Peptide Conformation Studies with Vibrational Spectroscopy and Site Selective Isotopic Labeling

本项目由化学学部实验物理化学项目资助，研究肽构象、能量学以及蛋白质结构和折叠的动力学。大多数寡肽是相当灵活的，因此抑制了传统的结构分析，特别是在一种结构转变为另一种结构的条件下，如折叠。为了克服这些困难，Keiderling将开展一项研究计划，将红外（IR）、拉曼、振动圆二色性（VCD）和拉曼光学活性的解释，以及随时间变化的拉曼和红外光谱实验建立在坚实的基础上。为此，他将(a)采用同位素标记系统来给出振动光谱的解析和位点特异性特征，以及(b)为在肽中测量的振动光谱强度带形状建立更可靠的解释基础。实验工作将通过DFT增广高斯98计算来辅助获得光谱的计算建模所需的光谱参数。大多数实验和计算工作将集中在-发夹和-薄片模型上。不同长度的多肽具有不同的β -turn稳定残基，将在热展开和折叠时进行研究。这项工作的总体目标是开发增强的结构生物学工具，包括实验和理论，并获得折叠能量学的基本理解，能够解决广泛的生物物理需求。这项研究将与学生和博士后研究人员一起进行。因此，他们将获得当代生物物理化学快速发展的前沿领域之一的技能和培训，为在我国经济的科学/技术部门进行深造或就业做准备。

This project, funded by the Experimental Physical Chemistry Program of the Chemistry Division, deals with peptide conformations, energetics, and dynamics of protein structure and folding. Most oligopeptides are quite flexible and thereby inhibit conventional structural analyses, especially under conditions where one structure is changing into another, such as folding. To overcome these difficulties Keiderling will conduct a research program to place the interpretation of infrared (IR), Raman, vibrational circular dichroism (VCD) and Raman optical activity, as well as time-dependent Raman and IR spectra experiments on a solid foundation. To this end he will (a) employ isotopically labeled systems to give the vibrational spectra resolved, site-specific character, and (b) develop a more reliable interpretative basis for the vibrational spectral intensity band shapes measured in peptides. The experimental efforts will be aided by DFT augmented Gaussian 98 calculations to obtain spectral parameters for computational modeling of the spectra. Most experimental and computational efforts will focus on beta-hairpin and beta-sheet modeling. Peptides of different lengths with various beta-turn stabilizing residues will be studied while thermally unfolded and refolded. The overall goal of the work is the development of enhanced structural biology tools, both experimental and theoretical, and obtain a basic understanding of folding energetics, capable of addressing broad biophysical needs. This research will be conducted with students and postdoctoral research associates. They will thereby acquire skills and training in one of the fast developing forefront areas of contemporary bio-physical chemistry, in preparation for advanced studies or employment in the scientific/technological sectors of our economy.