STRUCTURE AND FUNCTION OF THROMBOSPONDIN

血小板活化发生在损伤部位，广泛的组织 作为随后伤口愈合的一部分，重塑发生了。已激活 血小板分泌黏附蛋白，参与血小板的形成 细胞外基质，而基质的性质改变了粘附性， 细胞的迁移和增殖。这项建议是基于 蛋白质二硫键异构酶被激活释放的假说 并催化二硫键的异构化，导致 蛋白质构象变化与二硫键形成的关系 蛋白质-蛋白质复合体，从而改变组成和性质 细胞外基质。假设是建立在观察的基础上的 当激活的血小板分泌的物质在37℃孵育时 程度，凝血酶原蛋白显示二硫键异构化，还原 二硫键以及二硫键连接的多聚体和二硫键的形成- 与凝血酶-丝氨酸复合体相连的复合体。其中每一个都是相似的 与蛋白质二硫键异构酶催化的反应有关。初步 实验证实，大豆中存在二硫键异构酶活性。 活化的血小板上清液。更多的实验将 建立二硫键异构酶的特异性，要求 辅因子和酶的近似质量。二硫键异构酶 将被提纯，并将制备抗体。美国政府的角色 二硫键异构酶将通过三种方式进行测试：i)它将被添加到 纯化蛋白质的组合以确定哪种蛋白质成为二硫键 连接的，ii)抗体将用于免疫沉淀二硫化物 从血小板上清液中提取异构酶以确定 反应被抑制，以及iii)细胞黏附、扩散的能力 并在存在或不存在时形成的基质上迁移 二硫键异构酶将被检测。二硫化物生成的具体条件 将确定凝血酶-丝氨酸复合体与凝血酶反应蛋白的连接， 并对凝血酶敏感蛋白的硫醇进行了进一步的表征。

Platelet activation occurs at the sites of injury, where extensive tissue remodeling takes place as part of the subsequent wound healing. Activated platelets secrete adhesive proteins that participate in formation of the extracellular matrix, and the nature of the matrix alters the adhesion, migration and proliferation of cells. This proposal is based on the hypothesis that protein disulfide isomerase is released by activated platelets and catalyzes the isomerization of disulfide bonds, leading to changes in protein conformation and to formation of disulfide-linked protein-protein complexes, thereby modifying the composition and the nature of the extracellular matrix. The hypothesis is based on the observations that when material secreted by activated platelets is incubated at 37 degree, thrombospondin shows isomerization of disulfide bonds, reduction of disulfide bonds, and formation f disulfide-linked multimers and disulfide- linked complexes with thrombin-serpin complexes. Each of these is similar to reactions catalyzed by protein disulfide isomerase. Preliminary experiments confirmed the presence of disulfide isomerase activity in the supernatant solution of activated platelets. Additional experiments will establish the disulfide isomerase specificity, the requirement for cofactors and the approximate mass of the enzyme. The disulfide isomerase will be purified, and antibodies will be prepared. The role of the disulfide isomerase will be tested in three ways: i) it will be added to combinations of purified proteins to determine which become disulfide linked, ii) antibodies will be used to immunoprecipitate the disulfide isomerase from the platelet supernatant solution to determine which reactions are inhibited, and iii) the ability of cells to adhere, spread and migrate on the matrix formed in the presence or absence of the disulfide isomerase will be tested. The specific conditions for disulfide linking of thrombin-serpin complexes to thrombospondin will be determined, and the thiols of thrombospondin will be characterized further.