Reaction: coproporphyrinogen III + 2 S-adenosyl-L-methionine = protoporphyrinogen IX + 2 CO2 + 2 L-methionine + 2 5'-deoxyadenosine
For diagram of reaction click here.
Other name(s): oxygen-independent coproporphyrinogen-III oxidase; HemN; coproporphyrinogen III oxidase
Systematic name: coproporphyrinogen-III:S-adenosyl-L-methionine oxidoreductase (decarboxylating)
Comments: This enzyme differs from EC 1.3.3.3, coproporphyrinogen oxidase, by using S-adenosyl-L-methionine (AdoMet) instead of oxygen as oxidant. It occurs mainly in bacteria, whereas eukaryotes use the oxygen-dependent oxidase. The reaction starts by using an electron from the reduced form of the enzyme's [4Fe-4S] cluster to split AdoMet into methionine and the radical 5'-deoxyadenosin-5'-yl. This radical initiates attack on the 2-carboxyethyl groups, leading to their conversion into vinyl groups. This conversion, —·CH-CH2-COO- → —CH=CH2 + CO2 + e- replaces the electron initially used.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Layer, G., Verfürth, K., Mahlitz, E. and Jahn, D. Oxygen-independent coproporphyrinogen-III oxidase HemN from Escherichia coli. J. Biol. Chem. 277 (2002) 34136-34142. [PMID: 12114526]
2. Layer, G., Moser, J., Heinz, D.W., Jahn, D. and Schubert, W.D. Crystal structure of coproporphyrinogen III oxidase reveals cofactor geometry of radical SAM enzymes. EMBO J. 22 (2003) 6214-6224. [PMID: 14633981]