Sheikh I A, Kaplan A P
Biochem Pharmacol. 1986 Jun 15;35(12):1951-6. doi: 10.1016/0006-2952(86)90726-4.
We have studied the degradation of bradykinin, lysyl bradykinin and des-Arg9-bradykinin by the angiotensin converting enzyme. Bradykinin was cleaved at two sites to produce the pentapeptide Arg-Pro-Pro-Gly-Phe plus dipeptides Ser-Pro and Phe-Arg. Lysyl bradykinin was cleaved similarly to release the same dipeptides plus the hexapeptide Lys-Arg-Pro-Pro-Gly-Phe. The tripeptidase activity of ACE was observed when des-Arg9-bradykinin was digested. A single cleavage yielded the above pentapeptide plus Ser-Pro-Phe. Although des-Arg9-bradykinin was the most rapidly digested, when mixtures of des-Arg9-bradykinin and bradykinin or lysyl bradykinin were tested, virtually all of the bradykinin and most of the lysyl bradykinin was digested prior to the onset of digestion of des-Arg9-bradykinin. This was shown to be due to inhibition of des-Arg9-bradykinin cleavage by kinins and kinin-degradation products. The order in terms of potency was bradykinin greater than lysyl bradykinin greater than Ser-Pro much greater than Phe-Arg greater than Arg-Pro-Pro-Gly-Phe. The concentration of chloride ion was an important parameter which affected the rate of digestion of each substrate examined. des-Arg9-bradykinin was not digested by ACE in the absence of sodium chloride and the rate of digestion increased as the chloride concentration was increased to 100-150 mM. On the other hand, increasing NaCl concentration was inhibitory for bradykinin digestion. The rate of Lys-bradykinin digestion was increased from 0 to 1 mM NaCl and decreased thereafter up to physiologic concentration. A half-maximal rate was seen at 100-150 mM NaCl compared to no salt. Of the divalent cations examined, cupric ion inhibited further digestion of des-Arg9-bradykinin at physiologic concentrations. Our data indicate that the rate of degradation of kinins and the nature of the stable final cleavage products in plasma or serum (studied in vitro) are dependent upon the effects of chloride ion, metal ions, and the kinetic effects of multiple metabolites produced by at least two kininases.
我们研究了血管紧张素转换酶对缓激肽、赖氨酰缓激肽和去 -Arg9-缓激肽的降解作用。缓激肽在两个位点被切割，产生五肽Arg-Pro-Pro-Gly-Phe以及二肽Ser-Pro和Phe-Arg。赖氨酰缓激肽的切割方式类似，释放出相同的二肽以及六肽Lys-Arg-Pro-Pro-Gly-Phe。在消化去 -Arg9-缓激肽时观察到了ACE的三肽酶活性。单次切割产生上述五肽以及Ser-Pro-Phe。尽管去 -Arg9-缓激肽消化速度最快，但在测试去 -Arg9-缓激肽与缓激肽或赖氨酰缓激肽的混合物时，实际上所有缓激肽和大部分赖氨酰缓激肽在去 -Arg9-缓激肽开始消化之前就已被消化。这表明是由于激肽和激肽降解产物对去 -Arg9-缓激肽切割的抑制作用。就效力而言，顺序为缓激肽大于赖氨酰缓激肽大于Ser-Pro远大于Phe-Arg大于Arg-Pro-Pro-Gly-Phe。氯离子浓度是影响所检测的每种底物消化速率的重要参数。在没有氯化钠的情况下，去 -Arg9-缓激肽不被ACE消化，随着氯离子浓度增加到100 - 150 mM，消化速率增加。另一方面，增加氯化钠浓度对缓激肽消化有抑制作用。赖氨酰缓激肽的消化速率在氯化钠浓度从0增加到1 mM时增加，此后直至生理浓度时降低。与无盐情况相比，在100 - 150 mM氯化钠时出现半数最大速率。在所检测的二价阳离子中，铜离子在生理浓度下抑制去 -Arg9-缓激肽的进一步消化。我们的数据表明，激肽的降解速率以及血浆或血清中稳定的最终切割产物的性质（体外研究）取决于氯离子、金属离子的作用以及至少两种激肽酶产生的多种代谢产物的动力学效应。
