人α-间胰蛋白酶抑制剂。胰蛋白酶、纤溶酶、激肽释放酶和粒细胞弹性蛋白酶的有限蛋白水解作用及裂解产物的抑制特性。
Human inter-alpha-trypsin inhibitor. Limited proteolysis by trypsin, plasmin, kallikrein and granulocytic elastase and inhibitory properties of the cleavage products.
作者信息
Dietl T, Dobrinski W, Hochstrasser K
出版信息
Hoppe Seylers Z Physiol Chem. 1979 Sep;360(9):1313-8. doi: 10.1515/bchm2.1979.360.2.1313.
The acid-labile inter-alpha-trypsin inhibitor is cleaved enzymatically in vivo, liberating a smaller acid-stable inhibitor. The molar ratio of native inhibitor to this smaller inhibitor in plasma is significantly changed in some severe cases of inflammation and kidney injury. To clarify this observation on a molecular basis, the action of four different types of proteinases (trypsin, plasmin, kallikrein and granulocyte elastase) on the inter-alpha-trypsin inhibitor was studied. The initial rate of cleavage of the inter-alpha-trypsin inhibitor by a 1.3-fold molar excess of proteinase over inhibitor was found to be 4375 nM x min-1 with granulocyte elastase, 860 nM x min-1 with trypsin, 67 nM x min-1 with plasmin, and 0.3 nM X min-1 with kallikrein. Obviously, of the enzymes studied so far, the granulocyte elastase known to be released during severe inflammatory processes is by far the most potent proteinase in the transformation of the inter-alpha-trypsin inhibitor. The inter-alpha-trypsin inhibitor and its cleavage products inhibit bovine trypsin very strongly (Ki = 10(-9)--10(-11) M), porcine plasmin much less strongly, human plasmin very weakly and pancreatic kallikrein practically not at all.
酸不稳定的α-间胰蛋白酶抑制剂在体内被酶切，释放出一种较小的酸稳定抑制剂。在一些严重的炎症和肾损伤病例中，血浆中天然抑制剂与这种较小抑制剂的摩尔比发生了显著变化。为了从分子层面阐明这一现象，研究了四种不同类型的蛋白酶（胰蛋白酶、纤溶酶、激肽释放酶和粒细胞弹性蛋白酶）对α-间胰蛋白酶抑制剂的作用。当蛋白酶与抑制剂的摩尔比过量1.3倍时，粒细胞弹性蛋白酶对α-间胰蛋白酶抑制剂的初始切割速率为4375 nM·min⁻¹，胰蛋白酶为860 nM·min⁻¹，纤溶酶为67 nM·min⁻¹，激肽释放酶为0.3 nM·min⁻¹。显然，在目前所研究的酶中，已知在严重炎症过程中释放的粒细胞弹性蛋白酶是α-间胰蛋白酶抑制剂转化过程中最有效的蛋白酶。α-间胰蛋白酶抑制剂及其切割产物对牛胰蛋白酶有很强的抑制作用（Ki = 10⁻⁹ - 10⁻¹¹ M），对猪纤溶酶的抑制作用较弱，对人纤溶酶的抑制作用非常弱，对胰激肽释放酶几乎没有抑制作用。
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