RUI: Thermodynamics of Lipid-Lipid Interactions in Model Membranes

本提案提出了一个计划，以差示扫描量热法为主要技术，研究双棕榈酰磷脂酰胆碱双分子层凝胶相和流体相之间常见脂膜组分转移的热力学。实验方案包括在双层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评估用于评估溶质转移焓的自由能，从而确定熵变。最后，传递过程的完整热力学描述将允许在膜生物物理学中重要的各种脂类之间进行比较。通过系统地改变溶质分子的结构，可以设计出一组参数，将溶质的结构特征与整体热力学传递特性联系起来。磷脂、脂肪酸、鞘脂和类固醇等分子将被研究。生物膜的脂质组分之间的相互作用决定了膜中组分的物理和化学特性。评价这些相互作用的热力学是理解分子在双层膜环境中的行为的基础。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分热力学性质的方法。

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.