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首页> 外文期刊>Chemistry: A European journal >Oligosaccharides display both rigidity and high flexibility in water as determined by C-13 NMR relaxation and H-1,H-1 NOE spectroscopy: Evidence of anti-phi and anti-psi, torsions in the same glycosidic linkage
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Oligosaccharides display both rigidity and high flexibility in water as determined by C-13 NMR relaxation and H-1,H-1 NOE spectroscopy: Evidence of anti-phi and anti-psi, torsions in the same glycosidic linkage

机译：通过C-13 NMR弛豫和H-1，H-1 NOE光谱确定，寡糖在水中显示出刚性和高柔韧性：同一糖苷键中抗phi和抗psi的证据

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摘要

The trisaccharide beta -D-Glcp(1 --> 2)-beta -D-Glcp-(1 up arrow 3)-alpha -D-Glcp-OMe has been investigated by molecular dynamics (MD) simulations and NMR experiments in water. C-13 spin-lattice (T-1) and spin-spin (T-2) relaxation times, together with (HC)-H-1-C-13 NOE data were measured at two magnetic field strengths (9.4 and 14.1T) in a 277K D2O solution. Relaxation data interpreted by means of the model-free formalism revealed a rigid (S(2)similar to0.9) oligosaccharide tumbling in solution. H-1,H-1 Cross-relaxation rates were determined at 600 MHz by 1D DPFGSE NOESY and T-ROESY experiments, which provided high quality data and subsequently proton-proton distances within the trisaccharide. The presence of anti conformers at both torsions of a glycosidic linkage is demonstrated for the first time. MD simulations were carried out to facilitate analysis of the NOE data. In total, 15 simulations-starting from five different conformational states-were performed, with production runs of up to 10 ns, resulting in 83 ns of oligosaccharide dynamics in water. anti Conformers were populated to different degrees in the simulations, especially at the phi (2) torsion angle. By combining the results from the NOE experiments and the MD simulations, the anti conformers at the (1 --> 2)-linkage were quantified as 7% anti-phi (2), and 2% anti-psi (2), revealing a highly flexible trisaccharide in which large conformational changes occur. From the MD simulations, interresidue hydrogen bonding, from HO2" to O2 or O3, was significantly populated (similar to 40%) in both of the anti conformational states. The contentious issue over rigidity versus flexibility in oligosaccharides has thus been thoroughly examined, showing that the dynamics should be taken into account for a relevant description of the molecular system. [References: 87]
机译：已通过分子动力学（MD）模拟和NMR在水中对三糖β-D-Glcp（1-> 2）-β-D-Glcp-（1向上箭头3）-α-D-Glcp-OMe进行了研究。在两个磁场强度（9.4和14.1T）下测量了C-13自旋晶格（T-1）和自旋自旋（T-2）的弛豫时间以及（HC）-H-1-C-13 NOE数据）在277K D2O解决方案中。通过无模型形式主义解释的弛豫数据揭示了在溶液中翻滚的刚性（S（2）与0.9）低聚糖。 H-1，H-1交叉松弛速率是通过一维DPFGSE NOESY和T-ROESY实验在600 MHz处测定的，该实验提供了高质量的数据以及随后在三糖中的质子-质子距离。首次证明在糖苷键的两个扭转处都存在抗构象体。进行了MD模拟以促进NOE数据的分析。总共进行了15种模拟，从五个不同的构象状态开始，生产运行长达10 ns，从而在水中产生了83 ns的寡糖动力学。在仿真中，反协调器的填充程度不同，尤其是在phi（2）扭转角处。通过结合NOE实验和MD模拟的结果，将（1-> 2）连锁处的反构象体定量为7％的抗phi（2）和2％的抗psi（2），揭示了一种高度柔性的三糖，其中发生了很大的构象变化。从MD模拟中，在两个反构象状态下，从HO2“到O2或O3的残基氢键均被大量填充（大约40％）。因此，对寡糖的刚度与柔韧性之间的有争议的问题进行了彻底研究，表明关于分子系统的相关描述应考虑动力学[参考文献：87]

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