Uncharacterized subfamily of the cytochrome P460 family
This subfamily is composed mainly of hypothetical proteins, including Sphingopyxis alaskensis class I cytochrome C. Members of this subfamily belong to the cytochrome P460 family that 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. Cytochrome P460 family members 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. 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.