Horie Shuichi, Hiraishi Sayuri, Hamuro Tsutomu, Kamikubo Yu-ichi, Matsuda Juzo
Department of Clinical Biochemistry, Faculty of Pharmaceutical Sciences, Teikyo University, Tsukui, Kanagawa, Japan.
Thromb Haemost. 2002 Jan;87(1):80-5.
Tissue factor pathway inhibitor (TFPI) is a physiological protease inhibitor of the extrinsic blood coagulation pathway. Previously we have shown that TFPI associates quite rapidly with oxidized low-density lipoprotein (ox-LDL), with a reduction of the inhibitory activity on factor X activation. In the present study, it was found, by means of agarose gel electrophoresis, that the pre-incubation of full-length rTFPI with heparin or the carboxy (C)-terminal part (peptide 240-265) of TFPI prevented the association with ox-LDL in a dose-dependent manner. When rTFPI lacking the C-terminal basic part of the molecule (rTFPI-C) was mixed with ox-LDL, only a small amount of rTFPI-C was shifted to the position of ox-LDL on electrophoresis. Further, ox-LDL did not reduce the activity of rTFPI-C. These results indicate that the C-terminal domain of TFPI molecule plays a predominant role in the binding to ox-LDL and the binding through the C-terminal part is essential for the ox-LDL-dependent reduction of the anticoagulant activity of TFPI.
组织因子途径抑制物（TFPI）是外源性血液凝固途径的一种生理性蛋白酶抑制剂。此前我们已表明，TFPI与氧化型低密度脂蛋白（ox-LDL）的结合相当迅速，同时其对因子X激活的抑制活性降低。在本研究中，通过琼脂糖凝胶电泳发现，全长重组TFPI（rTFPI）与肝素或TFPI的羧基（C）末端部分（肽段240 - 265）预孵育后，可剂量依赖性地阻止其与ox-LDL的结合。当缺少分子C末端碱性部分的rTFPI（rTFPI-C）与ox-LDL混合时，电泳时只有少量rTFPI-C迁移至ox-LDL的位置。此外，ox-LDL并未降低rTFPI-C的活性。这些结果表明，TFPI分子的C末端结构域在与ox-LDL的结合中起主要作用，且通过C末端部分的结合对于ox-LDL依赖性降低TFPI的抗凝活性至关重要。
