Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:EXPT02288 (NADH)
 21,914 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The existence of two different D-glucose-6-phosphate dehydrogenases in Pseudomonas fluorescens has been demonstrated. Based on their different specificity and their different metabolic regulation one enzyme is appointed to the Entner-Doudoroff pathway and the other to the hexose monophosphate pathway. 2. A procedure is described for the isolation of that D-glucose-6-phosphate dehydrogenase which forms part of the Entner-Doudoroff pathway (Entner-Doudoroff enzyme). A 950-fold purification was achieved with an overall yield of 44%. The final preparation, having a specific activity of about 300 mumol NADH formed per min per mg protein, was shown to be homogeneous. 3. The molecular weight of the Entner-Doudoroff enzyme has been determined to be 220000 by gel permeation chromatography, and that of the other enzyme (Zwischenferment) has been shown to be 265000. 4. The pI of the Entner-Doudoroff enzyme has been shown to be 5.24 and that of the Zwischenferment 4.27. The Entner-Doudoroff enzyme is stable in the range of pH 6 to 10.5 and shows its maximal activity at pH 8.9. 5. The Entner-Doudoroff enzyme showed specificity for NAD+ as well as for NADP+ and exhibited homotropic effects for D-glucose 6-phosphate. It is inhibited by ATP which acts as a negative allosteric effector. Other nucleoside triphosphates as well as ADP are also inhibitory. 6. The enzyme catalyzes the transfer of the axial hydrogen at carbon-1 of beta-D-glucopyranose 6-phosphate to the si face of carbon-4 of the nicotinamide ring and must be classified as B-side stereospecific dehydrogenase.
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PMID:D-glucose-6-phosphate dehydrogenase (Entner-Doudoroff enzyme) from Pseudomonas fluorescens. Purification, properties and regulation. 0 Dec 57

The ability of 5-deazaisoalloxazines to substitute for the isoalloxazine (flavin) coenzyme has been examined with several flavoenzymes. Without exception, the deazaflavin is recognized at the active site and undergoes a redox change in the presence of the specific enzyme substrate. Thus, deazariboflavin is reduced catalytically by NADH in the presence of the Beneckea harveyi NAD(P)H:(flavin) oxidoreductase, the reaction proceeding to an equilibrium with an equilibrium constant near unity. This implies an E0 of -0.310 V for the deazariboflavindihydrodeazariboflavin couple, much lower than that for isoalloxazines. With this enzyme, both riboflavin and deazariboflavin show the same stereospecificity with respect to the pyridine nucleotide, and despite a large difference in Vmax for the two, both have the same rate-determining step (hydrogen transfer). Direct transfer of the hydrogen is seen between the nicotinamide and deazariboflavin in both reaction directions. DeazaFMN reconstituted yeast NADPH: (acceptor) oxidoreductase (Old Yellow Enzyme), and deazaFAD reconstituted D-amino acid:O2 oxidoreductase and Aspergillus niger D-glucose O2 oxidoreductase are all reduced by substrate at approximately 10(-5) the rate of holoenzyme; none are reoxidized by oxygen or any of the tested artificial electron acceptors, though deazaFADH-bound to D-amino acid:O2 oxidoreductase is rapidly oxidized by the imino acid product. Direct hydrogen transfer from substrate to deazaflavin has been demonstrated for both deazaFAD-reconstituted oxidases. These data implicate deazaflavins as a unique probe of flavin catalysis, in that any mechanism for the flavin catalysis must account for the deazaflavin reactivity as well.
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PMID:Enzyme-catalyzed redox reactions with the flavin analogues 5-deazariboflavin, 5-deazariboflavin 5'-phosphte, and 5-deazariboflavin 5'-diphosphate, 5' leads to 5'-adenosine ester. 0 7

When rat hearts were subjected to abrupt hypoxia the onset of NADH changes as measured by epicardial fluorescence and of depressed contractility occurred at similar times. Direct measurements of changes in tissue metabolism lagged behind changes in fluorescence and contractility. Calculated NAD:NADH ratios became reduced more rapidly and to a greater extent in the cytoplasm than in the mitochondria, but did not necessarily signal greater changes in total NADH. The detection of depressed contractility before a fall in intracellular pH or a rise in intracellular lactate casts doubt on the postulate that an increase in hydrogen ion is the primary cause of hypoxic myocardial failure.
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PMID:Early changes in myocardial hypoxia: relations among mechanical function, pH, and intracellular redox states. 0 55

