Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:1.1.1.1 (alcohol dehydrogenase)
9,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

By counting the volatile molecules produced by an immobilized-enzyme catalyzed reaction which is interfaced to a mass spectrometer via a semi-permeable membrane, a general approach to biochemical measurement and detection is obtained which offers the potential of high sensitivity, specificity and speed. In combination with molecule microscopy, this method should allow, for example, a mapping of suitable enzyme distributions in non-stained and non-fixed tissue slices. Immobilized urease (urea amidohyrdrolase, EC 3.5.1.5) was used to assay urea using CO2 as the volatile product, and alcohol dehydrogenase (alcohol:NAD+ oxidoreductase, EC 1.1.1.1) was used to assay NADH using ethanol as the volatile product.
...
PMID:Biochemical assay by immobilized enzymes and a mass spectrometer. 18 Oct 86

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.
...
PMID:Spectroscopic investigation of binary and ternary coenzyme complexes of yeast alcohol dehydrogenase. 18 Dec 50

1. The rate constants for NADH binding and dissociation for carboxymethylated alcohol dehydrogenase have been determined and compared to those for the native enzyme. 2. Steady-state and transient kinetic experiments have shown that the hydrogen transfer step is rate-determining for oxidation of ethanol by carboxymethylated alcohol dehydrogenase. The rate constant of 0.19 s-1 is considerably slower than that for the native enzyme. 3. The steady-state parameter, V/[E], was obtained for each of a series of alcohols and correlated with the Taft sigma parameter. The linear relationship obtained indicates that the same step, hydrogen transfer, is rate-determining for all the alcohols. The sigma value obtained is the same as for the native enzyme; the implications of this for the mechanism of hydrogen transfer are discussed.
...
PMID:Carboxymethylated liver alcohol dehydrogenase. Transient kinetic studies and effect of substrate structure on alcohol oxidation. 18 Dec 53

Kinetic studies of yeast alcohol dehydrogenase with NAD+ and ethanol, hexanol or decanol as substrates invariably result in non-linear Lineweaver-Burk plots if the alcohol is the variable substrate. The kinetic coefficients determined from secondary plots are consistent with an 'equilibrium random-order' mechanism for extremely low alcohol concentrations and for all alcohols, the transformation of the ternary complexes being the rate-limiting step of the reaction. This mechanism also applies to long-chain substrates at high concentrations, whereas the rate of the ethanol-NAD+ reaction at high ethanol concentrations is determined by the dissociation of the enzyme-NADH complex. The dissociation constants for the enzyme-NAD+ complex and for the enzyme-alcohol complexes obtained from the kinetic quotients satisfactorily correspond to the dissociation constants obtained by use of other techniques. It is suggested that the non-linear curves may be attributed to a structural change in the enzyme itself, caused by the alcohol.
...
PMID:Kinetics and reaction mechanism of yeast alcohol dehydrogenase with long-chain primary alcohols. 18 40

ADH from human liver forms binary complexes with NADH, associated with a blue shift of the peak of the fluorescence emission of NADH. The wavelength shift is the same for all isoenzymes but the accompanying intensification of the fluorescence is different. The fluorescence is further increased by the formation of the very tight ternary enzyme-NADH-isobutyramide complexes. These properties are similar to those for the horse liver ADH, as well as the molecular weight of E=40 000 per active site of the dimer molecule (EE). "Stopped-flow" determined velocity constants (ER in equilibrium E+R) were found to be in good agreement with ethanol activity constants previously determined by activity measurement, confirming the validity of the ordered ternary complex mechanism also for the human ADH. No single isoenzyme activity as high as that reported by Mourad and Woronick or Drum has been found.
...
PMID:Dissociation and rate constants of some human liver alcohol dehydrogenase isoenzymes. 18 31

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.
...
PMID:Kinetic transients in the reduction of aldehydes catalysed by liver alcohol dehydrogenase. 18 64

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...
...
PMID:Hepatic alcohol oxidation and its metabolic liability. 19 Dec 95

The technique of differential scanning calorimetry (DSC) has been applied to the study of temperature-induced irreversible denturation and thus to the heat stability of soluble and Sepharose-bound liver alcohol dehydrogenase (LADH, EC 1.1.1.1) and lactate dehydrogenase (LDH, EC 1.1.1.27) in the presence of various coenzymes or coenzyme fragments. The transition temperature (Ttr) of 82.5 degrees C obtained for soluble LADH was increased by 12.5 degrees C in the presence of a saturating concentration of NACH. In the presence of NAD+, Ttr increased by 8.5 degrees C, whereas ADP-ribose and AMP caused an increase in Ttr of only 2 and 1 degree C, respectively. The Ttr of 85.5 degrees C obtained for Sepharose-bound LADH was increased by about 12 degrees C after the addition of free NADH. However, when the enzyme was immobilized simultaneously with a NADH analogue (which also binds to the matrix), a broad endotherm with a Ttr of 91.5 degrees C was obtained, indicating the presence of immobilized enzyme molecules both with, and without, associated NADH. Corresponding increases in heat stability were observed for LDH in solution in the presence of NADH, NAD+, and AMP, leading to increases in Ttr from 72 to 79.5 and 74 and 73 degrees C, respectively. The addition of pyruvate and NAD+ to the enzyme to form an abortive ternary complex led to the same stabilization as that observed with NADH, attendant with a large increase in the enthalpy of transition, deltaHtr. In these studies the technique of DSC was utilized because it is applicable both to soluble and immobilized enzymes and (1) provides rapid information about Ttr and thus thermal stability of enzymes, (2) different energetic states of an enzyme molecule can be identified, and (3) an overall picture of the thermal process is rapidly obtained.
...
PMID:Studies on conformation of soluble and immobilized enzymes using differential scanning calorimetry. 1. Thermal stability of nicotinamide adenine dinucleotide dependent dehydrogenases. 19 52

The transfer of deuterium from chiral 1-monodeuteroethanols to various metabolites formed in the liver was studied in order to investigate the coupling of metabolic reductions to the alcohol dehydrogenase and the aldehyde dehydrogenase reactions. The ethanols were administered to female bile fistula rats for 10 h. The hydrogen at C-2 in the glycerol moiety of newly formed phosphatidylcholine molecules in bile, liver and plasma was derived to 22-25% from the 1-pro-R position and to 5-6% from the 1-pro-S position in the ethanol. sn-Glycerol 3-phosphate isolated from liver had a lower deuterium content at C-2. The ratio between the contributions from the two positions in ethanol to C-2 of free sn-glycerol 3-phosphate was the same as in the phosphatidylcholines. This indicates that the higher degree of labelling of this position in phosphatidylcholines is not due to a specific coupling between alcohol dehydrogenase and the formation of a phosphatidylcholine precursor. Cholesterol and chenodeoxycholic acid in bile became increasingly labelled, and the ratio between the incorporations from the 1-pro-S and the 1-pro-R positions of ethanol was about 0.37 in cholesterol and 0.46 in chenodeoxycholic acid. Thus, these NADPH-dependent reactions utilized hydrogen from the 1-pro-S position to a larger extent than NADH-dependent reactions.
...
PMID:Incorporation of the 1-pro-R and the 1-pro-S hydrogen atoms of ethanol into steroids and phosphatidylcholines in vivo. 19 53

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.
...
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


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---