ID 1.14.16.6 DE mandelate 4-monooxygenase. AN L-mandelate 4-hydroxylase. AN mandelic acid 4-hydroxylase. CA (S)-mandelate + (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin + O2 = (S)-4- CA hydroxymandelate + (6R)-L-erythro-6,7-dihydrobiopterin + H2O. //