Bacterial Synthesis of Nucleotides

Part VII. Acceptor Specificity of Nucleoside Phosphotransferase (III): Phosphorylation of Unusual Ribonucleosides and Their Ribosyl Derivatives

Abstract

1) Various kinds of unusual ribonucleosides including 5- or 6-substituted pyrimidine and 2- or 6-substituted purine were phosphorylated by the cell-free extracts of typical strains of both groups, using p-NPP as donor.
2) The bacteria characterized to synthesize 5'-isomer in the phosphorylation of naturally occurring ribonucleosides were observed to transfer the phosphoryl radical to 5'-CH₂OH, while the others were observed to phosphorylate at C_3' or C_2', even if C_5', is substituted by any radical.
3) Although the specificities of these nucleoside phosphotransferases were confirmed to be valid, regardless of the structure of unusual ribonucleosides or their derivatives, some steric effects on these reactions may be considered, just as observed in the failure of OR phosphorylation by the latter group of bacteria.