (δpara) in 13C NMR spectra on the size of the diamagnetic metal in the cluster. In particular, the δpara value in HoY2N@C80 is almost doubled in comparison to that in HoSc2N@C80. X-ray magnetic circular dichroism studies show that all Ho-nitride cluster fullerenes have the same magnetic ground state of Ho3+. Point-charge ligand-field splitting calculations show that the increase of the M3+ radius in going from Sc to Y results in a considerable increase of the energy splitting between different Jz states. This leads to a 19% higher magnetic anisotropy of Ho3+ in HoY2N@C80 than in HoSc2N@C80 at 300 K. Variations of the molecular geometry and cluster dynamics with the size of the cluster are found to have even greater influence on

  1. Itinerant and Localized Magnetization Dynamics in Antiferromagnetic Ho

    NASA Astrophysics Data System (ADS)

    Rettig, L.; Dornes, C.; Thielemann-Kühn, N.; Pontius, N.; Zabel, H.; Schlagel, D. L.; Lograsso, T. A.; Chollet, M.; Robert, A.; Sikorski, M.; Song, S.; Glownia, J. M.; Schüßler-Langeheine, C.; Johnson, S. L.; Staub, U.

    2016-06-01

    Using femtosecond time-resolved resonant magnetic x-ray diffraction at the Ho L3 absorption edge, we investigate the demagnetization dynamics in antiferromagnetically ordered metallic Ho after femtosecond optical excitation. Tuning the x-ray energy to the electric dipole (E 1 , 2 p →5 d ) or quadrupole (E 2 , 2 p →4 f ) transition allows us to selectively and independently study the spin dynamics of the itinerant 5 d and localized 4 f electronic subsystems via the suppression of the magnetic (2 1 3 -τ ) satellite peak. We find demagnetization time scales very similar to ferromagnetic 4 f systems, suggesting that the loss of magnetic order occurs via a similar spin-flip process in both cases. The simultaneous demagnetization of both subsystems demonstrates strong intra-atomic 4 f -5 d exchange coupling. In addition, an ultrafast lattice contraction due to the release of magneto-striction leads to a transient shift of the magnetic satellite peak.

  2. Itinerant and Localized Magnetization Dynamics in Antiferromagnetic Ho.

    PubMed

    Rettig, L; Dornes, C; Thielemann-Kühn, N; Pontius, N; Zabel, H; Schlagel, D L; Lograsso, T A; Chollet, M; Robert, A; Sikorski, M; Song, S; Glownia, J M; Schüßler-Langeheine, C; Johnson, S L; Staub, U

    2016-06-24

    Using femtosecond time-resolved resonant magnetic x-ray diffraction at the Ho L_{3} absorption edge, we investigate the demagnetization dynamics in antiferromagnetically ordered metallic Ho after femtosecond optical excitation. Tuning the x-ray energy to the electric dipole (E1, 2p→5d) or quadrupole (E2, 2p→4f) transition allows us to selectively and independently study the spin dynamics of the itinerant 5d and localized 4f electronic subsystems via the suppression of the magnetic (2 1 3-τ) satellite peak. We find demagnetization time scales very similar to ferromagnetic 4f systems, suggesting that the loss of magnetic order occurs via a similar spin-flip process in both cases. The simultaneous demagnetization of both subsystems demonstrates strong intra-atomic 4f-5d exchange coupling. In addition, an ultrafast lattice contraction due to the release of magneto-striction leads to a transient shift of the magnetic satellite peak.

  3. The uptake of HO2 radicals to organic aerosols

    NASA Astrophysics Data System (ADS)

    Matthews, Pascale; Krapf, Manuel; Dommen, Josef; George, Ingrid; Whalley, Lisa; Ingham, Trevor; Baeza-Romero, Maria Teresa; Ammann, Markus; Heard, Dwayne

    2014-05-01

    HOx (OH + HO2) radicals are responsible for the majority of the oxidation in the troposphere and control the concentrations of many trace species in the atmosphere. There have been many field studies where the measured HO2 concentrations have been smaller than the concentration predicted by model calculations [1,2]. The difference has often been attributed to HO2 uptake by aerosols. Organics are a major component of aerosols accounting for 10 - 70 % of their mass [3]. However, there have been very few laboratory studies measuring HO2 uptake onto organic aerosols [4]. Uptake coefficients (γ) were measured for a range of aerosols using a Fluorescence Assay By Gas Expansion (FAGE) detector combined with an aerosol flow tube. HO2 was injected into the flow tube using a moveable injector which allowed first order HO2 decays to be measured along the flow tube both with and without aerosols. Laboratory generated aerosols were made using an atomiser or by homogeneous nucleation. Secondary organic aerosols (SOA) were made using the Paul Scherrer Institute smog chamber and also by means of a Potential Aerosol Mass (PAM) chamber. The total aerosol surface area was then measured using a Scanning Mobility Particle Sizer (SMPS). Experiments were carried out on aerosols containing glutaric acid, glyoxal, malonic acid, stearic acid, oleic acid and squalene. The HO2 uptake coefficients for these species were measured in the range of γ < 0.004 to γ = 0.008 ± 0.004. Humic acid was also studied, however, much larger uptake coefficients (γ = 0.007 - 0.09) were measured, probably due to the fact that these aerosols contained elevated levels of transition metal ions. For humic acid the uptake coefficient was highly dependent on humidity and this may be explained by the liquid water content of the aerosols. Measurements were also performed on copper doped aerosols containing different organics. An uptake coefficient of 0.23 ± 0.07 was measured for copper doped ammonium sulphate

  4. Novel imidazole derivatives as heme oxygenase-1 (HO-1) and heme oxygenase-2 (HO-2) inhibitors and their cytotoxic activity in human-derived cancer cell lines.

    PubMed

    Salerno, Loredana; Pittalà, Valeria; Romeo, Giuseppe; Modica, Maria N; Marrazzo, Agostino; Siracusa, Maria A; Sorrenti, Valeria; Di Giacomo, Claudia; Vanella, Luca; Parayath, Neha N; Greish, Khaled

    2015-01-01

    Heme oxygenase (HO) is a cytoprotective enzyme that can be overexpressed in some pathological conditions, including certain cancers. In this work, novel imidazole derivatives were designed and synthesized as inhibitors of heme oxygenase-1 (HO-1) and heme oxygenase-2 (HO-2). In these compounds the imidazole ring, crucial for the activity, is connected to a hydrophobic group, represented by aryloxy, benzothiazole, or benzoxazole moieties, by means of alkyl or thioalkyl chains of different length. Many of the tested compounds were potent and/or selective against one of the two isoforms of HO. Furthermore, most of the pentyl derivatives showed to be better inhibitors of HO-2 with respect to HO-1, revealing a critical role of the alkyl chain in discriminating between the two isoenzymes. Compounds which showed the better profile of HO inhibition were selected and tested to evaluate their cytotoxic properties in prostate and breast cancer cell lines (DU-145, PC3, LnCap, MDA-MB-231, and MCF-7). In these assays, aryloxyalkyl derivatives resulted more cytotoxic than benzothiazolethioalkyl ones; in particular compound 31 was active against all the cell lines tested, confirming the anti-proliferative properties of HO inhibitors and their potential use in the treatment of specific cancers.

  5. Isolation of 163Ho from dysprosium target material by HPLC for neutrino mass measurements

    DOE PAGES

    Mocko, Veronika; Taylor, Wayne  A.; Nortier, Francois M.; ...

    2015-04-29

    The rare earth isotope 163Ho is of interest for neutrino mass measurements. This report describes the isolation of 163Ho from a proton-irradiated dysprosium target and its purification. A Dy metal target was irradiated with 16 MeV protons for 10 h. After target dissolution, 163Ho was separated from the bulk Dy via cation-exchange high performance liquid chromatography using 70 mmol dm–3 α-hydroxyisobutyric acid as the mobile phase. Subsequent purification of the collected Ho fraction was performed to remove the α-hydroxyisobutyrate chelating agent and to concentrate the Ho in a low ionic strength aqueous matrix. The final solution was characterized by MC-ICP-MSmore » to determine the 163Ho/165Ho ratio, 163Ho and the residual Dy content. The HPLC purification process resulted in a decontamination factor 1.4E5 for Dy. As a result, the isolated Ho fraction contained 24.8 ±1.3 ng of 163Ho corresponding to holmium recovery of 72 ± 3%.« less

  6. Sex-Dependent Effects of HO-1 Deletion from Adipocytes in Mice

    PubMed Central

    Hosick, Peter A.; Weeks, Mary Frances; Hankins, Michael W.; Moore, Kyle H.; Stec, David E.

    2017-01-01

    Induction of heme oxygenase-1 (HO-1) has been demonstrated to decrease body weight and improve insulin sensitivity in several models of obesity in rodents. To further study the role of HO-1 in adipose tissue, we created an adipose-specific HO-1 knockout mouse model. Male and female mice were fed either a control or a high-fat diet for 30 weeks. Body weights were measured weekly and body composition, fasting blood glucose and insulin levels were determined every six weeks. Adipocyte-specific knockout of HO-1 had no significant effect on body weight in mice fed a high-fat diet but increased body weight in female mice fed a normal-fat diet. Although body weights were not different in females fed a high fat diet, loss of HO-1 in adipocytes resulted in significant alterations in body composition. Adipose-specific HO-1 knockout resulted in increased fasting hyperglycemia and insulinemia in female but not male mice on both diets. Adipose-specific knockout of HO-1 resulted in a significant loss of HO activity and a decrease in the protein levels of adiponectin in adipose tissue. These results demonstrate that loss of HO-1 in adipocytes has greater effects on body fat and fasting hyperglycemia in a sex-dependent fashion and that expression of HO-1 in adipose tissue may have a greater protective role in females as compared to males. PMID:28287466

  7. Identical gamma-vibrational bands in {sup 165}Ho

    SciTech Connect

    Radford, D.C.; Galindo-Uribarri, A.; Janzen, V.P.

    1996-12-31

    The structure of {sup 165}Ho at moderate spins has been investigated by means of Coulomb excitation. Two {gamma}-vibrational bands (K{sup {pi}} = 11/2{sup {minus}} and K{sup {pi}} = 3/2{sup {minus}}) are observed, with very nearly identical in-band {gamma}-ray energies. Gamma-ray branching ratios are analyzed to extract information on Coriolis mixing, and the role of the K quantum number in identical bands is discussed.

  8. Smart Ho:YAG laser lithotriptor using optical correlation

    NASA Astrophysics Data System (ADS)

    Kokaj, Jahja O.; Marafi, Mustafa A.; Makdisi, Yacob; Bhatia, Kuldip S.; Mathew, K. J.; Caka, Nebi; Hasani, Rexhep

    1998-03-01

    Ultra fast imaging and destruction of the gall bladder stone is performed using Ho:YAG laser. A laser guided approach for lithotropsy is proposed. The correlation output peak is introduced as a feedback signal for firing the laser pulse for stone destruction and 'discrimination' of the tissue image so that the risk of damaging and perforation of the tissue is reduced. A system constituted by correlation of ballistic images and fluorescent signals is proposed.

  9. The uptake of HO2 on meteoric smoke analogues

    NASA Astrophysics Data System (ADS)

    James, Alexander D.; Moon, Daniel R.; Feng, Wuhu; Lakey, Pascale S. J.; Frankland, Victoria L.; Heard, Dwayne E.; Plane, John M. C.

    2017-01-01

    The kinetics of heterogeneous HO2 uptake onto meteoric smoke particles (MSPs) has been studied in the laboratory using analogues of MSP aerosol entrained into a flow tube. The uptake coefficient, γ, was determined on synthetic amorphous olivine (MgFeSiO4) to be (6.9 ± 1.2) × 10-2 at a relative humidity (RH) of 10%. On forsterite (Mg2SiO4), γ = (4.3 ± 0.4) × 10-3 at RH = 11.6% and (7.3 ± 0.4) × 10-2 at RH = 9.9% on fayalite (Fe2SiO4). These results indicate that Fe plays a more important mechanistic role than Mg in the removal of HO2 from the gas phase. Electronic structure calculations show that Fe atoms exposed at the particle surface provide a catalytic site where HO2 is converted to H2O2 via an Eley-Rideal mechanism, but this does not occur on exposed surface Mg atoms. The impact of this heterogeneous process in the middle atmosphere was then investigated using a whole atmosphere chemistry-climate model which incorporates a microphysical treatment of MSPs. Using a global MSP production rate from meteoric ablation of 44 t/day, heterogeneous uptake (with γ = 0.2) on MSPs significantly alters the HOx budget in the nighttime polar vortex. This impact is highly latitude dependent and thus could not be confirmed using currently available satellite measurements of HO2, which are largely unavailable at latitudes greater than 70°.

  10. Yb3+/Ho3+-codoped antimony-silicate optical fiber

    NASA Astrophysics Data System (ADS)

    Żmojda, Jacek; Dorosz, Dominik; Kochanowicz, Marcin; Miluski, Piotr; Dorosz, Jan

    2012-05-01

    The emission properties of Yb3+/Ho3+-codoped antimony-silicate optical fiber has been investigated. Luminescence at 2.1 μm corresponding to 5I7--> 5I8 transition in holmium was obtained by energy transfer between Yb3+ and Ho3+ ions. According to the Dexter-Miyakawa model, the parameters of energy migration CDD of the 2F5/2 (Yb3+) <--> 2F5/2 (Yb3+) transition and direct energy transfer CDA of the 2F5/2 (Yb3+) --> 5I6 (Ho3+) transition was calculated. The optimization of the activator content and the concentration ratio were conducted with the purpose of maximizing the efficiency of energy transfer. It made possible to select best-suited glass which was used to manufacture double-clad optical fiber. Strong and narrow bands of spontaneous emission which formed as a result of energy transfer between ytterbium and holmium ions were observed in the fiber under exciting with radiation at 978 nm wavelength.

  11. Yb3+/Ho3+-codoped antimony-silicate optical fiber

    NASA Astrophysics Data System (ADS)

    Żmojda, Jacek; Dorosz, Dominik; Kochanowicz, Marcin; Miluski, Piotr; Dorosz, Jan

    The emission properties of Yb3+/Ho3+-codoped antimony-silicate optical fiber has been investigated. Luminescence at 2.1 μm corresponding to 5I7--> 5I8 transition in holmium was obtained by energy transfer between Yb3+ and Ho3+ ions. According to the Dexter-Miyakawa model, the parameters of energy migration CDD of the 2F5/2 (Yb3+) <--> 2F5/2 (Yb3+) transition and direct energy transfer CDA of the 2F5/2 (Yb3+) --> 5I6 (Ho3+) transition was calculated. The optimization of the activator content and the concentration ratio were conducted with the purpose of maximizing the efficiency of energy transfer. It made possible to select best-suited glass which was used to manufacture double-clad optical fiber. Strong and narrow bands of spontaneous emission which formed as a result of energy transfer between ytterbium and holmium ions were observed in the fiber under exciting with radiation at 978 nm wavelength.

  12. Effects of Biotin Supplementation in the Diet on Adipose Tissue cGMP Concentrations, AMPK Activation, Lipolysis, and Serum-Free Fatty Acid Levels.

    PubMed

    Boone-Villa, Daniel; Aguilera-Méndez, Asdrubal; Miranda-Cervantes, Adriana; Fernandez-Mejia, Cristina

    2015-10-01

    Several studies have shown that pharmacological concentrations of biotin decrease hyperlipidemia. The molecular mechanisms by which pharmacological concentrations of biotin modify lipid metabolism are largely unknown. Adipose tissue plays a central role in lipid homeostasis. In the present study, we analyzed the effects of biotin supplementation in adipose tissue on signaling pathways and critical proteins that regulate lipid metabolism, as well as on lipolysis. In addition, we assessed serum fatty acid concentrations. Male BALB/cAnN Hsd mice were fed a control or a biotin-supplemented diet (control: 1.76 mg biotin/kg; supplemented: 97.7 mg biotin/kg diet) over 8 weeks postweaning. Compared with the control group, biotin-supplemented mice showed an increase in the levels of adipose guanosine 3',5'-cyclic monophosphate (cGMP) (control: 30.3±3.27 pmol/g wet tissue; supplemented: 49.5±3.44 pmol/g wet tissue) and of phosphorylated forms of adenosine 5'-monophosphate-activated protein kinase (AMPK; 65.2%±1.06%), acetyl-coenzyme A (CoA), carboxylase-1 (196%±68%), and acetyl-CoA carboxylase-2 (78.1%±18%). Serum fatty acid concentrations were decreased (control: 1.12±0.04 mM; supplemented: 0.91±0.03 mM), and no change in lipolysis was found (control: 0.29±0.05 μmol/mL; supplemented: 0.33±0.08 μmol/mL). In conclusion, 8 weeks of dietary biotin supplementation increased adipose tissue cGMP content and protein expression of the active form of AMPK and of the inactive forms of acetyl-CoA carboxylase-1 and acetyl-CoA carboxylase-2. Serum fatty acid levels fell, and no change in lipolysis was observed. These findings provide insight into the effects of biotin supplementation on adipose tissue and support its use in the treatment of dyslipidemia.

  13. Degradation of poly(3-hydroxyoctanoic acid) [P(3HO)] by bacteria: Purification and properties of a P(3HO) depolymerase from Pseudomonas fluorescens GK13

    SciTech Connect

    Schirmer, A.; Jendrossek, D.; Schlegel, H.G. )

    1993-04-01

    Poly(3-hydroxyoctanoic acid)[P(3HO)] and other poly(hydroxyalkanoic acids) PHA are widespread bacterial storage compounds of carbon and reducing power. They are biodegradable to carbon dioxide and water, and both aerobic and anaerobic P(3HB)-degradable bacteria are widely distributed in various ecosytems: soil, activated sludge, lake water and air, sea water, estuarine sediment, and anaerobic sewage sludge. This study describes the isolation and characterization of P(3HO) degrading bacteria: Alcaligenes eutrophus, Comamonas violaceum, Pseudomonas citronellolis, and P. fluorescenes (2 strains). The authors also describe purified P(3HO) depolymerase and compared it to PHB and PHA deploymerases. P(3HO) depolymerase activity was found not only in the sulture supernatant but also in the soluble fraction and membrane fractions of P(3HO) grown cells.39 refs.,5 figs.,3 tabs.

  14. A simple and rapid ultra-high-performance liquid chromatography-tandem mass spectrometry method to determine plasma biotin in hemodialysis patients.

    PubMed

    Yagi, Shigeaki; Nishizawa, Manabu; Ando, Itiro; Oguma, Shiro; Sato, Emiko; Imai, Yutaka; Fujiwara, Masako

    2016-08-01

    A simple, rapid, and selective method for determination of plasma biotin was developed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). After single-step protein precipitation with methanol, biotin and stable isotope-labeled biotin as an internal standard (IS) were chromatographed on a pentafluorophenyl stationary-phase column (2.1 × 100 mm, 2.7 μm) under isocratic conditions using 10 mm ammonium formate-acetonitrile (93:7, v/v) at a flow rate of 0.6 mL/min. The total chromatographic runtime was 5 min for each injection. Detection was performed in a positive electrospray ionization mode by monitoring selected ion transitions at m/z 245.1/227.0 and 249.1/231.0 for biotin and the IS, respectively. The calibration curve was linear in the range of 0.05-2 ng/mL using 300 μL of plasma. The intra- and inter-day precisions were all <7.1%. The accuracy varied from -0.7 to 8.2%. The developed UHPLC-MS/MS method was successfully applied to determine plasma biotin concentrations in hemodialysis patients. Copyright © 2016 John Wiley & Sons, Ltd.

  15. Y-shaped biotin-conjugated poly (ethylene glycol)-poly (epsilon-caprolactone) copolymer for the targeted delivery of curcumin.

    PubMed

    Zhu, Wenxia; Song, Zhimei; Wei, Peng; Meng, Ning; Teng, Fangfang; Yang, Fengying; Liu, Na; Feng, Runliang

    2015-04-01

    In order to improve curcumin's low water-solubility and selective delivery to cancer, we reported ligand-mediated micelles based on a Y-shaped biotin-poly (ethylene glycol)-poly (epsilon-caprolactone)2 (biotin-PEG-PCL2) copolymer. Its structure was characterized by (1)H NMR. The blank and drug-loaded micelles obtained by way of thin-film hydration were characterized by dynamic light scattering, X-ray diffraction, infrared spectroscopy and hemolytic test. Curcumin was loaded into micelles with a high encapsulating efficiency (93.83%). Curcumin's water-solubility was enhanced 170,400 times higher than free curcumin. Biotin-PEG-PCL2 micelles showed slower drug release in vitro than H2N-PEG-PCL2 micelles. In vitro cellular uptake and cytotoxicity tests showed that higher dosage of curcumin might overcome the effect of slow release on cytotoxicities because of its higher uptake induced by biotin, resulting in higher anticancer activities against MDA-MB-436 cells. In brief, Y-shaped biotin-PEG-PCL2 is a promising delivery carrier for anticancer drug.

  16. Efficient production of α-ketoglutarate in the gdh deleted Corynebacterium glutamicum by novel double-phase pH and biotin control strategy.

    PubMed

    Li, Yanjun; Sun, Lanchao; Feng, Jia; Wu, Ruifang; Xu, Qingyang; Zhang, Chenglin; Chen, Ning; Xie, Xixian

    2016-06-01

    Production of L-glutamate using a biotin-deficient strain of Corynebacterium glutamicum has a long history. The process is achieved by controlling biotin at suboptimal dose in the initial fermentation medium, meanwhile feeding NH4OH to adjust pH so that α-ketoglutarate (α-KG) can be converted to L-glutamate. In this study, we deleted glutamate dehydrogenase (gdh1 and gdh2) of C. glutamicum GKG-047, an L-glutamate overproducing strain, to produce α-KG that is the direct precursor of L-glutamate. Based on the method of L-glutamate fermentation, we developed a novel double-phase pH and biotin control strategy for α-KG production. Specifically, NH4OH was added to adjust the pH at the bacterial growth stage and NaOH was used when the cells began to produce acid; besides adding an appropriate amount of biotin in the initial medium, certain amount of additional biotin was supplemented at the middle stage of fermentation to maintain a high cell viability and promote the carbon fixation to the flux of α-KG production. Under this control strategy, 45.6 g/L α-KG accumulated after 30-h fermentation in a 7.5-L fermentor and the productivity and yield achieved were 1.52 g/L/h and 0.42 g/g, respectively.

  17. Biotin deficiency in a glycogen storage disease type 1b girl fed only with glycogen storage disease-related formula.

    PubMed

    Ihara, Kenji; Abe, Kiyomi; Hayakawa, Kou; Makimura, Mika; Kojima-Ishii, Kanako; Hara, Toshiro

    2011-01-01

    Glycogen storage disease type I is an autosomal recessive disorder caused by the defect in the glucose-6-phosphate enzyme system. Frequent intake of glucose-containing glycogen storage disease formula, uncooked cornstarch, or both, are usually needed to maintain normal blood glucose level. We report a glycogen storage disease type 1b girl with biotin deficiency caused by an exclusive glucose-containing glycogen storage disease formula for years, presenting with the appearance of severe skin lesions, and diagnosed by urinary organic acid analysis by gas chromato-spectrometry, and blood acylcarnitine analysis by tandem mass-spectrometry.

