Al-Horani Rami A, Gailani David, Desai Umesh R
Department of Medicinal Chemistry and Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, VA 23219, United States.
Departments of Pathology, Immunology and Microbiology, Vanderbilt University Medical Center, Nashville, TN 37203, United States.
Thromb Res. 2015 Aug;136(2):379-87. doi: 10.1016/j.thromres.2015.04.017. Epub 2015 Apr 22.
Recent development of sulfated non-saccharide glycosaminoglycan mimetics, especially sulfated pentagalloyl glucopyranoside (SPGG), as potent inhibitors of factor XIa (FXIa) (J. Med. Chem. 2013; 56:867-878 and J. Med. Chem. 2014; 57:4805-4818) has led to a strong possibility of developing a new line of factor XIa-based anticoagulants. In fact, SPGG represents the first synthetic, small molecule inhibitor that appears to bind in site remote from the active site. Considering that allosteric inhibition of FXIa is a new mechanism for developing a distinct line of anticoagulants, we have studied SPGG's interaction with FXIa with a goal of evaluating its pre-clinical relevance. Comparative inhibition studies with several glycosaminoglycans revealed the importance of SPGG's non-saccharide backbone. SPGG did not affect the activity of plasma kallikrein, activated protein C and factor XIIIa suggesting that SPGG-based anticoagulation is unlikely to affect other pathways connected with coagulation factors. SPGG's effect on APTT of citrated human plasma was also not dependent on antithrombin or heparin cofactor II. Interestingly, SPGG's anticoagulant potential was diminished by serum albumin as well as factor XI, while it could be reversed by protamine or polybrene, which implies possible avenues for developing antidote strategy. Studies with FXIa mutants indicated that SPGG engages Lys529, Arg530 and Arg532, but not Arg250, Lys252, Lys253 and Lys255. Finally, SPGG competes with unfractionated heparin, but not with polyphosphates and/or glycoprotein Ibα, for binding to FXIa. These studies enhance understanding on the first allosteric inhibitor of FXIa and highlight its value as a promising anticoagulant.
硫酸化非糖糖胺聚糖模拟物，尤其是硫酸化五倍子酰葡萄糖苷（SPGG）作为凝血因子XIa（FXIa）的有效抑制剂的最新进展（《药物化学杂志》2013年；56:867 - 878以及《药物化学杂志》2014年；57:4805 - 4818）使得开发基于凝血因子XIa的新型抗凝剂具有很大可能性。事实上，SPGG是首个似乎结合于远离活性位点区域的合成小分子抑制剂。鉴于对FXIa的变构抑制是开发一类独特抗凝剂的新机制，我们研究了SPGG与FXIa的相互作用，目的是评估其临床前相关性。与几种糖胺聚糖的比较抑制研究揭示了SPGG非糖主链的重要性。SPGG不影响血浆激肽释放酶、活化蛋白C和因子XIIIa的活性，这表明基于SPGG的抗凝作用不太可能影响与凝血因子相关的其他途径。SPGG对枸橼酸化人血浆活化部分凝血活酶时间（APTT）的影响也不依赖于抗凝血酶或肝素辅因子II。有趣的是，血清白蛋白以及因子XI会降低SPGG的抗凝潜力，而鱼精蛋白或聚凝胺可使其逆转，这意味着开发解毒策略可能有途径。对FXIa突变体的研究表明，SPGG与赖氨酸529、精氨酸530和精氨酸532结合，但不与精氨酸250、赖氨酸252、赖氨酸253和赖氨酸255结合。最后，SPGG与普通肝素竞争结合FXIa，但不与多磷酸盐和/或糖蛋白Ibα竞争。这些研究增进了对FXIa首个变构抑制剂的理解，并突出了其作为有前景的抗凝剂的价值。
