Bacterial Synthesis of Nucleotides

Abstract

General properties of bacterial nucleoside phosphotransferase were demonstrated. Nucleoside phosphotransferase activity was observed somewhere in cells, and the activity and the specificity for donor and product in this reaction are described to be due to the basic character of strains. Such aromatic phosphates as p-nitrophenylphosphate, phenylphosphate, benzylphosphate and the nucleotides were apparent to be useful for nucleotide synthesis, and the ability as donor did not always depend upon the energy consideration. The product specificity of this reaction was confirmed to correlate with nucleotide isomer added as donor; that is, the bacteria characterized to phosphorylate at 5′-position of nucleoside catalyzed the interconversion of phosphoryl or phosphate radical between 5′-nuclotides and those characterized to do at 3′(& 2′)-position of nucleoside catalyzed the interconversion of that between 3′(& 2′)-nucleotides. The phosphoryl or phosphate transfer reaction using nucleotide as donor is reversible but that using p-nitrophenylphosphate as donor is irreversible. The factors to get a good yield on the synthesis of 5′-inosinic acid were discussed, then the maximum yield was accounted to 80%. The effects of reagents known so far as the inhibitors of acid phosphatases and of the metallic ions on the nucleoside phosphotransferase activity were studied to get a good yield of 5′-inosinic acid using the intact cells of bacteria. The effects of them on phosphomonoesterase and 5′-nuclotidase activities which might correlate with the synthesis and accumulation of 5′-inosinic acid were also studied. From these experiments, it was apparent that few reagents inhibit the synthesis of 5′-inosinic acid, and that Cu++ or Zn++ has a stimulating effect on the synthesis of nucleotide (1), shifts the optimum pH of this activity from 5.0 to 4.0 (2), stimulates 5′-nucleotidase and phosphomonoesterase activities at pH 4.0 (3) and inhibits the ability to form hypoxanthine from inosine (4). These effects of metallic ions are described not to correlate with the permeability of cell membrane or with the nitro radical at para-position of phenylphosphate and to be different from each other on the protecting ability from acidic inactivation, on phosphomonoesterase activity and on the synthesis of nucleotide at pH 5.0.