[Amino-tRNA-synthetase activity of rabbit muscles in fasting and aging].

The aminoacyl-tRNA-synthetase activity of muscular soluble fraction was studied in normal rabbits, in those fasting for a long period and old rabbits. A rigion of linear dependence is found for the initial rate of the tRNA aminoacylation reaction on the concentration of the enzymic preparation and also on the substrate amount. Having valuated the initial rate of the aminoacylation reaction, the asparagil- and valyl-tRNA-synthetase activities of muscles were determined in normal rabbits, in those fasting for a long period and in old rabbits. The data obtained evidence for an increase of the studied activities in the muscles of the fasting animals and for their decrease in old animals.