Electrostatic dependence of the thrombin-thrombomodulin interaction
Electrostatic dependence of the thrombin-thrombomodulin interaction
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DOI：
10.1006/jmbi.1999.3447
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发表时间：
2000-02-18
影响因子：
5.6
通讯作者：
Komives, EA
中科院分区：
文献类型：
--
作者：
Baerga-Ortiz, A;Rezaie, AR;Komives, EA
凝血酶与其抗凝辅助因子血栓调节素的完全活性片段之间的结合相互作用的速率常数已经通过表面等离子体共振确定。在生理离子强度下，k(a)为6.7 x 10(6) M-1 s(-1)，解离速率常数为0.033 s（-1）。这些极快的结合和解离速率导致总体结合平衡常数为4.9 nM，这与先前报道的值相似。当离子强度从100 mM改变为250 mM NaCl时，缔合速率降低了10倍，而解离速率没有明显变化。在四甲基氯化铵中也观察到类似的效果。数据的Debye-Huckel图的斜率为-6，在0离子强度下的截距为10(9)M-1 s(-1)：在甘油存在下收集的数据获得了相同的斜率和截距，以减缓缔合速率。这些结果表明，凝血酶- tm456的相互作用非常迅速，几乎完全由静电控制。提出了TM456沿凝血酶分子偶极子方向接近凝血酶的关联模型。(C) 2000年学术出版社。
The rate constants for the binding interaction between thrombin and a fully active fragment of its anticoagulant cofactor, thrombomodulin, have been determined by surface plasmon resonance. At physiological ionic strength, the k(a) was 6.7 x 10(6) M-1 s(-1) and the dissociation rate constant was 0.033 s(-1). These extremely fast association and dissociation rates resulted in an overall binding equilibrium constant of 4.9 nM, which is similar to previously reported values. Changing the ionic strength from 100 mM to 250 mM NaCl caused a tenfold decrease in the association rate while the dissociation rate did not change significantly. A similar effect was observed with tetramethylammonium chloride. A Debye-Huckel plot of the data had a slope of -6 and an intercept at 0 ionic strength of 10(9) M-1 s(-1): The same slope and intercept were obtained for data that was collected in the presence of glycerol to slow the association rates. These results show that the thrombin-TM456 interaction is extremely rapid and nearly completely electrostatically steered. An association model is presented in which TM456 approaches thrombin along the direction of the thrombin molecular dipole. (C) 2000 Academic Press.