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 ¦Á-carbon to CO. Unlike this enzyme, which uses ferredoxin as its electron donor, the electron source for the related mammalian enzyme (EC 1.14.14.18) is EC 1.6.2.4, NADPH–hemoprotein reductase.
