PROTEIN DYNAMICS AND INTERACTIONS: VIBRATIONAL ECHOES

建议使用一种全新的方法来研究蛋白质动力学和蛋白质内部的相互作用，这些方法包括超快红外振动回波实验、激发振动回波、化学写成的激发振动回波和二维振动回波光谱。振动回波在皮秒和飞秒的时间尺度上运行，是核磁共振自旋回波的红外振动等价物，但它直接检查机械自由度之间的动力学和相互作用，而不是自旋。受激发的振动回波实验扩展了可以研究的时间尺度，允许在广泛的时间尺度上绘制结构波动动力学的频谱。振动回波实验将首先应用于肌红蛋白-CO(Mb-CO)、血红蛋白-CO(Hb-CO)、Mb-NO、溶菌酶、酰胺I带和模型结构的研究。对血红素蛋白质的时间相关振动回波研究将检查结合在活性部位的配体感受到的蛋白质动力学，并提供结构、温度和粘度如何影响蛋白质动力学的信息。将在室温下研究蛋白质/溶剂边界在蛋白质动力学中所起的作用，并将研究低温下玻璃状蛋白质动力学的性质。对完整蛋白质的实验将与对变性蛋白质的实验进行比较，以检查变性引起的结构动态变化。小分子将被用作结构动力学标记，它将允许检查蛋白质不同区域发生的结构波动。振动回波谱是一种频率和时间可变的二维方法，它将被用来获得蛋白质振动光谱中的背景抑制和峰值增强，这些光谱是传统红外光谱无法分辨的，例如Mb-NO。二次二维振动回波谱将被发展并应用于研究蛋白质中不同结构单元之间的机械耦合。振动回波实验是第一次在生物系统上使用红外相干实验，沿着在研究生物系统和过程中取得如此丰硕成果的路径移动振动光谱，以及磁共振。

Research is proposed to study protein dynamics and intraprotein interactions using an entirely new approach, ultrafast infrared vibrational echo experiments, stimulated vibrational echoes, chemically written stimulated vibrational echoes, and two dimensional vibrational echo spectroscopies. The vibrational echo, which operates on picosecond and femtosecond time scales, is the infrared vibrational equivalent of the NMR spin echo, but it directly examines dynamics and interactions among mechanical degrees of freedom rather than spins. The stimulated vibrational echo experiments extend the time scales that can be investigated, permitting the spectrum of structural fluctuation dynamics to be mapped out over a broad range of time scales. The vibrational echo experiments will initially be applied to the study myoglobin-CO (Mb-CO), hemoglobin-CO (Hb-CO), Mb-NO, lysozyme, Amide I bands and model structures. The time dependent vibrational echo studies of the heme proteins will examine protein dynamics that are felt by a ligand bound at the active site and provide information on how structure, temperature, and viscosity influence protein dynamics. The role played by the protein/solvent boundary in protein dynamics will be studied at room temperature, and the nature of glass like protein dynamics at low temperatures will be investigated. Experiments on intact proteins will be compared to experiments on denatured proteins to examine changes in structural dynamics caused by denaturing. Small molecules will be used as Structural Dynamics Labels that will permit examination of structural fluctuations occurring in different regions of a protein. Vibrational Echo Spectroscopy, a 2D method in which frequency and time are varied, will be used to obtain background suppression and peak enhancement in vibrational spectra of proteins that are not resolvable with conventional IR spectroscopy, e. g., Mb-NO. Two time 2D vibrational echo spectroscopy will be developed and applied to the study of the mechanical coupling between different structural units in proteins. The vibrational echo experiments are the first to use IR coherence experiments on biological systems, moving vibrational spectroscopy along the path that has been so fruitful in the study of biological systems and processes with of magnetic resonance.