Protein Structure, Dynamics, and Folding via Ultrafast Multidimensional Infrared Spectroscopy

在这项由生命过程化学项目支持的奖项中，加州大学欧文分校的葛念辉教授将使用飞秒多维红外(MultiD IR)光谱来研究多肽的构象动力学、分布和折叠。目标是提供对理解生物过程至关重要的蛋白质结构和动力学的详细知识。拟议的工作包括研究螺旋结构和延伸结构之间的相互作用，确定非折叠多肽的构象分布，研究超螺旋蛋白质基序的关联，以及阐明蛋白质-膜相互作用。多维红外实验将获得多肽的主链和侧链振动模式，并提供揭示结构单元之间的角度、距离和相关性的数据。在选定位置的同位素编辑将被用来提高空间分辨率，促进共振峰的分配，并将该方法扩展到更大的多肽和三级接触。我们将研究温度、pH、溶剂和链长对蛋白质稳定性的影响，以了解控制蛋白质稳定性的因素。多维红外光谱是一种相对较新的技术，是对核磁共振和X射线方法的补充，具有在从飞秒到毫秒的广泛时间尺度上原位探测结构演化的能力。将这项技术应用到多肽的研究中，将使我们能够深入了解传统技术所不能轻易实现的快速构象波动和转变。这样的实验数据对于验证理论预测和验证下一代力场是非常必要的。类似于异核核磁共振的双色多维红外方法的进一步发展，将允许直接探测非常不同频率的振子之间的耦合。将其应用于酰胺的振动模式，将使构象测定具有更高的精度。这些研究将提供关于多肽结构和动力学的详细信息，并有助于理解蛋白质折叠。参与研究的研究生和博士后研究人员将在先进的激光技术和核心物理科学方面获得宝贵的经验，这些经验可以加强他们未来的职业发展。将继续努力维护在线频谱数据库，并为K-12学生提供讲座和实验室课程。

In this award supported by the Chemistry of Life Processes Program, Professor Nien-Hui Ge of the University of California at Irvine will use femtosecond multidimensional infrared (MultiD IR) spectroscopy to study the conformational dynamics, distributions, and folding of peptides. The goal is to provide detailed knowledge of protein structure and dynamics that is essential to the understanding of biological processes. The proposed work includes investigating the interplay between helical and extended structures, determining conformational distributions of nonfolding peptides, studying the association of supercoiled protein motifs, and elucidating protein-membrane interactions. MultiD IR experiments will access the backbone and side chain vibrational modes of peptides, and provide data that reveal the angles, distances, and correlations between structural units. Isotope editing at selected locations will be employed to enhance the spatial resolution, facilitate the assignment of resonances, and extend the method to larger peptides and tertiary contacts. The effects of temperature, pH, solvent, and chain length will be investigated to understand the factors that control protein stability. MultiD IR spectroscopy is a relatively new technique that complements NMR and X-ray methods, with the capability of probing the structure in situ as it evolves over a wide range of time scales, from femtosecond to millisecond. Applying this technique to the study of peptides will allow us to gain insights into rapid conformational fluctuations and transitions, not readily amenable to conventional techniques. Such experimental data are much needed for verification of theoretical predictions and validation of the next generation of force fields. Further development of two-color MultiD IR methods, analogous to heteronuclear NMR, will allow direct probing of coupling between vibrators of very different frequencies. Its application to the amide vibrational modes will enable conformational determination with higher accuracy. These studies will provide detailed information on peptide structure and dynamics, and contribute to the understanding of protein folding. Graduate students and postdoctoral researchers participating in the research will gain valuable experience with advanced laser techniques and core physical sciences that can strengthen their future career development. Efforts on maintaining an online spectrum database and contributing lectures and laboratory courses for K-12 students will be continued.