Measuring Molecular Electric Fields at the Active Site of a Protein using Single Molecule and Hole-Burning Techniques

使用单分子和烧孔技术测量蛋白质活性位点的分子电场

• 批准号: 0911719
• 负责人: Peter Geissinger
• 金额: $ 52.28万
• 依托单位: University of Wisconsin-Milwaukee
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0911719&HistoricalAwards=false
• 关键词: Measuring; Molecular; Electric; Fields; Active

In this project funded by the Experimental Physical Chemistry Program, Professors Geissinger and Woehl of the University of Wisconsin-Milwaukee will develop methods to determine quantitatively internal electric fields at the active sites of proteins at molecular and atomic resolution. The approach to measuring these fields, which are generated by the protein charge distributions themselves, is based on high-resolution spectroscopic techniques (in particular single-molecule spectroscopy and hole-burning spectroscopy at cryogenic temperatures) combined with quantum-mechanical data analysis and electrostatic model calculations of proteins. Experimental work will focus on two closely related model systems, myoglobin and hemoglobin. It is expected that the availability of magnitude and direction of internal electric fields at a molecular or even at an atomic level will shed new light on the fundamental issue of ligand discrimination in these systems, because continuum dielectric approaches are unable to conclusively establish the link between electrostatic structure and function. Advancing understanding and discovery of the factors that are responsible for the physiological functions of myoglobin and hemoglobin is important for a number of biotechnological applications, such as the design of efficient blood substitutes or of substances that efficiently remove oxygen from foods or other oxygen-sensitive products. More generally, the methods that will be developed for the extraction of internal electric field values from spectroscopic data are expected to be readily adaptable to any biological system that contains one or more porphyrin molecules. In addition, providing experimental access to internal electric fields will allow for investigating the question whether biological systems were designed by nature with the goal of optimizing internal electric fields at certain functional sites of these systems.The availability of hole-burning and single-molecule spectra from the same systems will constitute a valuable resource for teaching and learning. Single molecule studies in particular provide excellent and unique educational resources for demonstrating how individual, molecular parameters lead to certain behavior of matter on the macroscopic scale. The pedagogical benefit is that abstract mathematical formulas such as distribution functions of statistical thermodynamics can be introduced as a direct consequence of very concrete and detailed experimental knowledge about properties of individual molecules, thereby improving student learning. Thus, the results of this project will form an integral part for the PIs' teaching of Physical Chemistry courses at both the undergraduate and graduate levels. Moreover, both PIs will provide opportunities for undergraduate and visiting high school students to participate in research activities in these areas, for example, through the state-supported UROP (Undergraduate Research Opportunities) and the Upward Bound program. These programs provide research opportunities for undergraduate and high-school students.

在这项由实验物理化学计划资助的项目中，威斯康星大学密尔沃基分校的盖辛格和沃尔教授将开发出在分子和原子分辨率下定量确定蛋白质活性部位的内部电场的方法。测量这些由蛋白质电荷分布本身产生的场的方法是基于高分辨率光谱技术(特别是低温下的单分子光谱和烧孔光谱)，并结合蛋白质的量子力学数据分析和静电模型计算。实验工作将集中在两个密切相关的模型系统上，肌红蛋白和血红蛋白。由于连续介质方法不能确定静电结构和功能之间的联系，分子甚至原子水平的内部电场的大小和方向的可获得性将为这些系统中的配位体识别的基本问题提供新的线索。促进对肌红蛋白和血红蛋白生理功能因素的了解和发现，对于一些生物技术应用非常重要，例如设计有效的血液替代品或有效地从食物或其他氧气敏感产品中去除氧气的物质。更广泛地说，将开发的从光谱数据中提取内部电场值的方法有望容易地适用于任何包含一个或多个卟啉分子的生物系统。此外，提供内部电场的实验通道将允许调查生物系统是否是自然界设计的，目的是优化这些系统某些功能部位的内部电场。来自相同系统的烧孔和单分子光谱的可获得性将构成宝贵的教学资源。特别是单分子研究提供了极好的和独特的教育资源，用于演示单个分子参数如何导致物质在宏观尺度上的某些行为。教学上的好处是，可以引入抽象的数学公式，如统计热力学的分布函数，作为关于单个分子性质的非常具体和详细的实验知识的直接结果，从而改善学生的学习。因此，这一项目的结果将成为PIS在本科生和研究生水平上教授物理化学课程不可或缺的一部分。此外，这两个PI将为本科生和来访的高中生提供参与这些领域的研究活动的机会，例如，通过国家支持的UROP(本科生研究机会)和向上跳跃计划。这些项目为本科生和高中生提供研究机会。