Microcalorimetric studies on the substrate - inhibitory kinetics of catalase

Catalase is an important enzyme of biological defense against oxygen toxici ty. It has been detected in a wide range of aerobe. The decomposition of hy drogen peroxide catalyzed by catalase is a bi - substrate enzyme - catalyze d reaction. rls Chance proposed, it is an overall first - order reaction, T he decomposition of hydrogen peroxide (H2O2) catalyzed by catalase is incom plete under high substrate concentration. It is because that there exists i rreversible substrate inhibition of catalase, We proposed a possible irreve rsible substrate inhibitory mechanism. Using this mechanism, we studied the kinetics of catalase while the reaction was incomplete. The result is sati sfactory. At 310.15 K and pH = 7.0, k(0) and k(1)/k(2) are calculated and t o be 9. 6 x 10(5) L mol(-1).s(-l) and 2.9 x 10(6), respectively.