Oxidation of Reduced Codehydrogenase I

Abstract

THE discovery of an enzyme^1,2 capable of catalysing the oxidation of reduced codehydrogenase I (cozymase, CoI) at an extremely rapid rate³ naturally raises the question as to what part this enzyme plays in hydrogen transport. There is considerable evidence^1,2,4,5 that this enzyme (diaphorase) catalyzes the reaction between dihydrocozymase and the cytochrome system, and Dewan and Green² have suggested that cytochromes A and B (but not C) and cytochrome oxidase are involved. The method of preparing diaphorase is such that succinic acid dehydrogenase is also present in large amounts. With the possible exception of the recent announcement³ that diaphorase had been obtained in highly purified form, it seems fairly certain that most of the data in the literature regarding either enzyme were obtained with preparations containing both enzymes. This statement has a very important bearing on the 4-carbon acid catalysis theory of Szent-Györgyi, since it raises the question as to the possibility that succinic acid dehydrogenase is an intermediary hydrogen carrier between diaphorase and cytochrome.