Deoxyribosyl-8-Azaadenine. its Deamination to Deoxyribosyl-8-Azahypoxanthine and effect on Nucleic Acid Synthesis in Ehrlich Ascites cells in Vitro
Biochimica et Biophysica Acta 87: 574-582
Deoxyribosyl-8-azaadenine has been prepared by deoxyribose transfer from thymidine or deoxyinosine to 8-azaadenine with nucleoside deoxyribosyltransferase (Ec 126.96.36.199) from Lactobacillus helveticus. Deoxyribosyl-8-azahypoxanthine was prepared by enzymatic deamination of deoxyribosyl-8-azaadenine. Deoxyribosyl-8-azaadenine is substrate for adenosine deaminase (Ec 188.8.131.52) with a Km value of 125·10−6 and a vmax about 4 times that of deoxyadenosine. Deoxyribosyl-8-azaadenien and deoxyribosyl-8-azahypoxanthine have no effect on deoxyribonucleic acid and ribonucleic acid synthesis in Ehrlich ascites cells in vitro. Deoxyribosyl-8-azaadenine is rapidly deaminated in the tumor cells, but 8-azaadenine-deoxyribotides could not be detected. Deoxyribosyl-8-azahypoxanthine is neither cleaved in Ehrlich cells nor by purine nucleoside phosphorylase (Ec 184.108.40.206).