Measurement of the Mitochondrial Membrane Potential and pH Gradient from the Redox Poise of the Hemes of the bc(1) Complex

作者：Kim N; Ripple M O; Springett R^*

来源：Biophysical Journal, 2012, 102(5): 1194-1203.

DOI：10.1016/j.bpj.2012.02.003

The redox potentials of the hemes of the mitochondrial bc(1) complex are dependent on the proton-motive force due to the energy transduction. This allows the membrane potential and pH gradient components to be calculated from the oxidation state of the hemes measured with multi-wavelength cell spectroscopy. Oxidation states were measured in living RAW 264.7 cells under varying electron flux and membrane potential obtained by a combination of oligomycin and titration with a proton ionophore. A stochastic model of bc(1) turnover was used to confirm that the membrane potential and redox potential of the ubiquinone pool could be measured from the redox poise of the b-hemes under physiological conditions assuming the redox couples are in equilibrium. The pH gradient was then calculated from the difference in redox potentials of cytochrome c and ubiquinone pool using the stochastic model to evaluate the Delta G of the bc(1) complex. The technique allows absolute quantification of the membrane potential, pH gradient, and proton-motive force without the need for genetic manipulation or exogenous compounds.

• 出版日期2012-3-7