The Polymerization Of Fibrin And The Clearance Of Fibrinopeptide B By Thrombin
The Polymerization Of Fibrin And The Clearance Of Fibrinopeptide B By Thrombin
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纤维蛋白的聚合和凝血酶对纤维蛋白肽B的清除
DOI：
10.1055/s-0038-1652517
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发表时间：
1981
影响因子：
6.7
通讯作者：
Robert E. Canfield
中科院分区：
文献类型：
--
作者：
James A. Koehn;A. Hurlet‐Jensen;Hymie L. Nossel;Robert E. Canfield
凝血酶裂解纤维蛋白原释放纤维蛋白肽A（FPA）和纤维蛋白肽B（FP B），分别形成纤维蛋白I和纤维蛋白II。最初FPA比FPB裂解更快，但后来FPB裂解速率增加，与FPA相似。在1.65 μ M纤维蛋白原浓度、0.02U凝血酶/ml、pH7.4、0.15M NaCl、37 ℃下进行研究。初始FPB裂解速率为7 pmol/min，然后增加到70 pmol/min。裂解的加速速率与纤维蛋白聚合相关，如光散射和吸光度测量所示。合成的四肽Gly-Pro-Arg-Pro可抑制纤维素聚合。在四肽的浓度为23 mM（1400倍的摩尔比，纤维蛋白原）没有检测到的聚合发生超过180分钟。在这个四肽浓度的FPA裂解率是不变的，从没有发生四肽，但FPB裂解的速度没有显示出通常与聚合相关的加速，虽然几乎所有的FPB裂解。然后比较FPB从纤维蛋白I聚合物和单体的裂解速率。纤维蛋白原I聚合物通过用立止血处理纤维蛋白原来制备，纤维蛋白I单体通过在过量四肽存在下的类似处理来制备。当凝血酶加入纤维蛋白原时，单体的裂解速率与初始缓慢裂解速率相似。从聚合物的裂解速率比从单体的裂解速率快25倍。这些数据表明凝血酶缓慢但完全地从纤维蛋白I单体裂解FPB，并且从聚合物裂解FPB的速度快至少25倍。数据未确定凝血酶从纤维蛋白原切割FPB。
Thrombin cleaves fibrinogen to release fibrinopeptide A (FPA) and B (FPB) to form fibrin I and II respectively. Initially FPA is cleaved more rapidly than FPB but later the FPB cleavage rate increases and is similar to that of FPA. Studies were made at 1.65 μM fibrinogen concentration, 0.02U thrombin/ml, pH 7.4, 0.15M NaCl, 37°. The initial FPB cleavage rate was 7 pmol/min and then increased to 70 pmol/min. The accelerated rate of cleavage was associated with fibrin polymerization as indicated by light scattering and absorbance measurements. Fibrin polymerization was inhibited by the synthetic tetrapeptide Gly-Pro-Arg-Pro. At a concentration of tetrapeptide of 23mM (1400 fold molar ratio to fibrinogen) no detectable polymerization occurred over 180 min. At this tetrapeptide concentration the FPA cleavage rate was unaltered from that occurring without tetrapeptide but the rate of FPB cleavage did not show the acceleration normally associated with polymerization although virtually all the FPB was cleaved. The cleavage rates of FPB from fibrin I polymer and monomer were then compared. Fibrin I polymer was prepared by treating fibrinogen with reptilase and fibrin I monomer by similar treatment in the presence of excess tetrapeptide. The cleavage rate from monomer was similar to the initial slow cleavage rate when thrombin was added to fibrinogen. The cleavage rate from polymer was 25 fold more rapid than that from monomer. These data indicate that thrombin cleaves FPB slowly but completely from fibrin I monomer and at least 25-fold more rapidly from polymer. The data do not establish that thrombin cleaves FPB from fibrinogen.