Mourier Pierre A J, Guichard Olivier Y, Herman Fréderic, Sizun Philippe, Viskov Christian
Sanofi, 13 Quai Jules Guesde, 94403 Vitry sur Seine, France.
In Memoriam: The authors would like to respectfully dedicate this article to Pr. B. Casu, a brilliant pioneer in glycosaminoglycan chemistry and analysis, who passed away on 11 November 2016..
Molecules. 2017 Mar 8;22(3):428. doi: 10.3390/molecules22030428.
Low Molecular Weight Heparins (LMWH) are complex anticoagulant drugs that mainly inhibit the blood coagulation cascade through indirect interaction with antithrombin. While inhibition of the factor Xa is well described, little is known about the polysaccharide structure inhibiting thrombin. In fact, a minimal chain length of 18 saccharides units, including an antithrombin (AT) binding pentasaccharide, is mandatory to form the active ternary complex for LMWH obtained by alkaline β-elimination (e.g., enoxaparin). However, the relationship between structure of octadecasaccharides and their thrombin inhibition has not been yet assessed on natural compounds due to technical hurdles to isolate sufficiently pure material. We report the preparation of five octadecasaccharides by using orthogonal separation methods including size exclusion, AT affinity, ion pairing and strong anion exchange chromatography. Each of these octadecasaccharides possesses two AT binding pentasaccharide sequences located at various positions. After structural elucidation using enzymatic sequencing and NMR, in vitro aFXa and aFIIa were determined. The biological activities reveal the critical role of each pentasaccharide sequence position within the octadecasaccharides and structural requirements to inhibit thrombin. Significant differences in potency, such as the twenty-fold magnitude difference observed between two regioisomers, further highlights the importance of depolymerisation process conditions on LMWH biological activity.
低分子量肝素（LMWH）是一类复杂的抗凝药物，主要通过与抗凝血酶的间接相互作用来抑制血液凝固级联反应。虽然对因子Xa的抑制作用已有充分描述，但关于抑制凝血酶的多糖结构却知之甚少。事实上，对于通过碱性β-消除法（如依诺肝素）获得的LMWH，要形成活性三元复合物，至少需要18个糖单元的链长，其中包括一个抗凝血酶（AT）结合五糖。然而，由于分离足够纯的材料存在技术障碍，尚未对天然化合物中十八糖的结构与其凝血酶抑制作用之间的关系进行评估。我们报告了通过使用包括尺寸排阻、AT亲和、离子对和强阴离子交换色谱在内的正交分离方法制备五种十八糖。这些十八糖中的每一种都具有位于不同位置的两个AT结合五糖序列。在使用酶促测序和核磁共振进行结构解析后，测定了体外抗Xa因子和抗IIa因子活性。生物学活性揭示了十八糖内每个五糖序列位置的关键作用以及抑制凝血酶的结构要求。效力上的显著差异，例如在两种区域异构体之间观察到的二十倍差异，进一步突出了降解过程条件对LMWH生物学活性的重要性。
