Suenson E, Petersen L C
Biochim Biophys Acta. 1986 Apr 22;870(3):510-9. doi: 10.1016/0167-4838(86)90260-8.
Plasminogen activation catalysed by tissue-type plasminogen activator (t-PA) has been examined in the course of concomitant fibrin formation and degradation. Plasmin generation has been measured by the spectrophotometric method of Petersen et al. (Biochem. J. 225 (1985) 149-158), modified so as to allow for light scattering caused by polymerized fibrin. Glu1-, Lys77- and Val442-plasminogen are activated in the presence of fibrinogen, des A- and des AB-fibrin and the rate of plasmin formation is found to be greatly enhanced by both des A- and des AB-fibrin polymer. Plasmin formation from Glu1- and Lys77-plasminogen yields a sigmoidal curve, whereas a linear increase is obtained with Val442-plasminogen. The rate of plasmin formation from Glu1- and Lys77-plasminogen declines in parallel with decreasing turbidity of the fibrin polymer effector. In order to study the effect of polymerization, this has been inhibited by the synthetic polymerization site analogue Gly-Pro-Arg-Pro, by fibrinogen fragment D1 or by prior methylene blue-dependent photooxidation of the fibrinogen used. Inhibition of polymerization by Gly-Pro-Arg-Pro reduces plasmin generation to the low rate observed in the presence of fibrinogen. Antipolymerization with fragment D1 or photooxidation has the same effect on Glu1-plasminogen activation, but only partially reduces and delays the stimulatory effect on Lys77- and Val442-plasminogen activation. The results suggest that protofibril formation (and probably also gelation) of fibrin following fibrinopeptide release is essential to its stimulatory effect. The gradual increase and subsequent decline in the rate of plasmin formation from Glu1- or Lys77-plasminogen during fibrinolysis may be explained by sequential exposure, modification and destruction of different t-PA and plasminogen binding sites in fibrin polymer.
已在伴随纤维蛋白形成和降解的过程中研究了组织型纤溶酶原激活物（t-PA）催化的纤溶酶原激活作用。纤溶酶的生成已通过彼得森等人的分光光度法（《生物化学杂志》225卷（1985年）149 - 158页）进行测定，并进行了改进，以考虑聚合纤维蛋白引起的光散射。在纤维蛋白原、去A - 和去AB - 纤维蛋白存在的情况下，Glu1 - 、Lys77 - 和Val442 - 纤溶酶原被激活，并且发现去A - 和去AB - 纤维蛋白聚合物都极大地增强了纤溶酶的形成速率。由Glu1 - 和Lys77 - 纤溶酶原形成纤溶酶产生S形曲线，而由Val442 - 纤溶酶原则呈线性增加。由Glu1 - 和Lys77 - 纤溶酶原形成纤溶酶的速率与纤维蛋白聚合物效应物浊度的降低平行下降。为了研究聚合作用的影响，已通过合成聚合位点类似物甘氨酰 - 脯氨酰 - 精氨酰 - 脯氨酸、纤维蛋白原片段D1或通过对所用纤维蛋白原进行预先的亚甲蓝依赖性光氧化来抑制聚合作用。甘氨酰 - 脯氨酰 - 精氨酰 - 脯氨酸对聚合作用的抑制将纤溶酶的生成降低到在纤维蛋白原存在下观察到的低速率。用片段D1进行抗聚合或光氧化对Glu1 - 纤溶酶原激活有相同的作用，但仅部分降低并延迟了对Lys77 - 和Val442 - 纤溶酶原激活的刺激作用。结果表明，纤维蛋白肽释放后纤维蛋白的原纤维形成（可能还有凝胶化）对其刺激作用至关重要。在纤维蛋白溶解过程中，由Glu1 - 或Lys77 - 纤溶酶原形成纤溶酶的速率逐渐增加并随后下降，这可能是由于纤维蛋白聚合物中不同的t-PA和纤溶酶原结合位点的顺序暴露、修饰和破坏所致。
