In enzymology, a 4-methoxybenzoate monooxygenase is an enzyme that catalyzes the chemical reaction 4-methoxybenzoate + AH2 + O2 ⇌ {\displaystyle \rightleftharpoons } 4-hydroxybenzoate + formaldehyde + A + H2OThe 3 substrates of this enzyme are 4-methoxybenzoate, an electron acceptor AH2, and O2, whereas its 4 products are 4-hydroxybenzoate, formaldehyde, the reduction product A, and H2O. Wikipedia