Flow-force relationships during energy transfer between mitochondrial proton pumps.
The effect of inhibitors of proton pumps, of uncouplers and of permeant ions on the relationship between input force, delta mu H+, and output flows of the ATPase, redox and transhydrogenase H(+)-pumps in submitochondrial particles was investigated. It is concluded that: (1) The decrease of output flow of the transhydrogenase proton pump, defined as the rate of reduction of NADP+ by NADH, is linearily correlated with the decrease of input force, delta mu H+, in an extended range of delta mu H+, independently of whether the H(+)-generating pump is the ATPase or a redox pump, or whether delta mu H+ is depressed by inhibitors of the H(+)-generating pump such as oligomycin or malonate, or by uncouplers. (2) The output flows of the ATPase and of the site I redox H(+)-pumps exhibit a steep dependence on delta mu H+. The flow-force relationships differ depending on whether the depression of delta mu H+ is induced by inhibitors of the H(+)-generating pump, by uncouplers or by lipophilic anions. (3) With the ATPase as H(+)-consuming pump, at equivalent delta mu H+ values, the output flow is more markedly inhibited by malonate than by uncouplers; the latter, however, are more inhibitory than lipophilic anions such as ClO4-. With redox site I as proton-consuming pump, at equivalent delta mu H+ values, the output flow is more markedly inhibited by oligomycin than by uncouplers; again, uncouplers are more inhibitory than ClO4-. (4) The results provide further support for a delocalized interaction of transhydrogenase with other H(+)-pumps.
Petronilli
V
V
CNR Unit for the Physiology of Mitochondria, University of Padova, Italy.
Persson
B
B
Zoratti
M
M
Rydström
J
J
Azzone
G F
GF
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002417:Cattle; D004734:Energy Metabolism; D008929:Mitochondria, Heart / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D009840:Oligomycins / Q000494:pharmacology; D011522:Protons; D013367:Submitochondrial Particles / Q000378:metabolism*; D013386:Succinates / Q000378:metabolism; D019802:Succinic Acid
D009840:Oligomycins; D011522:Protons; D013386:Succinates; D009243:NAD; D009249:NADP; D000255:Adenosine Triphosphate; D019802:Succinic Acid