STUDIES ON MAMMALIAN AND HUMAN PYRUVATE AND ALPHA-KETOGLUTARATE DEHYDROGENATION COMPLEXES.
Final rept. 15 Mar-14 Mar 67,
NAGASAKI UNIV (JAPAN) ATOMIC DISEASE INST
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Enzyme systems that catalyze a coenzyme A- and nicotinamide adenine dinucleotide-linked oxidative decarboxylation of pyruvate and alpha-ketoglutarate have been isolated from pig heart muscle as highly organized multienzyme complexes with molecular weights of 9 million and 2.7 million, respectively. On the oxidative decarboxylation of alpha-keto acids in pig heart complexes, Ca2 was strongly stimulatory to the same or more extent than Mg2. The pig heart pyruvate dehydrogenase complex was strongly inhibited by EDTA at low concentration, but the pig heart alpha-ketoglutarate dehydrogenase complex was little inhibited. The pig heart pyruvate dehydrogenase complex that catalyzes a multistage oxidative decarboxylation of pyruvate consisting successively of decarboxylation, acetyl generation, acetyl transfer and electron transfer was separated into lipoamide dehydrogenase and colorless fraction by the fractionation on a calcium phosphate gel-cellulose column in the presence of 4 M urea. An attempt was made to prepare rabbit anti-sera against a highly purified free lipoamide dehydrogenase from pig heart acid-precipitated particle. On the Ouchterlony double diffusion test and the titration studies of the several enzymatic activities with the immune globulin, immunochemical identity among three lipoamide dehydrogenase, free enzyme and other two enzymes from pyruvate and 2-oxoglutarate dehydrogenase complexes, was confirmed. Author