Purification and properties of the constitutive arginase of Evernia prunastri

Abstract

Constitutive arginase (molecular weight 330,000) 920-fold purified from Evernia prunastri thallus, is activated by putrescine, L-ornithine, and agmatine with Ka values of 2.7, 1.1, and 5.8 millimolar, respectively. Constitutive arginase is also activated by endogenous L-arginine, reaching its maximum activity at 16 hours of incubation on Tris-HCl (pH 9.15) with a subsequent decrease. Urea behaves as a mixed inhibitor of the enzyme with a Ki value of 2.6 millimolar. Atranorin and evernic acid behave as in vitro activators of the enzyme; usnic acid does not have any significant effect as activator.