Inhibition and Kinetic Studies of Tortoise (<i>Kinixys erosa</i>) Liver arginase

Abstract

The effect of amino acid on tortoise liver arginase showed that L-lysine, L-valine, L-serine, L-aspartic acid and L aspartic acid had significant inhibitory effect on the enzyme but proline and glutamic acid showed slight inhibition. Ethylenediaminetetraacetic acid (EDTA), citrate, ascorbic acid, boric acid and sodium borate completely inactivated the tortoise liver arginase. Inhibition studies on the enzyme with a number of cations showed decreased arginase activity. While Mn²⁺ satisfies the metal ion requirement of tortoise arginase, Sn²⁺, Hg²⁺, Ba²⁺ and Co²⁺, to a lesser extent inhibited the enzyme. The enzyme was markedly sensitive to inhibition by Zn²⁺, Ni²⁺ and Mg²⁺. The enzyme was also completely inactivated by thiol compounds: reduced glutathione (GSH), cysteine and 2-mercaptoethanol.