Benchmarks for Membrane Biophysics

该项目解决了我们对生物膜中脂质和蛋白质的理解的根本差距。 生物学功能由蛋白质和其他生物分子的分子特性决定，这些生物分子在活细胞提供的膜微环境中起作用。 随着对生物学认识的不断深入，计算方法对于预测细胞膜的性质变得越来越重要。 与此同时，需要通过实验测量来检查和验证计算方法，这些实验测量可以作为计算的基准。 该项目提供了这样一个实验框架，作为推进计算生物物理学预测能力的基础。 总体目标是了解膜蛋白的操作多样性，以实现和调节生物功能。该项目将维持社区外展，对话和本科生早期参与尖端研究。这项建议还将使年轻人接触科学，并通过“科学咖啡馆”方案招募他们从事研究。 该项目解决了预测膜生物物理学的核心问题，包括膜蛋白中His，Lys，Glu，Asp和Arg的指定功能侧链的分子取向，动力学性质和电离状态。 关键的方法包括肽合成，稳定同位素标记，圆二色光谱，固态磁共振（NMR）测量，以及与计算生物化学家的合作。 实验方法采用了一种新的“主机”肽设计，由研究人员开发，其中最小数量的界面芳香族氨基酸残基用于定位一个倾斜的跨膜螺旋附近的“临界点”在脂质双层膜。在这种情况下，系统地纳入特定的“客人”残基提供了重要的见解电离行为和蛋白质-脂质分子的相互作用，是必不可少的许多类膜蛋白的生物功能。该项目的实验结果预计将建立基本的基准，以帮助开发和验证计算方法，以解决控制特定膜蛋白（如钾通道，乙酰胆碱受体或生长因子受体等）功能的分子机制。 该项目得到了生物科学理事会分子和细胞生物科学司分子生物物理学小组的支持。

This project addresses fundamental gaps in our understanding of lipids and proteins in biological membranes. Biological function is governed by the molecular properties of proteins and other biomolecules that operate within the membrane micro-environment provided by and for living cells. As biological understanding progresses, computational methods are becoming increasingly important for predicting the properties of cell membranes. At the same time, the computational methods need to be checked and validated by means of experimental measurements that can serve as benchmarks for the calculations. This project provides such an experimental framework to serve as a basis for advancing the predictive power of computational biophysics. The overarching goal is to understand the operational diversity of membrane proteins for the performance and regulation of biological function. This project will sustain community outreach, dialogue, and early involvement of undergraduate students in cutting-edge research. This proposal will also expose young people to science and recruit them to engage in research through the "Science Café" program. This project addresses central issues in predictive membrane biophysics, including molecular orientation, dynamic properties and the ionization states of designated functional side chains of His, Lys, Glu, Asp and Arg in membrane proteins. The key methods involve peptide synthesis, stable isotope labeling, circular dichroism spectroscopy, solid-state magnetic resonance (NMR) measurements, and collaborations with computational biophysicists. The experimental approaches employ a novel "host" peptide design, developed by the investigators, in which minimal numbers of interfacial aromatic amino-acid residues serve to position a tilted transmembrane helix near a "tipping point" in lipid bilayer membranes. Within this context, the systematic incorporation of specific "guest" residues provides important insights concerning ionization behavior and protein-lipid molecular interactions that are essential for the biological functions of many classes of membrane proteins. The experimental results from this project are expected to establish fundamental benchmarks to aid the development and validation of computational methods for addressing the molecular mechanisms that govern the functioning of specific membrane proteins such as potassium channels, acetylcholine receptors or growth factor receptors, amongst others. This project is supported by the Molecular Biophysics Cluster of the Molecular and Cellular Biosciences Division in the Directorate for Biological Sciences.