Resonance Raman Studies of Electron-Nuclear Coupling, Time Resolved Dynamics, and Magnetic Perturbations of Biomolecules

该研究项目利用共振拉曼散射及其时域模拟，飞秒相干光谱（FCS），探测生物分子的电子和核结构/功能关系，如血红素蛋白（肌红蛋白，血红蛋白和细胞色素c）和光合系统（光捕获天线和反应中心）。 相关的技术，如电子吸收和红外光谱，也将被利用，和理论模型，占实验FCS测量将被开发。FCS信号，诱导快速光诱导的生化反应，将被用来提取关键参数，定量模拟描述反应的水平交叉动力学。 外部条件的变化，如温度，粘度和磁场将被用来探测蛋白质弛豫和自旋状态选择规则对反应动力学的影响。 使用定点突变体和发色团替换将探测蛋白质氨基酸和发色团外围取代基对FCS信号的影响。 将利用激光脉冲形状、光学载波频率和单色仪检测频率的变化对场和反应驱动的相干运动进行定量研究和比较。 振荡信号的相对相位的测量将用于测试Fe-L解离路径上中间自旋态的存在。 血红素配体结合和解离反应涉及NO，CO和O2将进行比较。进一步的实验和理论研究涉及蛋白质分布和构象相互转换的动态效应将进行。激光介导的热扰动将使用泵浦诱导的斯托克斯和反斯托克斯拉曼散射的变化来跟踪。 总的来说，该项目的目标是更好地了解生物分子的光学性质，无论是在平衡状态还是在平衡状态，并应用这些知识来阐明其作用机制。这些研究不仅在它们与生物科学的关系上具有重要意义，而且在它们与理解与凝聚相复杂系统相关的基本光-物质相互作用的关系上也具有重要意义。该项目得到了生物科学理事会分子和细胞生物科学部分子生物物理学计划以及数学和物理科学理事会物理学部和多学科活动办公室的支持。

ChampionSageMCB 9904516.This research project utilizes resonance Raman scattering and its time domain analog, femtosecond coherence spectroscopy (FCS), to probe the electronic and nuclear structure/function relationships of biological molecules such as heme proteins (myoglobin, hemoglobin and cytochrome c) and photosynthetic systems (light harvesting antenna and reaction centers). Related techniques, such as electronic absorption and infrared spectroscopy, will also be utilized, and theoretical models that account for the experimental FCS measurements will be developed. FCS signals, induced by rapid photoinduced biochemical reactions, will be used to extract key parameters that quantitatively model the level crossing dynamics describing the reaction. Variations of external conditions such as temperature, viscosity, and magnetic field will be used to probe the effects of protein relaxation and spin-state selection rules on the reaction dynamics. Use of site directed mutants and chromophore replacements will probe the effect of protein amino acids and chromophore peripheral substituents on the FCS signals. Quantitative studies and comparisons of field and reaction driven coherent motions will be carried out using variations in laser pulse shape, optical carrier frequency, and monochromator detection frequency. Measurements of the relative phases of the oscillatory signals will be used to test for the presence of intermediate spin-states on the Fe-L dissociation pathway. Heme-ligand binding and dissociation reactions involving NO, CO and O2 will be compared. Further experimental and theoretical studies involving the dynamic effects of protein distributions and conformational interconversions will be carried out. Laser mediated thermal perturbations will be followed using pump induced changes of the Stokes and anti-Stokes Raman scattering. Overall the project's objectives are to achieve a better understanding of the optical properties of biological molecules, both in and out of equilibrium, and to apply this knowledge to elucidate their mechanism of action. These studies are significant not only in their relationship to the biological sciences, but also in their connection to the understanding of basic light-matter interaction associated with complex systems in the condensed phase. This project is supported by the Molecular Biophysics Program in the Division of Molecular and Cellular Biosciences in the Directorate for Biological Sciences and the Divisions of Physics and the Office of Multidisciplinary Activities in the Mathematical and Physical Sciences Directorate.