COMPARATIVE ENZYMATIC STUDIES OF HUMAN RENIN ACTING ON PURE NATURAL OR SYNTHETIC SUBSTRATES
COMPARATIVE ENZYMATIC STUDIES OF HUMAN RENIN ACTING ON PURE NATURAL OR SYNTHETIC SUBSTRATES
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DOI：
10.1016/0167-4838(87)90226-3
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发表时间：
1987-05-27
期刊：
影响因子：
--
通讯作者：
CORVOL, P
中科院分区：
文献类型：
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作者：
CUMIN, F;LENGUYEN, D;CORVOL, P
研究了纯人肾素作用于纯人和大鼠血管紧张素原及其合成的十四肽底物的一些基本结构要求。人工合成的十四肽的5个羧基末端氨基酸在底物识别和/或人肾素的水解中起着重要的作用。不同的人肾素测定的动力学常数Km、kcat和kcat/Km因底物的不同而不同。S4‘’肾素亚基上天冬酰胺或苏氨酸残基的存在对动力学常数值没有显著影响。S3‘’肾素亚基上的酪氨酸残基而不是组氨酸残基是所研究的最好的合成底物。当S2‘’肾素亚基中存在酪氨酸残基时，观察到kcat显著降低。人血管紧张素原被人肾素水解值低于人和猪合成底物测得的Km和kcat值，表明人血管紧张素原的三维结构在水解度中起关键作用。这一发现得到了用大鼠血管紧张素原进行的分析的支持，人肾素以与大鼠十四肽相同的kcat值切割血管紧张素原，但Km降低了49倍。在使用人类底物的肾素测定中，人和大鼠血管紧张素原之间的kcat/Km值仅高出2倍。
Some of the essential structural requirements for the enzymatic reaction of pure human renin acting on pure human and rat angiotensinogen and on their synthetic tetradecapeptide substrates were investigated. The five carboxy terminal amino acids of synthetic tetradecapeptides played a significant role in substrate recognition and/or hydrolysis by human renin. Kinetic constants Km, kcat and kcat/Km of the various human renin assays were different according to the substrate used. The presence of either an asparagine or a threonine residue in the S4'' renin subsite did not affect significantly the kinetic constant values. A tyrosine residue, rather than a histidine residue, in the S3'' renin subsite gave the best synthetic substrate studied. When tyrosine residue was present in the S2'' renin subsite an important decrease in kcat was observed. Human angiotensinogen was hydrolysed by human renin with lower Km and kcat values than those measured with human and porcine synthetic substrates, suggesting that the 3-dimensional structure of human angiotensinogen plays a key role in the hydrolysis. This finding was supported by assays performed with rat angiotensinogen, which was cleaved by human renin with the same kcat value as rat tetradecapeptide, but with a 49-fold lower Km. Between human and rat angiotensinogen a kcat/Km value of only 2-fold higher has been found in the renin assay using human substrate.