Modification of Fungal L-arginase by Some Modifiers of the active Enzyme Residues

Arginase, known as L-arginine urea hydrolase or amidinohydrolase (EC 3.5.3.1), is an essential hydrolytic enzyme involved in the urea cycle catalyzing urea synthesis in the liver of mammals. The enzyme was extracted and partly purified from Penicillium chrysogenum, with a specific activity of 15.8 units per milligram of protein. Investigation was conducted on the impact of specific reagents, namely phenyl glyoxal (PGO), Woodward's reagent K (WRK), N-bromosuccinimide (NBS), and trinitromethane (TNM), on the active groups of L-arginase. The aforementioned chemicals exhibited a concentration-dependent inhibition of L-arginase activity at different tested concentrations (1, 2, 3, 4, and 5 M). The inhibitory effect of PGO on L-arginase at 5 M was 82.3%, whereas WRK exerted an inhibitory effect of 90.0%. Both TNM and NBS exhibited enzyme inhibition rates of 70.2% and 81.0%, respectively. The observed inhibition highlights the crucial involvement of arginyl, carboxyl, tyrosyl, and tryptophenyl residues in the process of enzyme catalysis.