Abstract: | Intact mitochondria, isolated from red coxal muscle of the American cockroach (Periplaneta americana L.), were incubated in the presence of 1,1,1-trichloro-2,2-bis(4-chloro[14C]phenyl)ethane ([14C]DDT) to isolate a suspected binding site for DDT in the membrane sector of the mitochondrial ATPase. The requirements for the binding of DDT were compared with those for the binding of dicyclohexyl[14C]carbodi-imide([14C]DCCD), a potent inhibitory probe of mitochondrial ATPase activity. [14C]DDT appeared to bind to a proteolipid of the membrane sector, which also binds [14C]DCCD. Exchange experiments, with [14C]DCCD, [14C]DDT and unlabelled DDT at different concentrations, indicated that DDT and DCCD may be acting on a similar protein. This protein may act as the energy transducing protonophore required for the synthesis and hydrolysis of ATP in coupled mitochondria. Inhibition of mitochondrial ATPase activity may be a consequence of DDT and DCCD binding to this proteolipid protonophore, resulting in the disruption of energy transduction in muscle and nerve. |