Accepted name: hydrogen peroxide-dependent heme synthase
Reaction: Fe-coproporphyrin III + 2 H2O2 = protoheme + 2 CO2 + 4 H2O (overall reaction)
(1a) Fe-coproporphyrin III + H2O2 = harderoheme III + CO2 + 2 H2O
(1b) harderoheme III + H2O2 = protoheme + CO2 + 2 H2O
Other name(s): coproheme III oxidative decarboxylase; hemQ (gene name)
Systematic name: Fe-coproporphyrin III:hydrogen peroxide oxidoreductase (decarboxylating)
Comments: The enzyme participates in a heme biosynthesis pathway found in Gram-positive bacteria. The initial decarboxylation step is fast and yields the three-propanoate harderoheme isomer III. The second decarboxylation is much slower. cf. EC, SAM-dependent heme synthase.
1.  Dailey, T.A., Boynton, T.O., Albetel, A.N., Gerdes, S., Johnson, M.K. and Dailey, H.A. Discovery and characterization of HemQ: an essential heme biosynthetic pathway component. J. Biol. Chem. 285 (2010) 25978–25986. [PMID: 20543190]
2.  Celis, A.I., Streit, B.R., Moraski, G.C., Kant, R., Lash, T.D., Lukat-Rodgers, G.S., Rodgers, K.R. and DuBois, J.L. Unusual peroxide-dependent, heme-transforming reaction catalyzed by HemQ. Biochemistry 54 (2015) 4022–4032. [PMID: 26083961]
3.  Hofbauer, S., Mlynek, G., Milazzo, L., Puhringer, D., Maresch, D., Schaffner, I., Furtmuller, P.G., Smulevich, G., Djinovic-Carugo, K. and Obinger, C. Hydrogen peroxide-mediated conversion of coproheme to heme b by HemQ-lessons from the first crystal structure and kinetic studies. FEBS J. 283 (2016) 4386–4401. [PMID: 27758026]
4.  Celis, A.I., Gauss, G.H., Streit, B.R., Shisler, K., Moraski, G.C., Rodgers, K.R., Lukat-Rodgers, G.S., Peters, J.W. and DuBois, J.L. Structure-based mechanism for oxidative decarboxylation reactions mediated by amino acids and heme propionates in coproheme decarboxylase (HemQ). J. Am. Chem. Soc. 139 (2017) 1900–1911. [PMID: 27936663]
[EC created 2019]
Accepted name: AdoMet-dependent heme synthase
Reaction: Fe-coproporphyrin III + 2 S-adenosyl-L-methionine = protoheme + 2 CO2 + 2 5′-deoxyadenosine + 2 L-methionine
Other name(s): ahbD (gene name); SAM-dependent heme synthase
Systematic name: Fe-coproporphyrin III:S-adenosyl-L-methionine oxidoreductase (decarboxylating)
Comments: This radical AdoMet enzyme participates in a heme biosynthesis pathway found in archaea and sulfur-reducing bacteria. cf. EC, hydrogen peroxide-dependent heme synthase.
1.  Bali, S., Lawrence, A.D., Lobo, S.A., Saraiva, L.M., Golding, B.T., Palmer, D.J., Howard, M.J., Ferguson, S.J. and Warren, M.J. Molecular hijacking of siroheme for the synthesis of heme and d1 heme. Proc. Natl. Acad. Sci. USA 108 (2011) 18260–18265. [PMID: 21969545]
2.  Kuhner, M., Haufschildt, K., Neumann, A., Storbeck, S., Streif, J. and Layer, G. The alternative route to heme in the methanogenic archaeon Methanosarcina barkeri. Archaea 2014:327637 (2014). [PMID: 24669201]
[EC created 2019]
Accepted name: coproporphyrin ferrochelatase
Reaction: Fe-coproporphyrin III + 2 H+ = coproporphyrin III + Fe2+
Glossary: Fe-coproporphyrin III = coproheme III
Other name(s): hemH (gene name)
Systematic name: protoheme ferro-lyase (protoporphyrin-forming)
Comments: The enzyme, present in Gram-positive bacteria, participates in heme biosynthesis. It can also catalyse the reaction of EC, protoporphyrin IX ferrochelatase, at a much lower level.
1.  Hansson, M. and Hederstedt, L. Purification and characterisation of a water-soluble ferrochelatase from Bacillus subtilis. Eur. J. Biochem. 220 (1994) 201–208. [PMID: 8119288]
2.  Al-Karadaghi, S., Hansson, M., Nikonov, S., Jonsson, B. and Hederstedt, L. Crystal structure of ferrochelatase: the terminal enzyme in heme biosynthesis. Structure 5 (1997) 1501–1510. [PMID: 9384565]
3.  Hansson, M.D., Karlberg, T., Soderberg, C.A., Rajan, S., Warren, M.J., Al-Karadaghi, S., Rigby, S.E. and Hansson, M. Bacterial ferrochelatase turns human: Tyr13 determines the apparent metal specificity of Bacillus subtilis ferrochelatase. J. Biol. Inorg. Chem. 16 (2011) 235–242. [PMID: 21052751]
4.  Dailey, H.A., Gerdes, S., Dailey, T.A., Burch, J.S. and Phillips, J.D. Noncanonical coproporphyrin-dependent bacterial heme biosynthesis pathway that does not use protoporphyrin. Proc. Natl. Acad. Sci. USA 112 (2015) 2210–2215. [PMID: 25646457]
[EC created 2016]