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)

The reaction of glutamate dehydrogenase and glutamate (gl) with NAD+ and NADP+ has been studied with stopped-flow techniques. The enzyme was in all experiments present in excess of the coenzyme. The results indicate that the ternary complex (E-NAD(P)H-kg) is present as an intermediate in the formation of the stable complex (E-NAD(P)H-gl). The identification of the complexes is based on their absorption spectra. The binding of the coenzyme to (E-gl) is the rate-limiting step in the formation of (E-NAD(P)H-kg) while the dissociation of alpha-ketoglutarate (kg) from this complex is the rate-limiting step in the formation of (E-NAD(P)H-gl). The Km for glutamate was 20-25 mM in the first reaction and 3 mM in the formation of the stable complex. The Km values were independent of the coenzyme. The reaction rates with NAD+ were approximately 50% greater than those with NADP+. Furthermore, high glutamate concentration inhibited the formation of (E-NADH-kg) while no substrate inhibition was found with NADP+ as coenzyme. ADP enhanced while GTP reduced the rate of (E-NAD(P)H-gl) formation. The rate of formation of (E-NAD(P)H-kg) was inhibited by ADP, while it increased at high glutamate concentration when small amounts of GTP were added. The results show that the higher activity found with NAD+ compared to NADP+ under steady-state assay conditions do not necessarily involve binding of NAD+ to the ADP activating site of the enzyme. Moreover, the substrate inhibition found at high glutamate concentration under steady-state assay condition is not due to the formation of (E-NAD(P)H-gl) as this complex is formed with Km of 3 mM glutamate, and the substrate inhibition is only significant at 20-30 times this concentration.
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PMID:Formation of transient complexes in the glutamate dehydrogenase catalyzed reaction. 0 39

The dose dependence of the acute effects of ethanol upon liver intermediary metabolism in vivo has been demonstrated in rats. Ethanol was given i.p. in doses of 0.69, 1.7, and 3.0 g/kg in equal volumes (20 ml/kg). The liver was freeze-clamped 120 min after injection, and multiple metabolites were measured in the perchloric acid extract of the tissue. Each group showed a significantly different pattern of metabolites, redox states, and phosphorylation potentials although the rate of ethanol disappearance, at least between the two highest dose groups, was not significantly different. The mitochondrial free [NAD+]/[NADH] ratios and the cytoplasmic free [NADP+]/[NADPH] ratio were paradoxically most reduced with the lowest dose of ethanol and became progressively more oxidized with increasing dose. Once established, the differences in these ratios between the groups tended to persist with time, relatively independent of the concentration of ethanol. In a somewhat different pattern, the phosphorylation potential ([ATP]/[ADP][P1]) remained at the control level in the low-dose group but was significantly elevated in the two higher-dose groups. The results, therefore, show distinct and complicated dose-dependent patterns of intermediary metabolism that cannot be explained completely by any one hypothesis but that imply significant dose-dependent effects of ethanol upon intermediary metabolism not directly related to NADH production.
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PMID:Dependence on dose of the acute effects of ethanol on liver metabolism in vivo. 0 Apr 22

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

Citrate synthase activity of Saccharomyces cerevisiae was determined by a radioactive assay procedure and the reaction product, 14C-citric acid, was identified by chromatographic techniques. ATP, d-ATP, GTP and NADH were most inhibitory to the citrate synthase invitro. The activity was inhibited to a lesser extent by ADP, UTP, and NADP whereas, AMP and CTP were much less inhibitory. NADH, like NAD, glutamic acid, glutamine, arginine, ornithine, proline, aspartic acid and alpha-ketoglutarate exhibited no inhibition. These results have been discussed in the light of the role of citrate synthase for the energy metabolism and glutamic acid biosynthesis.
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PMID:Regulation of citrate synthase activity of Saccharomyces cerevisiae. 0

