Uncoupler-inhibitor titrations of ATP-driven reverse electron transfer in isolated rat-liver mitochondria.
Uncoupler-inhibitor titrations of ATP-driven reverse electron transfer across the first site of the respiratory chain were performed in isolated rat-liver mitochondria, and the experimental results were compared with the predictions of a simple delocalized chemiosmotic mechanism. The rates of ATP hydrolysis (Jp) and reverse electron transfer (-J0) were measured at different uncoupler (S-13) concentrations, either in the absence or in the presence of rotenone. When the rates -J0 and Jp measured at different uncoupler concentrations were expressed as percentages of the activity at zero uncoupler concentration, it was found that the efficiency of S-13 to uncouple the reverse electron transfer and to stimulate ATP hydrolysis was not significantly changed upon partial inhibition with rotenone. These results are in contrast with data from a study of uncoupler-inhibitor titrations in submitochondrial particles published previously, in which a higher effectiveness of several uncouplers to inhibit ATP-driven reverse electron transfer was observed in the presence of rotenone.
Sánchez Olavarría
J
J
Laboratory of Biochemistry, University of Amsterdam, The Netherlands.
Lambers
A
A
van Dam
K
K
D000090:Acetoacetates / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D004579:Electron Transport / Q000187:drug effects; D006868:Hydrolysis; D007473:Ion Channels / Q000378:metabolism; D007700:Kinetics; D008930:Mitochondria, Liver / Q000378:metabolism*; D011522:Protons; D051381:Rats; D012402:Rotenone / Q000494:pharmacology; D013386:Succinates / Q000378:metabolism; D019802:Succinic Acid; D013816:Thermodynamics
D000090:Acetoacetates; D007473:Ion Channels; D011522:Protons; D013386:Succinates; D012402:Rotenone; C016635:acetoacetic acid; D000255:Adenosine Triphosphate; D019802:Succinic Acid