Activity of the succinic dehydrogenase-cytochrome system in different tissue preparations

DECOMPOSITION OF HYDROGEN PEROXIDE 205 that the transition to the steady rate cannot be due to any partial destruction of the enzyme. If it were, no increase in O2 evolution would be observed on dilution. The explanation for this transition from x- to ,-activity in the decomposition of H202 by cata- lase should be sought in the series of unit reactions involved in the peroxide decomposition. In this respect there is a similarity in the kinetics of the enzymatic decomposition and of the reaction catalyzed by ferrous iron (George, 1947), even though the iron in catalase is in the ferric state.