Conformational transitions induced in heparin octasaccharides by binding with antithrombin III
Conformational transitions induced in heparin octasaccharides by binding with antithrombin III
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DOI：
10.1042/bj20060656
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发表时间：
2006-10-15
影响因子：
4.1
通讯作者：
Mourier, Pierre
中科院分区：
文献类型：
--
作者：
Guerrini, Marco;Guglieri, Sara;Mourier, Pierre
本文研究了两种肝素八糖在溶液中的构象，它们含有五糖序列GlcN（NAc，6S）-GlcA-GlcN（NS，3，6S）-IdoA（2S）-GlcN（NS，6S）[阿加 *IA;其中GlcN（NAc，6S）是N-乙酰化、6-O-硫酸化的α-D-葡萄糖胺，GlcN（NS，3，6S）是N，3，6-O-三硫酸化α-D-葡糖胺和IdoA（2S）是2-O-硫酸化IdoA（α-L-艾杜糖醛酸）]，并侧重于建立阿加 * 内部和外部的IdoA残基（IdoA（2S）和IdoA）的几何结构IA序列。阿加 *IA构成AT（抗凝血酶）的活性位点，并且对于高抗凝血和抗血栓活性的表达是必需的。NMR参数分析[NOE（核Overhauser效应）、转移NOE和偶联常数]表明，在阿加 *IA内IdoA（2S）残基的游离状态下动态平衡中存在的C-1（4）和S-2（0）构象之间，AT选择S-2（0）形式，如先前所示[Hricovini，Guerrini，Bisio，Torri，Petitou和Casu（2001）Biochem.J.359，265-272]。值得注意的是，阿加 *IA之前的非硫酸化IdoA残基也采用S-2（0）构象，在不存在AT的情况下，其主要采用C-1（4）形式。这些结果进一步支持了肝素结合蛋白影响艾杜糖醛酸残基的构象平衡的概念，艾杜糖醛酸残基直接或间接参与结合，并选择它们的等能构象之一，以最好地拟合在复合物中。艾杜糖醛酸构象的完全逆转，优选在游离状态也证明了第一次。初步对接研究提供的八糖结合位置同意最密切的实验数据的信息。这些结果表明，阿加 *IA之前的非硫酸化IdoA残基可能具有生物学作用，以前认为不影响五糖的AT结合特性。因此，对于长于阿加 *IA的每个AT结合序列，与蛋白质的相互作用可能不同，并给予每个肝素片段特异性生物反应。
The present study deals with the conformation in solution of two heparin octasaccharides containing the pentasaccharide sequence GlcN(NAc,6S)-GlcA-GlcN(NS,3,6S)-IdoA(2S)-GlcN(NS,6S) [AGA*IA; where GlcN(NAc,6S) is N-acetylated, 6-O-sulfated alpha-D-glucosamine, GlcN(NS,3,6S) is N, 3,6-O-trisulfated alpha-D-glucosamine and IdoA(2S) is 2-O-sulfated IdoA (alpha-L-iduronic acid)] located at different positions in the heparin chain and focuses on establishing geometries of IdoA residues (IdoA(2S) and IdoA) both inside and outside the AGA*IA sequence. AGA*IA constitutes the active site for AT (antithrombin) and is essential for the expression of high anticoagulant and antithrombotic activities. Analysis of NMR parameters [NOEs (nuclear Overhauser effects), transferred NOEs and coupling constants] for the two octasaccharides indicated that between the C-1(4) and S-2(0) conformations present in dynamic equilibrium in the free state for the IdoA(2S) residue within AGA*IA, AT selects the S-2(0) form, as previously shown [Hricovini, Guerrini, Bisio, Torri, Petitou and Casu (2001) Biochem. J. 359, 265-272]. Notably, the S-2(0) conformation is also adopted by the non-sulfated IdoA residue preceding AGA*IA that, in the absence of AT, adopts predominantly the C-1(4) form. These results further support the concept that heparin-binding proteins influence the conformational equilibrium of iduronic acid residues that are directly or indirectly involved in binding and select one of their equi-energetic conformations for best fitting in the complex. The complete reversal of an iduronic acid conformation preferred in the free state is also demonstrated for the first time. Preliminary docking studies provided information on the octasaccharide binding location agreeing most closely with the experimental data. These results suggest a possible biological role for the nonsulfated IdoA residue preceding AGA*IA, previously thought not to influence the AT-binding properties of the pentasaccharide. Thus, for each AT binding sequence longer than AGA*IA, the interactions with the protein could differ and give to each heparin fragment a specific biological response.