Oxidation of Nicotinic Acid by a Bacillus Species: Source of Oxygen Atoms for the Hydroxylation of Nicotinic Acid and 6-Hydroxynicotinic Acid

Three types of evidence are presented to show that the enzymes that hydroxylate nicotinic acid to 2,6-dihydroxynicotinic acid use water as a source of oxygen atoms. (18)O is incorporated into the products from H(2) (18)O. Molecular oxygen acts as a terminal electron acceptor, one-half molecule being consumed per molecule of hydroxyl groups incorporated. An external electron acceptor is required for activity in purified preparations.