THE F(1)F(0)-ATPASE BINDING-SITE OF DIBUTYLTIN-3-HYDROXYFLAVONE - INTERACTIONS WITH VENTURICIDIN, OLIGOMYCIN AND DCCD

Dibutyltin-3-hydroxyflavone bromiide, Bu2Sn(of), is a fluorescent probe inhibitor of mitochondrial F1F0ATPase which reacts with and titrates a component of F0 with marked fluorescence enhancement and reacts similarly with chloroplast CF1CF0 and V-ATPases. Its use to monitor the interactions of other F0 inhibitors (venturicidin, oligomycin, DCCD) with F1F0ATPase, both membrane-bound and purified by solubilization is described. Trialkyltins (Bu3SnCl) back-titrate all Bu2Sn(of) interaction sites; whereas the macrolide inhibitor venturicidin backtitrates 60+/-5% and oligomycin only 30+/-3% of Bu2Sn(of) interaction sites. Bafilomycin, the macrolide inhibitor of V-ATPases, is inactive in this assay. DCCD acts in a different fashion from the other inhibitors. Current and potential applications of this fluorescent probe in mitochondrial bioenergetics and biogenesis are discussed.