Contribution of each complex of the mitochondrial respiratory chain in the generation of the proton-motive force*

Abstract

A new parameter is presented for considering the contribution from each complex of the mitochondrial respiratory chain to the creation of the electrochemical gradient. This parameter is the proton gradient generated in each complex per pair of electrons transported (ΔH(+) /2e(-) ) and may be calculated as the sum of the electrons taken up from the N-side and the electrons released at the P-side. The ΔH(+) /2e(-) values take into account all the electrons taken up and released in each complex and differentiate between the contribution from protons that are translocated from the N-side to the P-side and the contribution of scalar protons. Using these values, the P/O ratios for the oxidation of NADH and succinate are predicted to be 2.5 and 1.5, respectively.