  18. Kinetics of HO2 + HO2 -> H2O2 + O2: Implications for Stratospheric H2O2

    NASA Astrophysics Data System (ADS)

    Christensen, L. E.; Okumura, M.; Sander, S. P.; Salawitch, R. J.; Toon, G. C.; Sen, B.; Blavier, J.-F.; Jucks, K. W.

    2002-05-01

    The reaction HO2 + HO2 -> H2O2 + O2(1) has been studied at 100 Torr and 222 K to 295 K. Experiments employing photolysis of Cl2/CH3OH/O2/N2 and F2/H2/O2/N2 gas mixtures to produce HO2 confirmed that methanol enhanced the observed reaction rate. At 100 Torr, zero methanol, k1 = (8.8 +/- 0.9) 10-13 × exp[(210 +/- 26)/T] cm3 molecule-1 s-1 (2σ uncertainties), which agrees with current recommendations at 295 K but is nearly 2 times slower at 231 K. The general expression for k1, which includes the dependence on bath gas density, is k1 = (1.5 +/- 0.2) × 10-12 × exp[(19 +/- 31)/T] + 1.7 × 10-33 × [M] × exp[1000/T], where the second term is taken from the JPL00-3 recommendation. The revised rate largely accounts for a discrepancy between modeled and measured [H2O2] in the lower to middle stratosphere.

  19. High-power and highly efficient diode-cladding-pumped Ho3+-doped silica fiber lasers.

    PubMed

    Jackson, Stuart D; Bugge, Frank; Erbert, Götz

    2007-11-15

    We demonstrate high-power operation from a singly Ho3+-doped silica fiber laser that is cladding pumped directly with diode lasers operating at 1150 nm. Internal slope efficiencies approaching the Stokes limit were produced, and the maximum output power was 2.2W. This result was achieved using a low Ho3+-ion concentration and La3+-ion codoping, which together limit the transfer of energy between excited Ho3+ ions.

  20. Preferential labeling of alpha-amino N-terminal groups in peptides by biotin: application to the detection of specific anti-peptide antibodies by enzyme immunoassays.

    PubMed

    Sélo, I; Négroni, L; Créminon, C; Grassi, J; Wal, J M

    1996-12-15

    Experimental conditions (pH 6.5, 24 h reaction, peptide:biotin ratio 1:5) were defined for preferential incorporation of the biotin molecule in the N-terminal alpha-amino group of peptides. This strategy could be helpful in numerous applications when an entire peptide chain must remain accessible for antibody or receptor binding. We illustrate this advantage in a solid-phase enzyme immunoassay designed to detect antibodies specific for bovine beta-lactoglobulin present in rabbit or human sera. This test involves synthetic peptides biotinylated in different positions and immobilized on a solid phase. The use of biotin/streptavidin interactions permitted more efficient detection of specific anti-peptide antibodies than solid phases prepared using conventional passive-adsorption techniques. The highest levels of antibody binding were measured when biotinylation occurred at the N-terminal extremity of immobilized peptides.

  1. Dimerization of the Bacterial Biotin Carboxylase Subunit Is Required for Acetyl Coenzyme A Carboxylase Activity In Vivo

    PubMed Central

    Smith, Alexander C.

    2012-01-01

    Acetyl coenzyme A (acteyl-CoA) carboxylase (ACC) is the first committed enzyme of the fatty acid synthesis pathway. Escherichia coli ACC is composed of four different proteins. The first enzymatic activity of the ACC complex, biotin carboxylase (BC), catalyzes the carboxylation of the protein-bound biotin moiety of another subunit with bicarbonate in an ATP-dependent reaction. Although BC is found as a dimer in cell extracts and the carboxylase activities of the two subunits of the dimer are interdependent, mutant BC proteins deficient in dimerization are reported to retain appreciable activity in vitro (Y. Shen, C. Y. Chou, G. G. Chang, and L. Tong, Mol. Cell 22:807–818, 2006). However, in vivo BC must interact with the other proteins of the complex, and thus studies of the isolated BC may not reflect the intracellular function of the enzyme. We have tested the abilities of three BC mutant proteins deficient in dimerization to support growth and report that the two BC proteins most deficient in dimerization fail to support growth unless expressed at high levels. In contrast, the wild-type protein supports growth at low expression levels. We conclude that BC must be dimeric to fulfill its physiological function. PMID:22037404

  2. A photo-cleavable biotin affinity tag for the facile release of a photo-crosslinked carbohydrate-binding protein.

    PubMed

    Chang, Tsung-Che; Adak, Avijit K; Lin, Ting-Wei; Li, Pei-Jhen; Chen, Yi-Ju; Lai, Chain-Hui; Liang, Chien-Fu; Chen, Yu-Ju; Lin, Chun-Cheng

    2016-03-15

    The use of photo-crosslinking glycoprobes represents a powerful strategy for the covalent capture of labile protein complexes and allows detailed characterization of carbohydrate-mediated interactions. The selective release of target proteins from solid support is a key step in functional proteomics. We envisaged that light activation can be exploited for releasing labeled protein in a dual photo-affinity probe-based strategy. To investigate this possibility, we designed a trifunctional, galactose-based, multivalent glycoprobe for affinity labeling of carbohydrate-binding proteins. The resulting covalent protein-probe adduct is attached to a photo-cleavable biotin affinity tag; the biotin moiety enables specific presentation of the conjugate on streptavidin-coated beads, and the photolabile linker allows the release of the labeled proteins. This dual probe promotes both the labeling and the facile cleavage of the target protein complexes from the solid surfaces and the remainder of the cell lysate in a completely unaltered form, thus eliminating many of the common pitfalls associated with traditional affinity-based purification methods.

  3. A flexible mouse-on-mouse immunohistochemical staining technique adaptable to biotin-free reagents, immunofluorescence, and multiple antibody staining.

    PubMed

    Goodpaster, Tracy; Randolph-Habecker, Julie

    2014-03-01

    Immunohistochemistry on mouse tissue utilizing mouse monoclonal antibodies presents a challenge. Secondary antibodies directed against the mouse monoclonal primary antibody of interest will also detect endogenous mouse immunoglobulin in the tissue. This can lead to significant spurious staining. Therefore, a "mouse-on-mouse" staining strategy is needed to yield credible data. This paper presents a method that is easy to use and highly flexible to accommodate both an avidin-biotin detection system as well as a biotin-free polymer detection system. The mouse primary antibody is first combined with an Fab fragment of an anti-mouse antibody in a tube and allowed sufficient time to form an antibody complex. Any non-complexed secondary antibody is bound up with mouse serum. The mixture is then applied to the tissue. The flexibility of this method is confirmed with the use of different anti-mouse antibodies followed by a variety of detection reagents. These techniques can be used for immunohistochemistry (IHC), immunofluorescence (IF), as well as staining with multiple primary antibodies. This method has also been adapted to other models, such as using human antibodies on human tissue and using multiple rabbit antibodies in dual immunofluorescence.

  4. Enhanced growth of lactobacilli and bioconversion of isoflavones in biotin-supplemented soymilk upon ultrasound-treatment.

    PubMed

    Ewe, Joo-Ann; Wan Abdullah, Wan-Nadiah; Bhat, Rajeev; Karim, A A; Liong, Min-Tze

    2012-01-01

    This study aimed at utilizing ultrasound treatment to further enhance the growth of lactobacilli and their isoflavone bioconversion activities in biotin-supplemented soymilk. Strains of lactobacilli (Lactobacillus acidophilus BT 1088, L. fermentum BT 8219, L. acidophilus FTDC 8633, L. gasseri FTDC 8131) were treated with ultrasound (30 kHz, 100 W) at different amplitudes (20%, 60% and 100%) for 60, 120 and 180 s prior to inoculation and fermentation in biotin-soymilk. The treatment affected the fatty acids chain of the cellular membrane lipid bilayer, as shown by an increased lipid peroxidation (P<0.05). This led to increased membrane fluidity and subsequently, membrane permeability (P<0.05). The permeabilized cellular membranes had facilitated nutrient internalization and subsequent growth enhancement (P<0.05). Higher amplitudes and longer durations of the treatment promoted growth of lactobacilli in soymilk, with viable counts exceeding 9 log CFU/mL. The intracellular and extracellular β-glucosidase specific activities of lactobacilli were also enhanced (P<0.05) upon ultrasound treatment, leading to increased bioconversion of isoflavones in soymilk, particularly genistin and malonyl genistin to genistein. Results from this study show that ultrasound treatment on lactobacilli cells promotes (P<0.05) the β-glucosidase activity of cells for the benefit of enhanced (P<0.05) isoflavone glucosides bioconversion to bioactive aglycones in soymilk.

  5. Comparative evaluation of Bis(thiosemicarbazone)- Biotin and Met-ac-TE3A for tumor imaging

    NASA Astrophysics Data System (ADS)

    Singh, Sweta; Tiwari, Anjani K.; Varshney, Raunak; Mathur, R.; Shukla, Gauri; Bag, N.; Singh, B.; Mishra, Anil K.

    2016-01-01

    2,2‧,2″-(11-(2-((4-mercapto-1-methoxy-1-oxobutan-2-yl)amino)-2-oxoethyl)-1,4,8,11-tetraaza cyclotetradecane-1,4,8-triyl)triacetic acid, Met-ac-TE3A and (E)-N-methyl-2-((E)-3-(2-(2-(5-((3aS,4S,6aR)-2-oxohexahydro-1H-thieno[3,4-d]imidazol-4-yl)pentanoyl)hydrazinecarbono-thioyl)hydrazonobutan-2-ylidene)hydrazinecarbothioamide, Bis(thiosemicarbazone)- Biotin were synthesized and evaluated for imaging application. The pharmacokinetics of these ligands were determined by tracer methods. In vitro human serum stability of 99mTc Met-ac-TE3A/99mTc Bis(thiosemicarbazone)-Biotin after 24 h was found to be 96.5% and 97.0% respectively. Blood kinetics of both ligands in normal rabbits showed biphasic clearance pattern. Ex vivo biodistribution study revealed significant initial tumor uptake and high tumor/muscles ratio which is a pre-requisite condition for a ligand to work as SPECT-radiopharmaceutical for tumor imaging.

  6. Printed biotin-functionalised polythiophene films as biorecognition layers in the development of paper-based biosensors

    NASA Astrophysics Data System (ADS)

    Ihalainen, Petri; Pesonen, Markus; Sund, Pernilla; Viitala, Tapani; Määttänen, Anni; Sarfraz, Jawad; Wilén, Carl-Erik; Österbacka, Ronald; Peltonen, Jouko

    2016-02-01

    The integration of flexible electronic sensors in clinical diagnostics is visioned to significantly reduce the cost of many diagnostic tests and ultimately make healthcare more accessible. This study concentrates on the characterisation of inkjet-printed bio-functionalised polythiophene films on paper-based ultrathin gold film (UTGF) electrodes and their possible application as biorecognition layers. Physicochemical surface properties (topography, chemistry, and wetting) and electrochemical characteristics of water-soluble regioirregular tetraethylene-glycol polythiophene (TEGPT) and biotin-functionalised TEGPT (b-TEGPT) films were examined and compared. In addition, their specificity towards streptavidin protein was tested. The results show that stable supramolecular biorecognition layers of insulating b-TEGPT and streptavidin were successfully fabricated on a paper-based UTGF by inkjet-printing. Good adhesion of thiophene to UTGF can be attributed to covalent linkage between sulphur and gold, whereas the stability of the streptavidin layer is due to the high affinity between biotin and streptavidin. The device introduced can be utilised in the development of biosensors for clinically relevant analytes e.g. for detecting complementary DNA oligomers or antibody-antigen complexes.

  7. Successful Conversion of the Bacillus subtilis BirA Group II Biotin Protein Ligase into a Group I Ligase

    PubMed Central

    Henke, Sarah K.; Cronan, John E.

    2014-01-01

    Group II biotin protein ligases (BPLs) are characterized by the presence of an N-terminal DNA binding domain that allows transcriptional regulation of biotin biosynthetic and transport genes whereas Group I BPLs lack this N-terminal domain. The Bacillus subtilis BPL, BirA, is classified as a Group II BPL based on sequence predictions of an N-terminal helix-turn-helix motif and mutational alteration of its regulatory properties. We report evidence that B. subtilis BirA is a Group II BPL that regulates transcription at three genomic sites: bioWAFDBI, yuiG and yhfUTS. Moreover, unlike the paradigm Group II BPL, E. coli BirA, the N-terminal DNA binding domain can be deleted from Bacillus subtilis BirA without adverse effects on its ligase function. This is the first example of successful conversion of a Group II BPL to a Group I BPL with retention of full ligase activity. PMID:24816803

  8. Clinical signs of fatty liver and kidney syndrome in broilers and their alleviation by the short-term use of biotin or animal tallow.

    PubMed

    1977-11-01

    1. Birds affected by fatty liver and kidney syndrome (FLKS) had elevated concentrations of serum Na+, K+, lactate, pyruvate and uric acid and reduced concentrations of serum HCO-3 and glucose. 2. Short-term treatment with biotin or animal tallow reduced the mortality from FLKS and prevented the clinical signs. 3. Lactic acidosis may be a major factor contributing to the mortality and physical symptoms observed in birds affected by FLKS. The lactic acidosis and the hypoglycaemia observed in FLKS are due primarily to an accumulation of pyruvate as a result of an insufficiency of biotin for normal pyruvate carboxylase activity.

  9. Superdeformation studies in {sup 150}Tb and {sup 153}Ho

    SciTech Connect

    Nisius, D.; Janssens, R.V.F.; Crowell, B.

    1995-08-01

    There are now over 40 superdeformed (SD) bands known in the A {approximately} 150 region and in most cases the properties of these bands are understood in terms of single-particle excitations in the absence of pairing. By continuing the search for new SD bands we hope to gain insight into (1) the ordering of the proton and neutron orbitals near the Fermi surface in the SD well, (2) the effects that the alignment of those orbitals has on the moments of inertia, and (3) the collective excitations in the SD well. For {sup 150}Tb, which is one proton and one neutron away from the SD doubly-magic nucleus {sup 152}Dy, it should be possible to study SD bands based on both proton and neutron hole excitations. By adding one proton to the {sup 152}Dy nucleus (i.e. {sup 153}Ho) proton excitations above the Z = 66 shell gap can be studied. These excitations are important as calculations suggested that the proton intruder orbital N = 7 might become occupied. Interactions between this orbital and a N = 5 level may result in softness towards octupole vibrations. High spin states in {sup 150}Th and {sup 153}Ho were populated using the {sup 124}Sn({sup 31}P,5n) and {sup 120}Sn({sup 37}Cl,4n) reactions, respectively. In both cases the early implementation phase of Gammasphere was used to detect the decay gamma rays and over 1 x 10{sup 9} triple and higher fold coincidence events were recorded. In {sup 150}Tb, the data analysis is complete and two new SD bands were identified. The fact that Im{sup (2)} moments of inertia are sensitive to the specific high-N intruder content of the SD bands was used to suggest configurations for the two new bands. A paper reporting these results is being prepared. For {sup 153}Ho, data analysis is still in its early stages.

  10. Auxin 2012: a rich mea ho'oulu.

    PubMed

    Strader, Lucia C; Nemhauser, Jennifer L

    2013-03-01

    In December 2012, scientists from around the world gathered in Waikoloa, Hawaii for 'Auxin 2012', a meeting organized by Paula McSteen (University of Missouri, USA), Ben Scheres (Utrecht University, The Netherlands) and Yunde Zhao (University of California, San Diego, USA). At the meeting, participants discussed the latest advances in auxin biosynthesis, transport and signaling research, in addition to providing context for how these pathways intersect with other aspects of plant physiology and development. Fittingly, the meeting began with a traditional Hawaiian ceremony that recognized the centrality of the harvest of plant life ('mea ho'oulu' in Hawaiian) for continued human survival.

  11. Chaplygin gas Hořava-Lifshitz quantum cosmology

    NASA Astrophysics Data System (ADS)

    Ardehali, Hossein; Pedram, Pouria

    2016-02-01

    In this paper, we study the Chaplygin gas Hořava-Lifshitz quantum cosmology. Using Schutz formalism and Arnowitt-Deser-Misner decomposition, we obtain the corresponding Schrödinger-Wheeler-DeWitt equation. We obtain exact classical and quantum mechanical solutions and construct wave packets to study the time evolution of the expectation value of the scale factor for two cases. We show that unlike classical solutions and upon choosing appropriate initial conditions, the expectation value of the scale factor never tends to the singular point which exhibits the singularity-free behavior of the solutions in the quantum domain.

  12. Ho:YLF Laser Pumped by TM:Fiber Laser

    NASA Astrophysics Data System (ADS)

    Mizutani, Kohei; Ishii, Shoken; Itabe, Toshikazu; Asai, Kazuhiro; Sato, Atsushi

    2016-06-01

    A 2-micron Ho:YLF laser end-pumped by 1.94-micron Tm:fiber laser is described. A ring resonator of 3m length is adopted for the oscillator. The laser is a master oscillator and an amplifier system. It is operated at high repetition rate of 200-5000 Hz in room temperature. The laser outputs were about 9W in CW and more than 6W in Q-switched operation. This laser was developed to be used for wind and CO2 measurements.

  13. Diurnal HO2 cycles at clean air and urban sites in the troposphere

    NASA Technical Reports Server (NTRS)

    Hard, T. M.; Chan, C. Y.; Mehrabzadeh, A. A.; O'Brien, R. J.

    1992-01-01

    HO2 concentrations at two Oregon sites were determined for continuous periods of 36 to 48 hours, using fluorescence assay with gas expansion. At the sea level coastal site, NNW winds prevailed during daytime, and a point measurement of very low total nonmethane hydrocarbon concentration indicated the presence of remote tropospheric air of oceanic origin. At the urban site, HO2 was determined during moderately low ozone pollution levels. At both sites, maximum daily (HO2) was in the range of 1-2 x 10 exp 8/cu cm under clear-sky conditions, with an estimated overall uncertainty of 40 percent. HO2 was detected by continuous low-pressure sampling with flowing chemical conversion to HO, which was detected by laser-excited fluorescence. The instrumental response to HO2 was calibrated by the self-decay of HO2 at atmospheric pressure. Interference in the measured daytime HO2 concentrations by RO2 was estimated at less than 20 percent.

  14. HoCP 04-838 – A new sugarcane variety for Louisiana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    HoCP 04-838 was released to the Louisiana sugar industry on May 3, 2011 by the Agricultural Research Service of the United States Department of Agriculture in cooperation with the Louisiana State University Agricultural Center, and the American Sugar Cane League of the U.S.A., Inc. HoCP 04-838 re...

  15. Intense red upconversion emission of Yb/Tm/Ho triply-doped tellurite glasses.

    PubMed

    Zhan, Huan; Zhou, Zhiguang; He, Jianli; Lin, Aoxiang

    2012-05-20

    By conventional melting and quenching methods, 3Yb2O3-0.2Tm2O3-xHo2O3 (wt%, x=0.2~1.2) was doped into an easily fiberized tellurite glass with composition of 78TeO2-10ZnO-12Na2O (mol%) to form YTH-TZN78 glasses. Under 976 nm excitation, the direct sensitizing effect of Yb ions (Yb→Ho) and indirect sensitizing and self-depopulating effects of Tm ions (Yb→Tm→Ho) were found to present intense red upconversion emission at 657 nm (Red, Ho:5F5→5I8) and were responsible for the absence of the usually observed 484 nm emission (Blue, Tm:1G4→3H36). Regardless of the dopant concentration of Ho ions, the intensity of the red emission at 657 nm (Red, Ho:5F5→5I8) is about three times stronger than that of the green one at 543 nm (Green, Ho:5S2→5I8). For this certain red emission at 657 nm, 0.4 wt% Ho2O3-doped YTH-TZN78 glass was found to present the highest emission intensity and is therefore determined as a promising active tellurite glass for red fiber laser development.

  16. Ho 07-613 – A potential new sugarcane variety for Louisiana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The clone Ho 07-613 will be up for release to Louisiana sugarcane farmers in May of 2014. This potential new variety is a joint release of the United States Department of Agriculture, the Louisiana State University Agricultural Center, and the American Sugar Cane League of the U.S.A., Inc. Ho 07-613...

  17. Black strings in Hořava-Lifshitz gravity

    NASA Astrophysics Data System (ADS)

    Aliev, Alikram N.; Şentürk, Çetin

    2011-08-01

    We examine a class of cylindrically symmetric solutions in Hořava-Lifshitz gravity. For the relativistic value of the coupling constant, λ=1, we find the hedgehog-type static black string solution with the nonvanishing radial shift in the Arnowitt-Deser-Misner-type decomposition of the spacetime metric. With zero radial shift, this solution corresponds to the usual Banados-Teitelboim-Zanelli (BTZ) black string in general relativity. However, unlike the general relativity case, the BTZ-type black strings do naturally exist in Hořava-Lifshitz gravity, without the need for any specific source term. We also find a rotating BTZ-type black string solution which requires the nonvanishing radial shift for its very existence. We calculate the mass and the angular momentum of this solution, using the canonical Hamiltonian approach. Next, we discuss the Lemos-type black string, which is inherent in general relativity with a negative cosmological constant, and present the static metric for any value of λ>1/3. Finally, we show that while, for λ=1, the entropy of the Lemos-type black string is given by one quarter of the horizon area, the entropy of the static BTZ-type black string is one half of its horizon area.

  18. Gravitational collapse in Hořava-Lifshitz theory

    NASA Astrophysics Data System (ADS)

    Greenwald, Jared; Lenells, Jonatan; Satheeshkumar, V. H.; Wang, Anzhong

    2013-07-01

    We study gravitational collapse of a spherical fluid in nonrelativistic general covariant theory of the Hořava-Lifshitz gravity with the projectability condition and an arbitrary coupling constant λ, where |λ-1| characterizes the deviation of the theory from general relativity in the infrared limit. The junction conditions across the surface of a collapsing star are derived under the (minimal) assumption that the junctions be mathematically meaningful in terms of distribution theory. When the collapsing star is made of a homogeneous and isotropic perfect fluid, and the external region is described by a stationary spacetime, the problem reduces to the matching of six independent conditions. If the perfect fluid is pressureless (a dust fluid), it is found that the matching is also possible. In particular, in the case λ=1, the external spacetime is described by the Sch-(anti-)de Sitter solution written in Painlevé-Gullstrand coordinates. In the case λ≠1, the external spacetime is static but not asymptotically flat. Our treatment can be easily generalized to other versions of Hořava-Lifshitz gravity or, more generally, to any theory of higher-order derivative gravity.

  19. Containment-enhanced Ho:YAG photofragmentation of soft tissues

    NASA Astrophysics Data System (ADS)

    Christens-Barry, William A.; Guarnieri, Michael; Carson, Benjamin S.

    1998-01-01

    Laser surgery of soft tissue can exploit the power of brief, intense pulses of light to cause localized disruption of tissue with minimal effect upon surrounding tissue. In particular, studies of Ho:YAG laser surgery have shown that the effects of cavitation upon tissues and bone depend upon the physical composition of structures in the vicinity of the surgical site. For photofragmentation of occluding structures within catheters and other implant devices, it is possible to exploit the particular geometry of the catheter to amplify the effects of photofragmentation beyond those seen in bulk tissue. A Ho:YAG laser was used to photofragment occlusive material (tissue and tissue analogs) contained in glass capillary tubing and catheter tubing of the kind used in ventricular shunt implants for the management of hydrocephalus. Occluded catheters obtained from patient explants were also employed. Selection of operational parameters used in photoablation and photofragmentation of soft tissue must consider the physical composition and geometry of the treatment site. In the present case, containment of the soft tissue within relatively inelastic catheters dramatically alters the extent of photofragmentation relative to bulk (unconstrained) material. Our results indicate that the disruptive effect of cavitation bubbles is increased in catheters, due to the rapid displacement of material by cavitation bubbles comparable in size to the inner diameter of the catheter. The cylindrical geometry of the catheter lumen may additionally influence the propagation of acoustic shock waves that result from the collapse of the condensing cavitation bubbles.

