Oxidoreductases;
Acting on CH or CH2 groups;
With unknown physiological acceptors
BRITE hierarchy

ferroheme o:acceptor C-81-oxidoreductase (heme a-forming)

ferroheme o + H2O + 2 acceptor = ferroheme a + 2 reduced acceptor (overall reaction) [RN:R07412];
(1a) ferroheme o + H2O + acceptor = ferroheme i + reduced acceptor;
(1b) ferroheme i + H2O + acceptor = hydroxyferroheme i + reduced acceptor [RN:R12682];
(1c) hydroxyferroheme i = ferroheme a + H2O (spontaneous) [RN:R12683]

R07412 R12682 R12683
Reaction

ferroheme o;
H2O [CPD:C00001];
acceptor [CPD:C00028];
ferroheme i;
hydroxyferroheme i

Contains a heme b cofactor. The enzyme catalyses the conversion of heme o to heme a by two successive hydroxylations of the methyl group at C-8, using water as the oxygen source. The first hydroxylation forms heme i, the second hydroxylation results in an unstable dihydroxymethyl group, which spontaneously dehydrates, resulting in the formyl group of heme a [2,4]. The electrons produced by the reaction are transferred to a heme b cofactor [6]. However, the electron acceptor that is used to restore the heme b cofactor to its oxidized state is still not known (both a thioredoxin-like protein and menaquinol have been proposed).

EC 1.17.99.9 created 2020