Cytochrome P460 Cofactor Maturation Proceeds via Peroxide-Dependent Post-translational Modification.

Cytochrome P460s are heme enzymes that oxidize hydroxylamine to nitrous oxide. They bear specialized "heme P460" cofactors that are cross-linked to their host polypeptides by a post-translationally modified lysine residue. Wild-type cytochrome P460 may be isolated as a cross-link-deficient proenzyme following anaerobic overexpression in . When treated with peroxide, this proenzyme undergoes maturation to active enzyme with spectroscopic and catalytic properties that match wild-type cyt P460. This maturation reactivity requires no chaperones─it is intrinsic to the protein. This behavior extends to the broader cytochrome c' superfamily. Accumulated data reveal key contributions from the secondary coordination sphere that enable selective, complete maturation. Spectroscopic data support the intermediacy of a ferryl species along the maturation pathway.