Benchmarks for Membrane Biophysics

这个项目解决了我们对生物膜中的脂质和蛋白质的理解的基本空白。生物功能是由蛋白质和其他生物分子的分子特性所控制的，这些分子在活细胞提供的膜微环境中运作。随着生物学认识的进步，计算方法在预测细胞膜性质方面变得越来越重要。同时，计算方法需要通过实验测量来检验和验证，作为计算的基准。这个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对生物功能的性能和调节的操作多样性。该项目将维持社区外展、对话和本科生早期参与前沿研究。该提案还将使年轻人接触科学，并通过“科学咖啡馆”计划招募他们从事研究。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的分子取向、动态特性和指定功能侧链的电离状态。关键方法包括肽合成、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物理学家的合作。实验方法采用了一种新的“宿主”肽设计，由研究人员开发，其中最小数量的界面芳香氨基酸残基用于定位倾斜的跨膜螺旋在脂质双分子层膜的“临界点”附近。在这种背景下，特定“客体”残基的系统结合提供了关于电离行为和蛋白质-脂质分子相互作用的重要见解，这些相互作用对许多类膜蛋白的生物学功能至关重要。该项目的实验结果有望建立基本基准，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部分子生物物理组的支持。

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.