RUI: Thermodynamics of Lipid-Lipid Interactions in Model Membranes

本研究计划以差示扫描量热法为主要技术手段，研究二棕榈酰磷脂酰胆碱作为参考双分子膜的凝胶和液体相间常见脂膜组分转移的热力学。实验方案包括在双层膜中溶质组分的极稀溶液中进行测量，然后使用规则溶液模型来评估为评估溶质转移热而提出的自由能，从而也可以确定熵变。最后，对转移过程的完整热力学描述将允许在膜生物物理中重要的各种类脂之间进行比较。通过系统地改变溶质分子的结构，可以设计出一组将溶质的结构特征与整体热力学传递特性联系起来的参数。将研究磷脂、脂肪酸、鞘脂和类固醇等分子。生物膜脂类组分之间的相互作用决定了膜中各组分的物理和化学特性。评估这些相互作用的热力学是理解分子在双层膜环境中行为的基础。由于可用于研究相互作用的模型和技术的局限性，很难设计出评估膜组件热力学性质的方法。

This proposal presents a plan to study the thermodynamics of transfer of common lipid membrane components between gel and fluid phases of a reference bilayer, dipalmitoylphosphatidylcholine, using differential scanning calorimetry as the primary technique. The experimental protocols involve carrying out the measurements in very dilute solutions of the solute components in the bilayer, and then using the regular solution model to evaluate the free energy proposed for evaluation of the enthalpy of transfer of the solute, so that the entropy change can also be determined. In the end a complete thermodynamic description of the transfer process will allow comparisons between a variety of lipid classes that are important in membrane biophysics. By systematically varying the structures of solute molecules, a set of parameters can be devised that will relate structural features of the solutes to the overall thermodynamic transfer characteristics. Molecules such as the phospholipids, fatty acids, sphingolipids and steroids will be studied. %%% Interactions between the lipid components of biological membranes determine the physical and chemical characteristics of the components in the membrane. Evaluation of the thermodynamics of these interactions is fundamental to understanding the behavior of molecules in the bilayer membrane environment. It has been difficult to devise methods to evaluate the thermodynamic properties of membrane components because of the limitations of models and techniques that can be used to study the interactions.