STUDIES ON MAMMALIAN AND HUMAN PYRUVATE AND ALPHA-KETOGLUTARATE DEHYDROGENATION COMPLEXES.
Rept. no. 6 (Final), Mar 67-Mar 68,
NAGASAKI UNIV (JAPAN) ATOMIC DISEASE INST
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The pig heart pyruvate and alpha-ketoglutarate dehydrogenase complex were isolated in highly purified state as multienzyme units with molecular weights of approximately 9 million and 2.8 million, respectively. The aims were to resolve the pig heart pyruvate and alpha-ketoglutarate dehydrogenase complexes into their essential constituent enzymes, to characterize the latter, and to determine the composition and macromolecular structure of these two multienzymes. The pig heart pyruvate dehydrogenase complex was successively resolved into three constituent enzymes, 1 thiamine-PP-dependent pyruvate dehydrogenase, 2 lipoate acetyltransferase containing protein-bound lipoic acid, and 3 flavoprotein, lipoamide dehydrogenase by the fractionations with calcium phosphate gel-cellulose column chromatography. The macromolecular organization of the pyruvate dehydrogenase complex and its subunit enzymes was elucidated to a certain extent. Pig heart lipoamide dehydrogenase, one of the essential components of alpha-keto acid dehydrogenase complexes was isolated from three sources 1 pyruvate dehydrogenase complex, 2 alpha-ketoglutarate dehydrogenase, and 3 amber-color extract free from both complexes. Three enzymes were studied comparatively in respect to enzymatic activities, hydrodynamic parameters and biological function as one of the constituent enzymes to produce a large unit resembling the native pyruvate dehydrogenase complex. No significant differences in these properties were observed. Author