MOLECULAR MODELLING OF SOLVATION OF (PRO PRO GLY)10

我们已经研究了影响稳定的因素， （Pro-Pro-Gly）10的三螺旋构象的水溶液 [（PPG）10]，胶原蛋白三联体某些特征的简化模拟物 螺旋。 对稳定这种分子的因素的了解可能 有助于智能聚合物和生物材料的设计。 该多肽形成类似于 胶原蛋白。 然而，与胶原蛋白不同， 残基以形成链间或链内桥接氢键 包括束缚沃茨。 然而，我们已经建立了一个模型， （PPG）10中的结合沃茨，其中形成桥接氢键 在每个结合水和一对主链羰基之间， 多肽链。 这些沃茨被认为是有约束力的，而不是 大量溶剂化的沃茨，因为它们在空间上受到限制， 只能通过流动性有限的沃茨进入的区域， 而不是通过本体溶剂。 我们还表明，这些作用 结构稳定中空间拥挤沃茨水 定性地解释了更大的稳定性和更高的熔点 的（PPG）10在氧化氘比在水中，这是由于轻微 氢键中重原子间距离的变化 D2 O相对于结合H2O，这允许结构采用 对于脯氨酸间的货车范德华几何形状更有利 相互作用，同时仍保持最佳氢键 几何 MidasPlus和UCSF计算机图形学的设施 实验室已用于图形建模和可视化 分子几何结构，用于在起始阶段制备（PPG）10 理论计算的确认，用于监控 这些计算后的结构，并准备图像， 出版物和海报展示。

We have investigated the factors contributing to the stability in aqueous solution of the triple-helical conformation of (Pro-Pro-Gly)10 [(PPG)10], a simplified mimic of some features of the collagen triple helix. An understanding of the factors stabilizing this molecule may contribute to the design of intelligent polymers and biomaterials. This polypeptide forms a triple-stranded conformation similar to that of collagen. Unlike collagen, however, it has no hydroxyproline residues to form inter- or intra-chain bridging hydrogen bonds involving bound waters. However, we have constructed a model for bound waters in (PPG)10, in which bridging hydrogen bonds are formed between each bound water and a pair of backbone carbonyls on different polypeptide chains. These waters are considered bound, rather than waters of bulk solvation, because they are in sterically restricted regions which can only be accessed by waters with limited mobility and not by bulk solvent. We have also shown that the role of these sterically crowded bound waters in structure stabilization qualitatively explains the greater stability and higher melting point of (PPG)10 in deuterium oxide than in water This occurs due to slight changes in the inter-heavy atom distances in hydrogen bonds to bound D2O relative to bound H2O, which allow the structure to adopt a geometry somewhat more favorable for inter-proline van der Waals interactions while still maintaining optimal hydrogen-bonding geometry. MidasPlus and the facilities of the UCSF Computer Graphics Laboratory have been used for graphical modeling and visualization of the molecular geometry, for preparing (PPG)10 in the starting conformation for the theoretical calculations, for monitoring the structures after these calculations, and for preparing images for publication and poster presentation.