Cain D, Hutson S M, Wallin R
Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
Thromb Haemost. 1998 Jul;80(1):128-33.
Warfarin, the most used drug in the world in long-term anticoagulation prophylaxis, targets the vitamin K 2,3-epoxide reductase (VKOR) of the vitamin K cycle in liver. Recently, the enzyme has been identified as a multicomponent lipid-protein enzyme system in the endoplasmic reticulum (ER) membrane (17). As the first step towards understanding genetic resistance to warfarin, we present in this paper data on VKOR from normal and a strain of warfarin resistant laboratory rats maintained in the United States. Metal induced in vitro assembly of the enzyme complex demonstrates that the glutathione-S-transferase (GST) enzyme component of the complex loses its GST activity upon formation of VKOR. Less VKOR activity is measured upon assembly of the complex from warfarin resistant rats. The GST activity measured in warfarin resistant rats, before assembly of the complex, is 10-fold less sensitive to warfarin inhibition than the GST activity measured in normal rats. Microsomal epoxide hydrolase (mEH) is the second component of VKOR. When incubated with the components of VKOR before assembly of the complex, antibodies raised against mEH prevented formation of the enzyme complex. Sequencing of mEH cDNAs from normal and warfarin resistant rats revealed identical sequences. The data suggest that the mutation responsible for genetic warfarin resistance is associated with the GST component of VKOR.
华法林是世界上长期用于抗凝预防的最常用药物，其作用靶点是肝脏中维生素K循环的维生素K 2,3 - 环氧化物还原酶（VKOR）。最近，该酶已被鉴定为内质网（ER）膜中的一种多组分脂质 - 蛋白质酶系统（17）。作为理解对华法林遗传抗性的第一步，我们在本文中展示了来自美国饲养的正常大鼠和一种对华法林耐药的实验大鼠品系的VKOR数据。金属诱导的酶复合物体外组装表明，复合物中的谷胱甘肽 - S - 转移酶（GST）酶成分在VKOR形成时失去其GST活性。从对华法林耐药的大鼠组装复合物时，测得的VKOR活性较低。在复合物组装前，对华法林耐药的大鼠中测得的GST活性对华法林抑制的敏感性比正常大鼠中测得的GST活性低10倍。微粒体环氧化物水解酶（mEH）是VKOR的第二个成分。在复合物组装前，当与VKOR的成分一起孵育时，针对mEH产生的抗体可阻止酶复合物的形成。对正常大鼠和对华法林耐药的大鼠的mEH cDNA进行测序，结果显示序列相同。数据表明，导致对华法林遗传抗性的突变与VKOR的GST成分有关。
