THE EFFECT OF STRUCTURE ON NUCLEOSIDE KINASE ACTIVITY

Abstract

A study was made of the in vitro phosphorylation of some nucleosides in cell-free extracts from a thioguanine-resistant subline of Ehrlich ascites carcinoma which lacked inosine monophosphate – guanosine monophosphate pyrophosphorylase. The results indicated that there were kinases which catalyzed the phosphorylation of a variety of nucleosides. Ribofuranosyl-6-thiopurme was phosphorylated whereas the xylofuranosyl-, arabinofuranosyl-, and lyxofuranosyl-6-thiopurine were not substrates. The xylose and ribose derivatives of 6-methylthiopurine were phosphorylated but the arabinose derivative was not. Guanosine and some of its analogs were also phosphorylated but no correlation could be found between structure and phosphorylation of the guanosine analogs tested.The reaction showed dependence on the addition of divalent cation and an ATP-regenerating system.