HUMAN-KIDNEY ENKEPHALINASE, A NEUTRAL METALLOENDOPEPTIDASE THAT CLEAVES ACTIVE PEPTIDES
HUMAN-KIDNEY ENKEPHALINASE, A NEUTRAL METALLOENDOPEPTIDASE THAT CLEAVES ACTIVE PEPTIDES
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DOI：
10.1021/bi00282a035
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发表时间：
1983-01-01
期刊：
影响因子：
2.9
通讯作者：
HERSH, LB
中科院分区：
文献类型：
--
作者：
GAFFORD, JT;SKIDGEL, RA;HERSH, LB
从匀浆的人肾的膜级分中提取转化酶后，用Triton X-100溶解脑啡肽酶活性。离子交换色谱解析了脑啡肽酶活性的2个峰，这两个峰都在Gly 3-Phe 4键处裂解Leu 5-脑啡肽。主要的脑啡肽酶形式纯化1140倍，以14%的产率均匀。该均质脑啡肽酶以Leu 5-脑啡肽为底物时的比活性为46 μ mol min-1 mg-1。纯化的酶，除了水解Leu 5-脑啡肽，裂解合成底物与保护的N-和C-末端。根据酶的特异性和螯合剂对其的抑制作用，人脑啡肽酶可被分类为具有广泛底物特异性的中性金属内肽酶。将具有几种生物活性肽的这种中性内肽酶的活性与均质人肾转化酶的活性进行比较。这两种酶失活缓激肽释放的C-末端二肽，但特异性抑制剂抑制差异。缓激肽与其保护的C端肽水解的比较表明，中性内肽酶对较大底物的水解活性高于转化酶。虽然中性内肽酶不将血管紧张素I转化为II，但它确实在Pro 7-Phe 8处水解血管紧张素I，并通过在Tyr 4-Ile 5键处裂解来水解血管紧张素II。
After extracting converting enzyme from a membrane fraction of homogenized human kidney, enkephalinase activity was solubilized with Triton X-100. Ion-exchange chromatography resolved 2 peaks of the enkephalinase activity, both of which cleaved Leu5-enkephalin at the Gly3-Phe4 bond. The major enkephalinase form was purified 1140-fold to homogeneity with a 14% yield. This homogeneous enkephalinase had a specific activity of 46 .mu.mol min-1 mg-1 with Leu5-enkephalin as substrate. The purified enzyme, in addition to hydrolyzing Leu5-enkephalin, cleaved synthetic substrates with protected N- and C-terminal ends. On the basis of the specificity of the enzyme and its inhibition by chelating agents, human enkephalinase can be classified as a neutral metalloendopeptidase with a broad substrate specificity. The activity of this neutral endopeptidase with several biologically active peptides was compared to that of homogeneous human kidney converting enzyme. Both enzymes inactivated bradykinin by release of the C-terminal dipeptide but were inhibited differentially by specific inhibitors. Comparison of hydrolysis of bradykinin with that of its protected C-terminal peptide indicated that the neutral endopeptidase is more active torward the larger substrate than is converting enzyme. Although the neutral endopeptidase did not convert angiotensin I to II, it did hydrolyze angiotensin I at Pro7-Phe8 and inactivate angiotensin II by cleavage at the Tyr4-Ile5 bond.