Evidence for separate enzymes of pyruvate decarboxylation and pyruvate synthesis in soluble extracts of Clostridium pasteurianum.

Additional evidence to that already presented (Sauer, F. D., Bush, R. S., and Stevenson, I. L. (1976) Biochim. Biophys. Acta 445, 518-520) suggests that pyruvate-ferredoxin oxidoreductase isolated from Clostridium pasteurianum consists of two separate enzymes: (a) pyruvate lyase, which catalyzes the CoA and electron acceptor-dependent decarboxylation of pyruvate, and (b) pyruvate synthase, which catalyzes the reduced ferredoxin-dependent carboxylation of acetyl-CoA to pyruvate. The enzymes separated on Sephadex G-200 and with acrylamide gel electrophoresis but complete separation of one enzyme free of the other was not achieved. Extensive purification procedures were not used because both enzymes are unstable. The results confirm published reports that pyruvate lyase contains thiamin and a chromophore which participates in electron transfer. Pyruvate synthase, however, did not appear to be a thiamin enzyme and there was no evidence to indicate participation of an enzyme chromophore in the pyruvate synthase reaction.