PROTEIN DYNAMICS AND INTERACTIONS: VIBRATIONAL ECHOES

研究提出了研究蛋白质动力学和蛋白质内的相互作用，使用一种全新的方法，超快红外振动回波实验，受激振动回波，化学写的受激振动回波，和二维振动回波光谱。在皮秒和飞秒时间尺度上工作的振动回波是NMR自旋回波的红外振动等效物，但它直接检查力学自由度之间的动力学和相互作用，而不是自旋。受激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范围内绘制出结构波动动力学的谱。振动回波实验将初步应用于研究肌红蛋白-CO（Mb-CO）、血红蛋白-CO（Hb-CO）、Mb-NO、溶菌酶、酰胺I带和模型结构。血红素蛋白质的时间依赖性振动回波研究将检查蛋白质动力学，所感受到的活性位点结合的配体，并提供有关结构，温度和粘度如何影响蛋白质动力学的信息。蛋白质/溶剂边界在蛋白质动力学中所起的作用将在室温下进行研究，并将研究在低温下玻璃状蛋白质动力学的性质。完整蛋白质的实验将与变性蛋白质的实验进行比较，以检查变性引起的结构动力学变化。小分子将被用作结构动力学标签，这将允许检查蛋白质不同区域中发生的结构波动。振动回波光谱法是一种频率和时间变化的2D方法，将用于获得传统红外光谱法无法分辨的蛋白质振动光谱的背景抑制和峰增强。例如，在一个实施例中，我们将发展二次二维振动回波光谱技术，并将其应用于蛋白质不同结构单元之间的机械耦合研究。振动回波实验是第一个在生物系统上使用红外相干实验的实验，将振动光谱学沿着在磁共振生物系统和过程的研究中如此富有成效的路径移动。

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.