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 is responsible for the C-12 hydroxylation of the macrolactone ring, one of the last steps in erythromycin biosynthesis. It shows 1200-1900-fold preference for erythromycin D over the alternative substrate erythromycin B [1].