Caspase-1 (interleukin-1β-converting enzyme) is inhibited by the human serpin analogue proteinase inhibitor 9
Caspase-1 (interleukin-1β-converting enzyme) is inhibited by the human serpin analogue proteinase inhibitor 9
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DOI：
10.1042/0264-6021:3420655
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发表时间：
1999-09-15
影响因子：
4.1
通讯作者：
Giegel, DA
中科院分区：
文献类型：
--
作者：
Annand, RR;Dahlen, JR;Giegel, DA
半胱氨酸天冬氨酸蛋白酶，半胱氨酸蛋白酶，切割其底物后，天冬氨酸残基的调节，是知之甚少，即使他们参与了严格调控的细胞过程。最近发现的丝氨酸蛋白酶抑制剂类似物蛋白酶抑制剂9（PI 9）是人类丝氨酸蛋白酶抑制剂类似物中的独特之处在于，它在反应位点环的推定特异性决定位置具有酸性残基。我们测量了PI 9抑制几种半胱天冬酶的酰胺分解活性的能力。半胱天冬酶-1对多肽底物的水解（白细胞介素-1 β-转化酶）、半胱天冬酶-4和半胱天冬酶-8被PI 9以时间依赖性方式抑制;半胱天冬酶-1与PI 9的反应速率以及初始半胱天冬酶-PI 9复合物的底物水解速率显示出对PI 9浓度的双曲线依赖性，表明抑制的两步动力学机制，表观二级速率常数为7 × 10（2）M-1 s（-1）。3不被PI 9抑制。caspase-1和caspase-4与PI 9的复合物可以被免疫沉淀，但不能检测到与caspase-3的复合物。如果半胱天冬酶的活性位点被共价抑制剂阻断，则没有复合物可以被免疫沉淀。这些结果表明，PI 9是胱天蛋白酶-1的抑制剂，并且在较小程度上是胱天蛋白酶-4和胱天蛋白酶-8的抑制剂，但不是更远相关的胱天蛋白酶-3的抑制剂。PI 9是抑制这类半胱氨酸蛋白酶成员的人丝氨酸蛋白酶抑制剂类似物的第一个例子。
The regulation of caspases, cysteine proteinases that cleave their substrates after aspartic residues, is poorly understood, even though they are involved in tightly regulated cellular processes. The recently discovered serpin analogue proteinase inhibitor 9 (PI9) is unique among human serpin analogues in that it has an acidic residue in the putative specificity-determining position of the reactive-site loop. We measured the ability of PI9 to inhibit the amidolytic activity of several caspases. The hydrolysis of peptide:substrates by caspase-1 (interleukin-1 beta-converting enzyme), caspase-4 and caspase-8 is inhibited by PI9 in a time-dependent manner; The rate of reaction of caspase-1 with PI9, as well as the rate of Substrate hydrolysis of the initial caspase-PI9 complex, shows a hyperbolic dependence on the concentration of PI9, indicative of a two-step kinetic mechanism for inhibition with an apparent second-order rate constant of 7 x 10(2) M-1 s(-1) The hydrolysis of a tetrapeptide substrate by caspase-3 is not inhibited by PI9. The complexes of caspase-1 and caspase-4 with PI9 can be immunoprecipitated but no complex with caspase-3 can be detected. No complex can be immunoprecipitated if the active site of the caspase is blocked with a covalent inhibitor. These results show that PI9 is an inhibitor of caspase-1 and to a smaller extent caspase-4 and caspase-8, but not of the more distantly related caspase-3. PI9 is the first example of a human serpin analogue that inhibits members of this class of cysteine proteinases.