[Comparative study of the tRNA-methylases of normal and tumor tissues. I. Spectrum of renal and carcinoma RA methylases].

A comparative study of rat kidney and carcinoma RA tRNA-methylase activity has been carried out using partially purified enzyme preparations and total E. coli tRNA. Also the nuclease activity of the methylase preparations from kidney and carcinoma was compared. It was established that the methylase activity in carcinoma preparations is higher, whereas the nuclease activity is lower in comparison to the enzyme preparations from liver. No formation of some specific methylated compounds could be established in the case of carcinoma. It was established that the relative contribution of individual methylases to the elevated level of total tRNA-methylase activity in carcinoma is different. Maximal enhancement of activity was established for the methylase forming m5U, whereas the activity of the enzymes, transfering the methyl group to the fifth position of C is practically equal in kidney and carcinoma tissues. Experimental results and theoretical evaluation of the hypotheses suggested to explain the higher methylase activity in tumor tissues allowed to reject some of them.