Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.1.1.1 (alcohol dehydrogenase)
 9,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutants of yeast alcohol dehydrogenase have been produced that protect the cell against the poisonous aldehyde acrolein by increasing the NADH-NAD ratio. The altered properties include changes both in binding constants and in cooperativity. Such mutants may be useful in exploring the nature of adaptation at the molecular level.
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PMID:Production of yeast alcohol dehydrogenase isoenzymes by selection. 17 8

Corrected fluorescence properties of yeast alcohol dehydrogenase and its coenzyme complexes have been investigated as a function of temperature. Dissociation constants have been obtained for binary and ternary complexes of NAD and NADH by following the enhancement of NADH fluorescence or the quenching of the protein fluorescence. It is found that the presence of pyrazole increases the affinity of NAD to the enzyme approximately 100-fold. The formation of the ternary enzyme - NAD - pyrazole complex is accompanied by a large change in the ultraviolet absorption properties, with a new band in the 290-nm region. Significant optical changes also accompany the formation of the ternary enzyme-NADH-acetamide complex. The possible origin for the quenching of the protein fluorescence upon coenzyme binding is discussed, and it is suggested that a coenzyme-induced conformational change can cause it. Thermodynamic parameters associated with NAD and NADH binding have been evaluated on the basis of the change of the dissociation constants with temperature. Optical and thermodynamic properties of binary and ternary complexes of yeast alcohol dehydrogenase are compared with the analogous properties of horse liver alcohol dehydrogenase.
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PMID:Spectroscopic investigation of binary and ternary coenzyme complexes of yeast alcohol dehydrogenase. 18 Dec 50

The transient-state kinetics of enzymic reduction of acetaldehyde and benzaldehyde by NADH, catalyzed by horse liver alcohol dehydrogenase, have been examined under single-turnover conditions, obtained by carrying out reactions either with limiting amounts of enzyme in the presence of 20 mM pyrazole or with limiting amounts of substrate. Analysis of the variation with substrate, coenzyme, and enzyme concentrations of amplitudes and time constants for the exponential transients observed at 328 nm and 300 nm shows that the kinetics of enzymic aldehyde reduction are qualitatively and quantitatively consistent with the relationships derived in the preceding paper for an ordered ternary-complex mechanism involving identical and independent catalytic sites. It is concluded that there is no evidence whatsoever for the kinetic significance of a half-of-the-sites reactivity or any other kind of subunit interaction in the liver alcohol dehydrogenase system. The biphasic transients observed at 328 nm for the reduction of aromatic aldehydes such as benzaldehyde are a normal kinetic characteristic of the ordered ternary-complex mechanism, being attributable to accumulation of the ternary enzyme-NAD-product complex when product dissociation from this complex is slow in comparison to its formation by ternary-complex interconversion.
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PMID:Kinetic transients in the reduction of aldehydes catalysed by liver alcohol dehydrogenase. 18 64

The levels of several enzymes have been studied during sporulation of Saccharomyces cerevisia. The specific activities of ribonuclease and aminopeptidase I raised several-fold after transfer of the cells to sporulation medium, whereas the specific activities of phosphofructokinase, glucose-6-phosphate dehydrogenase, tryptophan synthase and pyruvate decarboxylase were not significantly altered. The specific activities of NAD-dependent glutamate dehydrogenase, isocitrate lyase, malate dehydrogenase and fructose bisphosphatase all decreased from the onset of sporulation. The inactivation of these latter enzymes was inhibited by cycloheximide and by inhibitors of energy metabolism. Hexokinase, alcohol dehydrogenase and glutamate oxaloacetate transaminase were partially lost from the cells during the period of ascus maturation. None of the enzyme changes observed proved to be 'sporulation-specific' in that it occurred exclusively in sporulating diploid yeast cells. Therefore it is postulated that the meiotic events and the metabolic changes required for ascospore formation are under separate genetic control in this organism. During sporulation, the cellular content of cytochromes b, c, and aa3 was reduced to 20% or less of that present in vegetative derepressed cells. Since the relative percentage of total to cycloheximide-insensitive mitochondrial protein synthesis was not significantly altered throughout sporulation, and the pattern of mitochondrially synthesized polypeptides was rather similar both in vegetative and in sporulating cells, it appeared that not only degradation but also synthesis and therefore turnover of the mitochondrially coded polypeptides of cytochromes b and aa3 took place during sporulation. The activity ratio of cytochrome c oxidase to F1-ATPase in submitochondrial particles isolated from vegetative cells and from purified asci was almost identical. This indicates that the loss of membrane-bound mitochondrial cytochromes during sporulation is probably due to a nonselective degradation of inner mitochondrial membrane proteins.
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PMID:Protein degradation during yeast sporulation. Enzyme and cytochrome patterns. 18 44

The pathways responsible for ethanol oxidation and the toxic results of its metabolism are reviewed. The predominant pathway for ethanol oxidation at low ethanol concentrations involves alcohol dehydrogenase. However, at high alcohol concentrations, up to 50% of ethanol uptake is 4-methylpyrazole-intensitive. Oxidation of ethanol under these conditions is associated with a change in the steady-stage concentration of catalase-H2O2. Based on recent evidence, we conclude that it is unnecessary to postulate that ethanol is oxidized directly via cytochrome P-450. Acetaldehyde production from ethanol via the microsomal subfraction can be accounted for by the combined activities of catalase-H2O2 and alcohol dehydrogenase. The metabolism of ehtanol via alcohol dehydrogenase produces a marked reduction in the hepatocellular NAD-NADH sytems. This reduction is indirectly responsible for the inhibition of glycolysis, gluconeogenesis, citric acid cycle activity, and fatty acid oxidation and may be related to some of the pathological effects observed following chronic consumption of alcohol. Attempts in inhibit alcohol dehydrogenase with alkylpyrazoles and activate catalase with substrates for peroxisomal H2O2-generating flavoproteins, while successful, may have limited applicability because of the native toxicity of the substrates themselves...
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PMID:Hepatic alcohol oxidation and its metabolic liability. 19 Dec 95

