S U M M A R YL-Asparaginase and L-glutaminase activities were detected in many microorganisms and the distribution of these activities was found to be related to the classification of micro-organisms.Among 464 bacteria, the activities occurred in many Gram-negative bacteria and in a few Gram-positive bacteria. Most members of the family Enterobacteriaceae possessed L-asparaginase. L-Asparaginase and L-glutaminase occurred together in a large proportion of pseudomonads. Among Gram-positive bacteria many strains of Bacillus pumilus showed strong L-asparaginase activity. Amidase activities were also observed in several strains in other families.L-Asparaginase activity was not detected in culture filtrates of 261 strains of species of the genera Streptomyces and Nocardia, but L-asparaginase and Lglutaminase were detected when these organisms were sonicated.The amidase activities in culture filtrates of 4158 fungal strains were tested. All the strains of Fusarium species formed L-asparaginase. Organisms of the genera Hjyomyces and Nectria, which are regarded as the perfect stage of the genus Fusarium, also formed L-asparaginase. Several Penicillium species formed L-asparaginase. Two organisms of the family Moniliaceae formed L-glutaminase together with L-asparaginase, and a few ascomycetous fungi formed L-asparaginase or L-glutaminase.Among I 326 yeasts, L-asparaginase or L-glutaminase occurred frequently in certain serological groups of yeasts : VI (Hansenula) group, Cryptococcus group and Rhodotorula group. Many strains of Sporobolomyces species also showed L-asparaginase activity. Several strains of Cryptococcus and Rhodotorula group possessed L-glutaminase and L-asparaginase. L-Glutaminase alone was formed in many strains of Candida scottii and Cryptococcus albidus, both of which are related to Basidiomycetes.
The enzymatic transfer of ribose and deoxyribose residues in pyrimidine nucleosides to purines was catalyzed by cell-free extracts of various bacteria. Almost all the strains belonging to Enterobacteriaceae were capable of catalyzing the transfer reactions. The transfer activities were also detected among some bacterial strains of other families: Pseudomonadaceae, Corynebacteriaceae, Micrococcaceae, Bacteriaceae, and Bacillaceae. The rates of the transfer reactions were greatly enhanced in the presence of phosphate ion, and the participation of nucleoside phosphorylases in the reactions was suggested. Uridine phosphorylase, thymidine phosphorylase, and purine nucleoside phosphorylase were purified from cell-free extract of Aerobacter aerogenes IFO 3321. The ribosyl transfer from uridine to hypoxanthine was found to be catalyzed by the coupled reactions of uridine and purine nucleoside phosphorylases and the deoxyribosyl transfer from thymidine to hypoxanthine by the coupled reactions of thymidine and purine nucleoside phosphorylases. MATERIALS AND METHODS Reagents. Hypoxanthine (Zellstofffabrik, Waldhof, Germany), cytidine, uridine (Nutritional Biochemicals Corp., Cleveland, Ohio), inosine (Katayam Chemical Co., Osaka, Japan), and thymidine (Calbiochem, Los Angeles, Calif.) were obtained from commercial sources. Deoxycytidine and deoxyuridine were prepared from codfish deoxyribonucleic acid by degradation with phosphodiesterases of Strep-1551
A number of Streptom yces 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. The hydrolysis of nucleoside N-glycosidic linkage is well known, but reports on the hydrolysis at the nucleotide level are scarce. HURWITZ et al. (1) found in Azotobacter vinelandii AMP-ribosidase which hydrolyzes 5'-AMP to adenine and ribose-5-phosphate (R5P). KUNINAKA (2, 3) reported on IMPribosidase of Aspergillus oryzae, which hydrolyzes 5'-IMP and 5'-GMP to their bases and R5P. These reports are mainly concerned with the cleavage of purine nucleotides. During the course of our investigation on the metabolism of pyrimidine compounds by microorganisms, the ability of Streptonyees to hydrolyze the N-glycosidic linkage in pyrimidine 5'-nucleotides was found. This paper deals with the distribution of such an enzyme, the degradation products and with some conditions for the degradation of the nucleotides.
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