Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Biotin localized in barley chloroplast lamellae is covalently bound to a single protein with an approximate molecular weight of 21 000. It contains one mole of biotin per mole of protein and functions as a carboxyl carrier in the acetyl-CoA carboxylase reaction. The protein was obtained by solubilization of the lamellae in phenol/acetic acid/8 M urea. Feeding barley seedlings with [14C]-biotin revealed that the vitamin is not degraded into respiratory substrates by the plant, but is specifically incorporated into biotin carboxyl carrier protein.
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PMID:Biotin carboxyl carrier protein in barley chloroplast membranes. 23 45

Anaerobic sea or fresh water media with acetate and elemental sulfur yielded enrichments of a new type of strictly anaerobic, rod-shaped, laterally flagellated, Gram-negative bacterium. Three pure culture-strains from different sulfide-containing sea water sources were characterized in detail and are described as a new genus and species Desulfuromonas acetoxidans. The new bacterium is unable to ferment organic substances; it obtains energy for growth by anaerobic sulfur respiration. Acetate, ethanol or propanol can serve as carbon and energy source for growth; their oxidation to CO2 is stoichiometrically linked to the reduction of elemental sulfur to sulfide. Organic disulfide compounds, malate or fumarate are the only other electron acceptors used. Butanol and pyruvate are used in the presence of malate only; no other organic compounds are utilized. Biotin is required as a growth factor. The following dry weight yields per mole of substrate are obtained: in the presence of sulfur: 4.21 g on acetate, 9.77 g on ethanol; in the presence of malate: 16.5 g on acetate, 34.2 g on ethanol and 46.2 g on pyruvate. Accumulations of cells are pink; cell suspensions exhibit absorption spectra resembling those of c-type cytochromes (abs. max. at 419, 523 and 553 nm). Malate-ethanol grown cells contain a b-type cytochrome in addition. In the presence of acetate, ethanol or propanol, Desulfuromonas strains form robust growing syntrophic mixed cultures with phototrophic green sulfur bacteria.
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PMID:Desulfuromonas acetoxidans gen. nov. and sp. nov., a new anaerobic, sulfur-reducing, acetate-oxidizing bacterium. 101 37

Waller, James R. (University of Cincinnati, Cincinnati, Ohio), and Herman C. Lichstein. Biotin transport and accumulation by cells of Lactobacillus plantarum. I. General properties of the system. J. Bacteriol. 90:843-852. 1965.-Resting cells of Lactobacillus plantarum were saturated with bound biotin by incubation in phosphate buffer with biotin and glucose for 2 hr. This bound biotin was stable to wide changes in temperature, pH, and reaction time. Free biotin could be eluted from the cells by suspending them in cold water or saline. Immersing the cells in boiling water for 30 sec released all free biotin. Recoveries of added biotin exceeded 92%. Free biotin uptake by bound biotin-saturated cells occurred by two mechanisms. One process was independent from temperature (Q(10), 1.25), pH, cellular metabolism, and inhibition by iodoacetate. The other mechanism was dependent upon temperature (Q(10), 2.58; optimum, 37 C), pH (optimum, 7.5), and active cellular metabolism, and was inhibited by iodoacetate. Activation energies of 3,700 and 13,800 cal per mole, respectively, were observed for glucose-independent and -dependent free biotin uptake. Both processes exhibited approximately the same degree of inhibition by homobiotin. Higher concentrations of homobiotin were required to inhibit growth than to inhibit free biotin uptake. Intracellular-extracellular ratios as high as 600 were established in the absence of glucose, whereas ratios of nearly 4,000 occurred in the presence of glucose.
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PMID:Biotin transport and accumulation by cells of Lactobacillus plantarum. I. General properties of the system. 584 5

