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 N. europaea cytochrome P460 may be isolated as a cross-link-deficient proenzyme following anaerobic overexpression in E. coli . 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' β 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.