  20. Itinerant and localized magnetization dynamics in antiferromagnetic Ho

    SciTech Connect

    Rettig, L.; Dornes, C.; Thielemann-Kuhn, N.; Pontius, N.; Zabel, H.; Schlagel, D. L.; Lograsso, T. A.; Chollet, M.; Robert, A.; Sikorski, M.; Song, S.; Glownia, J. M.; SchuBler-Langeheine, C.; Johnson, S. L.; Staub, U.

    2016-06-21

    Using femtosecond time-resolved resonant magnetic x-ray diffraction at the Ho L3 absorption edge, we investigate the demagnetization dynamics in antiferromagnetically ordered metallic Ho after femtosecond optical excitation. Here, tuning the x-ray energy to the electric dipole (E1, 2p → 5d) or quadrupole (E2, 2p → 4f) transition allows us to selectively and independently study the spin dynamics of the itinerant 5d and localized 4f electronic subsystems via the suppression of the magnetic (2 1 3–τ) satellite peak. We find demagnetization time scales very similar to ferromagnetic 4f systems, suggesting that the loss of magnetic order occurs via a similar spin-flip process in both cases. The simultaneous demagnetization of both subsystems demonstrates strong intra-atomic 4f–5d exchange coupling. In addition, an ultrafast lattice contraction due to the release of magneto-striction leads to a transient shift of the magnetic satellite peak.

  1. Itinerant and localized magnetization dynamics in antiferromagnetic Ho

    DOE PAGES

    Rettig, L.; Dornes, C.; Thielemann-Kuhn, N.; ...

    2016-06-21

    Using femtosecond time-resolved resonant magnetic x-ray diffraction at the Ho L3 absorption edge, we investigate the demagnetization dynamics in antiferromagnetically ordered metallic Ho after femtosecond optical excitation. Here, tuning the x-ray energy to the electric dipole (E1, 2p → 5d) or quadrupole (E2, 2p → 4f) transition allows us to selectively and independently study the spin dynamics of the itinerant 5d and localized 4f electronic subsystems via the suppression of the magnetic (2 1 3–τ) satellite peak. We find demagnetization time scales very similar to ferromagnetic 4f systems, suggesting that the loss of magnetic order occurs via a similar spin-flipmore » process in both cases. The simultaneous demagnetization of both subsystems demonstrates strong intra-atomic 4f–5d exchange coupling. In addition, an ultrafast lattice contraction due to the release of magneto-striction leads to a transient shift of the magnetic satellite peak.« less

  2. Development and Validation of Spectrofluorimetric Method for Determination of Biotin in Bulk and Pharmaceutical Preparations via its Oxidation with Cerium (IV).

    PubMed

    Walash, M I; Rizk, M; Sheribah, Z A; Salim, M M

    2010-09-01

    A simple and sensitive spectrofluorimetric method was developed for the determination of biotin in pure form and in pharmaceutical preparations. The proposed method is based on the oxidation of the drug with cerium (IV) ammonium sulfate in acidic medium. The fluorescence of the produced Cerium (III) was measured at 365 nm after excitation at 255 nm. The different experimental parameters affecting the development and stability of the reaction were carefully studied and optimized. The method is applicable over the concentration range of 30-120 ng/mL with correlation coefficient of 0.9998. The detection limit (LOD) of biotin was 2.41 ng/mL while quantitation limit (LOQ) was 7.29 ng/mL. The proposed procedure was successfully applied for the determination of biotin in pharmaceutical preparations with mean recoveries of 99.55 ± 0.83 and 101.67 ± 1.53 for biotin ampoules and capsules, respectively. The results obtained were in good agreement with those obtained using the official method.

  3. Biotin-conjugated N-methylisatoic anhydride: a chemical tool for nucleic acid separation by selective 2'-hydroxyl acylation of RNA.

    PubMed

    Ursuegui, S; Chivot, N; Moutin, S; Burr, A; Fossey, C; Cailly, T; Laayoun, A; Fabis, F; Laurent, A

    2014-06-01

    An isatoic anhydride derivative conjugated to a biotin and a disulfide linker was specifically designed for the separation of nucleic acids. Starting from a DNA-RNA mixture, a selective 2'-hydroxyl acylation of RNAs followed by capture with streptavidin-coated magnetic beads and cleavage of the disulfide led to elution of RNAs.

  4. Phage display evolution of a peptide substrate for yeast biotin ligase and application to two-color quantum dot labeling of cell surface proteins.

    PubMed

    Chen, Irwin; Choi, Yoon-Aa; Ting, Alice Y

    2007-05-23

    Site-specific protein labeling with Escherichia coli biotin ligase (BirA) has been used to introduce fluorophores, quantum dots (QDs), and photocross-linkers onto recombinant proteins fused to a 15-amino acid acceptor peptide (AP) substrate for BirA and expressed on the surface of living mammalian cells. Here, we used phage display to engineer a new and orthogonal biotin ligase-AP pair for site-specific protein labeling. Yeast biotin ligase (yBL) does not recognize the AP, but we discovered a new 15-amino acid substrate for yBL called the yeast acceptor peptide (yAP), using two generations of phage display selection from 15-mer peptide libraries. The yAP is not recognized by BirA, and thus, we were able to specifically label AP and yAP fusion proteins coexpressed in the same cell with differently colored QDs. We fused the yAP to a variety of recombinant proteins and demonstrated biotinylation by yBL at the N-terminus, C-terminus, and within a flexible internal region. yBL is extremely sequence-specific, as endogenous proteins on the surface of yeast and HeLa cells are not biotinylated. This new methodology expands the scope of biotin ligase labeling to two-color imaging and yeast-based applications.

  5. Theoretical study of reactions of HO{sub 2} in low-temperature oxidation of benzene

    SciTech Connect

    Altarawneh, Mohammednoor; Dlugogorski, Bogdan Z.; Kennedy, Eric M.; Mackie, John C.

    2010-07-15

    We have generated a set of thermodynamic and kinetic parameters for the reactions involving HO{sub 2} in the very early stages of benzene oxidation at low temperatures using density functional theory (DFT). In particular, we report the rate constants for the reactions of HO{sub 2} with benzene and phenyl. The calculated reaction rate constant for the abstraction of H-C{sub 6}H{sub 5} by HO{sub 2} is found to be in good agreement with the limited experimental values. HO{sub 2} addition to benzene is found to be more important than direct abstraction. We show that the reactions of HO{sub 2} with the phenyl radical generate the propagating radical OH in a highly exoergic reaction. The results presented herein should be useful in modeling the oxidation of aromatic compounds at low temperatures. (author)

  6. Kinetic and Thermochemical Studies of Weakly-Bound HO2 Complexes with Carboxylic acids

    NASA Astrophysics Data System (ADS)

    Zhao, Z.; Nicovich, J. M.; McKee, M. L.; Wine, P. H.

    2008-12-01

    Numerous theoretical and experimental studies have suggested that HO2 radicals are able to form strong hydrogen bonds with some closed-shell species, which can potentially influence our understanding of HO2 chemistry in the upper troposphere and lower stratosphere. In this study, a laser flash photolysis-tunable diode laser absorption spectroscopy technique has been employed to study the formation of HO2 complexes with formic and acetic acids. At low temperatures, equilibration kinetics have been observed, allowing adduct formation and dissociation rate coefficients to be obtained and adduct binding enthalpies to be determined. This is the first experimental study of the HO2-carboxylic acid complexes and the binding energies are in good agreement with the most recent theoretical estimates. The potential role of HO2-RC(O)OH adducts in atmospheric chemistry will be discussed.

  7. Magnetic properties of Ho1- x Lu x B12 solid solutions

    NASA Astrophysics Data System (ADS)

    Gabáni, S.; Gaz̆o, E.; Pristás̆, G.; Takác̆ová, I.; Flachbart, K.; Shitsevalova, N.; Siemensmeyer, K.; Sluchanko, N.

    2013-05-01

    Magnetic properties of the geometrically frustrated antiferromagnet HoB12 (with T N = 7.4 K) modified by substitution of magnetic Ho atoms through non-magnetic Lu ones are presented and discussed. In this case, in Ho1- x Lu x B12 solid solutions, both chemical pressure resulting from different Lu3+ and Ho3+ radii and magnetic dilution take place with increasing Lu content ( x) that change properties of the system. The received results show strong indication for the existence of a quantum critical point near x = 0.9, which separates the region of magnetic order (starting with HoB12 for x = 0) and the nonmagnetic region (ending with superconducting LuB12 for x = 1).

  8. Radical scavenging activity of antioxidants evaluated by means of electrogenerated HO radical.

    PubMed

    Oliveira, Raquel; Geraldo, Dulce; Bento, Fátima

    2014-11-01

    A method is proposed and tested concerning the characterization of antioxidants by means of their reaction with electrogenerated HO radicals in galvanostatic assays with simultaneous O2 evolution, using a Pt anode fairly oxidized. The consumption of a set of species with antioxidant activity, ascorbic acid (AA), caffeic acid (CA), gallic acid (GA) and trolox (T), is described by a first order kinetics. The rate of the processes is limited by the kinetics of reaction with HO radicals and by the kinetics of charge transfer. Information regarding the scavenger activity of antioxidants is obtained by the relative value of the rate constant of the reaction between antioxidants and HO radicals, k(AO,HO)/k(O2). The number of HO radicals scavenged per molecule of antioxidant is also estimated and ranged from 260 (ascorbic acid) to 500 (gallic acid). The method is applied successfully in the characterization of the scavenger activity of ascorbic acid in a green-tea based beverage.

  9. Energy transfer and lasing in LiYbF4:Ho, LiYbF4:Ho,Tm, and KYb(WO4)3 crystals

    NASA Astrophysics Data System (ADS)

    Sandulenko, Alexander V.; Sandulenko, V. A.; Tkachuk, Alexandra M.; Titov, Alexandre N.; Reiterov, V. M.; Ivanov, V. N.

    1998-12-01

    We have studied both theoretically and experimentally the energy transfer processes in YbLiF4:Ho3+ (0.4%) and YbLiF4:Ho3+ (0.4%),Tm3+ (10%) crystals and in the series of crystals KYb(WO4)2:Tm3+,Ho3+ (0.4%) with the thulium concentration 5; 10; and 20%. The population kinetics of the 5I7 holmium level was studied under the 1.047 micrometers Q-switched YLF:Nd3+ laser pumping. The efficiency of energy transfer processes in Ho3+ doped crystals, codoped with Yb3+ and Tm3+, was demonstrated. With an YbLiF4:Ho3+ (0.4%) laser rod we have obtained lasing at 2.06 micrometers with the total efficiency of 4.8% and the slope efficiency of 11%. In the KYb(WO4)2:Tm3+ (10%),Ho3+ (0.4%) crystal, lasing was obtained for the first time at 2 micrometers . The pumping threshold being approximately 150 mJ, total efficiency 6% and slope efficiency 9.7% was achieved.

  10. High dietary biotin levels affect the footpad and hock health of broiler chickens reared at different stocking densities and litter conditions.

    PubMed

    Sun, Z W; Fan, Q H; Wang, X X; Guo, Y M; Wang, H J; Dong, X

    2016-04-14

    Responses to stocking density (SD), dietary biotin concentration and litter condition were evaluated on 2016 Ross 308 male broilers in the fattening period (day 22-day 42). The birds were placed in 48 pens with either dry or wet litter to simulate the final stocking density of 30 kg (12 broilers/m(2) ; normal stocking density, NSD) and 40 kg (16 broilers/m(2) ; high stocking density, HSD) of body weight (BW)/m(2) floor space. A corn-soybean meal-based diet was supplemented with biotin to provide a normal (NB; 155 μg/kg) or high (HB, 1521 μg/kg) level of dietary biotin. There were six repetitions per treatment. The inappropriate moisture content of litter associated with HSD was avoided (p < 0.05) by good management (SD difference: dry litter, 6.65% vs. wet litter, 13.23%; 42 days), which made it advantageous (p < 0.01) for footpad (SD difference: dry litter, 0.118 vs. wet litter, 0.312; weekly average value) and hock health (SD difference: dry litter, 0.090 vs. wet litter, 0.303; weekly average value) of HSD birds, but not (p > 0.05) for growth and processing yield. In HSD, the biotin effect (gains, FCR) was significantly higher (p < 0.01) than in NSD. The similar response of HSD birds to supplemental biotin was observed (p < 0.05) for lesion scores of footpad and hock in particularly finishing chickens, and a significant interaction (p < 0.01) among stocking density, biotin supplementation and litter condition existed from 35 to 42 days of age. Taken together, increasing dietary biotin improves the performance and well-being of broiler chickens stocked at high densities in litter-independent and litter-dependent manners respectively.

  11. Mechanism-based Inactivation by Aromatization of the Transaminase BioA Involved in Biotin Biosynthesis in Mycobaterium tuberculosis

    SciTech Connect

    Shi, Ce; Geders, Todd W.; Park, Sae Woong; Wilson, Daniel J.; Boshoff, Helena I.; Abayomi, Orishadipe; Barry, III, Clifton E.; Schnappinger, Dirk; Finzel, Barry C.; Aldrich, Courtney C.

    2011-11-16

    BioA catalyzes the second step of biotin biosynthesis, and this enzyme represents a potential target to develop new antitubercular agents. Herein we report the design, synthesis, and biochemical characterization of a mechanism-based inhibitor (1) featuring a 3,6-dihydropyrid-2-one heterocycle that covalently modifies the pyridoxal 5'-phosphate (PLP) cofactor of BioA through aromatization. The structure of the PLP adduct was confirmed by MS/MS and X-ray crystallography at 1.94 {angstrom} resolution. Inactivation of BioA by 1 was time- and concentration-dependent and protected by substrate. We used a conditional knock-down mutant of M. tuberculosis to demonstrate the antitubercular activity of 1 correlated with BioA expression, and these results provide support for the designed mechanism of action.

  12. Three-Arm, Biotin-Tagged Carbazole-Dicyanovinyl-Chlorambucil Conjugate: Simultaneous Tumor Targeting, Sensing, and Photoresponsive Anticancer Drug Delivery.

    PubMed

    Venkatesh, Yarra; Karthik, S; Rajesh, Y; Mandal, Mahitosh; Jana, Avijit; Singh, N D Pradeep

    2016-12-19

    The design, synthesis, and in vitro biological studies of a biotin-carbazole-dicyanovinyl-chlorambucil conjugate (Bio-CBZ-DCV-CBL; 6) are reported. This conjugate (6) is a multifunctional single-molecule appliance composed of a thiol-sensor DCV functionality, a CBZ-derived phototrigger as well as fluorescent reporter, and CBL as the anticancer drug, and Bio as the cancer-targeting ligand. In conjugate 6, the DCV bond undergoes a thiol-ene click reaction at pH<7 with intracellular thiols, thereby shutting down internal charge transfer between the donor CBZ and acceptor DCV units, resulting in a change of the fluorescence color from green to blue, and thereby, sensing the tumor microenvironment. Subsequent photoirradiation results in release of the anticancer drug CBL in a controlled manner.

  13. A synthetic host-guest system achieves avidin-biotin affinity by overcoming enthalpy-entropy compensation.

    PubMed

    Rekharsky, Mikhail V; Mori, Tadashi; Yang, Cheng; Ko, Young Ho; Selvapalam, N; Kim, Hyunuk; Sobransingh, David; Kaifer, Angel E; Liu, Simin; Isaacs, Lyle; Chen, Wei; Moghaddam, Sarvin; Gilson, Michael K; Kim, Kimoon; Inoue, Yoshihisa

    2007-12-26

    The molecular host cucurbit[7]uril forms an extremely stable inclusion complex with the dicationic ferrocene derivative bis(trimethylammoniomethyl)ferrocene in aqueous solution. The equilibrium association constant for this host-guest pair is 3 x 10(15) M(-1) (K(d) = 3 x 10(-16) M), equivalent to that exhibited by the avidin-biotin pair. Although purely synthetic systems with larger association constants have been reported, the present one is unique because it does not rely on polyvalency. Instead, it achieves its extreme affinity by overcoming the compensatory enthalpy-entropy relationship usually observed in supramolecular complexes. Its disproportionately low entropic cost is traced to extensive host desolvation and to the rigidity of both the host and the guest.

  14. Survey of Surface Proteins from the Pathogenic Mycoplasma hyopneumoniae Strain 7448 Using a Biotin Cell Surface Labeling Approach

    PubMed Central

    Reolon, Luciano Antonio; Martello, Carolina Lumertz; Schrank, Irene Silveira; Ferreira, Henrique Bunselmeyer

    2014-01-01

    The characterization of the repertoire of proteins exposed on the cell surface by Mycoplasma hyopneumoniae (M. hyopneumoniae), the etiological agent of enzootic pneumonia in pigs, is critical to understand physiological processes associated with bacterial infection capacity, survival and pathogenesis. Previous in silico studies predicted that about a third of the genes in the M. hyopneumoniae genome code for surface proteins, but so far, just a few of them have experimental confirmation of their expression and surface localization. In this work, M. hyopneumoniae surface proteins were labeled in intact cells with biotin, and affinity-captured biotin-labeled proteins were identified by a gel-based liquid chromatography-tandem mass spectrometry approach. A total of 20 gel slices were separately analyzed by mass spectrometry, resulting in 165 protein identifications corresponding to 59 different protein species. The identified surface exposed proteins better defined the set of M. hyopneumoniae proteins exposed to the host and added confidence to in silico predictions. Several proteins potentially related to pathogenesis, were identified, including known adhesins and also hypothetical proteins with adhesin-like topologies, consisting of a transmembrane helix and a large tail exposed at the cell surface. The results provided a better picture of the M. hyopneumoniae cell surface that will help in the understanding of processes important for bacterial pathogenesis. Considering the experimental demonstration of surface exposure, adhesion-like topology predictions and absence of orthologs in the closely related, non-pathogenic species Mycoplasma flocculare, several proteins could be proposed as potential targets for the development of drugs, vaccines and/or immunodiagnostic tests for enzootic pneumonia. PMID:25386928

  15. Accelerated removal of antibody-coated red blood cells from the circulation is accurately tracked by a biotin label

    PubMed Central

    Mock, Donald M.; Lankford, Gary L.; Matthews, Nell I.; Burmeister, Leon F.; Kahn, Daniel; Widness, John A.; Strauss, Ronald G.

    2013-01-01

    BACKGROUND Safe, accurate methods to reliably measure circulating red blood cell (RBC) kinetics are critical tools to investigate pathophysiology and therapy of anemia, including hemolytic anemias. This study documents the ability of a method using biotin-labeled RBCs (BioRBCs) to measure RBC survival (RCS) shortened by coating with a highly purified monomeric immunoglobulin G antibody to D antigen. STUDY DESIGN AND METHODS Autologous RBCs from 10 healthy D+ subjects were labeled with either biotin or 51Cr (reference method), coated (opsonized) either lightly (n = 4) or heavily (n = 6) with anti-D, and transfused. RCS was determined for BioRBCs and for 51Cr independently as assessed by three variables: 1) posttransfusion recovery at 24 hours (PTR24) for short-term RCS; 2) time to 50% decrease of the label (T50), and 3) mean potential life span (MPL) for long-term RCS. RESULTS BioRBCs tracked both normal and shortened RCS accurately relative to 51Cr. For lightly coated RBCs, mean PTR24, T50, and MPL results were not different between BioRBCs and 51Cr. For heavily coated RBCs, both short-term and long-term RCS were shortened by approximately 17 and 50%, respectively. Mean PTR24 by BioRBCs (84 ± 18%) was not different from 51Cr (81 ± 10%); mean T50 by BioRBCs (23 ± 17 days) was not different from 51Cr (22 ± 18 days). CONCLUSION RCS shortened by coating with anti-D can be accurately measured by BioRBCs. We speculate that BioRBCs will be useful for studying RCS in conditions involving accelerated removal of RBCs including allo- and autoimmune hemolytic anemias. PMID:22023312

  16. A simplified method to attach antibodies on liposomes by biotin-streptavidin affinity for rapid and economical screening of targeted liposomes.

    PubMed

    Papadia, Konstantina; Markoutsa, Eleni; Antimisiaris, Sophia G

    2014-05-01

    The biotin-Streptavidin (STREP) technique for attachment of monoclonal antibodies (mAbs) (or other ligand types) on liposome surface offers high attachment yield, however it is time consuming and expensive due to the number of steps used and the consumption of large quantities of STREP. Herein, a simplified, fast and economic technique, by incubating pre-mixed biotin-mAb/STREP with biotin-liposomes, at a 3:1:1 biotin-mAb/STREP/biotin-LIP ratio (mol/mol/mol) was evaluated. The physichochemical properties, final mAb attachment yield and targeting potential of liposomes decorated with an anti-transferrin receptor mAb (TfR-mAb), prepared by the simple method (SM) and the conventional method (CM), were compared. The vesicle uptake by hCMEC/D3 cells (known to overexpress TfR) were considered as a measure of liposome targeting capability. Results show that both targeted liposome types (SM and CM) have small size (mean diameters around 150 nm), low poly-dispersity (approx. 0.20) and similar mAb attachment yield (between 64-88%). However, the uptake of the SM-liposomes is slightly lower compared to CM-LIP (24-30% decrease), suggesting that the modulated conformation of mAbs on the liposome surface (triplets attached to one single STREP molecule) results in decreased targeting capability. Nevertheless, the simpler and faster one-step preparation procedure which has very high lipid recovery (> 95%) compared to the CM (50-60%) and 15-30 times lower consumption of STREP, may be a good alternative for initial screening of various mAbs as ligands for targeted liposomal or other nanotechnologies, during pre-clinical development.

  17. Influences of increased levels of biotin, zinc or mannan-oligosaccharides in the diet on foot pad dermatitis in growing turkeys housed on dry and wet litter.

    PubMed

    Youssef, I M I; Beineke, A; Rohn, K; Kamphues, J

    2012-10-01

    Foot pad dermatitis (FPD) is very common in turkeys and it is an animal health and welfare issue affecting not only performance and walking ability but also the carcass quality. Thus, there is a great need to find out the preventive measures against this problem. The potential roles of extra dietary biotin, Zn and mannan-oligosaccharides (MOS) in preventing the development of FPD were assessed in this study which was conducted on 2-week-old female turkeys over a period of 4 weeks. The birds were allotted to four groups, with 29 each, and housed on dry wood shavings in floor pens. The turkeys were fed a control (300 μg biotin and 50 mg Zn/kg), high biotin (2000 μg/kg), high Zn (150 mg/kg) or MOS (1%) diet. Half of the turkeys in each group were additionally exposed to wet litter (27% DM) for 8 h daily in adjacent separate boxes. Foot pads of the birds were examined on days 0, 7, 14, 21 and 28 and assessed macroscopically and histopathologically for foot pad lesions. High dietary levels of biotin or Zn significantly reduced the severity of FPD on dry litter (score 1 vs. 2 in control) but not on wet litter. However, MOS did not affect the severity of foot pad lesions either on dry or wet litter. In addition, the severity was overall substantially higher on wet (approximately three times) than on dry litter. The present results suggest that adding high levels of biotin or Zn to the diet could reduce the development and severity of FPD on dry litter but without having any preventive effects on wet litter. Finally, the high litter moisture appears to be the major factor resulting in FPD. Therefore, the litter should be maintained dry to minimize the prevalence and severity of FPD in turkeys.

