Increase of the fluidity of the lipid bilayer of the inner mitochondrial membrane by succinate and phenylsuccinate: a study by EPR and fluorescence.

Electron paramagnetic resonance and fluorescence experiments have demonstrated that the lipid matrix of inner membrane of mitochondria was more fluid than the control membrane when incubated with succinate or with one of its non permeant and non metabolizable analog, phenylsuccinate, both of which induce a protein movement from the inner membrane towards the intermembrane space and the inner matrix. Besides, the increase of fluidity seemed more pronounced near the bilayer surface. Although the mechanisms involved in the protein movement are yet unknown, these results lead us to think that they are related to a membrane reorganization involving inter alia the lipid matrix.