DEGRADATION OF PYRIMIDINE NUCLEOTIDES BY ENZYME SYSTEMS OF STREPTOMYCES

Abstract

A number of Streptomyces strains degraded the N-glycosidic linkage of pyrimidine nucleotides. The products and some conditions of 5[image]-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 UV absorption at an alkaline pH. Pentose phosphate purified by ion-exchange chromatography was prepared as the Ba salt. It was identified with ribose-5-phosphate (R5P) by paper chromatography, paper electrophoresis and chemical analyses. The optimum pH and temperature for R5P formation were 5.5 and 55[degree], respectively. The 5[image]-UMP was quantiatively converted to uracil and R5P under this condition. At near neutral pH and at lower temperature, the rate of R5P formation was far lower than that of uracil, caused by coexisting R5P-metablizing activity. When the mixture of purine and pyrimidine nucleotides was subjected to the enzyme action, pyrimidine nucleotides were selectively degraded.