Reaction: protoheme + 6 reduced ferredoxin [iron-sulfur] cluster + 3 O2 + 6 H+ = biliverdin + Fe2+ + CO + 6 oxidized ferredoxin [iron-sulfur] cluster + 3 H2O
For diagram of reaction click here.
Other name(s): HO1 (gene name); HY1 (gene name); HO3 (gene name); HO4 (gene name); pbsA1 (gene name)
Systematic name: protoheme,reduced ferredoxin:oxygen oxidoreductase (α-methene-oxidizing, hydroxylating)
Comments: The enzyme, found in plants, algae, and cyanobacteria, participates in the biosynthesis of phytochromobilin and phytobilins. The terminal oxygen atoms that are incorporated into the carbonyl groups of pyrrole rings A and B of biliverdin are derived from two separate oxygen molecules. The third oxygen molecule provides the oxygen atom that converts the α-carbon to CO. Unlike this enzyme, which uses ferredoxin as its electron donor, the electron source for the related mammalian enzyme (EC 220.127.116.11) is EC 18.104.22.168, NADPHhemoprotein reductase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
1. Montgomery, B.L. and Lagarias, J.C. Phytochrome ancestry: sensors of bilins and light. Trends Plant Sci 7 (2002) 357-366. [PMID: 12167331]
2. Sugishima, M., Migita, C.T., Zhang, X., Yoshida, T. and Fukuyama, K. Crystal structure of heme oxygenase-1 from cyanobacterium Synechocystis sp. PCC 6803 in complex with heme. Eur. J. Biochem. 271 (2004) 4517-4525. [PMID: 15560792]
3. Dammeyer, T. and Frankenberg-Dinkel, N. Function and distribution of bilin biosynthesis enzymes in photosynthetic organisms. Photochem Photobiol Sci 7 (2008) 1121-1130. [PMID: 18846276]