Beta-carotene 3-hydroxylase (EC 1.14.13.129, beta-carotene 3,3'-monooxygenase, CrtZ) is an enzyme with systematic name beta-carotene,NADH:oxygen 3-oxidoreductase . This enzyme catalyses the following chemical reaction beta-carotene + 2 NADH + 2 H+ + 2 O2 zeaxanthin + 2 NAD+ + 2 H2O (overall reaction)(1a) beta-carotene + NADH + H+ + O2 beta-cryptoxanthin + NAD+ + H2O(1b) beta-cryptoxanthin + NADH + H+ + O2 zeaxanthin + NAD+ + H2O Beta-carotene 3-hydroxylase requires ferredoxin and Fe(II).