非洲爪蟾精氨酸酶的动力学特性

Kinetic properties of arginase from Xenopus laevis.

Peiser L, Balinsky J B

Comp Biochem Physiol B. 1982;73(2):215-20. doi: 10.1016/0305-0491(82)90274-7.

Abstract

Arginase from the liver of Xenopus laevis has a Michaelis constant (Km) for arginine of 42 mM, a minor component having a Km of 29 mM. The Km is independent of pH in the range of 7.0-11.0 and also independent of manganese ion concentration. 2. Manganese is required for activation, showing an optimum at 50 mM with inhibition at higher concentrations. 3. The enzyme is inhibited by high concentrations of the substrate L-arginine and by L-lysine and L-ornithine in a competitive manner with respect to arginine. 4. In its Michaelis constant for arginine and inhibition by high substrate concentration, Xenopus liver arginase resembles "ureotelic" arginases.

摘要

非洲爪蟾肝脏中的精氨酸酶对精氨酸的米氏常数（Km）为42 mM，有一个次要组分的Km为29 mM。该Km在7.0 - 11.0的pH范围内与pH无关，也与锰离子浓度无关。2. 激活需要锰，在50 mM时显示出最佳效果，在更高浓度时受到抑制。3. 该酶受到高浓度底物L - 精氨酸以及L - 赖氨酸和L - 鸟氨酸的竞争性抑制，相对于精氨酸而言。4. 在其对精氨酸的米氏常数以及被高底物浓度抑制方面，非洲爪蟾肝脏精氨酸酶类似于“排尿素型”精氨酸酶。