Barabé J, Huberdeau D
Département de Pharmacologie, Faculté de Médecine, Université de Sherbrooke, Québec, Canada.
Biochem Pharmacol. 1991 Mar 1;41(5):821-7. doi: 10.1016/0006-2952(91)90086-k.
Kininase II (EC 3.4.15.1) (KII) and kininase I (KI) (EC 3.4.12.7) activities of rat plasma were characterized by the hydrolysis of hippuryl-L-histidyl-L-leucine (HHL), hippuryl-L-arginine (HLA) [expressed as carboxypeptidase N1 (CN1) activity] and hippuryl-L-lysine (HLL) [expressed as carboxypeptidase N2 (CN2) activity]. Using a spectrophotometric assay, biochemical characteristics of the three enzymes were investigated. The Michaelis-Menten constants were as follows: KII: Km 2.55 +/- 0.22 mM, Vmax 0.357 +/- 0.017 mumol/min/mL; CN1: Km 6.93 +/- 0.32 mM, Vmax 0.748 +/- 0.019 mumol/min/mL; and CN2: Km 35.8 +/- 1.52 mM, Vmax 13.11 +/- 0.40 mumol/min/mL. EDTA and O-phenanthroline inhibited the three enzyme assays at the same Ki, whereas captopril and 2-mercaptomethyl-3-guanidinoethylthiopropanoic acid (MERGETPA), allowed for the demonstration of the specificity of each assay. Furthermore, Ki values of MERGETPA against both CN1 (4.75 microM) and CN2 (2.36 microM) activities do not support the hypothesis that KI activity may be accounted for by the presence of isoenzymes in rat plasma.
通过马尿酰-L-组氨酰-L-亮氨酸（HHL）、马尿酰-L-精氨酸（HLA）[以羧肽酶N1（CN1）活性表示]和马尿酰-L-赖氨酸（HLL）[以羧肽酶N2（CN2）活性表示]的水解作用来表征大鼠血浆中的激肽酶II（EC 3.4.15.1）（KII）和激肽酶I（KI）（EC 3.4.12.7）活性。采用分光光度法测定，研究了这三种酶的生化特性。米氏常数如下：KII：Km 2.55±0.22 mM，Vmax 0.357±0.017 μmol/min/mL；CN1：Km 6.93±0.32 mM，Vmax 0.748±0.019 μmol/min/mL；CN2：Km 35.8±1.52 mM，Vmax 13.11±0.40 μmol/min/mL。乙二胺四乙酸（EDTA）和邻菲罗啉以相同的抑制常数（Ki）抑制这三种酶的测定，而卡托普利和2-巯甲基-3-胍基乙基硫代丙酸（MERGETPA）则可用于证明每种测定的特异性。此外，MERGETPA对CN1（4.75 μM）和CN2（2.36 μM）活性的Ki值不支持大鼠血浆中存在同工酶可解释KI活性的假说。
