Multiple Mutations in the Non-Ordered Red Ω-Loop Enhance the Membrane-Permeabilizing and Peroxidase-like Activity of Cytochrome .

A key event in the cytochrome -dependent apoptotic pathway is the permeabilization of the outer mitochondrial membrane, resulting in the release of various apoptogenic factors, including cytochrome , into the cytosol. It is believed that the permeabilization of the outer mitochondrial membrane can be induced by the peroxidase activity of cytochrome in a complex with cardiolipin. Using a number of mutant variants of cytochrome , we showed that both substitutions of Lys residues from the universal binding site for oppositely charged Glu residues and mutations leading to a decrease in the conformational mobility of the red Ω-loop in almost all cases did not affect the ability of cytochrome to bind to cardiolipin.