Voluntary intake of ethanol solution (ETOH) was decreased in rats administered 2-aminoethylisothiouronium bromide hydrobromide (AET), an agent reported to alter NAD:NADH ratios in rat liver. Repeated administration of same dose of AET to ETOH-naive rats produced a significant inhibition of liver aldehyde dehydrogenase. Ethanol intake was decreased in rats given noreleagnine (NLG), a beta-carbone derivative reported to inhibit monoamine oxidase. Repeated administration of NLG exerted a significant inhibitory effect on liver alcohol dehydrogenase activity. It is concluded that the observed reduction of ethanol under AET which inhibits liver aldehyde dehydrogenase may reflect an antabuse-like reaction and the reduction of ethanol intake under NLG may be due, in part, to a build-up of alcohol in the blood and brain through inhibition of ethanol metabolism. The results are discussed in reference to the possible mechanism of action underlying voluntary intake of ethanol in rats, implicating alteration of NAD:NADH ratios in the biochemical processes underlying alcohol intake of rats.
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PMID:Voluntary ethanol drinking by the RAT: effects of 2-aminoethylisothiouronium Salt, a modifier of NAD:NADH and norelegnine, a beta-carboline derivative. 19 13

Energy metabolism was studied in rat myocardial mitochondria by estimation of respiratory enzymes activity and content of the Krebs cycle substrates under conditions of acute and chronic intoxication with ethyl alcohol. In the acute intoxication mitochondrial redox enzymes were inhibited (glutamate- and malate dehydrogenases, NADH cytochrome C oxidoreductase and cytochrome C oxidase), succinate- and lactate dehydrogenases were activated; at the same time, contents of pyruvate, succinate, and alpha-ketoglutarate were elevated and the content of oxalacetic acid was decreased. Prolonged administration of alcohol (within 2 months) caused an intensification of glycolysis and an increase in NADH cytochrome C oxidoreductase pathway with preferable oxidation of succinate and activation of cytochrome C oxidase; the phenomenon appears to be an adaptation to chronic "alcohol hypoxia". Discontinuation of alcohol administration led to deficiency of native substrates in myocardium (primarily, oxalacetic and succinic acids) due to decrease in NAD reduction via alcohol dehydrogenase reaction and to increase in oxidation of NAD-dependent endogenous substrates.
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PMID:[Energy metabolism disorders in the myocardium due to alcoholic intoxication]. 20 87

The interaction between horse liver alcohol dehydrogenase and the oxidized and reduced forms of the 3-thionicotinamide--adenine dinucleotide coenzyme analogues (sNAD and sNADH) has been investigated by ultraviolet absorption, fluorescence and circular dichroism. The fluorescence of sNADH is enhanced when bound to the enzyme, and the protein fluorescence is quenched by both sNADH (60--65%) and sNAD (65%). The possible origin of the larger quenching produced by sNAD with respect to that of NAD is discussed. Coenzyme dissociation constants have been determined by monitoring the quenching of the protein fluorescence, and some kinetic consequences of these dissociation constants are discussed. The dichroic properties of various enzyme complexes have been investigated, and are discussed in terms of conformational changes and environmental changes during coenzyme binding. The conformation of sNAD bound to the enzyme in the presence of trifluorethanol and the conformation of sNADH bound to the enzyme in the presence of isobutyramide have been analyzed in particular detail. Also the circular dichroic spectrum of the apoenzyme is discussed in terms of contributions of the aromatic amino acid residues in the highly resolved 240--310-nm region and in terms of helix content in the 220-nm region.
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PMID:Circular dichroic properties and conformation of thionicotinamide dinucleotides bound to horse-liver alcohol dehydrogenase. 20 83

1. The NAD analogue, N6-[N-(6-aminohexyl)carbamoylmethyl]-NAD, was covalently bound to horse liver alcohol dehydrogenase in a carbodiimide-mediated reaction and in such a way that it was active with the very same enzyme molecule to which it was coupled. 2. The degree of substitution, i.e. the number of NAD analogues per enzyme subunit, could be varied (0.3-1.6). In one preparation 1.6 coenzyme molecules were bound per subunit; the alcohol dehydrogenase activity of this preparation was 40% of the activity obtained after addition of free NAD in excess. 3. It was calculated that every fourth active site of this preparation was provided with a covalently bound functioning coenzyme analogue, and that this analogue had a cycling rate of about 40 000 cycles/h in a coupled substrate assay. 4. The presence of the covalently bound coenzyme made the active sites difficult to inhibit with a competitive inhibitor. For example, 10 mM AMP inhibited the activity of the preparation by 50% whereas a reference system containing native alcohol dehydrogenase was inhibited by 80% in spite of the fact that the reference system contained about 20 000 times as high a concentration of coenzyme.
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PMID:Covalent binding of an NAD analogue to liver alcohol dehydrogenase resulting in an enzyme-coenzyme complex not requiring exogenous coenzyme for activity. 20 26

New theoretical considerations and a new approximation strategy were applied to the kinetic analysis of the experimental relationship between the reaction velocity in the steady state and the concentrations of ethanol and NAD. It could be shown that horse-liver ADH consists of two kinetically heterogeneous components.
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PMID:Steady-state study of horse-liver ADH: detection of two kinetically heterogeneous components. 20 74


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