Passaglio K T, Vieira M A
Department of Physiology and Biophysics, ICB, Universidade Federal de Minas Gerais, Brazil.
Immunopharmacology. 1996 May;32(1-3):166-8. doi: 10.1016/0162-3109(95)00083-6.
Several enzymes of are capable of cleaving kinins at either the N- or C-terminal end. In this work, we investigated the hydrolysis of T-kinin (TK) and bradykinin (BK) by carboxypeptidase B (CpB) and angiotensin I-converting enzyme (ACE). The kinins were incubated with the enzymes in Tyrode solution kept at 37 degrees C for 25 min. The kinin residual activity in the incubation medium was bioassayed on the isolated guinea pig ileum. BK (5 micrograms/ml) and TK (5 micrograms/ml) were rapidly and similarly degraded by CpB (0.088 mU/ml) since half of both kinins was inactivated within 5 min of incubation. At 25 min of incubation with CpB the TK and BK-like activities were 20.8 +/- 3.9 (1.04 +/- 0.20 micrograms/ml) and 31.8 +/- 5.0% (1.59 +/- 0.25 micrograms/ml) of the initial kinin concentrations, respectively. BK was also rapidly inactivated by ACE (5 mU/ml) while TK activity was unaffected. At 25 min the BK and TK residual activities corresponded to 39.4 +/- 2.5 (1.97 +/- 0.13 micrograms/ml) and 93.8 +/- 9.2% (4.69 +/- 0.46 micrograms/ml) of the initial kinin concentrations, respectively. It was concluded that TK, a kinin elongated at the N-terminal position, is resistant to ACE degradation.
几种酶能够在N端或C端切割激肽。在这项研究中，我们研究了羧肽酶B（CpB）和血管紧张素I转换酶（ACE）对T-激肽（TK）和缓激肽（BK）的水解作用。将激肽与酶在37℃的台氏液中孵育25分钟。在分离的豚鼠回肠上对孵育培养基中的激肽残留活性进行生物测定。BK（5微克/毫升）和TK（5微克/毫升）被CpB（0.088毫单位/毫升）快速且相似地降解，因为在孵育5分钟内两种激肽的一半都被灭活。与CpB孵育25分钟时，TK和BK样活性分别为初始激肽浓度的20.8±3.9（1.04±0.20微克/毫升）和31.8±5.0%（1.59±0.25微克/毫升）。BK也被ACE（5毫单位/毫升）快速灭活，而TK活性未受影响。在25分钟时，BK和TK的残留活性分别相当于初始激肽浓度的39.4±2.5（1.97±0.13微克/毫升）和93.8±9.2%（4.69±0.46微克/毫升）。得出的结论是，TK是一种在N端延长的激肽，对ACE降解具有抗性。
