Kinetics of hydrolysis of a new peptide substrate containing p-guanidino-L-phenylalanine by trypsin and thrombin.
作者:HIDEAKI TSUNEMATSU、KOICHI MIZUSAKI、YOSHIHIRO HATANAKA、MASAO KAMAHORI、SATORU MAKISUMI
DOI:10.1248/cpb.34.1351
日期:——
A new peptide substrate containing p-guanidine-L-phenylalanine, Nα-benzoyl-L-phenylalanyl-L-prolyl-p-guanidino-L-phenylalanine p-nitroanilide (Bz-Phe-Pro-GPA-pNA), was synthesized, and the rates of hydrolyses of this substrate by bovine trypsin and thrombin were compared with those of the corresponding arginine peptide substrate (Bz-Phe-Pro-GPA-pNA). The specificity constants (kcat/Km) for the hydrolysis of GPA-peptide by the two enzymes were much smaller than those for Arg-peptide. Remarkably low kcat values were found in the hydrolyses of GPA-peptide by the two enzymes compared with the values in those of Arg-peptide. The effect of the peptide chain elongation was observed in the hydrolysis of GPA-peptide by thrombin, while it was not in the case of trypsin, suggesting that the subsite of trypsin is very different from that of thrombin. GPA-peptide was ascertained to be a useful peptide substrate to study the subsite specificities of trypsin-like enzymes.
合成了一种含有对胍基-L-苯丙氨酸的新肽底物--Nα-苯甲酰基-L-苯丙氨酰-L-脯氨酰-对胍基-L-苯丙氨酸对硝基苯胺(Bz-Phe-Pro-GPA-pNA),并比较了牛胰蛋白酶和凝血酶对这种底物与相应的精氨酸肽底物(Bz-Phe-Pro-GPA-pNA)的水解速率。两种酶水解 GPA 肽的特异性常数(kcat/Km)远小于水解 Arg 肽的特异性常数(kcat/Km)。两种酶水解 GPA 肽的 kcat 值明显低于水解 Arg 肽的 kcat 值。凝血酶水解 GPA 肽时观察到肽链拉长的影响,而胰蛋白酶则没有,这表明胰蛋白酶的亚位点与凝血酶的亚位点非常不同。GPA 肽被确定为研究胰蛋白酶类酶的亚位点特异性的一种有用的肽底物。