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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Isoenzymes of alcohol dehydrogenase extracted from Drosophila melanogaster are interconvertible and can be distinguished by electrophoretic mobility. When adsorbed on diethylaminoethyl cellulose, the faster-moving forms are converted to the slowest-moving form; the latter is converted to the former in the presence of 0.05 molar nicotinamide-adenine dinucleotide, and the conversion is accompanied by the binding of 3.5 moles of the dinucleotide per mole of enzyme. A change in heat stability accompanies the conversion of the slowest form of alcohol dehydrogenase to the fastest form; the latter becomes stable at 45 degrees C. The increased heat stability may indicate that a conformational change in the alcohol dehydrogenase occurs along with the binding of nicotinamide-adenine dinucleotide.
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PMID:Alcohol dehydrogenase of Drosophila: interconversion of isoenzymes. 429 40

During the aerobic growth of Streptococcus faecalis strain 10C1, with limiting levels of glucose as the substrate, a molar growth yield (Y) of 58.2 g (dry weight) per mole of glucose was obtained. Under these conditions of growth, glucose was dissimilated primarily to acetate and CO(2). The incorporation of (14)C-glucose into cell material was no greater under aerobic conditions than during anaerobic growth. Assuming an adenosine triphosphate coefficient of 10.5, the aerobic Y cannot be explained solely on the basis of substrate phosphorylation and would appear to substantiate previous enzymatic evidence for oxidative phosphorylation in this cytochromeless species. With mannitol as the substrate, an aerobic Y of 64.6 was obtained. Extracts of mannitol-grown cells contained a nicotinamide adenine dinucleotide (NAD)-linked mannitol-1-phosphate (M-1-P) dehydrogenase. The difference in aerobic Y values with mannitol and glucose as substrates would indicate that the in vivo P/O ratio from the oxidation of reduced NAD generated by the oxidation of M-1-P approximates 0.6. The Y values with pyruvate and glycerol as substrates under aerobic conditions were 15.5 and 24.7, respectively.
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PMID:Molar growth yields as evidence for oxidative phosphorylation in Streptococcus faecalis strain 10Cl. 430 99

By, means of al specific nicotinamide-adeninie dinucleotide-dependent prostaglanidin dehydrogenase from swine lung, an enizymatic method has been developed for the assay of prostaglandins. The method permits analysis with a lower limit of 10(-12) mole of prostaglandin.
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PMID:Prostaglandins: enzymatic analysis. 430 31

The influence of a H(2)-utilizing organism, Vibrio succinogenes, on the fermentation of limiting amounts of glucose by a carbohydrate-fermenting, H(2)-producing organism, Ruminococcus albus, was studied in continuous cultures. Growth of V. succinogenes depended on the production of H(2) from glucose by R. albus. V. succinogenes used the H(2) produced by R. albus to obtain energy for growth by reducing fumarate in the medium. Fumarate was not metabolized by R. albus alone. The only products detected in continuous cultures of R. albus alone were acetate, ethanol, and H(2). CO(2) was not measured. The only products detected in the mixed cultures were acetate and succinate. No free H(2) was produced. No formate or any other volatile fatty acid, no succinate or other dicarboxylic acids, lactate, alcohols other than ethanol, pyruvate, or other keto-acids, acetoin, or diacetyl were detected in cultures of R. albus alone or in mixed cultures. The moles of product per 100 mol of glucose fermented were approximately 69 for ethanol, 74 for acetate, 237 for H(2) for R. albus alone and 147 for acetate and 384 for succinate for the mixed culture. Each mole of succinate is equivalent to the production of 1 mol of H(2) by R. albus. Thus, in the mixed cultures, ethanol production by R. albus is eliminated with a corresponding increase in acetate and H(2) formation. The mixed-culture pattern is consistent with the hypothesis that nicotinamide adenine dinucleotide (reduced form), formed during glycolysis by R. albus, is reoxidized during ethanol formation when R. albus is grown alone and is reoxidized by conversion to nicotinamide adenine dinucleotide and H(2) when R. albus is grown with V. succinogenes. The ecological significance of this interspecies transfer of H(2) gas and the theoretical basis for its causing changes in fermentation patterns of R. albus are discussed.
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PMID:Glucose fermentation products in Ruminococcus albus grown in continuous culture with Vibrio succinogenes: changes caused by interspecies transfer of H 2 . 435 87