  18. Phase II trial of yttrium-90-DOTA-biotin pretargeted by NR-LU-10 antibody/streptavidin in patients with metastatic colon cancer

    SciTech Connect

    Knox, S J.; Goris, M L.; Tempero, M; Weiden, P L.; Gentner, L; Breitz, H; Adams, G P.; Axworthy, D; Gaffigan, S; Bryan, K; Fisher, Darrell R. ); Colcher, D; Horak, I D.; Weiner, L M.

    1999-12-01

    A Phase II study of yttrium-90-tetra-azacyclododecanetetra-acetic acid-biotin (Y-90-DOTA-biotin) pretargeted by NR-LU-10 antibody/streptavidin (SA) was performed. The primary objectives of the study were to evaluate the efficacy and safety of this therapy in patients with metastatic colon cancer. Twenty-five patients were treated with a single dose of 110 mCi/m{sup 2} (mean administered dose, 106.5-10.3 mCi/m{sup 2}) of Y-90-DOTA-biotin. There were three components of the therapy. Patients first received NR-LU-10/SA on day 1. A clearing agent (biotin-galactose-human serum albumin) was administered 48 h after the NR-LU-10/SA to remove residual circulating unbound NR-LU-10/SA. Lastly, 24 h after administration of clearing agent, patients received biotin-DOTA-labeled with 110 mCi/m{sup 2} Y-90. All three components of the therapy were administered i.v. Both hematological and nonhematological toxicities were observed. Diarrhea was the most frequent grade 4 nonhematological toxicity (16%; with 16% grade 3 diarrhea). Hematological toxicity was less severe with 8% grade 3 and 8% grade 4 neutropenia and 8% grade 3 and 16% grade 4 thrombocytopenia. The overall response rate was 8%. Two partial responders had freedom from progression of 16 weeks. Four patients (16%) had stable disease with freedom from progression of 10-20 weeks. Despite the relatively disappointing results of this study in terms of therapeutic efficacy and toxicity, proof of principle was obtained for the pretargeting approach. In addition, valuable new information was obtained about normal tissue tolerance to low-dose-rate irradiation that will help to provide useful guidelines for future study designs.

  19. Anti-diabetic activity of chromium picolinate and biotin in rats with type 2 diabetes induced by high-fat diet and streptozotocin.

    PubMed

    Sahin, Kazim; Tuzcu, Mehmet; Orhan, Cemal; Sahin, Nurhan; Kucuk, Osman; Ozercan, Ibrahim H; Juturu, Vijaya; Komorowski, James R

    2013-07-28

    The objective of the present study was to evaluate anti-diabetic effects of chromium picolinate (CrPic) and biotin supplementations in type 2 diabetic rats. The type 2 diabetic rat model was induced by high-fat diet (HFD) and low-dose streptozotocin. The rats were divided into five groups as follows: (1) non-diabetic rats fed a regular diet; (2) diabetic rats fed a HFD; (3) diabetic rats fed a HFD and supplemented with CrPic (80 μg/kg body weight (BW) per d); (4) diabetic rats fed a HFD and supplemented with biotin (300 μg/kg BW per d); (5) diabetic rats fed a HFD and supplemented with both CrPic and biotin. Circulating glucose, cortisol, total cholesterol, TAG, NEFA and malondialdehyde concentrations decreased (P< 0·05), but serum insulin concentrations increased (P< 0·05) in diabetic rats treated with biotin and CrPic, particularly with a combination of the supplements. Feeding a HFD to diabetic rats decreased PPAR-γ expression in adipose tissue and phosphorylated insulin receptor substrate 1 (p-IRS-1) expression of liver, kidney and muscle tissues, while the supplements increased (P< 0·001) PPAR-γ and p-IRS-1 expressions in relevant tissues. Expression of NF-κB in the liver and kidney was greater in diabetic rats fed a HFD, as compared with rats fed a regular diet (P< 0·01). The supplements decreased the expression of NF-κB in diabetic rats (P< 0·05). Results of the present study revealed that supplementing CrPic and biotin alone or in a combination exerts anti-diabetic activities, probably through modulation of PPAR-γ, IRS-1 and NF-κB proteins.

  20. Cosmological perturbations in Hořava-Lifshitz gravity

    NASA Astrophysics Data System (ADS)

    Gao, Xian; Wang, Yi; Brandenberger, R.; Riotto, A.

    2010-04-01

    We study cosmological perturbations in Hořava-Lifshitz Gravity, a recently proposed potentially ultraviolet-complete quantum theory of gravity. We consider scalar metric fluctuations about a homogeneous and isotropic space-time. Starting from the most general metric, we work out the complete second order action for the perturbations. We then make use of the residual gauge invariance and of the constraint equations to reduce the number of dynamical degrees of freedom. At first glance, it appears that there is an extra scalar metric degree of freedom. However, introducing the Sasaki-Mukhanov variable, the combination of spatial metric fluctuation and matter inhomogeneity for which the action in general relativity has canonical form, we find that this variable has the standard time derivative term in the second order action, and that the extra degree of freedom is nondynamical. The limit λ→1 is well behaved, unlike what is obtained when expanding about Minkowski space-time. Thus, there is no strong coupling problem for Hořava-Lifshitz gravity when considering cosmological solutions. We also compute the spectrum of cosmological perturbations. If the potential in the action is taken to be of “detailed balance” form, we find a cancellation of the highest derivative terms in the action for the curvature fluctuations. As a consequence, the initial spectrum of perturbations will not be scale-invariant in a general space-time background, in contrast to what happens when considering Hořava-Lifshitz matter leaving the gravitational sector unperturbed. However, if we break the detailed balance condition, then the initial spectrum of curvature fluctuations is indeed scale-invariant on ultraviolet scales. As an application, we consider fluctuations in an inflationary background and draw connections with the “trans-Planckian problem” for cosmological perturbations. In the special case in which the potential term in the action is of detailed balance form and in which

  1. Sticking of HO2 on fatty acids aggregates

    NASA Astrophysics Data System (ADS)

    Vardanega, Delphine; Briquez, Stéphane; Duflot, Denis; Monnerville, Maurice; Toubin, Céline

    2015-04-01

    Models of atmospheric chemistry are widely used to perform projections of future changes in the chemical composition of the global troposphere, including changes in climate related greenhouse gases and aerosol particles. However, large uncertainties are still associated with the chemistry implemented in these models, which in turn can lead to inaccurate long-term predictions. The proposed work seeks to improve our understanding of the oxidative capacity of the atmosphere, which drives the lifetime of trace gases, and therefore atmospheric composition. Recent measurements [1] of free radicals made in forested environments characterized by low levels of nitrogen oxides (NOx = NO and NO2) indicate that current models of atmospheric chemistry tend to overestimate the concentration of peroxy radicals (HO2 and RO2). An overestimation of peroxy radicals is an important issue since these radicals are the main precursors of the hydroxyl radical (OH), the most important atmospheric oxidant during daytime. This issue could lead to a significant overestimation of the oxidative capacity of the global atmosphere since more than 86% of the Earth surface is covered by forests, oceans, and polar regions. An analysis of this dataset indicates that the missing sink could be due to an underestimation of the rates of RO2+HO2 reactions, and/or the uptake of peroxy radicals onto aerosol particles. A thorough evaluation of scientific studies published in the literature shows that there is a lack of kinetic and mechanistic data to correctly assess the contribution of these two loss pathways of peroxy radicals in low NOx environments. Classical molecular dynamics simulations, using the Gromacs package [2], are performed to study the interaction of HO2 with organic (carboxylic acid) aerosols. The effect of the presence of water molecules on the surface are also be investigated. These calculations provide theoretical values for observable quantities such as uptake and mass accommodation

  2. Resonantly pumped high efficiency Ho:YAG laser.

    PubMed

    Shen, Ying-Jie; Yao, Bao-Quan; Duan, Xiao-Ming; Dai, Tong-Yu; Ju, You-Lun; Wang, Yue-Zhu

    2012-11-20

    High-efficient CW and Q-switched Ho:YAG lasers resonantly dual-end-pumped by two diode-pumped Tm:YLF lasers at 1908 nm were investigated. A maximum slope efficiency of 74.8% in CW operation as well as a maximum output power of 58.7 W at 83.2 W incident pump power was achieved, which corresponded to an optical-to-optical conversion efficiency of 70.6%. The maximum pulse energy of 2.94 mJ was achieved, with a 31 ns FWHM pulse width and a peak power of approximately 94.7 kW.

  3. BRIEF REVIEW Hořava-Lifshitz cosmology: a review

    NASA Astrophysics Data System (ADS)

    Mukohyama, Shinji

    2010-11-01

    Here we review the basic construction and cosmological implications of a power-counting renormalizable theory of gravitation, recently proposed by Hořava. We explain that (i) at low energy this theory does not exactly recover general relativity but instead mimics general relativity plus dark matter; (ii) higher spatial curvature terms allow bouncing and cyclic universes as regular solutions; (iii) the anisotropic scaling with the dynamical critical exponent z = 3 solves the horizon problem and leads to scale-invariant cosmological perturbations even without inflation. We also comment on issues related to an extra scalar degree of freedom called scalar graviton. In particular, for spherically-symmetric, static, vacuum configurations we prove non-perturbative continuity of the λ → 1 + 0 limit, where λ is a parameter in the kinetic action and general relativity has the value λ = 1. We also derive the condition under which linear instability of the scalar graviton does not show up.

  4. Migration and employment in Ho Chi Minh City.

    PubMed

    Truong Si Anh; Gubry, P; Vu Thi Hong; Huguet, J W

    1996-06-01

    This article presents findings from a survey of migrants conducted during September 1994 in Ho Chi Minh City, Vietnam. The sample includes 19,019 households in 34 residence blocks selected from the 17 districts that comprise the most populated areas of the city. 704 migrants and 296 nonmigrant households completed the basic demographic and socioeconomic questionnaire. One migrant and one nonmigrant completed a detailed questionnaire. Migrants are identified as those who migrated to the city after April 1984. Migrants are divided into those moving during 1984-89 and during 1990-94. The average annual rate of growth in population during the census years 1979-89 was 1.87% and during 1989-94 was 3.5%. Growth during 1989-94 was 1.6% due to natural increase and 1.9% due to net migration. 43% of population growth was due to natural increase and 57% was from net migration. Migration to large cities, such as Ho Chi Minh City, was stimulated by employment opportunities in the private sector. There were more female migrants in both study periods, and the proportion of females increased in the more recent past. About 15% of female migrants aged over 13 years were students and 58% were in the labor force. Most migrants were aged 15-29 years (41% during 1984-89 and 53% during 1990-94). Only 31% of nonmigrants were aged 15-29 years. About 33% of migrants originated from the Mekong River Delta in the south; 20% originated from the Red River Delta and Hanoi region; and 20% came from the Central Coast. Over time, the proportion of migrants from the coast increased and that from the Red River Delta decreased. Migrants and nonmigrants shared similar unemployment and economic activity rates. However, twice the proportion of migrants aged over 13 years were attending school. The author presents the evidence for the influence of urban economic policies on migration, specifically female migration.

  5. HO endonuclease-induced recombination in yeast meiosis resembles Spo11-induced events.

    PubMed

    Malkova, A; Klein, F; Leung, W Y; Haber, J E

    2000-12-19

    In meiosis, gene conversions are accompanied by higher levels of crossing over than in mitotic cells. To determine whether the special properties of meiotic recombination can be attributed to the way in which Spo11p creates double-strand breaks (DSBs) at special hot spots in Saccharomyces cerevisiae, we expressed the site-specific HO endonuclease in meiotic cells. We could therefore compare HO-induced recombination in a well-defined region both in mitosis and meiosis, as well as compare Spo11p- and HO-induced meiotic events. HO-induced gene conversions in meiosis were accompanied by crossovers at the same high level (52%) as Spo11p-induced events. Moreover, HO-induced crossovers were reduced 3-fold by a msh4Delta mutation that similarly affects Spo11p-promoted events. In a spo11Delta diploid, where the only DSB is made by HO, crossing over was significantly higher (27%) than in mitotic cells (HO-induced gene conversion tract lengths are shorter in meiotic than in mitotic cells. We conclude that a hallmark of meiotic recombination, the production of crossovers, is independent of the nature of Spo11p-generated DSBs at special hotspots, but some functions of Spo11p are required in trans to achieve maximum crossing over.

  6. Mechanical Stress Changes the Complex Interplay Between HO-1, Inflammation and Fibrosis, During Excisional Wound Repair.

    PubMed

    Cremers, Niels A J; Suttorp, Maarten; Gerritsen, Marlous M; Wong, Ronald J; van Run-van Breda, Coby; van Dam, Gooitzen M; Brouwer, Katrien M; Kuijpers-Jagtman, Anne Marie; Carels, Carine E L; Lundvig, Ditte M S; Wagener, Frank A D T G

    2015-01-01

    Mechanical stress following surgery or injury can promote pathological wound healing and fibrosis, and lead to functional loss and esthetic problems. Splinted excisional wounds can be used as a model for inducing mechanical stress. The cytoprotective enzyme heme oxygenase-1 (HO-1) is thought to orchestrate the defense against inflammatory and oxidative insults that drive fibrosis. Here, we investigated the activation of the HO-1 system in a splinted and non-splinted full-thickness excisional wound model using HO-1-luc transgenic mice. Effects of splinting on wound closure, HO-1 promoter activity, and markers of inflammation and fibrosis were assessed. After seven days, splinted wounds were more than three times larger than non-splinted wounds, demonstrating a delay in wound closure. HO-1 promoter activity rapidly decreased following removal of the (epi)dermis, but was induced in both splinted and non-splinted wounds during skin repair. Splinting induced more HO-1 gene expression in 7-day wounds; however, HO-1 protein expression remained lower in the epidermis, likely due to lower numbers of keratinocytes in the re-epithelialization tissue. Higher numbers of F4/80-positive macrophages, αSMA-positive myofibroblasts, and increased levels of the inflammatory genes IL-1β, TNF-α, and COX-2 were present in 7-day splinted wounds. Surprisingly, mRNA expression of newly formed collagen (type III) was lower in 7-day wounds after splinting, whereas, VEGF and MMP-9 were increased. In summary, these data demonstrate that splinting delays cutaneous wound closure and HO-1 protein induction. The pro-inflammatory environment following splinting may facilitate higher myofibroblast numbers and increase the risk of fibrosis and scar formation. Therefore, inducing HO-1 activity against mechanical stress-induced inflammation and fibrosis may be an interesting strategy to prevent negative effects of surgery on growth and function in patients with orofacial clefts or in patients with

  7. Development of a Chemiluminescence Method for Gas-Phase HO2 Detection

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Lloyd, J.; Springston, S.

    2003-12-01

    Hydroperoxyl Radical (HO2) is a highly reactive intermediate species that participates in photochemical processes in the troposphere. Accurate measurement of HO2 will facilitate the verification of the ozone production mechanism used by the atmospheric chemistry community. HO2 is also the major source of H2O2, which is responsible for the oxidation of SO2 in droplets. Here, we describe a new HO2 detection method based on flow injection analysis (FIA) with a chemiluminescence detector. Gas-phase HO2 is first scrubbed into a pH 9 borax buffer solution, then injected into a chemiluminescence detector, where HO2 and its conjugate base O2- react with MCLA, a synthetic analog of the luciferin from the crustacean Cypridina, to emit light at 465 nm. This technique shows high sensitivity (DL = 0.1 nM in liquid phase or 1 pptv in gas phase) and selectivity for the HO2 / O2- system. A unique feature of our technique is the calibration with a radiolytic method that uses a 60Co gamma ray source to quantitatively produce stable aqueous HO2 / O2- standards. This calibration method is highly reproducible, producing an instrument response that varies less than 5% from day to day. We tested our instrument in the meteorology field at Brookhaven National Laboratory (BNL), which is considered a clean remote rural site with background ozone levels about 30 ppbv. On July 17, 2003, a clear sunny day, with a steady NW wind, HO2 started to build up after sunrise and reached a maximum of 9 pptv at about 3 pm local time, approximately two hours after the maximum solar intensity. Our technique has the advantages of simplicity, low cost and ease of operation. It is especially suitable for field measurements, where space and energy resources are usually limited.

  8. Mechanical Stress Changes the Complex Interplay Between HO-1, Inflammation and Fibrosis, During Excisional Wound Repair

    PubMed Central

    Cremers, Niels A. J.; Suttorp, Maarten; Gerritsen, Marlous M.; Wong, Ronald J.; van Run-van Breda, Coby; van Dam, Gooitzen M.; Brouwer, Katrien M.; Kuijpers-Jagtman, Anne Marie; Carels, Carine E. L.; Lundvig, Ditte M. S.; Wagener, Frank A. D. T. G.

    2015-01-01

    Mechanical stress following surgery or injury can promote pathological wound healing and fibrosis, and lead to functional loss and esthetic problems. Splinted excisional wounds can be used as a model for inducing mechanical stress. The cytoprotective enzyme heme oxygenase-1 (HO-1) is thought to orchestrate the defense against inflammatory and oxidative insults that drive fibrosis. Here, we investigated the activation of the HO-1 system in a splinted and non-splinted full-thickness excisional wound model using HO-1-luc transgenic mice. Effects of splinting on wound closure, HO-1 promoter activity, and markers of inflammation and fibrosis were assessed. After seven days, splinted wounds were more than three times larger than non-splinted wounds, demonstrating a delay in wound closure. HO-1 promoter activity rapidly decreased following removal of the (epi)dermis, but was induced in both splinted and non-splinted wounds during skin repair. Splinting induced more HO-1 gene expression in 7-day wounds; however, HO-1 protein expression remained lower in the epidermis, likely due to lower numbers of keratinocytes in the re-epithelialization tissue. Higher numbers of F4/80-positive macrophages, αSMA-positive myofibroblasts, and increased levels of the inflammatory genes IL-1β, TNF-α, and COX-2 were present in 7-day splinted wounds. Surprisingly, mRNA expression of newly formed collagen (type III) was lower in 7-day wounds after splinting, whereas, VEGF and MMP-9 were increased. In summary, these data demonstrate that splinting delays cutaneous wound closure and HO-1 protein induction. The pro-inflammatory environment following splinting may facilitate higher myofibroblast numbers and increase the risk of fibrosis and scar formation. Therefore, inducing HO-1 activity against mechanical stress-induced inflammation and fibrosis may be an interesting strategy to prevent negative effects of surgery on growth and function in patients with orofacial clefts or in patients with

  9. A Reevaluation of Airborne HO(x) Observations from NASA Field Campaigns

    NASA Technical Reports Server (NTRS)

    Olson, Jennifer; Crawford, James H.; Chen, Gao; Brune, William H.; Faloona, Ian C.; Tan, David; Harder, Hartwig; Martinez, Monica

    2006-01-01

    In-situ observations of tropospheric HO(x) (OH and HO2) obtained during four NASA airborne campaigns (SUCCESS, SONEX, PEM-Tropics B and TRACE-P) are reevaluated using the NASA Langley time-dependent photochemical box model. Special attention is given to previously diagnosed discrepancies between observed and predicted HO2 which increase with higher NO(x) levels and at high solar zenith angles. This analysis shows that much of the model discrepancy at high NO(x) during SUCCESS can be attributed to modeling observations at time-scales too long to capture the nonlinearity of HO(x) chemistry under highly variable conditions for NO(x). Discrepancies at high NO(x) during SONEX can be moderated to a large extent by complete use of all available precursor observations. Differences in kinetic rate coefficients and photolysis frequencies available for previous studies versus current recommendations also explain some of the disparity. Each of these causes is shown to exert greater influence with increasing NO(x) due to both the chemical nonlinearity between HO(x) and NO(x) and the increased sensitivity of HO(x) to changes in sources at high NO(x). In contrast, discrepancies at high solar zenith angles will persist until an adequate nighttime source of HO(x) can be identified. It is important to note that this analysis falls short of fully eliminating the issue of discrepancies between observed and predicted HO(x) for high NO(x) environments. These discrepancies are not resolved with the above causes in other data sets from ground-based field studies. Nevertheless, these results highlight important considerations in the application of box models to observationally based predictions of HO(x) radicals.

  10. Mechanical properties, in vitro corrosion and biocompatibility of newly developed biodegradable Mg-Zr-Sr-Ho alloys for biomedical applications

    PubMed Central

    Ding, Yunfei; Lin, Jixing; Wen, Cuie; Zhang, Dongmei; Li, Yuncang

    2016-01-01

    Our previous studies have demonstrated that Mg-Zr-Sr alloys can be anticipated as excellent biodegradable implant materials for load-bearing applications. In general, rare earth elements (REEs) are widely used in magnesium (Mg) alloys with the aim of enhancing the mechanical properties of Mg-based alloys. In this study, the REE holmium (Ho) was added to an Mg-1Zr-2Sr alloy at different concentrations of Mg1Zr2SrxHo alloys (x = 0, 1, 3, 5 wt. %) and the microstructure, mechanical properties, degradation behaviour and biocompatibility of the alloys were systematically investigated. The results indicate that the addition of Ho to Mg1Zr2Sr led to the formation of the intermetallic phases MgHo3, Mg2Ho and Mg17Sr2 which resulted in enhanced mechanical strength and decreased degradation rates of the Mg-Zr-Sr-Ho alloys. Furthermore, Ho addition (≤5 wt. %) to Mg-Zr-Sr alloys led to enhancement of cell adhesion and proliferation of osteoblast cells on the Mg-Zr-Sr-Ho alloys. The in vitro biodegradation and the biocompatibility of the Mg-Zr-Sr-Ho alloys were both influenced by the Ho concentration in the Mg alloys; Mg1Zr2Sr3Ho exhibited lower degradation rates than Mg1Zr2Sr and displayed the best biocompatibility compared with the other alloys. PMID:27553403

  11. Preparation, characterization and photocatalytic properties of Ho doped ZnO nanostructures synthesized by sonochemical method

    NASA Astrophysics Data System (ADS)

    Phuruangrat, Anukorn; Yayapao, Oranuch; Thongtem, Titipun; Thongtem, Somchai

    2014-03-01

    The three-dimensional flowerlike undoped and Ho doped ZnO microstructure was successfully synthesized by a sonochemical method. The morphologies and structures of the phase were characterized by the analyses of XRD, SEM and TEM. The flower-like structure composed of numerous one-dimensional hexagonal nanoprisms ZnO and Ho doped ZnO were revealed as hexagonal crystal structure with exposure (0 0 1) facet. The Ho doped ZnO exhibited a relatively higher photocatalytic activity than the pure ZnO in the degradation of methylene blue under UV light.

  12. Measurements of HO2 chemical kinetics with a new detection method

    NASA Technical Reports Server (NTRS)

    Lee, L. C.; Manzanares, E. R.

    1985-01-01

    In this research program, HO2 was detected by the OH(A-X) photofragment from dissociative excitation of HO2 at 147 nm. This detection method was applied to measure the reaction rate constant of HO2 + O3. This reaction rate constant is needed for the understanding of stratospheric chemistry. Since C12 was used in the flow system, photoexcitation of C12 may produce fluorescence to interfere with the measurements. Thus, the photoexcitation process of C12 in the vacuum ultraviolet region was also examined in this research period using synchrotron radiation as a light source. The research results are summarized.

