Metabolic conversion of formycin B to formycin A and to oxoformycin B in Nocardia interforma.

A strain of Nocardia interforma having low productivity of formycin A was selected. Washed cells of this strain convert formycin B to oxoformycin B (reaction I), while those of the original strain collected during formycin A producing phase convert formycin B to formycin A (reaction II). Reaction I is inhibited by allopurinol, an inhibitor of xanthine oxidase. Reaction II is inhibited by hadacidin, an inhibitor of adenylosuccinate synthetase, but not by azaserine. As intermediates of reaction II, formycin B-monophosphate and formycin A-monophosphate were detected in the nucleotide pool of the cell. No other organisms than Nocardia interforma perform reaction II except Xanthomonas oryzae. Besides Nocardia interforma, Pseudomonas fluorescens and Streptomyces kasugaensis perform reaction I.