Spheroidene monooxygenase

Spheroidene monooxygenase (, CrtA, acyclic carotenoid 2-ketolase, spirilloxantin monooxygenase, 2-oxo-spirilloxanthin monooxygenase) is an enzyme with systematic name spheroidene, reduced-ferredoxin:oxygen oxidoreductase (spheroiden-2-one-forming). This enzyme catalyses the following chemical reaction


 * spheroidene + reduced ferredoxin + O2 $$\rightleftharpoons$$ spheroiden-2-one + oxidized ferredoxin + H2O
 * spirilloxantin + reduced ferredoxin + O2 $$\rightleftharpoons$$ 2-oxospirilloxanthin + oxidized ferredoxin + H2O
 * 2'-oxospirilloxanthin + reduced ferredoxin + O2 $$\rightleftharpoons$$ 2,2'-dioxospirilloxanthin + oxidized ferredoxin + H2O

The enzyme is involved in spheroidenone biosynthesis and in 2,2'-dioxospirilloxanthin biosynthesis.