In vivo role of the microsomal ethanol-oxidizing system in ethanol metabolism by deermice lacking alcohol dehydrogenase (original) (raw)

Interaction of cytoplasmic dehydrogenases: Quantitation of pathways of ethanol metabolism

Pharmacology Biochemistry and Behavior, 1983

VIND, C. AND N. GRUNNET. Interaction of cytoplasmic dehydrogenases: Quantitation of pathways of ethanol metabolism. PHARMACOL BIOCHEM BEHAV 18: Suppl. 1, 209-213, 1983.--The interaction between xylitol, alcohol and lactate dehydrogenase has been studied in hepatocytes from rats by applying specifically tritiated substrates. A simple model, describing the metabolic fate of tritium from [2-:~H] xylitol and (IR) [1-'~H]ethanol is presented. The model allows calculation of the specific radioactivity of free, cytosolic NADH, based on transfer of tritium to lactate, glucose and water. From the initial labelling rate of lactate and the specific radioactivity of cytosolic NADH, we have determined the reversible flow through the lactate dehydrogenase catalyzed reaction to 1-5/~mol/min.g wet wt. The results suggest that xylitol, alcohol and lactate dehydrogenase share the same pool of NAD(H) in the cytoplasma. This finding allows estimation of the ethanol oxidation rate by the non-alcohol dehydrogenase pathways from the relative yield of tritium in water and glucose. The calculations are based on a comparison of the fate of the l-pro-R hydrogen of ethanol and the hydrogen bound to carbon 2 of xylitol or carbon 2 of lactate under identical conditions.

Alcohol-oxidizing enzymes from various organisms

Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1978

1. Enzymes that catalyse the oxidation of aliphatic alcohols to aldehydes are reviewed. 2. Special attention is given to phenazine methosulphate-linked alcohol dehydrogenases from bacteria and to flavin-containing alcohol oxidases from yeasts, moulds and higher plants.

Separation and partial characterization of multiple forms of rat liver alcohol dehydrogenase

Archives of Biochemistry and Biophysics, 1983

Rat liver alcohol dehydrogenase was purified and four isoenzyme forms, demonstrated by starch gel electrophoresis, were separated by 0-(carboxymethyl)-cellulose chromatography. Each of the isoenzymes had a distinct isoelectric point. All isoenzymes were active with both ethanol (or acetaldehyde) and steroid substrates, and had similar Michaelis-Menten constants for each of the substrates and coenzymes studied. The three isoenzymes with the lowest migration toward the cathode exhibited the same pH optimum of 10.7 for ethanol oxidation, a greater activity with 5@androstan-3@oll'l-one than with ethanol as a substrate, and an unchanged electrophoretic mobility following storage in the presence of 100 PM dithiothreitol. By contrast the isoenzyme with the highest mobility toward the cathode exhibited a pH optimum of 9.5 for ethanol oxidation, a low steroid/ethanol ratio of activity, and converted to the migrating pattern of the two isoenzymes with intermediate mobility when stored. The similarities between the isoenzymes of rat liver alcohol dehydrogenase differ considerably from differences in substrate specificity exhibited by isoenzymes of horse liver alcohol dehydrogenase.

Purification and comparative studies of alcohol dehydrogenases

Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1987

Al~tract--1. Alcohol dehydrogenases from various animal and plant sources were purified by a common procedure which employed DEAE, Sephadex-G100 and affinity chromatographies.

Purification and molecular properties of mouse alcohol dehydrogenase isozymes

European Journal of Biochemistry, 1983

Alcohol dehydrogenase isozymes from mouse liver (A, and B,) and stomach (C,) tissues have been purified to homogeneity using triazine-dye affinity chromatography. The enzymes are dimers with similar but distinct subunit sizes, as determined by SDS/polyacrylamide gel electrophoresis: A, 43000; B, 39000, and C, 47000. Zinc analyses and 1,lO-phenanthroline inhibition studies indicated that the A and C subunits each contained two atoms of zinc, with at least one being involved catalytically, whereas the B subunit probably contained a single non-catalytic zinc atom. The isozymes exhibited widely divergent kinetic characteristics. A, exhibited a K,,, value for ethanol of 0.15 mM and a broad substrate specificity, with K, values decreasing dramatically with an increase in chain length; C, also exhibited this broad specificity for alcohols but showed a K , value of 232mM for ethanol. These isozymes also showed broad substrate specificities as aldehyde reductases. In contrast, B, showed no detectable activity as an aldehyde reductase for the aldehydes examined, and used ethanol as substrate only at very high concentrations (>0.5M). The isozyme exhibited low K, and high V,,, values, however, with medium-chain alcohols. Immunological studies showed that A, was immunologically distinct from the B, and C, isozymes. In vitro molecular hybridization studies gave no evidence for association between the alcohol dehydrogenase subunits. The results confirm genetic analyses [Holmes, Albanese, Whitehead and Duley (1981) J. Exp. Zool. 215, 151 -1 5 7 which are consistent with at least three structural genes encoding alcohol dehydrogenase in the mouse and confirm the role of the major liver isozyme (A,) in ethanol metabolism.

Mechanism of the Alcohol Dehydrogenases from Yeast and Horse Liver

European Journal of Biochemistry, 1971

Studies of the alcohol-acetaldehyde interchange, in the presence of analogues of NAD+ and brought about by yeast and horse liver alcohol dehydrogenases, have not provided any evidence in favour of the direct participation of the enzyme in the hydrogen transfer step. A new preparation of 1,4,5,6-tetrahydro-nicotinamide adenine dinucleotide is described. This analogue has been found to be a good competitive inhibitor for both enzymes, thus demonstrating the importance of fixation of the enzyme by a hydrogen bond to the group present in C-3 of the nicotinamide nucleus.