突变型环酰亚胺水解酶的底物专一性

摘要 目的：研究环酰亚胺水解酶（CIH293）C-末端区残基对其底物专一性的影响。方法：通过缺失或替代获得了环酰亚胺水解酶C-末端剔除2个或3个氨基酸残基及C-末端两个Lys替代为两个Glu的突变型酶CIH291、CIH290以及KK292,293EE，用比色法与高效液相色谱法分析了重组野生型酶与突变型酶的底物专一性和动力学参数。结果：突变型酶与野生型酶相比，底物专一性未发生显著改变，最适底物仍为琥珀酰亚胺，然突变型酶对最适底物的亲和力略有降低，导致反应速度减小。结论：环酰亚胺水解酶（CIH293）C-末端区残基的改变对其底物专一性的影响不大，但影响了酶对底物的亲和力。

The substrate specificity of mutant cyclic imide hydrolases

The effect of C-terminal region residues on the substrate specificity of a novel cyclic imide hydrolase (CIH), a recombinant cyclic imide hydrolase (CIH293), and its mutants deleted or substituted at C-terminus (CIH291, CIH290, KK292-293EE) was reported. The substrate specificity and kinetic parameters of the mutants were analyzed by both the spectrophotometric assay and high-performance liquid chromatography. Results show that the substrate specificity of mutants was not obviously changed, but slightly low for the affinity between the substrate and enzyme, compared with the wild-type enzyme, CIH293. In conclusion, the last three residues of CIH293 play an important role for the enzyme activity.