In vitro methylation of rat liver tRNA-synthesis of 3-methylcytosine and 1-methylhypoxantheine

Rat liver methylating enzymes could methylate tRNA extracted from the livers of rats treated with 35 mg/100 g L-ethionine 19 h prior to sacrifice. 1-methylhypoxanthine and 3-methylcytosine were among the methylated bases synthesized in vitro . The synthesis of 3-methylcytosine was dependent on the presence of Mg++ although this ion inhibited the overall methylation of the tRNA.