  13. Path-integral molecular dynamics simulations for water anion clusters (HO)5- and (DO)5-

    NASA Astrophysics Data System (ADS)

    Takayanagi, Toshiyuki; Yoshikawa, Takehiro; Motegi, Haruki; Shiga, Motoyuki

    2009-11-01

    Quantum path-integral molecular dynamics simulations have been performed for the (HO)5- and (DO)5- anion clusters on the basis of a semiempirical one-electron pseudopotential-polarization model. Due to larger zero-point vibrational amplitudes for H atoms than that of D atoms, hydrogen-bond lengths in the (HO)5- cluster are slightly larger than those in (DO)5-. The distribution of the vertical detachment energies for (HO)5- also show a broader feature than that for (DO)5-. The present PIMD simulations thus demonstrate the importance of nuclear quantum effects in water anion clusters.

  14. Major involvement of Na(+) -dependent multivitamin transporter (SLC5A6/SMVT) in uptake of biotin and pantothenic acid by human brain capillary endothelial cells.

    PubMed

    Uchida, Yasuo; Ito, Katsuaki; Ohtsuki, Sumio; Kubo, Yoshiyuki; Suzuki, Takashi; Terasaki, Tetsuya

    2015-07-01

    The purpose of this study was to clarify the expression of Na(+) -dependent multivitamin transporter (SLC5A6/SMVT) and its contribution to the supply of biotin and pantothenic acid to the human brain via the blood-brain barrier. DNA microarray and immunohistochemical analyses confirmed that SLC5A6 is expressed in microvessels of human brain. The absolute expression levels of SLC5A6 protein in isolated human and monkey brain microvessels were 1.19 and 0.597 fmol/μg protein, respectively, as determined by a quantitative targeted absolute proteomics technique. Using an antibody-free method established by Kubo et al. (2015), we found that SLC5A6 was preferentially localized at the luminal membrane of brain capillary endothelium. Knock-down analysis using SLC5A6 siRNA showed that SLC5A6 accounts for 88.7% and 98.6% of total [(3) H]biotin and [(3) H]pantothenic acid uptakes, respectively, by human cerebral microvascular endothelial cell line hCMEC/D3. SLC5A6-mediated transport in hCMEC/D3 was markedly inhibited not only by biotin and pantothenic acid, but also by prostaglandin E2, lipoic acid, docosahexaenoic acid, indomethacin, ketoprofen, diclofenac, ibuprofen, phenylbutazone, and flurbiprofen. This study is the first to confirm expression of SLC5A6 in human brain microvessels and to provide evidence that SLC5A6 is a major contributor to luminal uptake of biotin and pantothenic acid at the human blood-brain barrier. In humans, it was unclear (not concluded) about what transport system at the blood-brain barrier (BBB) is responsible for the brain uptakes of two vitamins, biotin and pantothenic acid, which are necessary for brain proper function. This study clarified for the first time that the solute carrier 5A6/Na(+) -dependent multivitamin transporter SLC5A6/SMVT is responsible for the supplies of biotin and pantothenic acid into brain across the BBB in humans. DHA, docosahexaenoic acid; NSAID, non-steroidal anti-inflammatory drug; PGE2, prostaglandin E2.

  15. Are models of catalytic removal of O3 by HO(x) accurate? Constraints from in situ measurements of the OH to HO2 ratio

    NASA Astrophysics Data System (ADS)

    Cohen, R. C.; Wennberg, P. O.; Stimpfle, R. M.; Koplow, J.; Anderson, J. G.; Fahey, D. W.; Woodbridge, E. L.; Keim, E. R.; Gao, R.; Proffitt, M. H.

    1994-11-01

    Measurements of the ratio OH/HO2, NO, O3, ClO, and BrO were obtained at altitudes from 15-20 km and latitudes from 15-60 deg N. A method is presented for interpreting the rates of chemical transformations that (1) are responsible for over half the ozone removal rate in the lower stratosphere via reactions of HO2; and (2) control the abundance of HO2 through coupling to nitrogen and halogen radicals. The results show our understanding of the chemical reactions controlling the partitioning of OH and HO2 is complete and accurate and that the potential effects of 'missing chemistry' are strickly constrained in the region of the atmosphere encompassed by the observations. The analysis demonstrates that the sensitivity of the ratio OH/HO2 to changes in NO is described to within 12% by current models. This reduces by more than a factor of 2 the effect of uncertainty in the coupling of hydrogen and nitrogen radicals on the analysis of the potential effects of perturbations to odd notrogen in the lower statosphere.

  16. Are models of catalytic removal of O3 by HO(x) accurate? Constraints from in situ measurements of the OH to HO2 ratio

    NASA Technical Reports Server (NTRS)

    Cohen, R. C.; Wennberg, P. O.; Stimpfle, R. M.; Koplow, J.; Anderson, J. G.; Fahey, D. W.; Woodbridge, E. L.; Keim, E. R.; Gao, R.; Proffitt, M. H.

    1994-01-01

    Measurements of the ratio OH/HO2, NO, O3, ClO, and BrO were obtained at altitudes from 15-20 km and latitudes from 15-60 deg N. A method is presented for interpreting the rates of chemical transformations that (1) are responsible for over half the ozone removal rate in the lower stratosphere via reactions of HO2; and (2) control the abundance of HO2 through coupling to nitrogen and halogen radicals. The results show our understanding of the chemical reactions controlling the partitioning of OH and HO2 is complete and accurate and that the potential effects of 'missing chemistry' are strickly constrained in the region of the atmosphere encompassed by the observations. The analysis demonstrates that the sensitivity of the ratio OH/HO2 to changes in NO is described to within 12% by current models. This reduces by more than a factor of 2 the effect of uncertainty in the coupling of hydrogen and nitrogen radicals on the analysis of the potential effects of perturbations to odd notrogen in the lower statosphere.

  17. Kinetics of the reactions of HBr with O3 and HO2: The yield of HBr from HO2 + BrO

    NASA Technical Reports Server (NTRS)

    Mellouki, Abdelwahid; Talukdar, Ranajit K.; Howard, Carleton J.

    1994-01-01

    An upper limit on the yield of HBr from reaction (R1) (HO2 + BrO yields products) has been determined by measuring an upper limit for the rate coefficient of the reverse reaction (R1') (HBr + O3 yields HO2 + BrO). The limits measured at 300 and 441 K were extrapolated to low temperatures to determine that the yield of HBr from reaction (R1) is negligible throughout the stratosphere (less than 0.01% of k(sub 1)). An upper limit for the rate coefficient of the reaction of HO2 with HBr was also determined to be very low less than or equal to 3 x 10(exp -17) cu cm/molecule/sec at 300 K and less than or equal to 3 x 10(exp -16) cu cm/molecule/sec at 400 K. The implications of these results to stratospheric chemistry are discussed.

  18. Potential Energy Surfaces for the Reactions of HO2 Radical with CH2O and HO2 in CO2 Environment.

    PubMed

    Masunov, Artëm E; Atlanov, Arseniy A; Vasu, Subith S

    2016-10-06

    We report on potential energies for the transition state, reactant, and product complexes along the reaction pathways for hydrogen transfer reactions to hydroperoxyl radical from formaldehyde H2CO + HO2 → HCO + H2O2 and another hydroperoxyl radical 2HO2 → H2O2 + O2 in the presence of one carbon dioxide molecule. Both covalently bonded intermediates and weak intermolecular complexes are identified and characterized. We found that reactions that involve covalent intermediates have substantially higher activation barriers and are not likely to play a role in hydrogen transfer kinetics. The van der Waals complexation with carbon dioxide does not affect hydrogen transfer from formaldehyde, but it lowers the barrier for hydroperoxyl self-reaction by nearly 3 kcal/mol. This indicates that CO2 environment is likely to have catalytic effect on HO2 self-reaction, which needs to be included in kinetic combustion mechanisms in supercritical CO2.

  19. Vapor complexation in the CsI-HoI 3 system up to 1300 K and the f ← f hypersensitive transition intensities of Ho(III) in different coordination geometries

    NASA Astrophysics Data System (ADS)

    Papatheodorou, G. N.; Chrissanthopoulos, A.

    2007-04-01

    Electronic absorption spectroscopy is used in the temperature range 850-1300 K, to study the vapor species over molten HoI 3-CsI (1:1), molten CsI and solid HoI 3. Quantitative absorbance measurements are used to calculate the following enthalpies of transition: Δ Hsubl(HoI 3) = 271 ± 3 kJ mol -1, Δ Hvap. (CsHoI 4) = 155 ± 2 kJ mol -1 and Δ Hvap. (CsI) = 151 ± 2 kJ mol -1. The ligand field components of the 5G 6 ← 5I 8 hypersensitive transition of Ho(III) for the three different, all iodide, coordination geometries of HoI 3(g), CsHoI 4(g) and HoI 63- (in molten CsI) have been examined in detail. The molar absorptivities ( ɛ) and oscillator strengths ( f) increase as the coordination decreases from the "octahedral" HoI 63- ( ɛ = 65 L mol -1 cm -1; f = 99 × 10 -6) to the distorted tetrahedral HoI 4- ( ɛ = 235 L mol -1 cm -1; f = 290 × 10 -6) to the trigonal HoI 3 ( ɛ = 390 L mol -1 cm -1; f = 500 × 10 -6). The main factors affecting the hypersensitive transition intensities are the coordination number and symmetry and the ligand polarizability as well as the Boltzmann population effects on the ground state levels which are responsible for the appearance of "hot" bands in the spectra. A C2v symmetry is anticipated for the CsHoI 4(g) with the HoI 4- "tetrahedra" distorted towards a square planar symmetry leading to a structure with a pseudo-like inversion center.

  20. A sensitive enzyme-linked immunosorbent assay amplified by biotin-streptavidin system for detecting non-steroidal anti-inflammatory drug ketoprofen.

    PubMed

    Bu, Dan; Zhuang, Hui S; Yang, Guang X

    2014-01-01

    A sensitive biotin-streptavidin-amplified enzyme-linked immunosorbent assay (BA-ELISA) method was developed for detecting non-steroidal anti-inflammatory drug ketoprofen. Compared with traditional ELISA method, the sensitivity of proposed immunoassay was enhanced by the biotin-streptavidin system. Under the optimal condition, the median inhibitory concentration (IC50) was 0.25 ng mL(-1), with minor cross-reactivity to a number of structural analogs. This developed assay was successfully applied to detect the ketoprofen residues in different fish samples, and good recoveries (72.6-105.5%) were obtained. The results indicated that this immunoassay method could specifically detect trace ketoprofen residues and could be widely used for routine monitoring of food samples.

  1. Injection-seeded operation of a Q-switched Cr,Tm,Ho:YAG laser

    NASA Technical Reports Server (NTRS)

    Henderson, Sammy W.; Hale, Charley P.; Magee, James R.

    1991-01-01

    Single-frequency Tm,Ho:YAG lasers operating near 2 microns are attractive sources for several applications including eye-safe laser radar (lidar) and pumping of AgGaSe2 parametric oscillators for efficient generation of longer wavelengths. As part of a program to develop a coherent lidar system using Tm,Ho:YAG lasers, a diode laser-pumped tunable CW single-longitudinal-mode (SLM) Cr:Tm:Ho:YAG laser and a flashlamp-pumped single-transverse-mode Q-switched Cr,Tm,Ho:YAG laser were developed. The CW laser was used to injection-seed the flashlamp-pumped laser, resulting in SLM Q-switched output. Operational characteristics of the CW and Q-switched lasers and injection-seeding results are reported.

  2. Low energy spin dynamics in the spin ice, Ho2Sn2O7

    SciTech Connect

    Ehlers, Georg; Huq, Ashfia; Diallo, Souleymane Omar; Adriano, Cris; Rule, K; Cornelius, A. L.; Fouquet, Peter; Pagliuso, P G; Gardner, Jason

    2012-01-01

    The magnetic properties of Ho{sub 2}Sn{sub 2}O{sub 7} have been investigated and compared to other spin ice compounds. Although the lattice has expanded by 3% relative to the better studied Ho{sub 2}Ti{sub 2}O{sub 7} spin ice, no significant changes were observed in the high temperature properties, T {approx}> 20 K. As the temperature is lowered and correlations develop, Ho{sub 2}Sn{sub 2}O{sub 7} enters its quantum phase at a slightly higher temperature than Ho{sub 2}Ti{sub 2}O{sub 7} and is more antiferromagnetic in character. Below 80 K a weak inelastic mode associated with the holmium nuclear spin system has been measured. The hyperfine field at the holmium nucleus was found to be {approx}700 T.

  3. An Efficient End-Pumped Ho:Tm:YLF Disk Amplifier

    NASA Technical Reports Server (NTRS)

    Yu, Ji-Rong; Petros, Mulugeta; Singh, Upendra N.; Barnes, Norman P.

    2000-01-01

    An efficient diode-pumped, room temperature Ho:Tm:YLF disk amplifier was realized by end-pump configuration. Compared to side pump configuration, about a factor three improvement in system efficiency has been demonstrated.

  4. In vivo analysis of the Saccharomyces cerevisiae HO nuclease recognition site by site-directed mutagenesis.

    PubMed Central

    Nickoloff, J A; Singer, J D; Heffron, F

    1990-01-01

    HO nuclease introduces a specific double-strand break in the mating-type locus (MAT) of Saccharomyces cerevisiae, initiating mating-type interconversion. To define the sequence recognized by HO nuclease, random mutations were produced in a 30-base-pair region homologous to either MAT alpha or MATa by a chemical synthesis procedure. The mutant sites were introduced into S. cerevisiae on a shuttle vector and tested for the ability to stimulate recombination in an assay that mimics mating-type interconversion. The results suggest that a core of 8 noncontiguous bases near the Y-Z junction of MAT is essential for HO nuclease to bind and cleave its recognition site. Other contacts must be required because substrates that contain several mutations outside an intact core reduce or eliminate cleavage in vivo. The results show that HO site recognition is a complex phenomenon, similar to promoter-polymerase interactions. Images PMID:2406563

  5. Spectral and lasing characteristics of 1% Ho:YAG ceramics under intracavity pumping

    SciTech Connect

    Bagayev, S N; Vatnik, S M; Vedin, I A; Kurbatov, P F; Osipov, V V; Shitov, V A; Maksimov, R N; Luk'yashin, K E; Pavlyuk, A A

    2015-01-31

    High-transparency 1% Ho:YAG ceramics with the transmission coefficient of 82% in the IR range at the sample thickness of 1 mm are synthesised from a mixture of the Ho:Y{sub 2}O{sub 3} and Al{sub 2}O{sub 3} nanopowders obtained by the laser method. Results of investigations of spectral and lasing characteristics of 1 % Ho:YAG ceramics under intracavity pumping by radiation of a 5% Tm:KLuW disk element are presented. Based on spectral intensity analysis of generation in the 1.8 – 2.1 mm range and on cavity parameters, the estimated lasing slope efficiency for 1% Ho:YAG ceramics is about 40%. (lasers)

  6. Net flux of nutrients across splanchnic tissues of lactating dairy cows as influenced by dietary supplements of biotin and vitamin B12.

    PubMed

    Girard, C L; Desrochers, A

    2010-04-01

    Biotin and vitamin B(12) are coenzymes in reactions that are essential to propionate metabolism in dairy cows. The objective of the present studies was to determine whether an increased dietary supply of these vitamins would change the net flux of nutrients through the rumen, the portal-drained viscera (PDV), the total splanchnic tissues (TSP), and the liver. Four lactating cows equipped with ultrasonic flow probes around the right ruminal artery and the portal vein and catheters in the right ruminal vein, the portal vein, one hepatic vein, and one mesenteric artery were fed 12 times per day a mixed ration at 95% of ad libitum dry matter intake. Daily supplements of 500 mg of vitamin B(12)+20mg of biotin or no vitamin supplement (study 1) or 500 mg of vitamin B(12) alone or with 20mg of biotin (study 2) were fed according to a crossover design with two 4-wk periods in each study. On the last day of each period, blood flow was recorded and blood samples were collected every 30 min for 4h. In study 1, biotin and vitamin B(12) given together increased milk production and milk protein yields compared with the control diet. The supplement increased appearance of the 2 vitamins across the PDV and TSP. It also reduced the net portal appearance of ammonia and total volatile fatty acids across the PDV. In study 2, compared with the 2 vitamins together, vitamin B(12) alone increased glucose flux across PDV and TSP as well as its arterial concentration and PDV flux of ammonia. With the diet used in the present experiment, the major effects of the vitamin supplements seem to be mediated through changes in ruminal fermentation and gastrointestinal tract metabolism rather than by effects on hepatic metabolism.

  7. Measurement of HOx• production rate due to radon decay in air

    SciTech Connect

    Ding, Huiling

    1993-08-01

    Radon in indoor air may cause the exposure of the public to excessive radioactivity. Radiolysis of water vapor in indoor air due to radon decay could produce (•OH and HO2 •) that may convert atmospheric constituents to compounds of lower vapor pressure. These lower vapor pressure compounds might then nucleate to form new particles in the indoor atmosphere. Chemical amplification was used to determine HOx• production rate in indoor air caused by radon decay. Average HOx• production rate was found to be (4.31±0.07) x 105 HOx• per Rn decay per second (Bq) 3.4 to 55.0% at 22C. This work provided G(HOx•)-value, 7.86±0.13 No./100 eV in air by directly measuring [HOx•] formed from the radiolysis procedure. This G value implies that HOx• produced by radon decay in air might be formed by multiple processes and may be result of positive ion-molecule reactions, primary radiolysis, and radical reactions. There is no obvious relation between HOx• production rate and relative humidity. A laser-induced fluorescence (LIF) system has been used for •OH production rate measurement; it consists of an excimer laser, a dye laser, a frequency doubler, a gaseous fluorescence chamber, and other optical and electronic parts. This system needs to be improved to eliminate the interferences of light scattering and artificial •OH produced from the photolysis of O3/H2O.

  8. Raman and infrared study of 4f electron-phonon coupling in HoVO3

    NASA Astrophysics Data System (ADS)

    Roberge, B.; Balli, M.; Jandl, S.; Fournier, P.; Palstra, T. T. M.; Nugroho, A. A.

    2016-11-01

    First-order Raman scattering and multiphonons are studied in RVO3 (R  =  Ho and Y) as a function of temperature in the orthorhombic and monoclinic phases. Raman spectra of HoVO3 and YVO3 unveil similar features since both compounds have nearly identical R-radii. However, the most important difference lies in the transition temperature involving the V3+ orbitals, the V3+ magnetic moments as well as the crystallographic structure. Particularly, the magnetic and orbital reorientations occur at T N2  =  40 K for HoVO3 instead T N2  =77 K in the case of YVO3. For both systems, anomalous phonon shifts which are related to spin-phonon coupling are observed below the V3+ magnetic ordering temperature (T N1  ≈  110 K) while additional phonon anomalies are exclusively observed in HoVO3 around T *  ≈  15 K. On the other hand, infrared (IR) transmittance measurements as a function of temperature reveal Ho3+5I8  →  5I7 excitations and additional excitations assigned as vibronics. These latter combined with drastic changes in Ho3+5I8  →  5I7 excitations at T N2, are indicative of a strong coupling between the Ho3+ ions and the ligand field. This could explain the large magnetocaloric capacity shown by HoVO3.

  9. The growth of Ho:YAG single crystals by Czochralski method and investigating the formed cores

    SciTech Connect

    Hasani Barbaran, J. Ghani Aragi, M. R.; Javaheri, I.; Baharvand, B.; Tabasi, M.; Layegh Ahan, R.; Jangjo, E.

    2015-12-15

    Ho:YAG single crystals were grown by Czochralski technique, and investigated by the X-ray diffraction (XRD) and optical methods. The crystals were cut and polished in order to observe and analyze their cores. It was found that the deviation of the cores formed in the Czochralski grown Ho:YAG single crystals are resulted from non-symmetrical status of thermal insulation around the Iridium crucible.

  10. 36 W Q-switched Ho:YAG laser at 2097 nm pumped by a Tm fiber laser: evaluation of different Ho3+ doping concentrations

    NASA Astrophysics Data System (ADS)

    Antipov, O. L.; Eranov, I. D.; Kositsyn, R. I.

    2017-01-01

    A laser oscillator based on Ho:YAG crystal pumped by a Tm fiber laser with an acousto-optical Q-switch was optimized for maximum output power and pulse-to-pulse stability. Stable operation at 2097 nm in Q-switched mode is demonstrated, with pulse repetition rates from 10 to 30 kHz, and output power of 36 W (at 55 W of pump power at 1908 nm) in the good quality beam. The influence of Ho ion up-conversion and thermal lensing on the oscillation efficiency is discussed.

  11. Isolation of 163Ho from dysprosium target material by HPLC for neutrino mass measurements

    SciTech Connect

    Mocko, Veronika; Taylor, Wayne  A.; Nortier, Francois M.; Engle, Jonathan  W.; Barnhart, Todd  E.; Nickles, Robert  J.; Pollington, Anthony  D.; Kunde, Gerd  J.; Rabin, Michael  W.; Birnbaum, Eva  R.

    2015-04-29

    The rare earth isotope 163Ho is of interest for neutrino mass measurements. This report describes the isolation of 163Ho from a proton-irradiated dysprosium target and its purification. A Dy metal target was irradiated with 16 MeV protons for 10 h. After target dissolution, 163Ho was separated from the bulk Dy via cation-exchange high performance liquid chromatography using 70 mmol dm–3 α-hydroxyisobutyric acid as the mobile phase. Subsequent purification of the collected Ho fraction was performed to remove the α-hydroxyisobutyrate chelating agent and to concentrate the Ho in a low ionic strength aqueous matrix. The final solution was characterized by MC-ICP-MS to determine the 163Ho/165Ho ratio, 163Ho and the residual Dy content. The HPLC purification process resulted in a decontamination factor 1.4E5 for Dy. As a result, the isolated Ho fraction contained 24.8 ±1.3 ng of 163Ho corresponding to holmium recovery of 72 ± 3%.

  12. Electrochemical immunosensor for N6-methyladenosine detection in human cell lines based on biotin-streptavidin system and silver-SiO2 signal amplification.

    PubMed

    Yin, Huanshun; Wang, Haiyan; Jiang, Wenjing; Zhou, Yunlei; Ai, Shiyun

    2017-04-15

    N6-methyladenosine (m6A), a kind of RNA methylation form and important epigenetic event, plays crucial roles in many biological progresses. Thus it is essential to quantitatively detect m6A in complicated biological samples. Herein, a simple and sensitive electrochemical method was developed for m6A detection using N6-methyladenosine-5'-triphosphate (m6ATP) as detection target molecule. In this detection strategy, anti-m6A antibody was selected as m6A recognition and capture reagent, silver nanoparticles and amine-PEG3-biotin functionalized SiO2 nanospheres (Ag@SiO2) was prepared and used as signal amplification label, and phos-tag-biotin played a vital role of "bridge" to link m6ATP and Ag@SiO2 through the two forms of specific interaction between phosphate group of m6ATP and phos-tag, biotin and streptavidin, respectively. Under the optimal experimental conditions, the immunosensor presented a wide linear range from 0.2 to 500nM and a low detection limit of 0.078nM (S/N=3). The reproducibility and specificity were acceptable. Moreover, the developed method was also validated for detect m6A content in human cell lines. Importantly, this detection strategy provides a promising immunodetection platform for ribonucleotides and deoxyribonucleotides with the advantages of simplicity, low-costing, specificity and sensitivity.

