Oligomycin inhibition of Na,K,ATPase. Analysis of half-of-sites moderator interaction with a dimeric enzyme.

It is shown that the incomplete, uncompetitive inhibition pattern exhibited by oligomycin toward Na,K,ATPase cannot be explained by a single-cycle enzyme model. In contrast, the experimental data are easily explained in terms of a dimeric enzyme, only one subunit of which can bind oligomycin at a time, and that subunit is then rendered inactive. In a brief analysis of the model thus obtained by way of numerical examples it is shown that it may show activation at small concentrations of moderator, which disappears at higher concentrations, a property observed for the hydrolysis of p-nitro-phenylphosphate, which is also catalyzed by Na,K,ATPase.