兔脑神经肽代谢肽酶的筛选。缓激肽增强肽9a（SQ 20881）对肽链内切酶B的抑制作用。

Screening for rabbit brain neuropeptide-metabolizing peptidases. Inhibition of endopeptidase B by bradykinin potentiating peptide 9a (SQ 20881).

作者信息

Martins A R, Caldo H, Coelho H L, Moreira A C, Antunes-Rodrigues J, Greene L J, Martins de Camargo A C

出版信息

J Neurochem. 1980 Jan;34(1):100-7. doi: 10.1111/j.1471-4159.1980.tb04626.x.

DOI:10.1111/j.1471-4159.1980.tb04626.x

Abstract

Neutral thiol-activated peptidases present in the pH 5-soluble fraction of rabbit brain (separated by step-elution chromatography on diethylaminoethyl cellulose) were screened for the hydrolysis of bradykinin. Lys-bradykinin, Met-Lys-bradykinin, angiotensin I, angiotensin II, substance P, luteinizing hormone-releasing hormone (LH-RH), and neurotensin by bioassay. The column effluent was monitored for bradykinin inactivation and arylamidase activity and combined in six pools on the basis of bradykinin inactivation. The pools were characterized by determining the peptide fragments and amino acids released from bradykinin with an amino acid analyzer. Pools 1 through 3 contained 80% of the kininase activity and essentially all of the endopeptidase A and B activity, whereas pools 4 through 6 accounted for 98% of the recovered arylamidase activity. Bradykinin, angiotensin I, angiotensin II, and substance P were inactivated by all the pools, whereas LH-RH and neurotensin were inactivated by pools 3 and 4, and pools 3, 4, and 5, respectively. These data show that rabbit brain contains peptidases having some selectivity for the inactivation of neuropeptides. Endopeptidase B purified from pool 3 is inhibited by bradykinin-potentiating peptide 9a (BPP9a, SQ 20881) (< Glu-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro), a competitive inhibitor of the hydrolysis of bradykinin (Km = 3.5 X 10(-5) M, Ki = 3 X 10(-6) M) which also completely inhibits the inactivation of LH-RH.

摘要

对存在于兔脑pH 5可溶部分（通过在二乙氨基乙基纤维素上进行分步洗脱色谱分离）中的中性硫醇激活肽酶进行筛选，以检测其对缓激肽的水解作用。通过生物测定法检测赖氨酸缓激肽、甲硫氨酸 - 赖氨酸缓激肽、血管紧张素I、血管紧张素II、P物质、促黄体生成素释放激素（LH - RH）和神经降压素。监测柱流出物中缓激肽的失活和芳基酰胺酶活性，并根据缓激肽失活情况将其合并为六个组分。通过用氨基酸分析仪测定从缓激肽释放的肽片段和氨基酸来表征这些组分。第1至3组分含有80%的激肽酶活性以及基本上所有的内肽酶A和B活性，而第4至6组分占回收的芳基酰胺酶活性的98%。所有组分均使缓激肽、血管紧张素I、血管紧张素II和P物质失活，而LH - RH和神经降压素分别被第3和第4组分以及第3、4和5组分失活。这些数据表明兔脑含有对神经肽失活具有一定选择性的肽酶。从第3组分中纯化的内肽酶B被缓激肽增强肽9a（BPP9a，SQ 20881）（<Glu - Trp - Pro - Arg - Pro - Gln - Ile - Pro - Pro）抑制，BPP9a是缓激肽水解的竞争性抑制剂（Km = 3.5×10(-5) M，Ki = 3×10(-6) M），它也完全抑制LH - RH的失活。