  13. Transcriptome and Gene Ontology (GO) Enrichment Analysis Reveals Genes Involved in Biotin Metabolism That Affect L-Lysine Production in Corynebacterium glutamicum.

    PubMed

    Kim, Hong-Il; Kim, Jong-Hyeon; Park, Young-Jin

    2016-03-09

    Corynebacterium glutamicum is widely used for amino acid production. In the present study, 543 genes showed a significant change in their mRNA expression levels in L-lysine-producing C. glutamicum ATCC21300 than that in the wild-type C. glutamicum ATCC13032. Among these 543 differentially expressed genes (DEGs), 28 genes were up- or downregulated. In addition, 454 DEGs were functionally enriched and categorized based on BLAST sequence homologies and gene ontology (GO) annotations using the Blast2GO software. Interestingly, NCgl0071 (bioB, encoding biotin synthase) was expressed at levels ~20-fold higher in the L-lysine-producing ATCC21300 strain than that in the wild-type ATCC13032 strain. Five other genes involved in biotin metabolism or transport--NCgl2515 (bioA, encoding adenosylmethionine-8-amino-7-oxononanoate aminotransferase), NCgl2516 (bioD, encoding dithiobiotin synthetase), NCgl1883, NCgl1884, and NCgl1885--were also expressed at significantly higher levels in the L-lysine-producing ATCC21300 strain than that in the wild-type ATCC13032 strain, which we determined using both next-generation RNA sequencing and quantitative real-time PCR analysis. When we disrupted the bioB gene in C. glutamicum ATCC21300, L-lysine production decreased by approximately 76%, and the three genes involved in biotin transport (NCgl1883, NCgl1884, and NCgl1885) were significantly downregulated. These results will be helpful to improve our understanding of C. glutamicum for industrial amino acid production.

  14. Biotin- and Glycoprotein-Coated Microspheres as Surrogates for Studying Filtration Removal of Cryptosporidium parvum in a Granular Limestone Aquifer Medium.

    PubMed

    Stevenson, M E; Blaschke, A P; Toze, S; Sidhu, J P S; Ahmed, W; van Driezum, I H; Sommer, R; Kirschner, A K T; Cervero-Aragó, S; Farnleitner, A H; Pang, L

    2015-07-01

    Members of the genus Cryptosporidium are waterborne protozoa of great health concern. Many studies have attempted to find appropriate surrogates for assessing Cryptosporidium filtration removal in porous media. In this study, we evaluated the filtration of Cryptosporidium parvum in granular limestone medium by the use of biotin- and glycoprotein-coated carboxylated polystyrene microspheres (CPMs) as surrogates. Column experiments were carried out with core material taken from a managed aquifer recharge site in Adelaide, Australia. For the experiments with injection of a single type of particle, we observed the total removal of the oocysts and glycoprotein-coated CPMs, a 4.6- to 6.3-log10 reduction of biotin-coated CPMs, and a 2.6-log10 reduction of unmodified CPMs. When two different types of particles were simultaneously injected, glycoprotein-coated CPMs showed a 5.3-log10 reduction, while the uncoated CPMs displayed a 3.7-log10 reduction, probably due to particle-particle interactions. Our results confirm that glycoprotein-coated CPMs are the most accurate surrogates for C. parvum; biotin-coated CPMs are slightly more conservative, while unmodified CPMs are markedly overly conservative for predicting C. parvum removal in granular limestone medium. The total removal of C. parvum observed in our study suggests that granular limestone medium is very effective for the filtration removal of C. parvum and could potentially be used for the pretreatment of drinking water and aquifer storage recovery of recycled water.

  15. Plasmon-induced photoelectrochemical biosensor for in situ real-time measurement of biotin-streptavidin binding kinetics under visible light irradiation.

    PubMed

    Guo, Jingchun; Oshikiri, Tomoya; Ueno, Kosei; Shi, Xu; Misawa, Hiroaki

    2017-03-08

    We developed a localized surface plasmon-induced visible light-responsive photoelectrochemical (PEC) biosensor using a titanium dioxide (TiO2) photoelectrode loaded with gold nanoislands (AuNIs) for in situ real-time measurement of biotin-streptavidin association. As a proof of concept, self-assembled thiol-terminated biotin molecules bound on a AuNIs/TiO2 photoelectrode were successfully utilized to explore the photocurrent response to streptavidin-modified gold nanoparticle (STA-AuNP) solutions. This plasmon-induced PEC biosensor is simple and easy to miniaturize. Additionally, the PEC biosensor achieves highly sensitive measurements under only visible light irradiation and prevents the UV-induced damage of samples. Furthermore, a novel approach has been proposed to realize the real-time monitoring of biotin-STA binding affinities and kinetics by analyzing the PEC sensing characteristics. This PEC biosensor and novel analysis method could provide a new approach for the specific electrical detection and real-time kinetic measurements for clinical diagnostics and drug development.

  16. Biotin- and Glycoprotein-Coated Microspheres as Surrogates for Studying Filtration Removal of Cryptosporidium parvum in a Granular Limestone Aquifer Medium

    PubMed Central

    Blaschke, A. P.; Toze, S.; Sidhu, J. P. S.; Ahmed, W.; van Driezum, I. H.; Sommer, R.; Kirschner, A. K. T.; Cervero-Aragó, S.; Farnleitner, A. H.; Pang, L.

    2015-01-01

    Members of the genus Cryptosporidium are waterborne protozoa of great health concern. Many studies have attempted to find appropriate surrogates for assessing Cryptosporidium filtration removal in porous media. In this study, we evaluated the filtration of Cryptosporidium parvum in granular limestone medium by the use of biotin- and glycoprotein-coated carboxylated polystyrene microspheres (CPMs) as surrogates. Column experiments were carried out with core material taken from a managed aquifer recharge site in Adelaide, Australia. For the experiments with injection of a single type of particle, we observed the total removal of the oocysts and glycoprotein-coated CPMs, a 4.6- to 6.3-log10 reduction of biotin-coated CPMs, and a 2.6-log10 reduction of unmodified CPMs. When two different types of particles were simultaneously injected, glycoprotein-coated CPMs showed a 5.3-log10 reduction, while the uncoated CPMs displayed a 3.7-log10 reduction, probably due to particle-particle interactions. Our results confirm that glycoprotein-coated CPMs are the most accurate surrogates for C. parvum; biotin-coated CPMs are slightly more conservative, while unmodified CPMs are markedly overly conservative for predicting C. parvum removal in granular limestone medium. The total removal of C. parvum observed in our study suggests that granular limestone medium is very effective for the filtration removal of C. parvum and could potentially be used for the pretreatment of drinking water and aquifer storage recovery of recycled water. PMID:25888174

  17. Detection of antibodies against Bordetella avium in turkeys by avidin-biotin enhancement of the enzyme-linked immunosorbent assay and the dot-immunobinding assay.

    PubMed

    Tsai, H J; Saif, Y M

    1991-01-01

    An avidin-biotin-enhanced enzyme-linked immunosorbent assay (AB-ELISA) and an avidin-biotin-enhanced dot-immunobinding (AB-DIB) assay for detecting antibody to Bordetella avium in turkey sera were developed and compared with the microagglutination (MA) test. Whole-cell antigen, biotin-labeled goat anti-turkey IgG conjugate, and horseradish-peroxidase-labeled streptavidin were used in the AB-ELISA and AB-DIB assay. The AB-ELISA and AB-DIB assay were sensitive, specific, and reproducible. These assays were superior to the MA test for measuring acquired and maternal antibodies against B. avium. All MA-positive sera were positive by two assays, but some sera negative by MA test had titers in the AB-ELISA and AB-DIB assay. AB-ELISA and AB-DIB titers showed a positive correlation (r = 0.866), and AB-ELISA was more sensitive than the AB-DIB assay.

  18. Production of Hev b5 as a fluorescent biotin-binding tripartite fusion protein in insect cells

    SciTech Connect

    Nordlund, Henri R. . E-mail: henri.nordlund@uta.fi; Laitinen, Olli H.; Uotila, Sanna T.H.; Kulmala, Minna; Kalkkinen, Nisse; Kulomaa, Markku S.

    2005-10-14

    The presented green fluorescent protein and streptavidin core-based tripartite fusion system provides a simple and efficient way for the production of proteins fused to it in insect cells. This fusion protein forms a unique tag, which serves as a multipurpose device enabling easy optimization of production, one-step purification via streptavidin-biotin interaction, and visualization of the fusion protein during downstream processing and in applications. In the present study, we demonstrate the successful production, purification, and detection of a natural rubber latex allergen Hev b5 with this system. We also describe the production of another NRL allergen with the system, Hev b1, which formed large aggregates and gave small yields in purification. The aggregates were detected at early steps by microscopical inspection of the infected insect cells producing this protein. Therefore, this fusion system can also be utilized as a fast indicator of the solubility of the expressed fusion proteins and may therefore be extremely useful in high-throughput expression approaches.

  19. Synthesis of a Cytokinin Linked by a Spacer to Dexamethasone and Biotin: Conjugates to Detect Cytokinin-Binding Proteins.

    PubMed

    Wang, You; Letham, David S; John, Peter C L; Zhang, Ren

    2016-04-30

    Yeast cells expressing cDNA libraries have provided two new approaches to facilitate further identification of cytokinin-binding proteins and receptors. These are the yeast three hybrid (Y3H) system and fluorescence activated cell sorting (FACS). The Y3H system requires a synthetic hybrid ligand comprising an "anchor" moiety (e.g., dexamethasone) linked to a cytokinin via a spacer. In the yeast nucleus, this ligand by binding connects two fusion proteins leading to a reporter gene activation and detection and characterisation of cytokinin binding proteins. Herein is reported the first synthesis of dexamethasone-cytokinin ligands with a spacer linkage. This was attached to the purine ring of 6-benzylaminopurine (BAP) at positions 2, 8 or 9. To achieve this, dexamethasone was modified by periodate oxidation yielding a carboxylic group used for conjugation to the spacer by amide formation. Biotinyl derivatives of cytokinins for FACS included those synthesised by reaction of an activated ester of biotin with 8-(10-amino-decylamino) derivatives of BAP and BAP 9-riboside. Properties of the conjugates and some biological situations where they could be applicable are discussed briefly.

  20. Enhanced anti-oxidative activity and lignocellulosic ethanol production by biotin addition to medium in Pichia guilliermondii fermentation.

    PubMed

    Qi, Kai; Xia, Xiao-Xia; Zhong, Jian-Jiang

    2015-01-01

    Commercialization of lignocellulosic ethanol fermentation requires its high titer, but the reactive oxygen species (ROS) accumulation during the bioprocess damaged the cells and compromised this goal. To improve the cellular anti-oxidative activity during non-detoxified corncob residue hydrolysate fermentation, seed cells were prepared to possess a higher level of intracellular biotin pool (IBP), which facilitated the biosyntheses of catalase and porphyrin. As a result, the catalase activity increased by 1.3-folds compared to control while the ROS level reduced by 50%. Cell viability in high-IBP cells was 1.7-folds of control and the final ethanol titer increased from 31.2 to 41.8 g L(-1) in batch fermentation. The high-IBP cells were further used for repeated-batch fermentation in the non-detoxified lignocellulosic hydrolysate, and the highest titer and average productivity of ethanol reached 63.7 g L(-1) and 1.2 g L(-1)h(-1). The results were favorable to future industrial application of this lignocellulosic bioethanol process.

  1. Immunosensor based on magnetic relaxation switch and biotin-streptavidin system for the detection of Kanamycin in milk.

    PubMed

    Chen, Yi Ping; Zou, Ming qiang; Qi, Cai; Xie, Meng-Xia; Wang, Da-Ning; Wang, Yan-Fei; Xue, Qiang; Li, Jin-Feng; Chen, Yan

    2013-01-15

    A rapid, sensitive, and simple immunosensor was developed for the detection of Kanamycin (KM) in milk. This immunosensor is based on magnetic relaxation switch (MRS) assay and biotin-streptavidin system (B-SA system). The target analyte (KM) competed with those on the surface of the superparamagnetic iron oxide (SPIO) nanoparticles and hence affected the formation of SPIO aggregates. The dispersed and aggregated states of SPIO can modulate the spin-spin relaxation time (T(2)) of the neighboring water molecule. T(2) was then changed as an effect of the target analyte. The B-SA system was used to amplify the SPIO binding, thus enhance the sensitivity. The detection working was 1.5 to 25.2ng mL(-1) and limit of detection (LOD) was determined to be 0.1ng mL(-1). The LOD of the immunosensor decreased tenfold, and its analysis time (45min) was much shorter than that of enzyme-linked immunosorbent assay (6h to 8h). The average recoveries of the KM at various spiking levels ranged from 80.2% to 85.6% with a relative standard deviation (RSD) below 4.0%. The results showed that the MRS immunosensor was a promising platform for the determination of small molecular residues because of its high sensitivity, specificity, homogeneity, and speed.

  2. An SH2 domain-based tyrosine kinase assay using biotin ligase modified with a terbium(III) complex.

    PubMed

    Sueda, Shinji; Shinboku, Yuki; Kusaba, Takeshi

    2013-01-01

    Src homology 2 (SH2) domains are modules of approximately 100 amino acids and are known to bind phosphotyrosine-containing sequences with high affinity and specificity. In the present work, we developed an SH2 domain-based assay for Src tyrosine kinase using a unique biotinylation reaction from archaeon Sulfolobus tokodaii. S. tokodaii biotinylation has a unique property that biotin protein ligase (BPL) forms a stable complex with its biotinylated substrate protein (BCCP). Here, an SH2 domain from lymphocyte-specific tyrosine kinase was genetically fused to a truncated BCCP, and the resulting fusion protein was labeled through biotinylation with BPL carrying multiple copies of a luminescent Tb(3+) complex. The labeled SH2 fusion proteins were employed to detect a phosphorylated peptide immobilized on the surface of the microtiter plate, where the phosphorylated peptide was produced by phosphorylation to the substrate peptide by Src tyrosine kinase. Our assay allows for a reliable determination of the activity of Src kinase lower than 10 pg/μL by a simple procedure.

  3. Sulfo-NHS-SS-biotin derivatization: a versatile tool for MALDI mass analysis of PTMs in lysine-rich proteins.

    PubMed

    Markoutsa, Stavroula; Bahr, Ute; Papasotiriou, Dimitrios G; Häfner, Ann-Kathrin; Karas, Michael; Sorg, Bernd L

    2014-03-01

    The discovery of PTMs in proteins by MS requires nearly complete sequence coverage of the detected proteolytic peptides. Unfortunately, mass spectrometric analysis of the desired sequence fragments is often impeded due to low ionization efficiency and/or signal suppression in complex samples. When several lysine residues are in close proximity tryptic peptides may be too short for mass analysis. Moreover, modified peptides often appear in low stoichiometry and need to be enriched before analysis. We present here how the use of sulfo-NHS-SS-biotin derivatization of lysine side chain can help to detect PTMs in lysine-rich proteins. This label leads to a mass shift which can be adjusted by reduction of the SS bridge and alkylation with different reagents. Low intensity peptides can be enriched by use of streptavidin beads. Using this method, the functionally relevant protein kinase A phosphorylation site in 5-lipoxygenase was detected for the first time by MS. Additionally, methylation and acetylation could be unambiguously determined in histones.

  4. Simulations of a protein crystal: Explicit treatment of crystallization conditions links theory and experiment in the streptavidin-biotin complex

    PubMed Central

    Cerutti, David S.; Le Trong, Isolde; Stenkamp, Ronald E.; Lybrand, Terry P.

    2009-01-01

    A 250ns molecular dynamics simulation of the biotin-liganded streptavidin crystal lattice, including cryo-protectant molecules and crystallization salts, is compared to a 250ns simulation of the lattice solvated with pure water. The simulation using detailed crystallization conditions preserves the initial X-ray structure better than the simulation using pure water, even though the protein molecules display comparable mobility in either simulation. Atomic fluctuations computed from the simulation with crystallization conditions closely reproduce fluctuations derived from experimental temperature factors (correlation coefficient 0.88, omitting two N-terminal residues with very high experimental B-factors). In contrast, fluctuations calculated from the simulation with pure water were less accurate, particularly for two of the streptavidin loops exposed to solvent in the crystal lattice. Finally, we obtain good agreement between the water and cryo-protectant densities obtained from the simulated crystallization conditions and the electron density due to solvent molecules in the X-ray structure. Our results suggest that detailed lattice simulations with realistic crystallization conditions can be used to assess potential function parameters, validate simulation protocols, and obtain valuable insights that solution-phase simulations do not easily provide. We anticipate that this will prove to be a powerful strategy for molecular dynamics simulations of biomolecules. PMID:18950193

  5. Comparison of 35S and biotin as labels for in situ hybridization: Use of an HPV model system

    SciTech Connect

    Unger, E.R.; Hammer, M.L.; Chenggis, M.L. )

    1990-01-01

    Colorimetric in situ hybridization is a method of potential importance in diagnosis and research. The largest criticism of the method has been a perceived loss of sensitivity compared with autoradiographic techniques. Our more positive experience with automation of colorimetric in situ hybridization led us to undertake a direct comparison of the sensitivity of 35S- and biotin-labeled probes. Serial sections of formalin-fixed, paraffin-embedded cell pellets from four human cervical carcinoma cell lines with known copies of HPV (CaSki, 400-600 copies HPV 16; HeLa, 10-50 copies HPV 18; SiHa, 1-2 copies HPV 16; HTB31, no known copies HPV) were hybridized with protocols optimized for autoradiographic or colorimetric detection. Both methods gave comparable results, with differences in each technique seen at the limits of sensitivity. The 1-2 copies of HPV 16 per SiHa cell can be detected with both methods; however, grain counting is required for interpretation of the autoradiographic result. This degree of sensitivity for colorimetric in situ hybridization in formalin-fixed, paraffin-embedded material is achieved through careful optimization of probe size and labeling, adequate tissue digestion, and removal of background. Autoradiography may be preferred in situations where quantitation is required, but colorimetric detection retains the advantages of speed, potential for automation, and improved localization of signal with comparable sensitivity.

  6. Correlation between magnon and magnetic symmetries of hexagonal RMnO3 (R = Er, Ho, Lu)

    NASA Astrophysics Data System (ADS)

    Nguyen, Thi Minh Hien; Nguyen, Thi Huyen; Chen, Xiang-Bai; Park, Yeonju; Jung, Young Mee; Lee, D.; Noh, T. W.; Cheong, Sang-Wook; Yang, In-Sang

    2016-11-01

    The correlation between the magnon scattering and the magnetic symmetries of hexagonal RMnO3 (R = Er, Ho) thin films and LuMnO3 single crystal was studied through the 2D Correlation Spectroscopy (2D COS) and Perturbation-Correlation Moving Window 2D (PCMW2D) Correlation Spectroscopy which were performed on the temperature-dependent Raman spectra of RMnO3 (R = Er, Ho, Lu). From the Raman spectra, we observed much stronger intensity and more asymmetrical magnon peak in LuMnO3 single crystal than in ErMnO3 and HoMnO3 thin films. While the ratio between magnon and phonon's linewidth of LuMnO3 and HoMnO3 display an anomalous behavior, that ratio of ErMnO3 is almost stable. The result from PCMW2D also supports these results. In addition, our 2D COS analysis showed that there are more overlap peaks in broad four-spin flipping magnon peak in LuMnO3 than that in ErMnO3 and HoMnO3. The differences of hexagonal RMnO3 (R = Er, Ho, Lu) in magnon scattering are very similar to the actual differences of the magnetic symmetries of these compounds. Therefore, we suggest that the magnon scattering of hexagonal RMnO3 is strongly correlated with the magnetic symmetries of these materials.

  7. The challenges of water governance in Ho Chi Minh City.

    PubMed

    van Leeuwen, Cornelis J; Dan, Nguyen P; Dieperink, Carel

    2016-04-01

    Population growth, urbanization, pollution, and climate change pose urgent water challenges in cities. In this study, the sustainability of integrated water resources management in Ho Chi Minh City (HCMC) was evaluated using the City Blueprint approach. The City Blueprint is a set of 24 dedicated indicators divided over 8 categories (i.e., water security, water quality, drinking water, sanitation, infrastructure, climate robustness, biodiversity and attractiveness, and governance including public participation). The analysis showed that the rapid increase of water use for urban, industrial, and agricultural activities in HCMC has resulted in depletion of groundwater and severe pollution of both groundwater and surface water. Surface water quality, groundwater quality, biodiversity, and the sanitation of domestic and industrial wastewater are matters that need serious improvement. Current and future water supply in HCMC is at risk. HCMC can cope with it, but the 7 governance gaps as described by the Organisation for Economic Co-operation and Development (OECD) are major obstacles for HCMC. Rainwater harvesting, pollution reduction, as well as wastewater reuse are among the practical options. Wastewater reuse could lower the water stress index to 10%. The window to do this is narrow and rapidly closing as a result of the unprecedented urbanization and economic growth of this region.

  8. Ho:YAG laser irradiation in blood vessel as a vasodilator: ex vivo study

    NASA Astrophysics Data System (ADS)

    Nakatani, E.; Iwasaki, T.; Kaneko, K.; Shimazaki, N.; Arai, T.

    2007-02-01

    We studied Ho:YAG laser irradiation in blood vessel as a vasodilator ex vivo. We thought that the Ho:YAG laser-induced bubble expansion might be able to dilate the vessel because we found the vessel wall expansion after the Ho:YAG laser irradiation, that is steady deformation, in the vessel ex vivo. There have been many reports regarding to the Ho:YAG laser irradiation in the vessel. Most of studies concentrated on the interaction between Ho:YAG laser irradiation and vessel wall to investigate side effect on Ho:YAG laser angioplasty. We proposed to use the Ho:YAG laser-induced bubble expansion as a vasodilator. We studied vasodilation effect of the Ho:YAG laser-induced bubble ex vivo. The flash lamp excited Ho:YAG laser surgical unit (IH102, NIIC, Japan) (λ=2.1μm) was used. The laser energy was delivered by a silica glass fiber (outer diameter: 1000μm, core diameter: 600μm). The laser-induced bubble was generated in the extracted fresh porcine carotid artery with the warmed saline perfusion. The laser energy at the fiber tip was ranging from 170-1300mJ per pulse. Number of the laser irradiation was ranged from 20pulses to 100pulses. The outer diameter of the vessel was observed. To examine the change in mechanical properties of the vessel wall, the stress-strain curve of the laser-irradiated vessel was measured. Birefringence observation and microscopic observation of staining specimen were performed. When the laser energy was set to 1300mJ per pulse, the outer diameter of the vessel after the laser irradiation was expanded by 1.4 times comparing with that of before the laser irradiation and the dilatation effect was kept even at 10minutes after the irradiation. The elasticity modulus of the artery by collagen was changed by the laser irradiation. In the polarized microscopic observation, the brightness of the intimal side of the vessel is increased comparing with that of the normal. We think this brightness increasing may be attributed to birefringence change

  9. Dual protective role of HO-1 in transplanted liver grafts: A review of experimental and clinical studies

    PubMed Central

    Wang, Chun-Feng; Wang, Zhen-Yu; Li, Ji-Yu

    2011-01-01

    Liver transplantation is considered as the most effective treatment for end-stage liver disease. However, serious complications still exist, particularly in two aspects: ischemia and subsequent reperfusion of the liver, causing postoperative hepatic dysfunction and even failure; and acute and chronic graft rejections, affecting the allograft survival. Heme oxygenase (HO), a stress-response protein, is believed to exert a protective function on both the development of ischemia-reperfusion injury (IRI) and graft rejection. In this review of current researches on allograft protection, we focused on the HO-1. We conjecture that HO-1 may link these two main factors affecting the prognosis of liver transplantations. In this review, the following aspects were emphasized: the basic biological functions of HO-1, its roles in IRI and allograft rejection, as well as methods to induce HO-1 and the prospects of a therapeutic application of HO-1 in liver transplantation. PMID:21912452

  10. TRACE-P OH and HO2 Measurements with the Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS) on the DC-8

    NASA Technical Reports Server (NTRS)

    Brune, William H.; Martinez-Harder, Monica; Harder, Hartwig

    2004-01-01

    The Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS) measures OH and HO2 from the NASA DC-8. This instrument detects OH by laser induced fluorescence (LIF) in detection chambers at low pressure and detects HO2 by chemical conversion with NO followed by LIF detection. The demonstrated detection limit (S/N=2, 5 min.) for OH is about 0.005 pptv (1x10(exp 6)/cu cm at 2 km altitude) and for HO2 is 0.05 pptv (1x10(exp 6)/cu cm at 2 km altitude). We will use ATHOS to measure OH, HO2, and HO2/OH during TRACE- P, analyze these results by comparing them against fundamental relationships and computer models, and publish the analyses. TRACE-P HO(x), measurements will help develop a clearer picture of the atmospheric oxidation and 0 3 production that occur as Asian pollution spreads across the Pacific Ocean.