Mitochondria may be isolated from various types of leukocyte (neutrophil polymorphs and lymphocytes from human blood, neutrophil polymorphs and macrophages from peritoneal exudates of the guinea pig) after destruction by heparin of the cell membrane. This procedure is very simple and less traumatic for these subcellular structures than the usual mechanical procedures. The enzyme activities of the respiratory chain and oxygen consumption may be measured in these mitochondrial preparations. The oxygen consumption is determined using oxyhemoglobin which serves both as oxygen donor, as in the respiratory system in vivo, and as indicator of the reaction at 435.8 nm. The integrity of the mitochondria may be demonstrated by determination of the "acceptor control index", the existence of ADP phosphorylation coupled with oxygen consumption (phosphorylating oxidation) was proved in all the cells studied even if the ADP/O ratio can only be calculated for certain of them (lymphocytes, macrophages). In these cases, the ratios obtained are close to theoretical values whatever the oxidation substrate used. The mitochondria of leukemic cells have a higher oxidation activity than the corresponding reference cells. Determination of leukocyte coenzymes by enzyme cycling (NAD, NADH, NADP, NADPH) showed the following facts: -- Generally, the NAD concentrations remain constant, those of NADH increase whilst those of NADP and NADPH fall during incubation of neutrophil polymorphs in Dulbecco's medium. -- The metabolic changes observed during S. albi heat-induced endocytosis are in favour of simultaneous stimulation of NADH oxidase and NADPH oxidase in human polymorphs, and of NADPH oxidase in the corresponding cells of peritoneal exudates in guinea pigs.
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PMID:[Enzyme system and coenzymes involved in the energy metabolism of leukocytes. Function and metabolism of polymorphonuclear neutrophils]. 0 34

Acetyl-coenzyme A synthetase (EC 6.2.1.1) activity of Saccharomyces cerevisiae was determined by a radioactive assay procedure. The activity in vitro was inhibited significantly by NADPH, NADH, or AMP and to a lesser extent by NADP, NAD, or ADP. Glutamic acid and alpha-ketoglutaric acid were not inhibitory. The enzyme level was repressed when the cells were grown in a complex nutrient medium as opposed to the minimal medium. However, a glutamic acid auxotroph glul, when grown in excess glutamic acid, demonstrated a fivefold increase of acetyl-CoA synthetase.
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PMID:Regulation of acetyl-CoA synthetase of Saccharomyces cerevisiae. 0 41

The oxidoreductase inhibitor is not formed from NADH as previously thought, but only from NAD under alkaline conditions. Analogues of NAD (e.g. NADP) and components of the NAD molecule (e.g. ADP) have no effect on the formation of the inhibitor. The most favourable pH, temperature, duration of incubation, type of buffer and NAD concentration for the formation of the inhibitor were investigated. The method for the formation and chromatographic isolation of the oxidoreductase inhibitor is briefly described.
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PMID:[Formation and purification of the oxidoreductase inhibitor from NAD (AUTHOR'S TRANSL)]. 0 16

Oxygen-consuming reactions of cholesterol oxidase [EC 1.1.3.6] and microsomes were measured with a galvanic oxygen electrode which was attached to an offset amplifier for sensitive measurement of the reaction processes. The sensitivity of this oxygraphic method for detection of oxygen consumption was ten times greater than that of the usual method. The minimum rate of slow oxygen-consuming reactions which could be estimated was about 5 nmoles of oxygen per min, and the minimum amount of oxygen consumption which could be determined was also about 5 nmoles. An oxygraphic method for direct and rapid determination of cholesterol was demonstrated using one-twentieth the amount of cholesterol oxidase which is used for the colorimetric method. The processes of cyanide-suppressed beta-NADH-dependent oxygen consumption and cyanide-insensitive alpha-NADH-dependent oxygen consumption, which were difficult to follow by the usual method, were followed using a small amount of microsomes (less than 1mg protein/ml). Furthermore, the temporary cessation of alpha-NADH-dependent oxygen consumption caused by ferricyanide and the corresponding oxidation-reduction of reduced cytochrome b5 were followed in the presence of ADP. ADP did not inhibit the oxygen consumption. The results indicate that the oxygen consumption with alpha-NADH is due to electron transfer from alpha-NADH via NADH-cytochrome b5 reductase and cytochrome b5, in which the rate-determining step lies at some reaction after the reduction of cytochrome b5.
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PMID:An oxygraphic method for the determination of cholesterol and measurement of the slow oxygen-consuming reactions of hepatic microsomes. 0 59

