THE ACTIVATION OF GLUTAMIC ACID AND GLUTAMINE IN MAMMALIAN TISSUES

Abstract
Measurements of α-glutamyl-RNA synthetase and glutaminyl-RNA synthetase activities have been made in fractions derived from 105,000 × g supernatants of homogenates of rat liver and of mouse Ehrlich ascites carcinoma cells. Evidence is presented which indicates that each amino acid is activated by a specific enzyme. Both enzymes catalyze amino acid dependent ATP-32PP exchange. The α-glutamyl-RNA synthetase purified 42-fold from rat liver 105,000 × g supernatant is free of glutamine synthetase.