Breakdown of the oxidized forms of coenzymes I and II by an enzyme from the central nervous system

Abstract

Prepns. from the mammalian central nervous system, which rapidly inactivated cozymase, inactivated also coenzyme II at 76-85% of the rate of their reaction with cozymase. Inactivation of coenzyme II, like that of cozymase, was accompanied by liberation of nicotinamide. Competition took place between the 2 coenzymes for the degrading system, and presumably, therefore, a common enzyme was responsible for the 2 reactions. Nicotinamide ribofuranoside, nicotinamide glycosides less closely related to cozymase, and several other nicotinamide derivatives were not affected by the enzyme. Dihydrocoenzymes I and II were not affected by the enzyme, and did not affect the breakdown by it of coenzymes I and n.