Abstract
A number of Streptomyces strains degraded the N-glycosidic linkage of pyrimidine nucleotides. The products and some conditions of 5′-UMP degradation were studied using cell-free extracts of Streptomyces virginiae IFO 3729. Formation of uracil was recognized by paper electrophoresis and by the shift of ultraviolet absorption at an alkaline pH. Pentose phosphate was purified by ion-exchange chromatography and prepared as Ba salt. It was identified with R5P by paper chromatography, paper electrophoresis and by chemical analyses.
Optimum pH and temperature for R5P formation were 5.5 and 55°, respectively. 5′-UMP was quantitatively converted to uracil and R5P under this condition. At near neutral pH and at lower temperatures, the rate of R5P formation was far lower than that of uracil, caused by coexisting R5P-metabolizing activity.
When the mixture of purine and pyrimidine nucleotides was subjected to the enzyme action, pyrimidine nucleotides were selectively degraded