Biotin synthase catalyzes the chemically difficult final step in the biotin biosynthetic pathway and is encoded by the bioB gene in Escherichia coli. In the present work, we extend our characterization of this enzymatic reaction and the extensive set of factors required by it. A defined mixture of components that supports the biotin synthase reaction has been found. The mixture contains biotin synthase, flavodoxin, flavodoxin reductase, NADPH, Ado-Met, Fe, fructose-1,6-bisphosphate, cysteine, and dithiothreitol. Even though this defined mixture supports the biotin synthase reaction, and in that regard is an important step forward in the study of this enzyme, it is unlikely that it contains all the physiologically significant factors involved in the biotin synthase reaction since it supports as an upper limit the synthesis of only 2 mol of biotin per mole of biotin synthase monomer. Progress in our efforts to identify additional physiologically significant factors is also reported. First, we describe evidence that the fructose 1,6-bisphosphate in the defined reaction mixture is substituting for an unknown factor of considerably higher potency present in crude extracts. Second, we have found that a labile low-molecular-weight product of the 7,8-diaminopelargonic acid aminotransferase reaction stimulates the rate of biotin formation in the defined biotin synthase reaction mixture and can increase the final amount of biotin formed by threefold. This product seems to be derived from Ado-Met, which 7,8-diaminopelargonic acid aminotransferase uses as its amino donor. However, 5'-deoxy-5'-methylthioadenosine, the postulated breakdown product from the action of 7,8-diaminopelargonic acid aminotransferase on Ado-Met, cannot be the active material since it has no stimulatory effect when added to the biotin synthase reaction mixture. Third, with a defined reaction mixture in hand, [35S]cysteine and [35S]Ado-Met, two potential sulfur donors present in the defined reaction mixture, were tested separately as sulfur donors. No 35S was incorporated into newly formed biotin when either [35S]cysteine or [35S]Ado-Met was added to the defined biotin synthase reaction mixture.
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PMID:Escherichia coli biotin synthase: an investigation into the factors required for its activity and its sulfur donor. 857 71

In addition to the pharmacokinetic interest, serum concentrations of biotin and biotin metabolites are important because biotin in serum might interfere with assays that use avidin-biotin detection systems. With acute and chronic oral administration of biotin the serum concentration of biotin increases. Because of limited specificity of bioassays or avidin-binding assays used in previous studies, the proportion of the increase attributable to biotin metabolites (if any) remains unknown. To address these questions 15 adults consumed 1,200 microg biotin daily for 14 days. Blood samples were obtained before biotin ingestion and at 3 hours after biotin ingestion on the first day ("acute supplementation") and the fourteenth day ("chronic supplementation"). Biotin, bisnorbiotin, and biotin sulfoxide were measured with a chemically specific high-pressure liquid chromatography/avidin-binding assay. Serum concentrations of biotin, bisnorbiotin, and biotin sulfoxide increased approximately fiftyfold with acute supplementation of biotin; each increased further with chronic supplementation. With acute supplementation the proportion of the total attributable to metabolites did not decrease significantly, suggesting that pathways for biotin catabolism are not easily saturated. With chronic supplementation the proportion of the total attributable to metabolites did not increase significantly, suggesting that biotin catabolism was not substantially induced. We conclude that on a mole basis the contribution of biotin metabolites is important, and we provide an estimate of the biotin and biotin metabolite concentration that might be encountered in individuals who self-select large biotin supplements.
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PMID:Serum concentrations of bisnorbiotin and biotin sulfoxide increase during both acute and chronic biotin supplementation. 904 24

Mixed self-assembled monolayers (SAMs) to immobilize streptavidin on a gold surface were investigated by measuring the pull-off force between an AFM tip and a biotin-modified surface using CFM. Biotin-LC-NHS was modified on SAMs prepared from a mixed solution of cystamine and MEOH. Increased pull-off forces between the AFM tip and the surface were observed with an increased cystamine mole fraction in the solution. Streptavidin was immobilized onto biotin-LC-NHS modified mixed SAMs and analyzed by tapping AFM. Also, the formation of mixed SAMs containing MUOH and MBDA was confirmed using CFM. The measured pull-off forces on the only MBDA surface were larger than those on the surface with MUOH. These results can be applied to determine an optimal mixing ratio of MUOH and MBDA SAMs that reduces non-specific streptavidin binding onto a surface.
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PMID:Characterization of mixed self-assembled monolayers for immobilization of streptavidin using chemical force microscopy. 1855 12