Rat liver glutamyl ribonucleic acid synthetase. I. Purification and evidence for separate enzymes for glutamic acid and glutamine.

Glutamyl ribonucleic acid synthetase was purified approximately 150-fold from homogenates of rat liver to a specific activity of 60 mpmoles of glutamyl-RNA formed per min per mg of protein. The enzyme at this stage of purification was judged to be about 40% pure, but in a state of aggregation. Although the enzyme was quite stable to storage, it was very heat labile, and lost activity during its assay. The purified enzyme required Mg++, adenosine triphosphate, L-glutamate, and soluble RNA for activity. Evidence is presented for the existence of distinct enzymes for glutamyl-RNA and glutaminyl-RNA formation. A rapid method for obtaining pure soluble RNA from liver is also described.