Magnesium protoporphyrin IX monomethyl ester (oxidative) cyclase

Magnesium-protoporphyrin IX monomethyl ester (oxidative) cyclase (EC 1.14.13.81, Mg-protoporphyrin IX monomethyl ester (oxidative) cyclase) is an enzyme with systematic name magnesium-protoporphyrin-IX 13-monomethyl ester,NADPH:oxygen oxidoreductase (hydroxylating) . This enzyme catalyses the following chemical reaction

magnesium-protoporphyrin IX 13-monomethyl ester + 3 NADPH + 3 H⁺ + 3 O₂ ⇌ divinylprotochlorophyllide + 3 NADP⁺ + 5 H₂O (overall reaction)(1a) magnesium-protoporphyrin IX 13-monomethyl ester + NADPH + H⁺ + O₂ ⇌ 131-hydroxy-magnesium-protoporphyrin IX 13-monomethyl ester + NADP⁺ + H₂O(1b) 131-hydroxy-magnesium-protoporphyrin IX 13-monomethyl ester + NADPH + H⁺ + O₂ ⇌ 131-oxo-magnesium-protoporphyrin IX 13-monomethyl ester + NADP⁺ + 2 H₂O(1c) 131-oxo-magnesium-protoporphyrin IX 13-monomethyl ester + NADPH + H⁺ + O₂ ⇌ divinylprotochlorophyllide + NADP⁺ + 2 H₂O

This enzyme requires Fe(II) for activity.