Substrate effects on the activation kinetics of Chinese hamster dihydrofolate reductase by p-chloromercuribenzoate (pCMB) have been studied. On the basis of the kinetic equation of substrate reaction in the presence of pCMB, all modification kinetic constants for the free enzyme, enzyme-substrate binary and ternary complexes have been determined. The results of the present study indicate that the modification of Chinese hamster dihydrofolate reductase by pCMB shows a single-phase kinetics, and changes in the enzyme activity and tertiary structure proceed simultaneously during the modification process.
展开▼
