CATALYTIC PROPERTIES OF THE 2 ACTIVE-SITES OF ANGIOTENSIN-I-CONVERTING ENZYME ON THE CELL-SURFACE
CATALYTIC PROPERTIES OF THE 2 ACTIVE-SITES OF ANGIOTENSIN-I-CONVERTING ENZYME ON THE CELL-SURFACE
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DOI：
10.1006/bbrc.1995.1845
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发表时间：
1995-06-15
影响因子：
3.1
通讯作者：
ALHENCGELAS, F
中科院分区：
文献类型：
--
作者：
JASPARD, E;ALHENCGELAS, F
血管紧张素 I 转换酶是一种锌金属肽酶，包含两个非常相似的结构域，每个结构域都有一个活性位点。尽管血管紧张素 I 转换酶是一种跨膜外肽酶，但这些活性位点的酶学研究始终是在溶解的酶上进行的。表达野生型重组酶和突变体（其中两个活性位点之一已通过定点诱变失活）的转染 CHO 细胞的可用性允许研究细胞表面上每个活性位点的特性以及锚定和膜环境的影响。两个活性中心在细胞膜锚定酶中均具有催化活性，并将血管紧张素 I 转化为血管紧张素 II。转染细胞的动力学参数与纯化酶的动力学参数的比较揭示了 Kcat 的差异，但表明在酶锚定到细胞膜上时这些活性位点没有发生主要的构象变化。氯离子活化曲线表明，细胞结合酶中的两个结构域也经历与溶解酶中相同的阴离子诱导的构象变化。 (C) 1995 学术出版社
Angiotensin I converting enzyme is a zinc metallopeptidase that contains two very similar domains, each with an active site. Enzymatic studies of these active sites have always been performed on solubilized enzyme, although angiotensin I converting enzyme is a transmembrane ectopeptidase. The availability of transfected CHO cells expressing wild-type recombinant enzyme and mutants in which one of the two active sites has been inactivated by site-directed mutagenesis allowed the properties of each active site on the cell surface and the effect of anchorage and membrane environnement to be studied. Both active centers are catalytically active in the cell membrane-anchored enzyme and convert angiotensin I to angiotensin II. Comparison of the kinetic parameters for the transfected cells with those for the purified enzymes reveals differences in Kcat but suggests that no major conformational changes of these active sites occur upon anchorage of the enzyme to the cell membrane. The chloride activation profiles show that the two domains in the cell-bound enzyme also undergo the same anion-induced conformational changes as in the solubilized enzyme. (C) 1995 Academic Press Inc.