Scientia Sinica

STUDIES ON SUCCINIC DEHYDROGENASE

I. ISOLATION, PURIFICATION, AND PROPERTIES*

Wane Tstnc-Yinc (JEM), Tsou Cuen-Lu ( SiS), and Wane Yinc-Lar ( EIRPR )

(Institute of Physiology and Biochemistry, Academia Sinica)

The nature of succinic dehydrogenase, the enzyme specifically concerned with the activation of succinate as defined previously by one of us", has been a matter of controversy for a number of years. Bach, Dixon and Zerfas“), Ball, Anfinsen and Cooper™!, and Pappenheimer and Hendee™! were of the opinion that it was identical with cytochrome 4. Based on a study of the cyanide inactivation of succinic dehydrogenase, one of. us’! has shown that these two are, in fact, not identical. This conclusion has since been confirmed by Chance!!, using a totally different method. Axelrod, Potter and Elvehjem™ reported that livers of rats maintained on a riboflavin-deficient diet were low in succinic oxidase activity, suggesting the implication of the vitamin in the enzyme system, but exactly which component of the complex system was affected could not be ascertained from their experiments. A more detailed analysis of the enzyme system during riboflavin deficiency carried out in our own laboratory"! showed that only the dehydrogenase component was involved. All of these are, however, indirect evidences and a final solution of the nature of succinic dehydrogenase must await the preparation of the enzyme in a pure state.

Succinic dehydrogenase occurs in tissues tightly bound to the particulate matter of the cell and cannot be solubilized by ordinary treatments. It has ‘resisted all attempts at its isolation and purification by enzyme chemists for over twenty years. In a brief communication, Morton”! claimed to have obtained the enzyme in aqueous solution by treatment with n-butanol, but further purification has not been reported since. Neufeld, Scott and Stotz!'*! obtained a soluble succinic dehydrogenase by ammonium sulphate fractionation in the presence of bile salts, but the purification achieved was not very high. Recently, Singer and his coworkers!*"!, using phenazine methosulphate as

=Communicated to the 3rd International Congress of Biochemistry, Brussels, 5 August, 1955, by Wang, Tsou, and Wangl!] and to appear in Chinese in Acta Physiologica Sinica, Vol. XX, No. 2, 1956.