Spheroidene monooxygenase

Spheroidene monooxygenase (EC 1.14.15.9, 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 ⇌ spheroiden-2-one + oxidized ferredoxin + H₂Ospirilloxantin + reduced ferredoxin + O₂ ⇌ 2-oxospirilloxanthin + oxidized ferredoxin + H₂O2'-oxospirilloxanthin + reduced ferredoxin + O₂ ⇌ 2,2'-dioxospirilloxanthin + oxidized ferredoxin + H₂O

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