Identification of the Cytokinin-Active Ribonucleosides in Pure Escherichia coli tRNA Species

The distribution of the two cytokinin-active ribonucleosides 6-(3-methyl-2-butenylamino)-9-β-D-ribofuranosylpurine (1) and 6-(3-methyl-2-butenylamino)-2-methylthio-9-β-D-ribofuranosylpurine (2) in tRNAPhe , tRNAUUG Leu , tRNAUCR Ser , tRNATyr , tRNACys , and tRNA2 Trp from stationary phaseEscherichia coli has been studied. Compound 2 predominated in all these species except tRNAPhe , in which compound 1 was greatly in excess. Compound 1 was present in relatively small amounts in tRNAUUG Leu , tRNACys , and tRNA2 Trp , and was not detected in tRNAUCR Ser and tRNATyr . Cells from the early logarithmic phase had the highest cytokinin content in their tRNA. Stationary phase tRNA had a slight increase in the amount of 1, which may be explained by the appearance of the new tRNAPhe . No differences were observed between the chromatographic patterns of tRNAs from early-, mid-, and latelogarithmic phases.