Thermokinetic study on the reversible competitive inhibition of bovine liver arginase

Abstract

AbstractA new thermokinetic reduced extent method for studying of the reversible Competitive inhibition of single substrate enzyme‐catalyzed reactions was proposed in this paper. The reaction that arginase‐catalyzed hydrolysis of L‐arginine to L‐ornithine and urea and the inhibition of this reaction by the product, L‐ornithine, and exogenous L‐lysine were studied at 37 °C in 40 mmol−L−1 sodium barbiturate‐HC1 buffer solution (pH=9.4). Michealis constant Km for arginine and maximum velocity Vm of the reaction were determined to be 5.14 mmol.L−1 and 1.13X 10−‐2 mmol‐L−1.s‐1, respectively. The product inhibition constant Kp and inhibitory constant K1 of L‐lysine were determined to be 1.18 and 5.6 mmol.L−1, respectively. All the results have better repeatability and self‐consistency and are in agreement with literature values. This new method using more direct thermal information from the process would give more reliable kinetic information than the traditional initial rate method.