Chemical synthesis of 5-azacytidine nucleotides and preparation of tRNAs containing 5-azacytidine in its 3'-terminus.

5-azacytidine-5'-triphosphate prepared from 5-azacytidine by chemical phosphorylation is a substrate for AMP (CMP) tRNA nucleotidyl transferase from yeast. tRNAsPhe from yeast containing 5-azacytidine in their 3'-termini were prepared enzymatically. tRNAPhe-Cpn5CpA and tRNAPhe-n5Cpn5CpA can be aminoacylated by phenylalanyl-tRNA synthetase from yeast and they are active in the poly(U)-dependent synthesis of poly(Phe) on E. coli ribosomes. The decomposition of 5-azacytidine via hydrolysis of the triazine ring is significantly accelerated by a phosphate group on the 5'-position of the nucleotide. After the incorporation of 5-azacytidine-5'-phosphate into a polynucleotide chain the rate of hydrolysis of the triazine ring decreases considerably.