1. Glutathione reductase (NAD(P)H:oxidized-glutathione oxidoreductase, EC. 1.6.4.2) from human erythrocytes was purified 49 000-fold with an overall yield of 15% and a 280/460 nm absorbance ratio of 6.03. The procedure used was the method of Worthington and Rosemeyer modified by addition of heating and recrystallization. 2. It was concluded from the results of purification, electrofocusing and inhibition studies that glutathione reductase is a single enzyme which used both NADPH and NADH as hydrogen donors. 3. Apoenzyme cross-reacts with the antibody to the holoenzyme but has a slightly reduced affinity to the antibody. Apoenzyme can be removed from the hemolysate by heating and centrifugation without loss of holoenzyme. 4. Indirect immunological assay of the specific activity of the erythrocyte glutathione reductase is possible in the enzyme saturated with FAD.
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PMID:Human erythrocyte glutathione reductase. I. Purification and properties. 0 43

The three purified proteins which are required for microsomal stearyl-CoA desaturation, NADH-cytochrome b5 reductase, cytochrome b5, and desaturase, have been combined with egg lecithin or dimyristyl lecithin vesicles to reconstruct a functional electron transport system capable of utilizing NADH and O2 in the desaturation of stearyl-CoA. Such preparations appear to consist of phospholipid vesicles which contain the three proteins bound to the outer surface of the vesicles. Acyl-CoA derivatives containing 12 to 19 carbon fatty acyl chains are required for desaturase activity while derivatives containing 9 to 20 carbons are capable of binding to the enzyme. Shorter chain acyl-CoA derivatives, free CoA, and free fatty acids do not appear to bind to the enzyme. Inhibition and analog studies suggest that the methylene chain of stearyl-CoA assumes an eclipsed ("gauche") conformation at carbon atoms 9,10 in the enzyme-substrate complex. Furthermore, isotope rate effects obtained with deuterated stearyl-CoA derivatives indicate that hydrogen removal is the rate-limiting step of desaturation. Stearyl-CoA binds to pure liposomes and desaturase-containing liposomes, and it is this form of stearyl-CoA which appears to be the substrate for desaturase. The Arrhenius plots of desaturase activity obtained using desaturase bound to egg lecithin liposomes, in which the liquid crystalline to crystalline phase transition temperature is -5 degrees, was linear between 15 and 35 degrees, while that obtained using desaturase bound to dimyristyl lecithin liposomes showed a break at 24 degrees coinciding with the liquid crystalline to crystalline phase transition temperature for this lipid. The decrease observed in the deuterium isotope rate effect below the transition temperature indicates that a step in the reaction sequence other than hydrogen abstraction becomes rate-limiting when the lipid is in the crystalline state. In this system translational diffusion does not emerge as the rate-limiting step. The liposomes contained sufficient reductase and cytochrome b5 so that translational diffusion was not rate-limiting.
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PMID:Mechanism of rat liver microsomal stearyl-CoA desaturase. Studies of the substrate specificity, enzyme-substrate interactions, and the function of lipid. 0 53

Porcine and rat microsomal stearyl-CoA desaturases require reduced pyridine nucleotide and oxygen, are cyanide sensitive, and are insensitive to carbon monoxide. The Km for stearyl-CoA is somewhat larger for liver than for the adipose desaturases, but, in general, assay conditions are quite similar. Adipose tissue microsomes contain cytochromes b5 and P-450, as well as the NADH- and NADPH-specific cytochrome reductases. Compared to liver, the specific contents and activities of electron carriers are much lower in adipose tissue, and activities of 4-methyl sterol oxidase of cholesterol biosynthesis, as well as the cytochrome P-450-dependent aminopyrene demethylase and benzypyrene hydroxylase, are negligible in adipose tissue microsomes. Furthermore, unlike hepatic desaturase, administration of insulin stimulates the adipose desaturase 3-fold without affecting either the amounts or activities of microsomal oxidation-reduction proteins; the changes in desaturase activities produced either by altering dietary fat or by fasting and/or fasting followed by refeeding are, in general, both more extensive and more permanent in adipose compared to liver microsomes. The effects produced by isotopic hydrogen substitution both in stearyl-CoA and in the medium (2H2O) are similar with microsomes from both tissues. The rate-determining step of desaturase appears to be similar in both tissues. The primary isotope effect, k H/Tr, observed with [9,10-3H2]stearyl-CoA is relatively small, 2.88. Since little, if any, primary isotope effect is associated with methyl sterol oxidase, these two mixed function oxidases of biosynthetic processes also appear to share this property in common.
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PMID:Investigation of microsomal oxygenases of biosynthetic processes. Stearyl-CoA desaturase of adipose tissue and liver. 1 66

