Sensitivity of tonoplast-bound adenosine-triphosphatase from hevea to inhibitors

The tonoplast-bound H⁺-translocating ATPase from Hevea latex was found to be insensitive to vanadate, diethylstilbestrol, and octylguanidine, which are specific inhibitors of the plasma membrane ATPase. The inhibitors of the mitochondrial ATPase, oligomycin and azide, and also rotenone and antimycin A, were all without effect. In contrast, trimethyltin chloride strongly inhibited the activity of Hevea tonoplast ATPase.

Among the different carbodiimides tested, which strongly inhibit the Hevea tonoplast ATPase, N,N′-dicyclohexylcarbodiimide was the most inhibitory. N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline was also an efficient inhibitor.

This unique inhibitor sensitivity of the Hevea tonoplast H⁺-translocating ATPase suggests that this enzyme differs in its mode of operation from all other known H⁺-translocating ATPases.