A hitherto undescribed sphingomyelinase (sph'ase 7.4) of human brain has been studied in crude and partially purified (3- to 4- fold) extracts of grey matter, and compared to the known sphingomyelinase with an acid pH optimum (sph'ase 5.0). Its specificity for sphingomyelin as substrate is similar to that of sph'ase 5.0, but it differs from sph'ase 5.0 in its pH optimum (7.4 vs 5.0) and in a requirement for Mg2+ for optimal activity. Other properties of sph'ase 7.4 that distinguish it from sph'ase 5.0 include (a) its lack of appreciable solubilization during dialysis of crude homogenates (b) a more marked concentrations in grey matter than in white matter (9- to 13- fold vs 1.5- to 2-fold for sph'ase 5.0); (c) inhibition by Ca2+ and Cd2+ ions, and by EDTA; (D) stimulation by dithiothreitol, and inhibition by cysteine, N-ethylmaleimide, and p-hydroxymercuribenzoate; (e) lack of inhibition by nucleotides (AMP.ADP, and ATP) and by NAD plus NADH; and (f) relative instability to storage or manipulation between -20degrees C and 40degrees C. These differences indicate the SPH'ASE 7.4 is a different enzyme protein from sph'ase 5.0. Unlike sph'ase 5.0, which is widely distributed in mammalian tissues, sph'ase 7.4 occurs predominantly in grey matter and little activity was observed is spleen, liver, or leukocytes. The high levels of this enzyme in brain suggest a role related to the specific functions of this organ or to the need for a more stringent control of sphingomyelin catabolism in brain as compared to other organs.
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PMID:Sphingomyelinase activity at pH 7.4 in human brain and a comparison to activity at pH 5.0. 0 63

Adenylate kinase (ATP:AMP phosphotransferase, EC 2.7.4.3) from the mantle muscle of the squid, Loligo pealeii, was purified over 170-fold to homogeneity as judged by polyacrylamide and starch gel electrophoresis. The tissue contains a single isozyme of adenylate kinase, the enzyme from cytoplasmic and mitochondrial compartments (90 and 10% of total activity, respectively) being identical in physical and kinetic properties. Molecular weight was found to be 27,000 +/- 400. The enzyme shows a pH optimum of 8.2 in the forward (APD utilizing) and 7.4 in the reverse direction. Michaelis constants for ADP, ATP, and AMP are 0.70, 0.13, and 0.15 mM, respectively, with optimal Mg2+:adenylate ratios being 1:2 for ADP and 1:1 for ATP. A comparison of mass action ratios with the equilibrium constant indicated that squid adenylate kinase is held out of equilibrium in resting, but not active, muscle. A search for metabolic modulators of adenylate kinase revealed that NADH (Ki of 0.1 mM) was the only modulator which exerted a significant effect within its in vivo concentration range. The data presented indicate that NADH inhibition is the factor maintaining adenylate kinase in a nonequilibrium state in resting muscle and that release of this inhibition can serve to integrate adenylate kinase into the known scheme of intermediary metabolism in this tissue. A sharp drop in NADH levels at the onset on muscular work co-ordinates that activation of aerobic metabolism in this tissue and allows adenylate kinase to return to equilibrium function. At equilibrium, the enzyme can function to ampligy the concentration of AMP, a potent activator and deinhibitor of key glycolytic and Krebs cycle enzymes. The effect of modulators of adenylate kinase in preventing denaturation by heat or proteolysis revealed that NADH and substrates induced conformational changes in the enzyme which rendered it less susceptible to denaturation. The conformation state induced by NADH differed from that induced by substrate.
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PMID:Purification and properties of squid mantle adenylate kinase. Role of NADH in control of the enzyme. 1 79


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