Ent-kaurenoic acid oxidase (EC 1.14.13.79) is an enzyme with systematic name ent-kaur-16-en-19-oate,NADPH:oxygen oxidoreductase (hydroxylating).^[1] This enzyme catalyses the following chemical reaction

ent-kaur-16-en-19-oate + 3 NADPH + 3 H⁺ + 3 O₂ ${\displaystyle \rightleftharpoons }$ gibberellin A12 + 3 NADP⁺ + 4 H₂O (overall reaction)

(1a) ent-kaur-16-en-19-oate + NADPH + H⁺ + O₂ ${\displaystyle \rightleftharpoons }$ ent-7alpha-hydroxykaur-16-en-19-oate + NADP⁺ + H₂O

(1b) ent-7alpha-hydroxykaur-16-en-19-oate + NADPH + H⁺ + O₂ ${\displaystyle \rightleftharpoons }$ gibberellin A12 aldehyde + NADP⁺ + 2 H₂O

(1c) gibberellin A12 aldehyde + NADPH + H⁺ + O₂ ${\displaystyle \rightleftharpoons }$ gibberellin A12 + NADP⁺ + H₂O

Ent-kaurenoic acid oxidase requires cytochrome P450.