A new thermokinetic reduced extent method for studying of the reversible competitive inhibition of single sub-strate enzyme-catalyzed reactions was proposed in this paper. The reaction that arginase-catalyzed hydrolys...A new thermokinetic reduced extent method for studying of the reversible competitive inhibition of single sub-strate 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 ℃ in 40 mmolL-1 sodium barbiturate-HCl buffer solution (pH=9.4). Michealis con-stant Km for arginine and maximum velocity Vm of the reaction were determined to be 5.14 mmolL-1 and 1.13× 10-2 mmolL-1s-1, respectively. The product inhibition constant KP and inhibitory constant KI of L-lysine were de-termined to be 1.18 and 5.6 mmolL-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 proc-ess would give more reliable kinetic information than the traditional initial rate method.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 30070200) and the Major Project of Hubei Province Department of Education China (No. 2003A009).
文摘A new thermokinetic reduced extent method for studying of the reversible competitive inhibition of single sub-strate 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 ℃ in 40 mmolL-1 sodium barbiturate-HCl buffer solution (pH=9.4). Michealis con-stant Km for arginine and maximum velocity Vm of the reaction were determined to be 5.14 mmolL-1 and 1.13× 10-2 mmolL-1s-1, respectively. The product inhibition constant KP and inhibitory constant KI of L-lysine were de-termined to be 1.18 and 5.6 mmolL-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 proc-ess would give more reliable kinetic information than the traditional initial rate method.
