Palladino L O, Tung J S, Dunwiddie C, Alves K, Lenny A B, Przysiecki C, Lehman D, Nutt E, Cuca G C, Law S W
Department of Cellular and Molecular Biology, Merck Sharp & Dohme Research Laboratories, Rahway, New Jersey 07065.
Protein Expr Purif. 1991 Feb;2(1):37-42. doi: 10.1016/1046-5928(91)90007-6.
Antistasin, a 15-kDa anticoagulant protein isolated from the salivary glands of the Mexican leech Haementeria officinalis, has been shown to be a potent inhibitor of factor Xa in the blood coagulation cascade. Antistasin possesses a twofold internal homology between the N- and C-terminal halves of the molecule, suggesting a gene duplication event in the evolution of the antistasin gene. This structural feature also suggests that either or both halves of the protein may possess biological activity if expressed as separate domains. Because the N-terminal domain contains a factor Xa P1-reactive site, we chose to express this domain in an insect cell baculovirus expression system. Characterization of this recombinant half antistasin molecule reveals that the N-terminal domain inhibits factor Xa in vitro, with a K(i) of 1.7 nM.
抗凝血酶原酶是从墨西哥水蛭药用南美山蛭唾液腺中分离出的一种15千道尔顿的抗凝血蛋白，已被证明是血液凝固级联反应中Xa因子的有效抑制剂。抗凝血酶原酶分子的N端和C端之间具有双重内部同源性，这表明抗凝血酶原酶基因在进化过程中发生了基因复制事件。这种结构特征还表明，如果该蛋白的任一半或两半都作为单独的结构域表达，可能都具有生物活性。由于N端结构域包含一个Xa因子P1反应位点，我们选择在昆虫细胞杆状病毒表达系统中表达该结构域。对这种重组半抗凝血酶原酶分子的表征显示，N端结构域在体外可抑制Xa因子，抑制常数（K(i)）为1.7纳摩尔。
