Spheroidene monooxygenase (EC1.14.15.9, CrtA, acyclic carotenoid 2-ketolase, spirilloxantin monooxygenase, 2-oxo-spirilloxanthin monooxygenase) is an enzyme with systematic namespheroidene, reduced-ferredoxin:oxygen oxidoreductase (spheroiden-2-one-forming).[1][2] This enzyme catalyses the following chemical reaction
^Gerjets T, Steiger S, Sandmann G (February 2009). "Catalytic properties of the expressed acyclic carotenoid 2-ketolases from Rhodobacter capsulatus and Rubrivivax gelatinosus". Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids. 1791 (2): 125–31. doi:10.1016/j.bbalip.2008.12.006. PMID19136077.