The cytochrome P460 family is composed mostly of monoheme, ~17 kDa, c-cytochromes typified by the cytochromes P460 of Nitrosomonas europaea and Methylococcus capsulatus (Bath), and the cytochrome c'-beta of M. capsulatus. Members of this family can be characterized by a predominantly beta-sheet structure as opposed to the four elongate, tightly-packed alpha-helices of the widely distributed cytochromes c' of photoheterotrophic and denitrifying bacteria. They are involved in the oxidation/reduction or ligation of N-oxides for detoxification or energy generation. Phylogenetic studies suggest that cytochrome P460 (cytL) genes evolved from ancestral cytochrome c'-beta genes (cytS) by acquisition of features including the lysine-heme cross-link. The protein-bound c-type heme cofactor, heme P460, named for its characteristic ferrous Soret peak maximum at 460 nm, has the distinction of being the only known heme in biology to withdraw electrons from an iron coordinated substrate.
Lu S et al.(2020). "CDD/SPARCLE: the conserved domain database in 2020.",