ABSTRACT
Decreased activity of pyruvate dehydrogenase was found in myocardium of rats consuming ethanol as compared with animals consuming water. Acute alcoholization did not alter this pattern. Myocardial pyruvate kinase exhibited increased affinity to substrate in animals consuming ethanol.
Subject(s)
Alcohol Drinking/psychology , Alcoholic Intoxication/metabolism , Cardiomyopathy, Alcoholic/metabolism , Glycolysis , Myocardium/metabolism , Alcoholic Intoxication/psychology , Animals , Cardiomyopathy, Alcoholic/etiology , Male , Mitochondria, Heart/enzymology , Pyruvate Dehydrogenase Complex/metabolism , Pyruvate Kinase/metabolism , RatsABSTRACT
Inhibitory effects of 23 thiamin derivatives on the bovine heart pyruvate dehydrogenase complex (PDC) were studied. Oxythiamin diphosphate and tetrahydroxythiamin diphosphate exhibited the most pronounced effect on the PDC activity, affecting the complex by a competitive type of inhibition for thiamin diphosphate (TDP). The apparent affinity of TDP and the anticoenzyme derivatives for apo PDC depended on presence of phosphate and divalent metal ions. Phosphate considerably increased the Km values for TDP (up to 0.17 microM) and the Ki values for oxythiamin diphosphate (0.40 microM) as well as for tetrahydroxythiamin diphosphate (0.23 microM). In presence of Mn2+, Km value for TDP was 3.5-fold lower as compared with Mg2+ containing medium.
