At high substrate concentrations the ratio of substrate to inhibitor (sub/inh) is very large. That is there is much more substrate than there is inhibitor. The substrate and inhibitor compete for the active site of the enzyme. Since, at high substrate concentrations, there is much more substrate than there is inhibitor, the only substance to bind to the active site is the substrate. At high substrate concentrations the rate of reaction is dependent upon the substrate concentration. Thus the Vmax with inhibitor is the same as the Vmax without inhibitor.
return to competitive inhibition