Imidazoleacetate 4-monooxygenase

In enzymology, an imidazoleacetate 4-monooxygenase (EC 1.14.13.5) is an enzyme that catalyzes the chemical reaction

4-imidazoleacetate + NADH + H⁺ + O₂ ${\displaystyle \rightleftharpoons }$ 5-hydroxy-4-imidazoleacetate + NAD⁺ + H₂O

The 4 substrates of this enzyme are 4-imidazoleacetate, NADH, H⁺, and O₂, whereas its 3 products are 5-hydroxy-4-imidazoleacetate, NAD⁺, and H₂O.

The enzyme is a flavin-containing monooxygenase that uses molecular oxygen as oxidant and incorporates one of its atoms into the starting material. The systematic name of this enzyme class is 4-imidazoleacetate,NADH:oxygen oxidoreductase (5-hydroxylating). Other names in common use include imidazoleacetic hydroxylase, imidazoleacetate hydroxylase, and imidazoleacetic monooxygenase. This enzyme participates in histidine metabolism. It employs one cofactor, FAD.