The role of selenium and molybdenum in the metabolism of Escherichia coli was explored by growing cells in a simple salts medium and examining the metabolic consequences of altering the concentration of molybdenum and selenium compounds in the medium. The addition of tungstate increased the molybdate deficiency of this medium, as reflected by lowered levels of enzyme systems previously recognized to require compounds of molybdenum and selenium for their formation [formate-dependent oxygen reduction, formate dehydrogenase (FDH) (EC 1.2.2.1), and nitrate reductase (EC 1.9.6.1)]. The requirement for selenium and molybdenum appears to be unique to the enzymes of formate and nitrate metabolism since molybdate- and selenite-deficient medium had no effect on the level of several dehydrogenase and oxidase systems, for which the electron donors were reduced nicotinamide adenine dinucleotide, succinate, d- or l-lactate, and glycerol. In addition, no effect was observed on the growth rate or cell yield with any carbon source tested (glucose, glycerol, dl-lactate, acetate, succinate, and l-malate) when the medium was deficient in molybdenum and selenium. dl-Selenocystine was about as effective as selenite in stimulating the formation of formate dehydrogenase, whereas dl-selenomethionine was only 1% as effective. In aerobic cells, an amount of FDH was formed such that 3,200 or 3,800 moles of formate were oxidized per min per mole of added selenium (added as dl-selenocystine or selenite, respectively).
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PMID:Effects of molybdate, tungstate, and selenium compounds on formate dehydrogenase and other enzyme systems in Escherichia coli. 455 2

Nicotinamide adenine dinucleotide phosphate-specific isocitrate dehydrogenase was extracted from etiolated pea (Pisum sativum L.) seedlings and was purified 65-fold. The purified enzyme exhibits one predominant protein band by polyacrylamide gel electrophoresis, which corresponds to the dehydrogenase activity as measured by the nitro blue tetrazolium technique. The reaction is readily reversible, the pH optima for the forward (nicotinamide adenine dinucleotide phosphate reduction) and reverse reactions being 8.4 and 6.0, respectively. The enzyme has different cofactor and inhibitor characteristics in the two directions. Manganese ions can be used as a cofactor for the reaction in each direction but magnesium ions only act as a cofactor in the forward reaction. Zinc ions, and to a lesser extent calcium ions, inhibit the enzyme at low concentrations when magnesium but not manganese is the metal activator. It is suggested that there is a fundamental difference between magnesium and manganese in the activation of the enzyme. The enzyme shows normal kinetics and the Michaelis contant for each substrate was determined. The inhibition by nucleotides, nucleosides, reaction products, and related compounds was studied. The enzyme shows a linear response to the mole fraction of reduced nicotinamide adenine dinucleotide phosphate when total nicotinamide adenine dinucleotide phosphate (nicotinamide adenine dinucleotide phosphate plus reduced nicotinamide adenine dinucleotide phosphate) is kept constant. Isocitrate in the presence of divalent metal ions will protect the enzyme from inactivation by p-chloromercuribenzoate. Protection is also afforded by manganese ions alone but not by magnesium ions alone There is a concerted inhibition of the enzyme by oxalacetate and glyoxylate.
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PMID:Nicotinamide adenine dinucleotide phosphate-specific isocitrate dehydrogenase from a higher plant. Isolation and charactertization. 554 83

Thermoanaerobium brockii was shown to catabolize glucose via the Embden-Meyerhof-Parnas pathway into ethanol, acetic acid, H(2)-CO(2), and lactic acid. Radioactive tracer studies, employing specifically labeled [(14)C]glucose, demonstrated significant fermentation of (14)CO(2) from C-3 and C-4 of the substrate exclusively. All extracts contained sufficient levels of activity (expressed in micromoles per minute per milligram of protein at 40 degrees C) to assign a catabolic role for the following enzymes: glucokinase, 0.40; fructose-1,6-diphosphate aldolase, 0.23; glyceraldehyde-3-phosphate dehydrogenase, 1.73; pyruvate kinase, 0.36; lactate dehydrogenase (fructose-1,6-diphosphate activated), 0.55; pyruvate dehydrogenase (coenzyme A acetylating), 0.53; hydrogenase, 3.3; phosphotransacetylase, 0.55; acetaldehyde dehydrogenase (coenzyme A acetylating), 0.15; ethanol dehydrogenase, 1.57; and acetate kinase, 1.50. All pyridine nucleotide-linked oxidoreductases examined were specific for nicotinamide adenine dinucleotide, except ethanol dehydrogenase which displayed both nicotinamide adenine dinucleotide- and nicotinamide adenine dinucleotide phosphate-linked activities. Fermentation product balances and cell growth yields supported the glucose catabolic pathway described. Representative balanced end product yields (in moles per mole of glucose fermented) were: ethanol, 0.94; l-lactate, 0.84; acetate, 0.20; CO(2), 1.31; and H(2), 0.50. Growth yields of 16.4 g of cells per mole of glucose were demonstrated. Both growth and end product yields varied significantly in accordance with the specific medium composition and incubation time.
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PMID:Glucose fermentation pathway of Thermoanaerobium brockii. 676 5

