UNIQUE ASPECTS OF C1-- INHIBITOR STRUCTURE / FUNCTION

C1-inhibitor是serpin家族的血浆蛋白酶抑制剂。C1抑制剂的生理靶点是补体组分C1活化的C1r和C1s亚基，以及接触体系的酶。c1抑制剂的缺乏，无论是遗传性的还是获得性的，都可能导致血管性水肿，这是一种潜在的致命疾病。尽管c1抑制剂与其他蛇形蛋白有许多共同之处，但它也有一些独特的特性，这些特性尚未得到详细的研究。首先，与其他蛇形蛋白酶相比，它抑制蛋白酶的速度较慢。造成这种情况的结构性原因尚不清楚。首先，我们将证实C1s的抑制作用在其生理形态下是缓慢发生的，作为C1的一部分。然后利用c1抑制剂突变体和c1抑制剂- α - 1蛋白酶抑制剂嵌合体研究其抑制活性的结构基础。c1 -抑制剂具有高度糖基化的110残基氨基末端结构域，与其他蛇形蛋白酶无同源性。该区域的功能将被研究，特别是测试它对C1的快速抑制和随后的解离至关重要的想法。为了测试这一重组c1抑制剂的变体缺失部分或全部氨基末端将被制作。此外，单个半胱氨酸将被引入氨基末端结构域，可以用荧光团标记以评估该区域与C1和目标蛋白酶的相互作用。这些主题将在以下三个目的下进行研究：目的1)确定分离时和在C1复合物中时C1s的抑制率；目的2)确定c1抑制剂抑制活性的结构基础；3)确定c1抑制剂氨基末端结构域的功能。这些研究将提供有关c1抑制剂结构-功能关系的重要信息，这对蛋白质的体内功能，蛋白质的治疗用途以及由自然发生的功能失调变异引起的缺乏状态具有重要意义。

C1-inhibitor is a plasma proteinase inhibitor of the serpin family. The physiological targets for C1-inhibitor are the activated C1r and C1s subunits of complement component C1, and enzymes of the contact system. Deficiency of C1-inhibitor, either hereditary or acquired can cause angioedema, a potentially fatal condition. Although C1-inhibitor has much in common with other serpins, it has some unique characteristics which have not been investigated in detail. Firstly, it inhibits proteinases slowly compared to other serpins. The structural reasons for this are not known. Initially it will be confirmed that C1s inhibition occurs slowly when in its physiological form, as part of C1. Then the structural basis for the inhibitory activity will be studied by use of C1-inhibitor mutants and C1-inhibitor- alpha1-proteinase inhibitor chimeras. C1-inhibitor has a highly glycosylated 110 residue amino-terminal domain which has no homology with other serpins. The function of this region will be investigated, in particular testing the idea that it is essential for rapid inhibition and subsequent dissociation of C1. To test this recombinant C1-inhibitor variants lacking part or all of the amino-terminal will be made. Also single cysteines will be introduced into the amino-terminal domain which can be labeled with fluorophore to assess the interaction of this region with C1 and the target proteinases. These topics will be studied in the following three aims: Aim 1) To determine the rate of C1s inhibition when isolated and when in the C1 complex; Aim 2) To determine the structural basis for the inhibitory activity of C1-inhibitor; and Aim 3) To determine the function of the amino-terminal domain of C1-inhibitor. These studies will provide important information regarding structure-function relationships in C1-inhibitor, which has implications for the in vivo function of the protein, the therapeutic use of the protein, and for the deficiency states caused by naturally occurring dysfunctional variants.