THE EFFECT OF CORTISONE UPON AMINO ACID ACTIVATING ENZYMES OF RAT LIVER CORRELATED WITH INCREASED TRYPTOPHAN PYRROLASE ACTIVITY1

Abstract

Studies were conducted concerning possible variations in the activity of amino acid activating enzymes accompanying increased tryptophan pyrrolase activity in rat liver resulting from cortisone injection. Though cortisone injection produced the expected significant increase in tryptophan pyrrolase activity, it caused no significant rise in either the total or specific activity of several amino acid activating enzymes. It would appear that the administration of cortisone results in the increased synthesis of certain liver protein fractions (1–4). There is increasing indirect evidence that enhanced tryptophan pyrrolase activity following cortisone administration may involve the de novo synthesis of the apoenzyme. Ethionine has been shown to inhibit the cortisoneevoked stimulation of the enzyme and the inhibition is reversed by methionine. (5).