Oxidation of Hypoxanthine to Uric Acid by streptomyces

The cells of a strain of Streptomyces sp. previously grown in a peptone-glucose medium were incubated with hypoxanthine in a mixture consisting of K-phosphate buffer (pH 7.0), MgCl2 and glucose. Two ultraviolet absorbing substances were found to be accumulated in the mixture. One of them was identified as xanthine and the other as 6,8-dihydroxy-purine from their ultraviolet absorption and chromatographic characteristics. During a further incubation, both of them disappeared from the mixture and were found to be oxidized to uric acid. Thus, the simultaneous operation of two metabolic pathways, hypoxanthine → xanthine → uric acid and hypoxanthine → 6,8-dihydroxypurine → uric acid, was suggested for the oxidation of hypoxanthine by this microorganism. When the cells were incubated with hypoxanthine in the presence of chloramphenicol, xanthine and 6,8-dihydroxypurine were accumulated in the mixture and the amount of xanthine decreased during a prolonged incubation as in the absence of the antibiotic. However,...