cytochrome P460 from Methylococcus capsulatus (Bath) and similar proteins
Cytochrome (cyt) P460 is a small soluble periplasmic protein that binds the c-type heme cofactor, heme P460, named for its characteristic ferrous Soret peak maximum at 460 nm, which has the distinction of being the only known heme in biology to withdraw electrons from an iron coordinated substrate. M. capsulatus (Bath) cytochrome P460, encoded by the cytL gene, catalyzes the oxidation of hydroxylamine (NH2OH) to form nitrous oxide (N2O) under anaerobic conditions. Similar to Nitrosomonas europaea cyt P460, it is defined by an unusual porphyrin (heme)-lysine cross link. This subfamily belongs to a family, called the cytochrome P460 family, of small mono-heme c-type cytochromes that are predominantly of beta-sheet structure, as opposed to the four elongate, tightly-packed alpha-helices of the widely distributed cytochromes c' of photoheterotrophic and denitrifying bacteria.