TEMPERATURE-DEPENDENCE OF THE COUPLING EFFICIENCY OF RAT-LIVER OXIDATIVE-PHOSPHORYLATION - ROLE OF ADENINE-NUCLEOTIDE TRANSLOCATOR

We have reinvestigated the temperature dependence of the coupling effi ciency of energy conversion in isolated rat liver mitochondria. We obs erved that respiratory control increased with temperature. Moreover, i n the same conditions, the ATP/O ratio increased. The measurement of t he control coefficients of adenine nucleotide translocator on respirat ory and ATP synthesis rates showed that at 28 degrees C, this transloc ator exerted the same control (about 0.5) on both fluxes. At 4 degrees C, it no longer exerted control on respiratory flux when its control on ATP synthesis flux came close to 1. In addition, ATP/O ratio values and control coefficients on ATP synthesis flux were bound by a unique linear relationship irrespective of temperature. In conclusion, the d ecrease in ATP/O ratio with temperature is a direct consequence of an increase in the kinetic control exerted (C) 1994 Academic Press, Inc.