A Synthetic Analog of Fibrinogen α27–50 Is an Inhibitor of Thrombin
A Synthetic Analog of Fibrinogen α27–50 Is an Inhibitor of Thrombin
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DOI：
10.1055/s-0038-1647477
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发表时间：
1991-02
影响因子：
6.7
通讯作者：
C. Binnie;S. Lord
中科院分区：
文献类型：
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作者：
C. Binnie;S. Lord
通过抑制实验和亲和层析研究了合成的纤维蛋白原α27-50类似物AAKDSDWPEASDEDWNYKAPSGAR与凝血酶的结合。肽α27-50对应凝血酶裂解位点下游的一段人纤维蛋白原，28、36、45和49位的半胱氨酸残基被丙氨酸取代。该肽抑制纤维蛋白原凝血，抑制常数为190 ~ 400 μM。该肽可抑制纤维蛋白肽A和B的裂解，并可与纤维蛋白原竞争凝血酶。没有观察到对小底物toyl - gly - proarg -p- nitro苯胺的抑制作用，这表明该肽没有阻断酶的活性位点。与Sepharose结合活性位点共价连接的肽α27-50在低离子强度下抑制凝血酶，并在高盐浓度下洗脱。反相高效液相色谱法测定，肽暴露于凝血酶过夜后未被裂解。综上所述，肽结合，但不是凝血酶的底物。这些结果表明该纤维蛋白原区域参与凝血酶的结合。
Summary Binding of the synthetic peptide AAKDSDWPEASDEDWNYKAPSGAR, a fibrinogen α27–50 analog, to thrombin was studied by inhibition assays and affinity chromatography. Peptide α27–50 corresponds to a segment of human fibrinogen downstream from the thrombin cleavage site, with cysteine residues at positions 28, 36, 45 and 49 replaced by alanine. The peptide inhibited clotting of fibrinogen with an inhibition constant of 190–400 μM. Cleavage of fibrinopeptides A and B was inhibited by the peptide and the peptide was competitive with fibrinogen for thrombin. Inhibition of the small substrate tosyl-Gly-Pro-Arg-p-nitroaniline was not observed indicating that the peptide did not block the active site of the enzyme. Peptide α27–50 that was covalently linked to Sepharose bound active siteinhibited thrombin at low ionic strength and was eluted at higher salt concentration. The peptide was not cleaved on overnight exposure to thrombin as determined by reverse phase HPLC. In summary, the peptide bound to, but was not a substrate for thrombin. These results suggest that this region of fibrinogen contributes to binding of thrombin.