β-Naphthylamides of p-guanidino-L-phenylalanine (GPA) and p-guanidino-DL-phenylglycine (GPG) were synthesized and tested as substrates of bovine leukocyte aminopeptidase (BL-APase) and porcine liver aminopeptidase B (PL-APaseB) in comparison with L-arginine β-naphthylamide (Arg-βNA). BL-APase-catalyzed bydrolysis of GPA-βNA proceeded as fast as that of Arg-βNA, while the rate of hydrolysis of GPG-βNA was much slower. The specificity constant (Vmax/Km) for the hydrolysis of GPA-βNA by BL-APase was somewhat larger than that for the hydrolysis of Arg-βNA. The benzene ring in the side chain of GPA-βNA is considered to contribute to the binding of this substrate to the specificity side to this enzyme, based on comparison of the Km values for the two β-naphthylamide substrates. Substrate inhibition was observed with BL-APase in the hydrolysis of GPA-βNA in the substrate concentration range higher than about 0.1 mM. Neither GPA-βNA nor GPG-βNA was hydrolyzed by PL-APaseB and they inhibited the hydrolysis of Arg-βNA by this enzyme. GPA-βNA is expected to be a useful substrate in the study of the binding and catalytic specificities of aminopeptidases.
合成了对-
胍基-
L-苯丙氨酸(GPA)和对-
胍基-D
L-苯甘氨酸(G
PG)的β-
萘甲酰胺,并将其作为牛白细胞
氨肽酶(BL-APase)和猪肝
氨肽酶 B(PL-APaseB)的底物与
L-精氨酸β-
萘甲酰胺(Arg-βNA)进行了比较试验。BL-APase 催化 GPA-βNA 的
水解速度与 Arg-βNA 一样快,而 G
PG-βNA 的
水解速度要慢得多。BL-AP 酶
水解 GPA-βNA 的特异性常数(Vmax/Km)略大于
水解 Arg-βNA。根据两种 β-
萘甲酰胺底物 Km 值的比较,GPA-βNA 侧链中的苯环被认为有助于该底物与该酶特异性侧的结合。在底物浓度高于约 0.1 mM 的范围内,观察到 BL-APase 在
水解 GPA-βNA 时存在底物抑制作用。PL-APaseB 不
水解 GPA-βNA 也不
水解 G
PG-βNA,而且它们抑制该酶
水解 Arg-βNA。预计 GPA-βNA 将成为研究
氨基肽酶结合和催化特异性的有用底物。