The protease specificity of heparin cofactor II. Inhibition of thrombin generated during coagulation.
The protease specificity of heparin cofactor II. Inhibition of thrombin generated during coagulation.
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发表时间：
1985-03
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通讯作者：
K. A. Parker;D. Tollefsen
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作者：
K. A. Parker;D. Tollefsen
将 125I 标记的肝素辅因子 II (HCII) 与血浆混合，并通过添加 CaCl2、磷脂和高岭土或组织因子引发凝血。在 67 微克/ml 硫酸皮肤素存在下，在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳上检测到对应于凝血酶-HCII 复合物 (Mr = 96,000) 的条带中的放射性。没有观察到其他复合物。当存在 5 单位/ml 肝素或使用缺乏凝血酶原的血浆时，无法检测到凝血酶-HCII 复合物。在使用纯化蛋白酶的实验中，HCII 不会显着抑制凝血因子 VIIa、IXa、Xa、XIa、XIIa、激肽释放酶、活化蛋白 C、纤溶酶、尿激酶、组织纤溶酶原激活剂、白细胞弹性蛋白酶、神经生长因子的 γ 亚基和表皮生长因子结合蛋白。在硫酸皮肤素存在下，HCII 缓慢抑制白细胞组织蛋白酶 G，速率常数为 8 X 10(4) M-1 min-1。这些结果表明，HCII 的蛋白酶特异性比其他血浆蛋白酶抑制剂更受限制，并表明硫酸皮肤素的抗凝作用完全是由于 HCII 对凝血酶的抑制。
125I-labeled heparin cofactor II (HCII) was mixed with plasma and coagulation was initiated by addition of CaCl2, phospholipids, and kaolin or tissue factor. In the presence of 67 micrograms/ml of dermatan sulfate, radioactivity was detected in a band which corresponded to the thrombin-HCII complex (Mr = 96,000) upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. No other complexes were observed. The thrombin-HCII complex was undetectable when 5 units/ml of heparin was present or when prothrombin-deficient plasma was used. In experiments with purified proteases, HCII did not significantly inhibit coagulation factors VIIa, IXa, Xa, XIa, XIIa, kallikrein, activated protein C, plasmin, urokinase, tissue plasminogen activator, leukocyte elastase, the gamma-subunit of nerve growth factor, and the epidermal growth factor-binding protein. HCII inhibited leukocyte cathepsin G slowly, with a rate constant of 8 X 10(4) M-1 min-1 in the presence of dermatan sulfate. These results indicate that the protease specificity of HCII is more restricted than that of other plasma protease inhibitors and suggest that the anticoagulant effect of dermatan sulfate is due solely to inhibition of thrombin by HCII.