Kaiser B, Jeske W, Hoppensteadt D, Fareed J
Loyola University Medical Center, Department of Pathology, Maywood, IL.
Thromb Res. 1994 Dec 15;76(6):561-8. doi: 10.1016/0049-3848(94)90285-2.
Using a fast kinetic centrifugal analyzer, the inhibitory effects of glycosylated and unglycosylated full-length and truncated forms of TFPI on protease generation were studied in fibrinogen-deficient human plasma after extrinsic (EA) or intrinsic (IA) activation of coagulation. When the assay system was supplemented with increasing amounts of the TFPI variants the generation of both thrombin and factor Xa was inhibited in a concentration-dependent manner. Clear differences in the effectiveness of the TFPI variants were found. After EA, the unglycosylated full-length TFPI was most effective followed by the glycosylated full-length form. The C-terminal truncated TFPI showed the lowest inhibitory activity in this system. However, its efficiency increased several fold when coagulation was activated via the intrinsic pathway. Comparing the IC50 values after IA, the truncated TFPI was more effective than the unglycosylated full-length form and nearly as effective as the glycosylated full-length TFPI. After both EA and IA the thrombin generation inhibition by TFPI variants was more pronounced than the inhibition of factor Xa generation. The results show that chemical modifications of the TFPI structure can result in changes of TFPI's inhibitory properties to activated clotting factors leading to differences in protease generation inhibition.
使用快速动力学离心分析仪，在凝血因子缺乏的人血浆中，通过外源性（EA）或内源性（IA）凝血激活后，研究了糖基化和非糖基化的全长及截短形式的组织因子途径抑制物（TFPI）对蛋白酶生成的抑制作用。当检测系统中添加越来越多的TFPI变体时，凝血酶和因子Xa的生成均以浓度依赖性方式受到抑制。发现TFPI变体的有效性存在明显差异。外源性激活后，非糖基化的全长TFPI最有效，其次是糖基化的全长形式。C末端截短的TFPI在该系统中显示出最低的抑制活性。然而，当通过内源性途径激活凝血时，其效率提高了几倍。比较内源性激活后的IC50值，截短的TFPI比非糖基化的全长形式更有效，几乎与糖基化的全长TFPI一样有效。外源性和内源性激活后，TFPI变体对凝血酶生成的抑制作用比对因子Xa生成的抑制作用更明显。结果表明，TFPI结构的化学修饰可导致TFPI对活化凝血因子的抑制特性发生变化，从而导致蛋白酶生成抑制的差异。
