Effect of 2-aminopurine and 2-aminopurine 2′-deoxyriboside on nucleic acid synthesis in ehrlich ascites cells in vitro

Abstract

2-Aminopurine 2′-deoxyriboside has been prepared by transfer of 2′-deoxyribose from 2′-deoxythymidine to 2-aminopurine catalysed by nucleoside deoxyribosyltransferase from L. helveticus. 2-Aminopurine and 2-aminopurine 2′-deoxyriboside (in concentration of 2 μmoles/ml) inhibited the incorporation of 32P i and adenine-8- 14C into DNA of Ehrlich ascites tumor cells in vitro. Incorporation of 32P i into RNA was slightly inhibited by the two analogues, but the incorporation of adenine-8- 14C was not. 2-Aminopurine and 2-aminopurine 2′-deoxyriboside was recovered quantitatively from the acid soluble fraction of Ehrlich cells incubated with the compounds. No ribotides or deoxyribotides could be detected by the paper-chromatographic method used. 2-Aminopurine is not a substrate for a purine nucleoside phosphorylase from calf spleen. 5-Phosphoribosyl-2-aminopurine was formed in low yield from 2-aminopurine and 5-phosphoribosyl-1-pyrophosphate when incubated with a cell-free extract of Ehrlich cells. 2-Aminopurine 2′-deoxyriboside is not deaminated by an adenosine deaminase isolated from calf intestine, but is the strongest competitive inhibitor hitherto found of this enzyme.