【作者】 张鹏；

【导师】 韩圣浩； 李济晨；

【作者基本信息】 山东大学 ， 凝聚态物理， 2006， 博士

【摘要】 水是生命之源。虽然从其化学式来看，水无疑是一种简单的化合物，然而，其独特的性质对于完成每个生物有机体的功能都具有重要的作用。尽管人们对于水的性质已经有过大量的研究，我们至今仍不能全部理解其独有的特性。英国曼彻斯特大学李济晨教授等人利用中子散射技术观测到冰的两种氢键的存在，此发现揭开了冰的研究领域的新篇章。重要的是，水分子在细胞环境中的行为看起来与在体水中有所不同。中子散射是研究含氢化合物的理想实验手段，因此，在过去的20年中，中子散射也成为研究水的有利工具。本文的所做的研究试图利用中子散射和拉曼散射探讨水分子与生物分子特别是氨基酸在分子水平上的相互作用。这项研究证明水分子在直接接触生物分子后具有与体水不同的动力学行为。非弹中子散射是种极好的实验手段，可广泛应用于分子及结构生物学。 氨基酸是最重要的生物体系之一。它被广泛用作蛋白质和缩氨酸在溶液中的状态及热力学行为的研究模型，尤其是用于预测其在经过结构简单迭加而衍生的生物体系的性质方面应用广泛。水与不同蛋白质官能团之间的相互作用使得蛋白质在溶液中保持稳定的折叠结构。由于蛋白质大分子的复杂结构，直接研究其与水分子的相互作用十分困难。因为氨基酸是蛋白质的基本结构单元，所以研究氨基酸-水分子的相互作用可以模拟蛋白质的某些特殊性质。在对生物化学制备的工业过程进行优化设计时，氨基酸在水溶液中的物理性质起着重要的作用。 每个氨基酸都有一个氨基和羧基官能团。各种氨基酸的区别在于其侧链R基的不同。在气相中，氨基酸大多以中性形式存在，而在溶液或固态中它们以两性离子NH₃⁺-CH（-R）-COO^-的形式存在。通过与周围的分子以氢键结合，氨基酸分子在生物介质中以相当稳定的两性离子状态存在。 拉曼设备是空间光谱分辨率为1微米的紫外—近红外共焦显微、多道模块式三级拉曼光谱仪，法国Jobin Yvon拉曼光谱公司，型号为JY-T64000。使用50倍长焦显微物镜将激光束汇聚到样品表面并收集散射光线。在我们的实验中使用氩离子激光器，激发波长是488nm。打到样品的激光功率低于3mW并且光谱捕获时间为200秒。所有的实验均在室温下进行。更多还原

【Abstract】 Water is the key element for life on earth. Despite its simple formula water is by no means a simple compound. Its unique properties make it so important for the function of every organism. Neutron Scattering is an ideal technique for studying hydrogenous compounds, thus during the last 20 years it has become very useful for the study of water. The aim of this research was to study the interaction of water with different biomolecules on the molecular level using that technique. Bands appearing in the neutron scattering spectrum (predominated by H motion) in the low energy transfers region are mainly due to hydrogen bonding between water and amino acids, or between water molecules. Inelastic neutron scattering can be employed as a vibrational spectroscopy method that provides information in the same energy ranges as Raman spectroscopy. However, Raman has better resolution in the high-energy transfer (in C-H, O-H, N-H bending and stretching) regions. Combining Raman is complemented so that we can extend the comparison of the vibrational spectrum. This study has proved that the water molecules that come into immediate contact with the biomolecules have a different dynamical behaviour to the bulk ones.The vibrational dynamics of water around some typical amino acids (i.e. glycine, alanine, serine, cysteine and proline) was investigated by using inelastic neutron scattering (INS) and Raman spectroscopy. The study clearly show that for some of the amino acids, such as glycine, the presence of water hardly changes the main features, illustrated the hydrophobic nature of these amino acids, however the water spectra are perturbed considerably from bulk water. For others, such as serine, the main features (versus the dry sample) have been altered considerably, new sharp peaks appeared in the INS spectrum and the hydrogen bonding between water and serine extraordinary disturbed the structure of amino acids molecules. The hydrogen bonding related to inter-molecule interaction can be analyzed from INS spectra in detail. The change of molecular vibrations can be complemented by Raman spectroscopy. Deep studies of a series of amino acids make us understand the interaction mechanism between amino acids and aqueous solution.更多还原