[Interaction of cytochrome c with bilayer membranes].

Cytochrome c when adsorbed on bilayer phospholipid membrane (BLM) induced an adsorption potential of the order of 50 mv which relaxes gradually. The value and the sign of the adsorption potential depend upon the initial polarisation of the membrane. On the positively charged surface of the membrane (polarisation above 120 mv) the orientation of adsorbing molecules of the protein inverts. Ferri- and ferrocytochrome c have different affinity to phospholipids of BLM. The reduction of protein electrostatically bound to lipid bilayer causes its partial desorption when oxidation results additional adsorption of cytochrome c. Protein does not penetrate through the membrane. Electric conductivity and capacity of BLM are slightly influenced by cytochrome c adsorption. The capacity of BLM formed from an isooctane soluble complex of cytochrome c with phospholipid is less than the capacity of pure lipid bilayers.