Experimental Studies on Fibrin Polymerization and Intrinsic Fibrinolysis

对于血凝块的产生至关重要的是，由于凝血酶从α和β链的氨基末端切割肽，纤维蛋白原转化为纤维蛋白。然而，纤维蛋白形成的完整机制解释所需的细节，包括聚合位点尚未澄清，直到现在，在这个项目中，我们研究了利用合成肽的β链的氨基末端的纤维蛋白聚合位点的表征。发现合成肽Gly-His-Arg-Pro-amide（对应于β链的氨基末端）与片段D1的结合取决于钙离子的浓度，在10 μ M时最大<-4>，在室温下在其两侧降低。与此相反，钙离子对结合的影响是不同的，当检查使用片段D1琼脂糖凝胶柱处理与唾液酸酶。这些结果强调了钙结合位点和肽结合位点在碳水化合物附着的β链的羧基末端的紧密接近。此外，我们还发现合成肽Gly-His-Arg对D1片段的γ链残基有轻微的保护作用，其作用方式与钙离子相同，说明β链氨基端的结合位点之一位于β链的羧基端，另一个位于γ链的羧基端。

It is essential for blood clot generation that fibrinogen is converted into fibrin as a result of thrombin cleaving peptides from the amino-terminal ends of the alpha and beta chains. However, the details required for a full mechanistic explanation of the fibrin formation including the polymerization sites has not been clarified until now.In this project, we investigated the characterization of the fibrin polymerization site in the amino-terminus of the beta chain utilizing synthetic peptides. The binding of the synthetic peptide, Gly-His-Arg-Pro-amide, which corresponds to the amino-terminus of the beta chain, to fragment D1 was found to depend on the concentration of calcium ions, being maximal at 10^<-4>M and decreasing on either side of this at room temperature. In contrast, the effect of calcium ions on the binding was different when examined using a fragment D1 sepharose column treated with sialidase. These results emphasize the close proximity of the calcium-binding and peptide-binding sites in the calboxy-terminus of beta chain to which the carbohydrate attaches. Furthermore, we found the synthetic peptide Gly-His-Arg to have a slight protective effect on the gamma chain remnant of fragment D1 against plasmin in the same fashion as calcium ions.These date indicate that one of the binding sites of the amino-terminal ends of beta chain is located in the carboxy-terminus of beta chain and the other is located in the carboxy-terminus of gamma chain.