Takada A, Takada Y, Sugawara Y
Department of Physiology, Hamamatsu University, School of Medicine, Shizuoka, Japan.
Haemostasis. 1988;18(2):106-12. doi: 10.1159/000215790.
Equimolar concentrations of Lys-plasminogen (Lys-PLG) and streptokinase (SK) were mixed with various concentrations of fibrin, fibrinogen, fragment D or E (potentiating agents). The activity of the mixture was measured by the hydrolysis of S-2251. Kinetic analyses indicated that catalytic rate constant (kcat) of the hydrolysis of S-2251 increased in the presence of increasing amounts of potentiating agents. Km did not change in their presence. Effectiveness of the enhancement of the hydrolysis of S-2251 was in the order of fibrin greater than fibrinogen greater than E greater than D. It could be concluded that a complex of SK, Lys-PLG and potentiating agent is a better enzyme, thus activator, than a complex of SK and Lys-PLG. Since Lys-PLG does not change its conformation and its activation rate upon interaction with fibrin, the enhanced activator activity of complex of SK, Lys-PLG and potentiating agent may not be due to the conformational change of Lys-PLG.
将等摩尔浓度的赖氨酸纤溶酶原（Lys-PLG）和链激酶（SK）与不同浓度的纤维蛋白、纤维蛋白原、D片段或E片段（增强剂）混合。通过S-2251的水解来测定混合物的活性。动力学分析表明，在存在越来越多增强剂的情况下，S-2251水解的催化速率常数（kcat）增加。Km在它们存在时没有变化。增强S-2251水解的有效性顺序为纤维蛋白大于纤维蛋白原大于E大于D。可以得出结论，SK、Lys-PLG和增强剂的复合物是比SK和Lys-PLG的复合物更好的酶，因此是激活剂。由于Lys-PLG在与纤维蛋白相互作用时不会改变其构象和激活速率，SK、Lys-PLG和增强剂复合物增强的激活剂活性可能不是由于Lys-PLG的构象变化。