  11. Modeling and predicting pKa values of mono-hydroxylated polychlorinated biphenyls (HO-PCBs) and polybrominated diphenyl ethers (HO-PBDEs) by local molecular descriptors.

    PubMed

    Yu, Haiying; Wondrousch, Dominik; Yuan, Quan; Lin, Hongjun; Chen, Jianrong; Hong, Huachang; Schüürmann, Gerrit

    2015-11-01

    Hydroxylated polychlorinated biphenyls (HO-PCBs) and polybrominated diphenyl ethers (HO-PBDEs) are attracting considerable concerns because of their multiple endocrine-disrupting effects and wide existence in environment and organisms. The hydroxyl groups enable these chemicals to be ionizable, and dissociation constant, pKa, becomes an important parameter for investigating their environmental behavior and biological activities. In this study, a new pKa prediction model was developed using local molecular descriptors. The dataset contains 21 experimental pKa values of HO-PCBs and HO-PBDEs. The optimized geometries by ab initio HF/6-31G(∗∗) algorithm were used to calculate the site-specific molecular readiness to accept or donate electron charges. The developed model obtained good statistical performance, which significantly outperformed commercial software ACD and SPARC. Mechanism analysis indicates that pKa values increase with the charge-limited donor energy EQocc on hydroxyl oxygen atom and decrease with the energy-limited acceptor charge QEvac on hydroxyl hydrogen atom. The regression model was also applied to calculate pKa values for all 837 mono-hydroxylated PCBs and PBDEs in each class, aiming to provide basic data for the ecological risk assessment of these chemicals.

  12. A new measurement of the half-life of (166m)Ho.

    PubMed

    Nedjadi, Y; Bailat, C; Caffari, Y; Froidevaux, P; Wastiel, C; Kivel, N; Guenther-Leopold, I; Triscone, G; Jaquenod, F; Bochud, F

    2012-09-01

    The work presented here is a new and precise measurement of the half-life of (166m)Ho by determining the activity concentration, using an ionisation chamber calibrated for this nuclide, and measuring the number of (166m)Ho atoms using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Since the isotope (166)Er interferes with the mass spectrometric measurement, Er has to be eliminated from the (166m)Ho radioactive solution. The elimination was achieved using ion-exchange chromatography with the cation exchange resin Dowex AG 50W-X8 and 2-Hydroxybutanoic acid as the mobile phase. After a first transit through the chromatographic column, the purified (166m)Ho eluate was spiked with natural Er to get a resulting Er isotopic composition close to that of natural Er at better than 99.5%, and then it underwent two further separations to eliminate the Er. The activity concentration of this Er-free radioactive (166m)Ho solution was measured in our reference ionisation chamber calibrated for this nuclide by means of the 4πβ(PC)-γ and 4πβ(PS)-4πγ coincidence techniques and integral counting with a well-type NaI(Tl) detector and Monte Carlo efficiencies. An aliquot of this standardized solution was sent to the Paul Scherrer Institute (PSI) for mass concentration determination using an isotope dilution MC-ICP-MS approach. The mass concentration of (166m)Ho in this solution was determined with 0.25% relative standard uncertainty. This value was corroborated by two other independent measurements. The new half-life of (166m)Ho, 1132.6(39) years (k=1), is compatible with the value determined in 1965, but is 5.6% shorter and about 43 times more precise.

  13. HO(x) Measurements in SONEX with the Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS)

    NASA Technical Reports Server (NTRS)

    Brune, William M.

    1997-01-01

    SONEX, which was delayed by aircraft inspection problems, began the second week of October and concluded in mid-November with 16 flights. These flights covered the Pacific Ocean off the western United States, transits across the United States, the western coast of Europe, and the North and Central Atlantic Ocean. Particular attention was paid to the North Atlantic Flight Corridor. ATHOS collected high-quality HO(x) data on 15 flights. Observations taken at 5 Hz were typically averaged into 20-second measurements. Each 20-second measurement has precision 1(sigma) of less than 0.01 pptv. OH measurements were generally made from the surface to flight altitudes. HO2 measurements, which require reagent NO flow, were made from flight altitudes to near the top of the planetary boundary layer. Measured OH and HO2 during SONEX was generally lower than the measured OH and HO2 during SUCCESS (April-May, 1996, central United States). Whereas during SUCCESS midday OH was 0.1-0.5 pptv and HO2 was 3-15 pptv, during SONEX midday OH was 0.02-0.2 pptv and HO2 was 0.5-8 pptv. Part of this difference results from the midday solar zenith angles, which were larger during SONEX than during SUCCESS due to both the season and the generally higher latitudes sampled during SONEX. However, some of the difference may be due to differences in HOx sources, since less air influenced by convection was sampled during SONEX. These possibilities await post-flight calibrations of ATHOS and analysis of observations of HO(x) and simultaneously measured meteorology and trace species.

  14. Single Longitudinal Mode, High Repetition Rate, Q-switched Ho:YLF Laser for Remote Sensing

    NASA Technical Reports Server (NTRS)

    Bai, Yingxin; Yu, Jirong; Petzar, Paul; Petros, M.; Chen, Songsheng; Trieu, Bo; Lee, Nyung; Singh, U.

    2009-01-01

    Ho:YLF/LuLiF lasers have specific applications for remote sensing such as wind-speed measurement and carbon dioxide (CO2) concentration measurement in the atmosphere because the operating wavelength (around 2 m) is located in the eye-safe range and can be tuned to the characteristic lines of CO2 absorption and there is strong backward scattering signal from aerosol (Mie scattering). Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of with a repetition rate of 5 Hz and pulse energy of 75 mJ [1]. For highly precise CO2 measurements with coherent detection technique, a laser with high repetition rate is required to averaging out the speckle effect [2]. In addition, laser efficiency is critically important for the air/space borne lidar applications, because of the limited power supply. A diode pumped Ho:Tm:YLF laser is difficult to efficiently operate in high repetition rate due to the large heat loading and up-conversion. However, a Tm:fiber laser pumped Ho:YLF laser with low heat loading can be operated at high repetition rates efficiently [3]. No matter whether wind-speed or carbon dioxide (CO2) concentration measurement is the goal, a Ho:YLF/LuLiF laser as the transmitter should operate in a single longitudinal mode. Injection seeding is a valid technique for a Q-switched laser to obtain single longitudinal mode operation. In this paper, we will report the new results for a single longitudinal mode, high repetition rate, Q-switched Ho:YLF laser. In order to avoid spectral hole burning and make injection seeding easier, a four mirror ring cavity is designed for single longitudinal mode, high repetition rate Q-switched Ho:YLF laser. The ramp-fire technique is chosen for injection seeding.

  15. Blot-based detection of dehydroalanine-containing glutathione peroxidase with the use of biotin-conjugated cysteamine.

    PubMed

    Rhee, Sue Goo; Cho, Chun-Seok

    2010-01-01

    Dehydroalanine (DHA), alpha,beta-unsaturated amino acid, is found in the position corresponding to the serine, cysteine, and selenocysteine (Sec) residues of various proteins. Proteinaceous Sec is readily oxidized and subsequently undergoes beta-elimination to produce DHA. Glutathione peroxidase (GPx), which contains a Sec at the active site, is irreversibly inactivated by its own substrate as the result of the oxidation of selenium atom followed by the conversion of oxidized Sec to DHA. We developed a convenient method for estimation of the amount of DHA-GPx1 in cell homogenates. This blot-based method depends on specific addition of biotin-conjugated cysteamine to the DHA residue followed by detection of biotinylated protein based on its interaction with streptavidin. The method required an immunoprecipitation of GPx1 before labeling with the cysteamine derivative because many other proteins contain DHA. With the use of this method, we found that conversion of the Sec residue at the active site of GPx1 to DHA occurred during aging of red blood cells (RBCs) in vivo as well as in RBCs exposed to H(2)O(2) generated either externally by glucose oxidase or internally as a result of aniline-induced Hb autoxidation. Accordingly, the content of DHA-GPx1 in each RBC likely reflects total oxidative stress experienced by the cell during its lifetime of 120 days. Previous studies suggested that the activity of GPx1 in RBCs is most influenced by lifestyle and environmental factors such as the use of dietary supplements and smoking habit. Therefore, DHA-GPx1 in RBCs might be a suitable surrogate marker for evaluation of oxidative stress in the body. Our blot-based method for the detection of DHA-GPx1 will be very useful for evaluation of such stress. In addition, similar blot detection method can be devised for other proteins for which immunoprecipitating antibodies are available.

  16. Urological applications of Ho/Nd:Yag laser

    NASA Astrophysics Data System (ADS)

    Grifoni, Riccardo; Pierangeli, Tiziana; Gioacchini, Andrea; Muraro, Giovanni B.

    2001-10-01

    The introduction of Ho:Yag laser has brought many advantages in urology. By this work we want show you our experience with this technology. Between April 1998 and May 2000 we treated 137 patients. Of these 28 had urinary lithiasis (18 bladder and 10 ureteral stones 3 in the upper, 2 in the middle and 5 in the distal tract), 40 were affected by enlargement of prostatic gland: 32 had B.P.H., 8 P.C.; 36 had T.C.C. and 33 strictures of urethra (27) or bladder neck (6). For ureteral lithiasis we used 200 micrometer fiber, energy of 0.5 - 1.4 J with 10 Hz of frequency. In case of bladder stones a 550 or 1000 micrometer using a power of 80 W. The prostatic gland were resected by a 550 micrometer fiber, 2.2 - 2.8 J, 25 - 30 Hz and 70 -80 W. The superficial bladder tumors were removed by 1.4 J with 10 - 15 Hz and 10 - 14 W. In the large tumors we completed the procedure by Nd:YAG at the base of the tumor. Urethra and bladder neck strictures were treated by 1.2 - 1.8 J and 10 - 30 Hz. We successful treated 26 patients with urinary lithiasis obtained the complete vaporization of the stones, 2 had endoscopic ancillary procedures. Out of 32 patients with B.P.H. 41% had the complete resection of the gland the others the resection of the 3d lobe. We removed 114 superficial bladder tumors and only 4 patients had a local recurrence. Of the patients with the strictures 4 had more than one treatment and about 87% had good result. From our experience the use of Holmium:Yag laser has been very efficacy to treat different urological diseases, also in patients with important comorbid disorders and its use reduce the stay in hospital and so the costs.

  17. Identification of protein phosphatase interacting proteins from normal and UVA-irradiated HaCaT cell lysates by surface plasmon resonance based binding technique using biotin-microcystin-LR as phosphatase capturing molecule.

    PubMed

    Bécsi, Bálint; Dedinszki, Dóra; Gyémánt, Gyöngyi; Máthé, Csaba; Vasas, Gábor; Lontay, Beáta; Erdődi, Ferenc

    2014-09-05

    Identification of the interacting proteins of protein phosphatases is crucial to understand the cellular roles of these enzymes. Microcystin-LR (MC-LR), a potent inhibitor of protein phosphatase-1 (PP1), -2A (PP2A), PP4, PP5 and PP6, was biotinylated, immobilized to streptavidin-coupled sensorchip surface and used in surface plasmon resonance (SPR) based binding experiments to isolate phosphatase binding proteins. Biotin-MC-LR captured PP1 catalytic subunit (PP1c) stably and the biotin-MC-LR-PP1c complex was able to further interact with the regulatory subunit (MYPT1) of myosin phosphatase. Increased biotin-MC-LR coated sensorchip surface in the Surface Prep unit of Biacore 3000 captured PP1c, PP2Ac and their regulatory proteins including MYPT1, MYPT family TIMAP, inhibitor-2 as well as PP2A-A and -Bα-subunits from normal and UVA-irradiated HaCaT cell lysates as revealed by dot blot analysis of the recovered proteins. Biotin-MC-LR was used for the subcellular localization of protein phosphatases in HaCaT cells by identification of phosphatase-bound biotin-MC-LR with fluorescent streptavidin conjugates. Partial colocalization of the biotin-MC-LR signals with those obtained using anti-PP1c and anti-PP2Ac antibodies was apparent as judged by confocal microscopy. Our results imply that biotin-MC-LR is a suitable capture molecule in SPR for isolation of protein phosphatase interacting proteins from cell lysates in sufficient amounts for immunological detection.

  18. Determination of equilibrium constants for the reaction between acetone and HO2 using infrared kinetic spectroscopy.

    PubMed

    Grieman, Fred J; Noell, Aaron C; Davis-Van Atta, Casey; Okumura, Mitchio; Sander, Stanley P

    2011-09-29

    The reaction between the hydroperoxy radical, HO(2), and acetone may play an important role in acetone removal and the budget of HO(x) radicals in the upper troposphere. We measured the equilibrium constants of this reaction over the temperature range of 215-272 K at an overall pressure of 100 Torr using a flow tube apparatus and laser flash photolysis to produce HO(2). The HO(2) concentration was monitored as a function of time by near-IR diode laser wavelength modulation spectroscopy. The resulting [HO(2)] decay curves in the presence of acetone are characterized by an immediate decrease in initial [HO(2)] followed by subsequent decay. These curves are interpreted as a rapid (<100 μs) equilibrium reaction between acetone and the HO(2) radical that occurs on time scales faster than the time resolution of the apparatus, followed by subsequent reactions. This separation of time scales between the initial equilibrium and ensuing reactions enabled the determination of the equilibrium constant with values ranging from 4.0 × 10(-16) to 7.7 × 10(-18) cm(3) molecule(-1) for T = 215-272 K. Thermodynamic parameters for the reaction determined from a second-law fit of our van't Hoff plot were Δ(r)H°(245) = -35.4 ± 2.0 kJ mol(-1) and Δ(r)S°(245) = -88.2 ± 8.5 J mol(-1) K(-1). Recent ab initio calculations predict that the reaction proceeds through a prereactive hydrogen-bonded molecular complex (HO(2)-acetone) with subsequent isomerization to a hydroxy-peroxy radical, 2-hydroxyisopropylperoxy (2-HIPP). The calculations differ greatly in the energetics of the complex and the peroxy radical, as well as the transition state for isomerization, leading to significant differences in their predictions of the extent of this reaction at tropospheric temperatures. The current results are consistent with equilibrium formation of the hydrogen-bonded molecular complex on a short time scale (100 μs). Formation of the hydrogen-bonded complex will have a negligible impact on the

  19. Identification of Natural Infections in Sheep/Goats with HoBi-like Pestiviruses in China.

    PubMed

    Shi, H; Kan, Y; Yao, L; Leng, C; Tang, Q; Ji, J; Sun, S

    2016-10-01

    The natural infections of HoBi-like pestiviruses in cattle have been reported in South America, Europe and Asia. In China, although the detections of HoBi-like pestivirus have been reported, the epidemiological investigation was limited. From January 2014 to October 2015, several flocks of sheep/goats in Henan province in central China suffered respiratory diseases which were recovered slowly after antibiotics treatment. To test whether it is the HoBi-like pestivirus caused this symptom, 49 serum samples and 22 nasal swabs were then collected for analysis by serology and RT-PCR. Serological result revealed that prevalence of pestivirus in small ruminants was 12.2% (6/49) in central China. Sequence analysis of partial 5'-UTR nucleotides of pestivirus-positive samples suggested that HoBi-like pestivirus might have circulated in sheep/goats of China for a period and have evolved into new genotype clusters. It is apparent that the study provides the molecular evidence of natural infections in goat/sheep species with HoBi-like pestiviruses in China.

  20. Luminescent properties of Tm3+/ Ho3+ co-doped LiYF4 crystals

    NASA Astrophysics Data System (ADS)

    Li, Shan-shan; Xia, Hai-ping; Dong, Yan-ming; Fu, Li; Gu, Xue-mei; Zhang, Jian-li; Wang, Dong-jie; Jiang, Hao-chuan; Chen, Bao-jiu

    2014-11-01

    Ho3+ with various concentrations and Tm3+ with molar concentration of 1.28% are co-doped in LiYF4 (YLF) single crystals. The luminescent properties of the crystals are investigated through emission spectra, emission cross section and decay curves under the excitation of 808 nm. The energy transfer from Tm3+ to Ho3+ and the optimum fluorescence emission of Ho3+ around 2.05 μm are investigated. The emission intensity at 2.05 μm keeps increasing with the molar concentration of Ho3+ improved from 0.50% to 1.51% when the molar concentration of Tm3+ is kept at 1.28%. Moreover, for the co-doped crystals in which the molar concentrations of Tm3+ and Ho3+ are 1.28% and 1.51%, respectively, the maximum emission cross section reaches 0.760×10-20 cm2 and the maximum fluorescence lifetime is 21.98 ms. All the parameters suggest that these materials have more advantages in the future 2.0 μm laser applications.

  1. Hepatitis B Stigma and Knowledge among Vietnamese in Ho Chi Minh City and Chicago

    PubMed Central

    Dam, Lan; Cheng, Anita; Tran, Phuong; Wong, Shirley S.; Hershow, Ronald; Cotler, Sheldon

    2016-01-01

    Stigma regarding viral hepatitis and liver disease has psychological and social consequences including causing negative self-image, disrupting relationships, and providing a barrier to prevention, testing, and treatment. The aim of this study was to characterize and compare HBV knowledge and stigma in Vietnamese in Ho Chi Minh City and Chicago and to begin to evaluate the cultural context of HBV stigma. Methods. A written survey including knowledge questions and a validated HBV stigma questionnaire was distributed to Vietnamese in Ho Chi Minh City and Chicago. 842 surveys from Ho Chi Minh City and 170 from Chicago were analyzed. Results. Vietnamese living in Chicago had better understanding of HBV transmission and that HBV can cause chronic infection and liver cancer. Vietnamese in Chicago had higher stigma scores on a broad range of items including guilt and shame about HBV and were more likely to feel that persons with HBV can bring harm to others and should be isolated. Conclusions. Vietnamese in Ho Chi Minh City and Chicago have knowledge deficits about HBV, particularly regarding modes of transmission. Persons in Ho Chi Minh City expressed lower levels of HBV stigma than Vietnamese living in Chicago, likely reflecting changing cultural attitudes in Vietnam. Culturally appropriate educational initiatives are needed to address the problem of HBV stigma. PMID:28101498

  2. Investigation of loss processes of Tm and Tm,Ho in YAG

    NASA Technical Reports Server (NTRS)

    Armagan, G.; Buoncristiani, A. M.; Bair, C. H.; Inge, A. T.; Hess, R. V.

    1991-01-01

    The loss of excitation from various manifolds of Tm and Tm,Ho in YAG as a function of temperature and concentration is studied. Two probable loss mechanisms - a Tm up-conversion and a Ho up-conversion - are identified. A 785-nm CW diode laser with 400-nW peak power was focused to a small spot on the sample. The emission from the sample observed at 90 deg was monitored through a monochromator with slits open to 3 mm. Intensity of emission was measured by varying the power of the excitation source using a set of neutral density filters. Power is reported as the percentage of the peak power, and the intensity curves were normalized below 20 percent of transmission. The fact that there is emission above the pump energy indicates an up-conversion from excited manifolds. Nonlinear changes in the intensity of the emission from the Tm 3F4 manifold with the pump power reveals a loss of excitation from this manifold. The linear dependence of the 5I7 manifold emission with pump power at low Tm and high Ho concentrations and the gain of energy in the 5I6 manifold of Ho indicate that the 5I7 manifold loss is due to the coupling of Tm and Ho ions.

  3. Comparison of spectroscopic properties of Tm and Ho in YAG and YLF crystals

    NASA Technical Reports Server (NTRS)

    Armagan, G.; Buoncristiani, A. M.; Inge, A. T.; Di Bartolo, B.

    1991-01-01

    The paper compares the cross-relaxation, energy transfer and loss processes in Tm- and Ho-doped YAG and YLF as a function of temperature, Tm concentration, and excitation power. Significant differences in the behavior of Tm and Tm,Ho in YAG and YLF crystals were found. The cross-relaxation rates of Tm(6 pct) are faster in YLF (about 5 microsec) than YAG (about 10 microsec). The energy transfer rates between Tm and Ho are faster in YLF than YAG. The time it takes for the maximum intensity of 1.7-micron emission to drop 10 percent is 25 microsec for YLF:Tm(6 pct),Ho(0.6 pct) and 65 microsec YAG:Tm(6 pct),Ho(0.5 pct). The losses occurring with increasing pump power for 2.1-micron emission of the above samples are 30 percent less in YLF than YAG. These qualitative differences point to YLF as a valuable 2-micron laser host material.

  4. Ghrelin attenuates the growth of HO-8910 ovarian cancer cells through the ERK pathway

    PubMed Central

    Bai, R.X.; Wang, W.P.; Zhao, P.W.; Li, C.B.

    2016-01-01

    Ovarian cancer is one of the most common causes of death from gynecologic tumors and is an important public health issue. Ghrelin is a recently discovered bioactive peptide that acts as a natural endogenous ligand of the growth hormone secretagogue receptor (GHSR). Several studies have identified the protective effects of ghrelin on the mammalian reproductive system. However, little research has been done on the effects of ghrelin on ovarian cancer cells, and the underlying mechanisms of these effects. We sought to understand the potential involvement of mitogen-activated protein kinases (MAPKs) in ghrelin-mediated inhibition of growth of the ovarian line HO-8910. We applied different concentrations of ghrelin and an inhibitor of the ghrelin receptor (D-Lys3-GHRP-6) to HO-8910 cells and observed the growth rate of cells and changes in phosphorylation of the MAPKs ERK1/2, JNK and p38. We discovered that ghrelin-induced apoptosis of HO-8910 cells was though phosphorylated ERK1/2, and that this phosphorylation (as well as p90rsk phosphorylation) was mediated by the GHSR. The ERK1/2 pathway is known to play an essential part in the ghrelin-mediated apoptosis of HO-8910 cells. Hence, our study suggests that ghrelin inhibits the growth of HO-8910 cells primarily through the GHSR/ERK pathway. PMID:26840702

  5. Near-IR diode laser absorption for measurement of tropospheric HO2

    NASA Technical Reports Server (NTRS)

    Stanton, Alan C.

