Cytokinins in Pisum Transfer Ribonucleic Acid

Five cytokinin-active ribonucleosides have been isolated from the transfer RNA of 7-day-old green pea shoots (Pisum sativum L. var. Alaska). Ultraviolet spectroscopy and mass spectrometry have been used to identify 6-(3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine, 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-beta- d-ribofuranosylpurine, and 6-(4-hydroxy-3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine. The latter was separated into the cis- and trans-isomers by thin layer chromatography. The fifth cytokinin is indicated to be 6-(3-methyl-2-butenylamino)-2-methylthio-9-beta-d -ribofuranosylpurine on the basis of its chromatographic properties.