RAMAN STUDIES OF PORPHYRINS/PROTEIN MAQUETTES/PROTEINS

这项研究的目标是表征结构，电子， 和振动，性质不同的四聚吡咯大环 环境，包括溶液、血红素蛋白、血红素蛋白模型 (合成小蛋白)和超分子组装体(合成 纳米结构)。主要的研究工具是共振拉曼 (RR)光谱，尽管UV-Vis、红外(IR)和电子 顺磁共振波谱；电化学技术； 而振动分析方法也发挥着重要作用。长期的 目的是将环的物理性质与它们的 功能特性(配体结合和运输、电子 转移、能量转移、催化)在合成和天然中 蛋白质。具体目标如下：(L)低频振动 将获得光谱并将其分配给不同的5-和6- 配合使用卟啉和氢卟啉。最佳力场将是 专为环的平面外变形而开发。这些力量 FIELS将明确包括组氨酸作为轴向配体。(2)RR 将获得一系列远端肌红蛋白突变体的光谱 它的X射线晶体结构和配体结合动力学都很好 特色化的。RR数据将在完整的 血红素(轴向配位体)低频模式的振动模型 单元，以开发可靠的频率/结构/配体结合 亲和力相关性。突变体的RR数据也将用于 离面模的力场的进一步改进 血红素/轴向配基单元。这个力场应该比 仅从模型综合体发展而来的一个，应该会促进更多 分子动力学模拟中血红素运动的精确建模。 (3)将获得一系列小分子(62个氨基酸)的RR谱 合成单血红素和双血红素结合肽。这些数据将用于 评估血红素的结构如何影响它们的氧化还原化学。这 信息将成为未来合成蛋白质设计的基准 旨在精确控制亚铁氰化物的氧化还原特性。(4) 将获得各种新的、 共价连接的卟啉组合物。这些数据将用于 确定部件中环的几何排列方式 影响大循环之间的电子通讯。

The goals of the research are to characterize the structural, electronic, and vibrational, properties of tetrapyrrolic macrocycles in various environments including solutions, heme proteins, heme protein maquettes (small synthetic proteins), and supramolecuIar assemblies (synthetic nanostructures). The principal investigative tool is resonance Raman (RR) spectroscopy, although Uv-Vis, infrared (IR), and electron paramagnetic resonance (EPR) spectroscopies; electrochemical techniques; and vibrational analysis methods also play important roles. The long-term objective is to relate the physical properties of the rings to the their functional characteristics (ligand binding and transport, electron transfer, energy transfer, catalysis) in both synthetic and natural proteins. The specific aims are as follows: (l) Low-frequency vibrational spectra will be obtained and assigned for various five- and six- coordinate porphyrins and hydroporphyrins. Optimum force fields will be developed for the out-of-plane deformations of the rings. These force fields will explicitly include histidine as an axial ligand. (2) RR spectra will be obtained for a series of distal-site myoglobin mutants whose X-ray crystal structures and ligand-binding kinetics have been well characterized. The RR data will be assessed in the context of a complete vibrational model for the low-frequency modes of the heme(axial-ligand unit in order to develop reliable frequency/structure/ligand-binding affinity correlations. The RR data for the mutants will also be used for further refinement of the force field for the out-of-plane modes of the heme/axial-ligand unit. This force field should be more reliable than one developed from model complexes alone and should facilitate more accurate modeling of the heme motions in molecular dynamics simulations. (3) RR spectra will be obtained for a series of small (62 amino acids) synthetic mono- and diheme binding peptides. These data will be used to assess how the structure of the hemes affects their redox chemistry. This information will serve as a benchmark for future synthetic protein design aimed at precise control of the redox properties of the hemes. (4) Optical, RR, and EPR spectra will be obtained for a variety of novel, covalently linked porphyrinic assemblies. These data will be used to determine how the geometrical arrangement of the rings in the assembly affects the electronic communication between the macrocycles.