Almond Andrew, Petersen Bent O, Duus Jens Ø
Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom.
Biochemistry. 2004 May 18;43(19):5853-63. doi: 10.1021/bi0354886.
Fucosylated O- and N-linked glycans are essential recognition molecules in plants and animals. To understand how they impart their functions, through interactions with proteins, requires a detailed analysis of structure and dynamics, but this is presently lacking. In this study, the three-dimensional structure and dynamics of three fucosylated oligosaccharides are investigated using a combination of high field (800 MHz) nuclear magnetic resonance and long (50 ns) molecular dynamics simulations in explicit water. Predictions from dynamics simulations were in agreement with nuclear Overhauser cross-peak intensities. Similarly, a theory of weak alignment in neutral media resulted in reasonable predictions of residual dipolar couplings for the trisaccharide fucosyllactose. However, for larger penta- and hexasaccharides (LNF-1 and LND-1), the anisotropic component of the alignment was underestimated, attributed to shape irregularities of the fucosyl branches on an otherwise linear core, being more pronounced in a singly branched than a doubly branched oligosaccharide. Simulations, confirmed by experiment, predicted fucosylated molecules that are restricted to librations about a single average conformation. This restriction is partly due to microscopic water interactions, which act to stabilize intramolecular hydrogen bonds and maintain tight and ordered conformations; a view not forthcoming from simpler, nonaqueous simulations. Such a conclusion is crucial for understanding how these molecules interact with proteins and impart their recognition properties.
岩藻糖基化的 O-连接和 N-连接聚糖是植物和动物中的重要识别分子。要了解它们如何通过与蛋白质相互作用发挥功能，需要对结构和动力学进行详细分析，但目前尚缺乏此类研究。在本研究中，结合高场（800 MHz）核磁共振和在明确水环境中的长时间（50 ns）分子动力学模拟，对三种岩藻糖基化寡糖的三维结构和动力学进行了研究。动力学模拟的预测结果与核Overhauser交叉峰强度一致。同样，中性介质中的弱取向理论对岩藻糖基乳糖三糖的剩余偶极耦合给出了合理预测。然而，对于较大的五糖和六糖（LNF-1和LND-1），取向的各向异性成分被低估，这归因于在原本线性的核心上岩藻糖基分支的形状不规则，在单分支寡糖中比双分支寡糖中更为明显。经实验证实的模拟预测了局限于围绕单一平均构象摆动的岩藻糖基化分子。这种限制部分归因于微观水相互作用，其作用是稳定分子内氢键并维持紧密且有序的构象；这一观点在更简单的非水模拟中并未出现。这样的结论对于理解这些分子如何与蛋白质相互作用并赋予其识别特性至关重要。
