Transfer RNA methylase activity in normal and dystrophic chicken muscle

Abstract

Adult-dystrophic chicken muscle had 30% higher tRNA methylase activity and 42% higher tRNA methylating capacity than normal-adult chicken muscle. Eighty percent of the tRNA methylase activity of the dystrophic muscle resulted in the synthesis of N 2-methylguanine, and 9% in the formation of N 2,N 2-dimethylguanine. From adult-normal muscle extracts, 33% of the tRNA methylase activity was due to the synthesis of N 2-methylguanine, and 45% to the formation of N 2,N 2-dimethylguanine. Eight other methylated bases accounted for 5–15% of the enzyme activity in both tissues. Dialyzed and nondialyzed adult-normal muscle extracts had equivalent tRNA methylase activity. However, the dialyzed extracts synthesized 22% more N 2-methylguanine and 18% less N 2,N 2-dimethylguanine than the nondialyzed extracts. Dialysis had no effect on the tRNA methylase activity or tRNA methylation pattern produced by adult-dystrophic muscle.