The stereospecificity of the hydrogen removal from reduced pyridine nucleotides catalyzed by nitrate reductase (NADH : nitrate oxidoreductase, EC 1.6.6.1, and NAD(P)H : nitrate oxidoreductase, EC 1.6.6.2) was investigated. A high degree of enzyme purification was required to obtain conclusive results. Improvements are described for the purification of nitrate reductase from Chlorella fusca and from spinach (Spinacea oleracea, L.) leaves. The latter enzyme is shown to contain a cytochrome. With highly purified nitrate reductase preparations from Cl. fusca, Neurospora crassa, Rhodotorula glutinis and spinach leaves the stereospecificity of the reaction was determined to be predominantly of the A-type in all cases.
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PMID:The stereospecificity of nitrate reductase for hydrogen removal from reduced pyridine nucleotides. 1 53

The biosynthesis of fatty acids from malonyl-CoA and acetyl-CoA was investigated with an enzyme preparation which was purified 100-fold from Brevibacterium ammoniagenes. Fatty acids synthesized in the presence of D2O and stereospecifically deuterated NADPH and NADH were isolated and analyzed by mass chromatography to examine the localization of deuterium in the molecule. The following results were obtained: 1) HB hydrogen of NADPH was used for beta-ketoacyl reductase. 2) HB hydrogen of NADH was used for enoyl reductase. 3) Hydrogen atoms from water were found on the even-numbered methylene carbon atoms (2-hydrogen atoms per carbon atom) and some were also found on the odd-numbered methylene carbon atoms. 4) Hydrogen atoms from NADPH was found on the odd-numbered methylene carbon atoms (1 hydrogen per carbon). 5) Hydrogen atoms from NADH was also found on the odd-numbered methylene carbon atoms, but the number of incorporated hydrogen atoms was less than expected. The exchange of HB hydrogen of NADH with water catalyzed by enoyl reductase was suspected. 6) The exchange of methylene hydrogen atoms of malonyl-CoA with protons of water was suggested by 13C NMR analysis.
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PMID:Stereochemical studies of hydrogen incorporation from nucleotides with fatty acid synthetase from Brevibacterium ammoniagenes. 1 49

An enzyme system of Mycobacterium smegmatis catalyzing the elongation of medium-chain fatty acids with acetyl-CoA was obtained free from de novo fatty acid synthetase by ammonium sulfate fractionation. The system was resolved by gel filtration and DEAE-cellulose chromatography into three fractions, all of which were required for reconstitution of the elongation activity. The three fractions were highly purified enoyl-CoA hydratase, highly purified 3-hydroxyacyl-CoA dehydrogenase, and a fraction containing both enoyl-CoA reductase and thiolase. The reconstituted system was avidin-insenstive, required NADH as a sole hydrogen donor, and was sensitive to pCMB, but not to N-ethylmaleimide or monoiodoacetate. Decanoyl-CoA and octanoyl-CoA were the best primers for the elongation system. When decanoyl-CoA was used as the primer, the major product was found to be a lauroyl derivative (probably lauroyl-CoA). Evidence was obtained suggesting that acyl-CoA dehydrogenase, catalyzing the first step of beta-oxidation, was not functional in the elongation system.
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PMID:Acetyl-CoA-dependent elongation of fatty acids in Mycobacterium smegmatis. 2 Nov 75

Optimal reaction conditions for assaying human lactate dehydrogenase pyruvate-to-lactate were determined for isoenzymes 1 and 5 at 25, 30, and 37 degrees C. Three of the nine different buffers examined--imidazole, triethanolamine, and N-tris(hydroxymethyl)-methyl-2-aminoethane sulfonic acid--are satisfactory. Beta-NADH, pyruvate, and hydrogen ion concentrations were chosen to measure both isoenzymes with maximal-equal-sustainable efficiency at the lowest substrate concentrations. Approximately 95% of each isoenzyme is measured, for activities up to threefold the upper normal limit, if the measurements are made immediately after the reaction is initiated. The Arrhenius relationship for each isoenzyme is unique. Interconversion of results from one temperature to another is practical only with reservations. Results at 37 degrees C are not as reliable as those at 25 degrees C.
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PMID:Optimal reaction conditions for assaying human lactate dehydrogenase pyruvate-to-lactate at 25, 30, and 37 degrees C. 2 10


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