Oxidoreductases;
Acting on paired donors, with incorporation or reduction of molecular oxygen;
With NADH or NADPH as one donor, and incorporation of one atom of oxygen into the other donor
The enzyme, characterized from the bacterium Streptomyces rimosus, is bifunctional, catalysing two successive monooxygenation reactions. It starts by catalysing the stereospecific hydroxylation of anhydrotetracycline at C-6 (EC 1.14.13.38). If the released product is captured by EC 1.3.98.4, 5a,11a-dehydrotetracycline dehydrogenase (OxyR), it is reduced to tetracycline. However, if the released product is recaptured by OxyS, it performs an additional hydroxylation at C-5, producing 5a,11a-dehydrooxytetracycline, which, following the action of OxyR, becomes oxytetracycline.