:2-Hydroxy-1,4-benzoxazin-3-one monooxygenase

{{Short description|Class of enzymes}}

{{Infobox enzyme

| Name = 2-Hydroxy-1,4-benzoxazin-3-one monooxygenase

| EC_number = 1.14.13.140

| CAS_number =

| GO_code =

| image =

| width =

| caption =

}}

2-Hydroxy-1,4-benzoxazin-3-one monooxygenase ({{EC number|1.14.13.140}}, BX5 (gene), CYP71C3 (gene)) is an enzyme with systematic name 2-hydroxy-2H-1,4-benzoxazin-3(4H)-one,NAD(P)H:oxygen oxidoreductase (N-hydroxylating).{{cite journal | vauthors = Bailey BA, Larson RL | title = Maize microsomal benzoxazinone N-monooxygenase | journal = Plant Physiology | volume = 95 | issue = 3 | pages = 792–6 | date = March 1991 | pmid = 16668055 | pmc = 1077607 | doi = 10.1104/pp.95.3.792 }}{{cite journal | vauthors = Glawischnig E, Grün S, Frey M, Gierl A | title = Cytochrome P450 monooxygenases of DIBOA biosynthesis: specificity and conservation among grasses | journal = Phytochemistry | volume = 50 | issue = 6 | pages = 925–30 | date = March 1999 | pmid = 10385992 | doi = 10.1016/s0031-9422(98)00318-5 }} This enzyme catalyses the following chemical reaction

: 2-hydroxy-2H-1,4-benzoxazin-3(4H)-one + NAD(P)H + H⁺ + O₂ $\backslash rightleftharpoons$ 2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one + NAD(P)+ + H₂O

2-Hydroxy-1,4-benzoxazin-3-one monooxygenase is involved in the biosynthesis of protective and allelopathic benzoxazinoids in some plants.