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

冠军SageMCB 9904516本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)来探索生物分子如血红素蛋白(肌红蛋白、血红蛋白和细胞色素c)和光合作用系统(捕光天线和反应中心)的电子和核结构/功能关系。还将利用电子吸收和红外光谱等相关技术，并开发解释实验FCS测量的理论模型。由快速光诱导生化反应产生的FCS信号将被用来提取描述反应的水平穿越动力学的定量模型的关键参数。温度、粘度、磁场等外界条件的变化将被用来探索蛋白质弛豫和自旋态选择规则对反应动力学的影响。利用定点突变体和生色团替换将探索蛋白质、氨基酸和生色团外围取代基对FCS信号的影响。将利用激光脉冲形状、光载波频率和单色仪检测频率的变化来进行场驱动和反应驱动的相干运动的定量研究和比较。振荡信号相对相位的测量将被用来测试Fe-L解离路径上是否存在中间自旋态。将比较涉及NO、CO和O2的血红素-配体结合和解离反应。进一步的实验和理论研究将涉及蛋白质分布和构象相互转化的动态效应。利用泵浦引起的斯托克斯和反斯托克斯拉曼散射的变化来跟踪激光引起的热微扰。总体而言，该项目的目标是更好地了解生物分子的光学性质，无论是处于平衡状态还是非平衡状态，并应用这些知识来阐明它们的作用机制。这些研究的意义不仅在于它们与生物科学的关系，而且在于它们与理解与凝聚相中的复杂系统相关的基本光-物质相互作用的联系。该项目得到了生物科学局分子和细胞生物科学部的分子生物物理学计划以及数学和物理科学局的物理司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.