Microscopic Dielectric Relaxation as a Tool for Studying Protein Dynamics

微观介电弛豫作为研究蛋白质动力学的工具

• 批准号: 0416965
• 负责人: Ludwig Brand
• 金额: $ 42万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-01 至 2008-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0416965&HistoricalAwards=false
• 关键词: Microscopic; Dielectric; Relaxation; Tool; Studying

Collective motion of protein domains usually takes place on the nanosecond or picosecond time scales and is important for protein function. Time- and spectrally-resolved fluorescence emission of tryptophan residues contains information about protein relaxation dynamics on these time scales. This type of dynamic information is complementary to the structural and dynamic information available from X-ray diffraction and NMR data. Exciting a Trp residue with a short laser pulse alters the electrostatic forces acting between it and charged residues and throws the system out of equilibrium. As the system relaxes to a new equilibrium, the Trp emission spectrum shifts to lower energies, and this shift can be recorded with picosecond time resolution. Preliminary studies revealed that the relaxation curves for a few tested proteins contain three or more exponential terms with different relaxation times in the range from 60ps to 8ns. The faster exponentials represent the motion of small chemical groups, while the slower exponentials represent the relative motions of bulky domains or secondary-structure elements. The goal of this research is to establish quantitative correspondence between the experimental relaxation curves obtained from fluorescence data and theory. By changing the location of the Trp residue and of charged residues, the dynamics of different kinds of vibrations will be studied. This technique will be used to separate intradomain motions from the relative motions of different domains. The second part of the work will focus on changes in the relaxation curves associated with the addition and removal of a single charge.The intellectual merit of the proposed activity is in the new information about picosecond and nanosecond dynamics of collective motions in proteins. In addition to training graduate students, the PI will train undergraduate and high school students in his laboratory. The aim with these students is to impart the excitement of scientific research to them and to show them what career options are available to them in Biophysics.

蛋白质结构域的集体运动通常发生在纳秒或皮秒的时间尺度上，对蛋白质功能非常重要。色氨酸残基的时间和光谱分辨荧光发射包含了这些时间尺度上的蛋白质弛豫动力学信息。这种类型的动态信息是对可从X射线衍射和NMR数据获得的结构和动态信息的补充。用短激光脉冲激发色氨酸残基，改变了它和带电残基之间的静电力，使系统失去平衡。当系统松弛到一个新的平衡时，Trp发射光谱向较低的能量移动，这种移动可以用皮秒时间分辨率记录下来。初步研究表明，一些被测蛋白质的弛豫曲线包含三个或更多的指数项，其弛豫时间在60 ps至8ns的范围内。较快的指数表示小化学基团的运动，而较慢的指数表示大的域或二级结构元素的相对运动。本研究的目的是建立定量的荧光数据和理论得到的实验弛豫曲线之间的对应关系。通过改变色氨酸残基和带电残基的位置，将研究不同种类的振动的动力学。该技术将用于从不同域的相对运动中分离域内运动。第二部分的工作将集中在与添加和删除一个单一的电荷的弛豫曲线的变化。拟议的活动的智力价值是在新的信息皮秒和纳秒的集体运动的蛋白质。 除了培养研究生，PI还将在他的实验室培养本科生和高中生。与这些学生的目的是传授科学研究的兴奋给他们，并向他们展示什么职业选择，他们在生物物理学。