Digestion of purified acetyl-aminoacyl tRNA Ser CAG with RNase T1 also gave only a 14 C-labeled CCA fragment, as shown in Figure 1C . When the acetylated amino acid released from the fragment purified from the corresponding spot on TLC was analyzed by TLC, the ratio of acetylleucine to acetylserine was also found to be 3% ( Figure  4D ), indicating that acetylleucine is covalently attached to the tRNA Ser CAG fragment with G73. It thus became clear that the tRNA Ser CAG of C.zeylanoides was in fact charged with leucine by 3% of the amount of serylation of the same tRNA Ser CAG in C.zeylanoides cells.