Gan Z R, Li Y, Chen Z, Lewis S D, Shafer J A
Department of Biological Chemistry, Merck Research Laboratories, West Point, Pennsylvania 19486.
J Biol Chem. 1994 Jan 14;269(2):1301-5.
The therapeutically important anticoagulant heparin catalyzes inactivation of thrombin by antithrombin III via formation of an intermediary ternary thrombin-heparin-antithrombin III complex that is subsequently converted to a stable thrombin-antithrombin III complex with the release of heparin. Point mutations at Arg-180, Arg-245, Lys-248, and Lys-252 in thrombin markedly reduced the efficiency of heparin catalysis by decreasing the stability of the ternary intermediate, whereas the inactivation of thrombin by antithrombin alone was not affected by these mutations. These results together with an analysis of the x-ray crystal structure of thrombin yielded a model for the thrombin-heparin interaction, wherein heparin forms salt linkages along a groove in thrombin defined by Lys-252, Lys-248, Arg-245, Arg-89, Arg-98, and Arg-180.
具有治疗重要性的抗凝剂肝素通过抗凝血酶III使凝血酶失活，其机制是形成一个中间三元凝血酶-肝素-抗凝血酶III复合物，该复合物随后转化为稳定的凝血酶-抗凝血酶III复合物并释放出肝素。凝血酶中精氨酸-180、精氨酸-245、赖氨酸-248和赖氨酸-252处的点突变通过降低三元中间体的稳定性显著降低了肝素催化的效率，而单独抗凝血酶使凝血酶失活不受这些突变的影响。这些结果连同对凝血酶X射线晶体结构的分析产生了一个凝血酶-肝素相互作用模型，其中肝素沿着凝血酶中由赖氨酸-252、赖氨酸-248、精氨酸-245、精氨酸-89、精氨酸-98和精氨酸-180所界定的凹槽形成盐键。
