Studies on the Formation of Uricase by Streptomyces

The cells of a strain of Streptomyces sp. grown in a medium consisted of peptone, glucose and inorganic salts had little activity of urate degradation. The activity, however, was considerably promoted if the cells were incubated potassium phosphate buffer containing MgCl₂ and glucose, even in the absence of urate. Uricase activity of the cells was also significantly increased during the incubation without urate. The cells were shown to possess the activities of metabolizing adenine, guanine, hypoxanthine to urate. The incubation with these purines caused an acceleration of urate breakdown by the cells and a remarkable increase of uricase activity in the cells. However, the amounts of uricase produced differed considerably with the kind of purines added to the incubation mixture even in the same molar concentration, and was largest with hypoxanthine. The induced formation of uricase by the endogenously generated urate was discussed.