蛋白质结构和功能的紫外共振喇曼光谱研究

Ultraviolet Resonance Raman Spectroscopy Study of Protein Structure and Function

紫外共振喇曼光谱技术是研究复杂大分子结构的有力工具。结合作者在美国PittsburghUniversity期间所做的工作 ,介绍了用紫外共振喇曼光谱研究肽和蛋白质结构与功能的现状和进展 ,N methylacetamide和glycyglycine水溶液光化学异构过程的紫外共振喇曼光谱研究 ,简述了紫外共振喇曼光谱实验技术要点。本文还跟踪国际最新研究成果 。

Ultraviolet resonance Raman spectroscopy (UVRR) is a very powerful tool to study molecular structure and dynamics. Resonance Raman scattering requires excitation within an eletronic absorption band and results in a large increase of scattering, it has the additional benefit of avoiding interference from fluorescence. Furthermore, this method make it possible that selectively excite electrons of different functional groups with different excitation wavelengths in order to study the specific parts molecules. Based on the research work the writer did in Pittsburgh University, This paper introduced the status and recent progresses of UVRR spectroscopy used in the study of protein secondary structure and fuctions, the UVRR studies of photochemical isomerization process for aqueous dipeptides NMA and Gly Gly. The UVRR experimental main points also be demonstrated. A protein consists of one or more amino acides linked by peptide bonds, they are folded into a specific three dimentional shape maintained by further chemical bonding, such as hydrogen bonds and disulfide bridges. Since the Raman frequencies and intensities of these amide bonds are sensitive to the secondary structure, it is very important to study UV resonance Raman spectroscopy of proteins. Protein spectra obtained using the excitation at 206 5nm are dominated by amide bands.Thirteen proteins give the average pure α helix, β sheet and random coil spectra,these average spectra are used as standards to directly determine protein secondary structure. Protein's biological function is determined by its three dimentional structure. Since the majority of native protein structure self assemble,these three dimentional structure must be encode by the protein's primary sequences.Prediction of native protein structure has become more urgent due to the imminent completion of the sequencing of the human genome. The encoding rules must be complex since for most proteins the primary sequence will encode both the native static structure as well as the folding dynamics. These folding dynamics are likely to be complex. A new method has been developed to measure protein folding and unfolding dynamics. Many native proteins unfold(denature) when the solution temperature is raised or lowed. Using the pump probe technique the folding and unfolding process was monitored in the time scale when they occur. UVRR spectra are obtained at intervals ranging from ten nanoseconds to several hundred nanoseconds following the heat producing pump pulse.