    1994-01-01

    The possibility of using tunable lead salt diode lasers in the infrared for measurement of tropospheric HO2 has been frequently considered. Although the sensitivity of diode laser absorption has been improved through the use of high frequency detection techniques, nature has been unkind in that the HO2 absorption cross sections are weak. Even using the most optimistic assumptions about attainable path length and detectable absorbance, measurement of tropospheric HO2 by diode laser absorption in the mid-IR appears marginal. A possible alternative method for measuring HO2 is by absorption at near-infrared wavelengths. Several absorption bands of HO2 occur in the wavelength region between 1.2 and 1.6 micron due to electronic transitions and overtones of the fundamental vibrational modes. InGaAsP diode lasers operate in this wavelength region and can be used for high resolution spectroscopy in a manner analogous to the lead salt lasers. A diode laser system in the near-IR offers some advantages.

  6. Clinical Presentation Resembling Mucosal Disease Associated with 'HoBi'-like Pestivirus in a Field Outbreak.

    PubMed

    Weber, M N; Mósena, A C S; Simões, S V D; Almeida, L L; Pessoa, C R M; Budaszewski, R F; Silva, T R; Ridpath, J F; Riet-Correa, F; Driemeier, D; Canal, C W

    2016-02-01

    The genus Pestivirus of the family Flaviviridae consists of four recognized species: Bovine viral diarrhoea virus 1 (BVDV-1), Bovine viral diarrhoea virus 2 (BVDV-2), Classical swine fever virus (CSFV) and Border disease virus (BDV). Recently, atypical pestiviruses ('HoBi'-like pestiviruses) were identified in batches of contaminated foetal calf serum and in naturally infected cattle with and without clinical symptoms. Here, we describe the first report of a mucosal disease-like clinical presentation (MD) associated with a 'HoBi'-like pestivirus occurring in a cattle herd. The outbreak was investigated using immunohistochemistry, antibody detection, viral isolation and RT-PCR. The sequence and phylogenetic analysis of 5'NCR, N(pro) and E2 regions of the RT-PCR positive samples showed that four different 'HoBi'-like strains were circulating in the herd. The main clinical signs and lesions were observed in the respiratory and digestive systems, but skin lesions and corneal opacity were also observed. MD characteristic lesions and a pestivirus with cytopathic biotype were detected in one calf. The present study is the first report of a MD like presentation associated with natural infection with 'HoBi'-like pestivirus. This report describes the clinical signs and provides a pathologic framework of an outbreak associated with at least two different 'HoBi'-like strains. Based on these observations, it appears that these atypical pestiviruses are most likely underdiagnosed in Brazilian cattle.

  7. Growth and magneto-optical characteristic of Ho2Ti2O7 crystal

    NASA Astrophysics Data System (ADS)

    Kang, Junbiao; Xu, Wenming; Zhang, Wenhui; Chen, Xiang; Liu, Wei; Guo, Feiyun; Wu, Shuting; Chen, Jianzhong

    2014-06-01

    A pyrochlore crystal with magneto-optical effect-Ho2Ti2O7 crystal has been grown by Czochralski method. X-ray powder diffraction, magnetic susceptibility, transmission spectrum and Faraday rotation of single crystal Ho2Ti2O7 were measured. The results of Rietveld refinement revealed that the crystal belongs to cubic system and the lattice parameters calculated by Jade 7.0 (Materials Data, Inc.) were a=1.00915(7) nm and V=1.0277 nm3. The effective magnetic moment and Curie-Weiss temperature of Ho2Ti2O7 crystal are 10.4 μB and 1.86 K, respectively. The transmittance of Ho2Ti2O7 crystals grown in Ar can be more than 72% in 700-1080 nm and 1260-1500 nm. The Verdet constant of Ho2Ti2O7 crystal at 1064 nm comes up to -54.1 rad/(mT), which is 1.35 times as large as that of Tb3Ga5O12 reported.

  8. Hepatitis B Stigma and Knowledge among Vietnamese in Ho Chi Minh City and Chicago.

    PubMed

    Dam, Lan; Cheng, Anita; Tran, Phuong; Wong, Shirley S; Hershow, Ronald; Cotler, Sheldon; Cotler, Scott J

    2016-01-01

    Stigma regarding viral hepatitis and liver disease has psychological and social consequences including causing negative self-image, disrupting relationships, and providing a barrier to prevention, testing, and treatment. The aim of this study was to characterize and compare HBV knowledge and stigma in Vietnamese in Ho Chi Minh City and Chicago and to begin to evaluate the cultural context of HBV stigma. Methods. A written survey including knowledge questions and a validated HBV stigma questionnaire was distributed to Vietnamese in Ho Chi Minh City and Chicago. 842 surveys from Ho Chi Minh City and 170 from Chicago were analyzed. Results. Vietnamese living in Chicago had better understanding of HBV transmission and that HBV can cause chronic infection and liver cancer. Vietnamese in Chicago had higher stigma scores on a broad range of items including guilt and shame about HBV and were more likely to feel that persons with HBV can bring harm to others and should be isolated. Conclusions. Vietnamese in Ho Chi Minh City and Chicago have knowledge deficits about HBV, particularly regarding modes of transmission. Persons in Ho Chi Minh City expressed lower levels of HBV stigma than Vietnamese living in Chicago, likely reflecting changing cultural attitudes in Vietnam. Culturally appropriate educational initiatives are needed to address the problem of HBV stigma.

  9. Density-functional study of the structures and properties of holmium-doped silicon clusters HoSi n (n = 3-9) and their anions.

    PubMed

    Hou, Liyuan; Yang, Jucai; Liu, Yuming

    2017-04-01

    The structures and properties of Ho-doped Si clusters, including their adiabatic electron affinities (AEAs), simulated photoelectron spectra (PESs), stabilities, magnetic moments, and charge-transfer characteristics, were systematically investigated using four density-functional methods. The results show that the double-hybrid functional (which includes an MP2 correlation component) can accurately predict the ground-state structure and properties of Ho-doped Si clusters. The ground-state structures of HoSi n (n = 3-9) are sextuplet electronic states. The structures of these Ho-doped Si clusters (aside from HoSi7) are substitutional. The ground-state structures of HoSi n(-) are quintuplet electronic states. Their predicted AEAs are in excellent agreement with the experimental ones. The mean absolute error in the theoretical AEAs of HoSi n (n = 4-9) is only 0.04 eV. The simulated PESs for HoSi n(-) (n = 5-9) are in good agreement with the experimental PESs. Based on its simulated PES and theoretical AEA, we reassigned the experimental PES of HoSi4(-) and obtained an experimental AEA of 2.2 ± 0.1 eV. The dissociation energies of Ho from HoSi n and HoSi n(-) (n = 3-9) were evaluated to test the relative stabilities of the clusters. HOMO-LUMO gap analysis indicated that doping the Si clusters with the rare-earth metal atom significantly increases their photochemical reactivity. Natural population analysis showed that the magnetic moments of HoSi n (n = 3-9) and their anions derive mainly from the Ho atom. It was also found that the magnetic moments of Ho in the HoSi n clusters are larger than the magnetic moment of an isolated Ho atom.

  10. Exogenous induction of HO-1 alleviates vincristine-induced neuropathic pain by reducing spinal glial activation in mice.

    PubMed

    Shen, Yan; Zhang, Zhi-Jun; Zhu, Ming-Di; Jiang, Bao-Chun; Yang, Tian; Gao, Yong-Jing

    2015-07-01

    Chemotherapy drugs such as vincristine can produce painful peripheral neuropathy for which is still lack of effective treatment. Recent studies have demonstrated that neuroinflammation plays an important role in the pathogenesis of neuropathic pain. Heme oxygenase 1 (HO-1) was shown to mediate the resolution of inflammation. In this study, we investigated the contribution of HO-1 in the modulation of vincristine-induced pain and the mechanisms implicated. Injection of vincristine induced persistent mechanical allodynia and thermal hyperalgesia in mice. The expression of HO-1 mRNA and protein was increased in 2 weeks in the spinal cord. Immunostaining showed that HO-1 was mainly expressed in neurons of spinal cord dorsal horn in naïve animals, but induced in astrocytes and microglia after vincristine injection. Intraperitoneal injection of HO-1 inducer increased HO-1 expression in the spinal cord and attenuated vincristine-induced pain. Persistent induction of HO-1 by intraspinal injection of HO-1-expressing lentivirus alleviated vincristine-induced pain for more than 2 weeks. Furthermore, vincristine induced activation of glial cells (astrocytes and microglia), phosphorylation of MAPKs (JNK, ERK, and p38), and production of TNF-α and monocyte chemoattractant protein-1 in the spinal cord, which were all reduced by intrathecal injection of HO-1 inducer. Taken together, our data provide the first evidence that induction of HO-1 attenuates vincristine-induced neuropathic pain via inhibition of glia-mediated neuroinflammation in the spinal cord. This suggests that exogenously induced HO-1 may have potential as therapy in chemotherapy-induced neuropathic pain.

  11. Consistency of the Health of the Nation Outcome Scales (HoNOS) at inpatient-to-community transition

    PubMed Central

    Harvey, Richard; Phung, Dinh; Venkatesh, Svetha; Connor, Jason P

    2016-01-01

    Objectives The Health of the Nation Outcome Scales (HoNOS) are mandated outcome-measures in many mental-health jurisdictions. When HoNOS are used in different care settings, it is important to assess if setting specific bias exists. This article examines the consistency of HoNOS in a sample of psychiatric patients transitioned from acute inpatient care and community centres. Setting A regional mental health service with both acute and community facilities. Participants 111 psychiatric patients were transferred from inpatient care to community care from 2012 to 2014. Their HoNOS scores were extracted from a clinical database; Each inpatient-discharge assessment was followed by a community-intake assessment, with the median period between assessments being 4 days (range 0–14). Assessor experience and professional background were recorded. Primary and secondary outcome measures The difference of HoNOS at inpatient-discharge and community-intake were assessed with Pearson correlation, Cohen's κ and effect size. Results Inpatient-discharge HoNOS was on average lower than community-intake HoNOS. The average HoNOS was 8.05 at discharge (median 7, range 1–22), and 12.16 at intake (median 12, range 1–25), an average increase of 4.11 (SD 6.97). Pearson correlation between two total scores was 0.073 (95% CI −0.095 to 0.238) and Cohen's κ was 0.02 (95% CI −0.02 to 0.06). Differences did not appear to depend on assessor experience or professional background. Conclusions Systematic change in the HoNOS occurs at inpatient-to-community transition. Some caution should be exercised in making direct comparisons between inpatient HoNOS and community HoNOS scores. PMID:27121703

  12. Molecular cloning and expression of a cucumber (Cucumis sativus L.) heme oxygenase-1 gene, CsHO1, which is involved in adventitious root formation.

    PubMed

    Li, Mei-Yue; Cao, Ze-Yu; Shen, Wen-Biao; Cui, Jin

    2011-10-15

    Our previous work showed that in cucumber (Cucumis sativus), auxin rapidly induces heme oxygenase (HO) activity and the product of HO action, carbon monoxide (CO), then triggers the signal transduction events leading to adventitious root formation. In this study, the cucumber HO-1 gene (named as CsHO1) was isolated and sequenced. It contains four exons and three introns and encodes a polypeptide of 291 amino acids. Further results show that CsHO1 shares a high homology with plant HO-1 proteins and codes a 33.3 kDa protein with a 65-amino transit peptide, predicting a mature protein of 26.1 kDa. The mature CsHO1 was expressed in Escherichia coli to produce a fusion protein, which exhibits HO activity. The CsHO1:GFP fusion protein was localized in the chloroplast. Related biochemical analyses of mature CsHO1, including Vmax, Km, Topt and pHopt, were also investigated. CsHO1 mRNA was found in germinating seeds, roots, stem, and especially in leaf tissues. Several well-known adventitious root inducers, including auxin, ABA, hemin, nitric oxide donor sodium nitroprusside (SNP), CaCl(2), and sodium hydrosulfide (NaHS), differentially up-regulate CsHO1 transcripts and corresponding protein levels. These results suggest that CsHO1 may be involved in cucumber adventitious rooting.

  13. The effect of moderate-intensity exercise on the expression of HO-1 mRNA and activity of HO in cardiac and vascular smooth muscle of spontaneously hypertensive rats.

    PubMed

    Ren, Cailing; Qi, Jie; Li, Wanwei; Zhang, Jun

    2016-04-01

    The objective of this study was to observe the effects of moderate-intensity training on the activity of heme oxygenase (HO) and expression of HO-1 mRNA in the aorta and the cardiac muscle of spontaneously hypertensive rats (SHRs). After 9 weeks of swimming exercise, the activity of HO and expression of HO-1 mRNA in the SHRs were measured. The resting blood pressure in the exercise group was increased by 1.7% (P > 0.05), whereas it was significantly elevated by 10.3% (P < 0.01) in the SHR rats. Compared with animals in the control and sedentary groups, the expression level of HO-1 mRNA of aorta and cardiac muscle in the exercise group was significantly enhanced (P < 0.01). The HO activity and the content of plasma carbon monoxide (CO) in the sedentary group were dramatically decreased (P < 0.05 and P < 0.01, respectively) compared with the control group. HO activity and content of plasma CO in the exercise group were significantly higher compared with those in the sedentary group (P < 0.05 and P < 0.01, respectively). The HO/CO metabolic pathway might be involved in the regulation of blood pressure of the SHR models.

  14. Oral administration of supplementary biotin differentially influences the fertility rate and oviductal expression of avidin and avidin-related protein-2 in low- and high-fertility broiler line hens.

    PubMed

    Daryabari, H; Akhlaghi, A; Zamiri, M J; Pirsaraei, Z Ansari; Mianji, G Rahimi; Deldar, H; Eghbalian, A N

    2015-02-01

    Probable involvement of avidin and avidin-related protein-2 (AVR2) in sperm viability in the sperm storage tubules of turkeys has been suggested. The high affinity of biotin to avidin and its analogs is also well documented. The present study aimed to determine the effect of oral biotin on reproductive performance and oviductal mRNA expression of avidin and AVR2 in 2 broiler hen lines with different fertility rates. Low-fertility (line B) and high-fertility (line D) hens (n=144) were randomly allotted to receive 0 (T0), 0.30 (T1), or 0.45 (T2) mg/L biotin in drinking water from 30 through 33 wk of age. The reproductive performance of the hens was evaluated using artificial insemination. At the end of the treatment period, 24 hens per line were killed to assay the expression of avidin and AVR2 in the uterovaginal junction. Supplementary biotin increased egg production from 73.5% for T0 to 87.8% for T2. Hens administered with biotin in line B, but not in line D, showed an increase (8.4%) in fertility rate. Hatchability, chick quality, and overall embryonic mortality were not different among the experimental groups. Real-time PCR data showed that both avidin (P=0.0013) and AVR2 (P<0.0001) expressions were influenced by a biotin×line interaction effect, where low-fertility line B hens receiving the high biotin level recorded respectively a 3.9 and 15.3% increase in avidin and AVR2 mRNA expression, although biotin did not affect these traits in line D hens. Control hens in line D had a dramatically higher AVR2 expression record (7.4-fold) compared with the control hens in line B. The correlation coefficients of fertility rate and avidin expression were 0.73 and 0.66 in lines B and D, respectively. However, the correlation of fertility and AVR2 (r=0.65) was significant for line D hens only. Overall, fertility rate and oviductal expression of avidin and AVR2 were dichotomously affected by oral biotin in low- and high-fertility line hens, where only low-fertility birds

  15. Active targeting behaviors of biotinylated pluronic/poly(lactic acid) nanoparticles in vitro through three-step biotin-avidin interaction.

    PubMed

    Xiong, Xiang Yuan; Gong, Yan Chun; Li, Zi Ling; Li, Yu Ping; Guo, Liang

    2011-01-01

    In order to prepare targeted drug carriers, previously a biotin group has been attached by our group to the end of Pluronic F87/poly(lactic acid) and Pluronic P85/poly(lactic acid) block co-polymers to obtain B-F87-PLA and B-P85-PLA, respectively. In this paper, the active targeting properties of B-F87-PLA and B-P85-PLA nanoparticles in vitro were investigated through a three-step biotin-avidin interaction by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) tests and fluorescence microscopy (FM). Two kinds of human ovarian cancer cells (OVCAR-3 and SKOV-3) and paclitaxel were chosen for the cytotoxicity tests. CA-125 antigen is over-expressed on OVCAR-3 cells but not on SKOV-3 cells. The loading and release behavior of paclitaxel loaded in B-Pluronic-PLA nanoparticles were also studied. Paclitaxel loaded in both B-F87-PLA and B-P85-PLA nanoparticles shows an initial rapid release followed by a slow release period. Compared with SKOV-3 cells, the cytotoxicity results implied that paclitaxel-loaded B-Pluronic-PLA nanoparticles were delivered more effectively to OVCAR-3 cells due to the specific interaction between the biotin groups on the surface of B-Pluronic-PLA nanoparticles and the avidin/biotinylated MAb X306/CA-125 antigen complexes on the surface of OVCAR-3 cells. The active targeting properties of B-F87-PLA nanoparticles were further confirmed by FM.

  16. Transcriptome and Gene Ontology (GO) Enrichment Analysis Reveals Genes Involved in Biotin Metabolism That Affect l-Lysine Production in Corynebacterium glutamicum

    PubMed Central

    Kim, Hong-Il; Kim, Jong-Hyeon; Park, Young-Jin

    2016-01-01

    Corynebacterium glutamicum is widely used for amino acid production. In the present study, 543 genes showed a significant change in their mRNA expression levels in l-lysine-producing C. glutamicum ATCC21300 than that in the wild-type C. glutamicum ATCC13032. Among these 543 differentially expressed genes (DEGs), 28 genes were up- or downregulated. In addition, 454 DEGs were functionally enriched and categorized based on BLAST sequence homologies and gene ontology (GO) annotations using the Blast2GO software. Interestingly, NCgl0071 (bioB, encoding biotin synthase) was expressed at levels ~20-fold higher in the l-lysine-producing ATCC21300 strain than that in the wild-type ATCC13032 strain. Five other genes involved in biotin metabolism or transport—NCgl2515 (bioA, encoding adenosylmethionine-8-amino-7-oxononanoate aminotransferase), NCgl2516 (bioD, encoding dithiobiotin synthetase), NCgl1883, NCgl1884, and NCgl1885—were also expressed at significantly higher levels in the l-lysine-producing ATCC21300 strain than that in the wild-type ATCC13032 strain, which we determined using both next-generation RNA sequencing and quantitative real-time PCR analysis. When we disrupted the bioB gene in C. glutamicum ATCC21300, l-lysine production decreased by approximately 76%, and the three genes involved in biotin transport (NCgl1883, NCgl1884, and NCgl1885) were significantly downregulated. These results will be helpful to improve our understanding of C. glutamicum for industrial amino acid production. PMID:27005618

  17. Combination of chromium and biotin improves coronary risk factors in hypercholesterolemic type 2 diabetes mellitus: a placebo-controlled, double-blind randomized clinical trial.

    PubMed

    Albarracin, Cesar; Fuqua, Burcham; Geohas, Jeff; Juturu, Vijaya; Finch, Manley R; Komorowski, James R

    2007-01-01

    Dyslipidemia, often found in type 2 diabetes mellitus (T2DM) patients, plays an important role in the progression of cardiometabolic syndrome. Two essential nutrients, chromium and biotin, may maintain optimal glycemic control. The authors report here a randomized, double-blind placebo-controlled trial (N=348; chromium picolinate and biotin combination [CPB]: 226, placebo: 122; T2DM participants with hemoglobin A1c [HbA1c] >or=7%) evaluating the effects of CPB on lipid and lipoprotein levels. Participants were randomly assigned (2:1 ratio) to receive either CPB (600 microg chromium as chromium picolinate and 2 mg biotin) or a matching placebo once daily for 90 days. Statistical analyses were conducted in all eligible participants. Subsequent supplemental analyses were performed in T2DM participants with hypercholesterolemia (HC) and in those using stable doses of statins. In the primary analysis, CPB lowered HbA1c (P<.05) and glucose (P<.02) significantly compared with the placebo group. No significant changes were observed in other lipid levels. In participants with HC and T2DM, significant changes in total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels and atherogenic index were observed in the CPB group (P<.05). Significant decreases in LDL-C, total cholesterol, HbA1c , and very low-density cholesterol levels (P<.05) were observed in the CPB group taking statins. CPB treatment was well tolerated with no adverse effects, dissimilar from those associated with placebo. These data suggest that intervention with CPB improves cardiometabolic risk factors.

  18. Kinetics of the reaction OH + HO2 yields H2O + O2 at 296 K

    NASA Technical Reports Server (NTRS)

    Sridharan, U. C.; Kaufman, F.; Qiu, L. X.

    1981-01-01

    The rate constant of the title reaction was measured in a discharge-flow reactor by addition of excess HO2 from a movable double injector to a gas stream containing small concentrations of OH. The concentration of OH was measured by laser-induced fluorescence, HO2 by conversion to OH, and H and O by vacuum-UV resonance fluorescence. Five sets of experiments, each with different excess concentration of HO2, gave an average rate constant of (7.5 + or - 1.2) x 10 to the -11th cu cm/s where the error limits (single sigma) include uncertainties of all experimental parameters. This result is compared with other findings and is discussed in terms of its importance in stratospheric chemistry and in rate theory.

  19. In vitro investigation on Ho:YAG laser-assisted bone ablation underwater.

    PubMed

    Zhang, Xianzeng; Chen, Chuanguo; Chen, Faner; Zhan, Zhenlin; Xie, Shusen; Ye, Qing

    2016-07-01

    Liquid-assisted hard tissue ablation by infrared lasers has extensive clinical application. However, detailed studies are still needed to explore the underlying mechanism. In the present study, the dynamic process of bubble evolution induced by Ho:YAG laser under water without and with bone tissue at different thickness layer were studied, as well as its effects on hard tissue ablation. The results showed that the Ho:YAG laser was capable of ablating hard bone tissue effectively in underwater conditions. The penetration of Ho:YAG laser can be significantly increased up to about 4 mm with the assistance of bubble. The hydrokinetic forces associated with the bubble not only contributed to reducing the thermal injury to peripheral tissue, but also enhanced the ablation efficiency and improve the ablation crater morphology. The data also presented some clues to optimal selection of irradiation parameters and provided additional knowledge of the bubble-assisted hard tissue ablation mechanism.

  20. Tm,Ho:YLF laser end-pumped by a semiconductor diode laser array

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid (Inventor)

    1990-01-01

    An Ho:YLF crystal including Tm as sensitizers for the activator Ho, is optically pumped with a semiconductor diode laser array to generate 2.1 micron radiation with a pump power to output power of efficiency as high as 68 percent. The prior-art dual sensitizer system of Er and Tm requires cooling, such as by LN2, but by using Tm alone and decreasing the concentrations of Tm and Ho, and decreasing the length of the laser rod to about 1 cm, it has been demonstrated that laser operation can be obtained from a temperature of 77 K with an efficiency as high as 68 percent up to ambient room temperature with an efficiency at that temperature as high as 9 percent.