A soluble yellow CO dehydrogenase from CO-autotrophically grown cells of Pseudomonas carboxydohydrogena was purified 35-fold in seven steps to better than 95% homogeneity with a yield of 30%. The final specific activity was 180 mumol of acceptor reduced per min per mg of protein as determined by an assay based on the CO-dependent reduction of thionin. Methyl viologen, nicotinamide adenine dinucleotide (phosphate), flavin mononucleotide, and flavin adenine dinucleotide were not reduced by the enzyme, but methylene blue, thionin, and toluylene blue were reduced. The molecular weight of native enzyme was determined to be 4 x 10(5). Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed at least three nonidentical subunits of molecular weights 14,000 (alpha), 28,000 (beta), and 85,000 (gamma). The ratio of densities of each subunit after electrophoresis was about 1:2:6 (alpha/beta/gamma), suggesting an alpha(3)beta(3)gamma(3) structure for the enzyme. The purified enzyme was free of formate dehydrogenase and nicotinamide adenine dinucleotide-specific hydrogenase activities, but contained particulate hydrogenase-like activity with thionin as electron acceptor. Known metalchelating agents tested had no effect on CO dehydrogenase activity. No divalent cations tested stimulated enzyme activity. The native enzyme does not contain Ni since cells assimilated little (63)Ni during growth, and the specific (63)Ni content of the enzyme declined during purification. The isoelectric point of the native enzyme was found to be 4.5 to 4.7. The K(m) for CO was found to be 63 muM. The spectrum of the enzyme and its protein-free extract revealed that it contains bound flavin. The cofactor was flavin adenine dinucleotide based on enzyme digestion and thin-layer chromatography. One mole of native enzyme contains at least 3 mol of noncovalently bound flavin adenine dinucleotide.
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PMID:Purification and some properties of carbon monoxide dehydrogenase from Pseudomonas carboxydohydrogena. 689 15

Reactive coenzyme analogues omega-(3-diazoniumpyridinium)alkyl adenosine diphosphate were prepared by reaction of omega-(3-aminopyridinium)alkyl adenosine diphosphate with nitrous acid. In these compounds the nicotinamide ribose is substituted by hydrocarbon chains of varied lengths (n-ethyl to n-pentyl). The diazonium compounds are very unstable and decompose rapidly at room temperature. They show a better stability to 0 degree C. Lactate and alcohol dehydrogenase do not react with any of the analogues. Glyceraldehyde-3-phosphate dehydrogenase reacts rapidly with the diazoniumpentyl compound. Decreasing the length of the alkyl chain significantly decreases the inactivation velocity. 3 alpha, 20 beta-Hydroxysteroid dehydrogenase reacts at 0 degree C with the ethyl homologue and slowly with the propyl compound. The butyl- and pentyl analogues do not inactivate at 0 degree C. Tests with 14C-labeled 2-(3-diazoniumpyridinium)ethyl adenosine diphosphate show that complete loss of enzyme activity results after incorporation of 2 moles of inactivator into 1 mole of tetrameric enzyme. 4-(3-Acetylpyridinium)butyl 2'-phospho-adenosine diphosphate, a structural analogue of NADP+, was prepared by condensation of adenosine-2,3-cyclophospho-5'-phosphomorpholidate with (3-acetylpyridinium)butyl phosphate, followed by hydrolysis of the cyclic phosphoric acid with 2':3'-cyclonucleotide-3'-phosphodiesterase. Because of the redox potential (-315 mV) and the distance between the pyridinium and phosphate groups, this analogue is a hydrogen acceptor and its reduced form a hydrogen donor in tests with alcohol dehydrogenase from Thermoanaerobium brockii. The reduced form of the coenzyme analogue also is a hydrogen donor with glutathione reductase. With other NADP+-dependent dehydrogenases the compound has been shown to be a competitive inhibitor against the natural coenzyme. The acetyl group reacts with bromine to form the bromoacetyl group. This reactive bromoacetyl analogue is a specific active-site directed irreversible inhibitor of isocitrate dehydrogenase.
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PMID:New reactive coenzyme analogues for affinity labeling of NAD+ and NADP+ dependent dehydrogenases. 754 38

The thermodynamics of six reactions of nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate is discussed both from the viewpoint of the chemical equations and the biochemical equations for these reactions. Tables of the standard enthalpies of formation and standard Gibbs energies of formation of species are presented and are used to calculate standard enthalpies of reaction, standard Gibbs energies of reaction, and equilibrium constants K of chemical reactions at 25 degrees C, 1 bar, and ionic strengths of 0, 0.1, and 0.25 M. These tables are used to calculate standard transformed enthalpies of formation and standard transformed Gibbs energies of formation of reactants, standard transformed enthalpies of reaction, standard transformed Gibbs energies of reaction, and apparent equilibrium constants K' of biochemical reactions at 25 degrees C, 1 bar, pH 7, and ionic strengths of 0, 0.1, and 0.25 M. Since these reactions do not involve pK's of acid groups in the vicinity of pH 7, these reactions produce exactly 0, 1, or 2 mol of H+ per mole of reaction. The calculations are compared with experimental values.
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PMID:Thermodynamics of reactions of nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate. 823 68


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