Adenosylcobinamide-GDP ribazoletransferase (EC 2.7.8.26, CobS, cobalamin synthase, cobalamin-5'-phosphate synthase, cobalamin (5'-phosphate) synthase) is an enzyme with systematic name adenosylcobinamide-GDP:alpha-ribazole ribazoletransferase.
[1][2][3] This enzyme catalyses the following chemical reaction This enzyme is part of the biosynthetic pathway to cobalamin (vitamin B12) in bacteria.