Characterisation of the supramolecular organisation of the mitochondrial respiratory chain: a methodological approach by Metabolic Control Analysis.

We have exploited metabolic flux control analysis to differentiate between randomly distributed respiratory complexes and substrate channelling in supercomplexes in mitochondria. Blue-native gel electrophoresis shows supercomplexes comprising Complexes I, III and IV in most systems examined, however our flux control studies demonstrated that electron channelling occurs only between Complexes I and III in mammalian mitochondria, whereas Complex IV is functionally distinct and is fed electrons by the pool behaviour of cytochrome c. This is at difference with plant mitochondria where Complexes I, III and IV represent a single functional unit. The stability of supercomplexes is dictated by the lipid content and is strongly decreased by lipid peroxidation.