Effects of Lipid Polymerization on Membrane Mechanical Properties and Transmembrane Protein Activity

亚利桑那大学的Scott Saavedra教授得到了分析和表面化学计划的支持，目的是研究光聚合的、支撑的、平面脂质双层对嵌入的跨膜蛋白(TMP)的性质和活性的影响。要检验的假设是，需要膜弹性来适应重组的TMP的构象变化，而不是流动性。PI计划通过研究聚合和非聚合平面支撑的脂双层中G蛋白偶联受体(一种TMP)的光引发构象变化，并将构象变化的程度与膜的机械性能联系起来，来测试这一点。正在建造一种仪器，用于在平面集成光波导上进行衰减全反射几何形状的闪光光解，以监测平面支撑的脂质双层中变紫红质II(MII)中间体的形成和衰变。监测MII的系统将使用NdYAG光分解激光和Ar离子激光探测MIi。第二，正在组装一台微吸管吸引器，以测量巨大单层囊泡的机械拉伸性能。最后，测试了脂类单体组成和聚合度对光活化的影响，以及脂类的机械性能。不同聚合组分的浓度比以及交联剂沿脂尾的位置是不同的。蛋白质在细胞膜上形成的通道放大了细胞间的通讯信号。这项研究的长期目标是能够利用这些系统的敏感性进行药物发现、筛选、分析和作为生物传感器。为了实现这些目标，需要对膜在表面稳定蛋白质的作用进行更多的基础研究。

Professor Scott Saavedra of the University of Arizona is supported by the Analytical and Surface Chemistry Program to investige the effects of photopolymerized, supported, planar lipid bilayers on the properties and activities of embedded transmembrane proteins (TMPs.) The hypothesis to be tested is that rather than fluidity, membrane elasticity is required to accommodate conformational changes in reconstituted TMPs. The PI plans to test this by studying the photo-initiated conformational change of a G protein coupled receptor (a type of TMP) in polymerized and non-polymerized planar supported lipid bilayers, and relating the extent of conformational change to the mechanical properties of the membrane. An instrument is being constructed to perform flash photolysis in an attenuated total reflection geometry on a planar integrated optical waveguide for monitoring formation and decay of the metarhodopsin II(MII)intermediate in planar supported lipid bilayers. The system to monitor MII will use a Nd:YAG laser for photolysis and an argon ion laser for probing MII. Second, a micropipette aspiration apparatus is being assembled to measure mechanical stretch properties of giant unilamellar vesicles. Finally, the effects on photoactivation of lipid monomer composition and degree of polymerization, as well as mechanical properties of the lipids, are being tested. Concentration ratios of different polymerizing components are being varied, as well as position of the cross linker along the lipid tails. Channels created in membranes by proteins amplify communication signals from cell to cell. The long-term goal of this research is to be able to harnass the sensitivity of these systems for drug discovery screening assays and as biosensors. In order to accomplish these goals, more fundamental research is needed about the role of the membrane in stabilizing proteins at surfaces.