Spectroscopic studies of light-driven electron transfer

光驱动电子转移的光谱研究

• 批准号: 7161792
• 负责人: BRIDGETTE ANNE BARRY
• 金额: $ 31.43万
• 依托单位: GEORGIA INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-01-01 至 2009-07-15
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7161792
• 关键词: Active Sites; Address; Amides; Amino Acids; Binding; Biological; Biological Models; Catalysis; Chlorophyll; Electron Spin Resonance Spectroscopy; Electron Transport; Electrons; Environment; Environmental Risk Factor; Enzymes; Equipment and supply inventories; Galactose Oxidase; Goals; Heme; Histidine; Isotopes; Kinetics; Label; Light; Link; Object Attachment; Oxidation-Reduction; Peptides; Pheophytins; Photosynthesis; Photosynthetic Reaction Centers; Photosystem I; Play; Property; Prostaglandin-Endoperoxide Synthase; Prosthesis; Proteins; Protons; Rate; Reaction; Research; Research Project Grants; Ribonucleotide Reductase; Role; Side; Site; Solvents; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis; Structure; Techniques; Testing; Tetrapyrroles; Time; Tyrosine; Work; cofactor; crosslink; cytochrome c oxidase; density; infrared spectroscopy; photosystem; photosystem II; theories

DESCRIPTION (provided by applicant): This proposal has three specific aims, which probe three different sets of biologically relevant electron transfer reactions in proteins. These electron transfer reactions involve redox-active amino acid residues and chlorophyll (chl). We will test three hypotheses: (A) that tyrosyl radical spin density delocalizes into the peptide/protein amide bond in a conformationaUy-sensitive, sequence-dependent manner; (13) that electron transfer-linked proton transfer distinguishes the redox-active tyrosines in photosystem II (PSID; and (C) that a difference in chlorophyll tautomerization state contributes to the difference in midpoint potential between the primary chl donors in PSII and photosystem I (PSI). To address these questions, electron paramagnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, and transient kinetics will be used. In collaborative efforts, electron spin-echo envelope modulation and density functional theory will also be employed. Long distance electron transfer in proteins involves step-wise electron transfer reactions between pairs of redox-active prosthetic groups, which act as catalytic intermediates. These prosthetic groups include covalently and non-covalently bound cofactors, such as heme, pheophytin, and chl, as well as amino acid side chains. An important long-term goal of this research project is to determine how electron transfer rates are influenced by changes in the structure and environment of these redox intermediates. The overall goal of this proposal is to elucidate the structural and environmental factors that are important in the control of midpoint potential and electron transfer in PSII and PSI. The spectroscopic studies to be described here will give new information concerning electron transfer mechanisms in photosynthetic reaction centers. The factors that influence the efficiency of electron transfer reactions are likely to be important in other enzymatic redox reactions, and photosynthetic proteins provide a unique and useful model system, because the reactions can be controlled by light.

描述（由申请人提供）：该提案有三个具体目标，探测蛋白质中三组不同的生物学相关电子转移反应。这些电子转移反应涉及具有氧化还原活性的氨基酸残基和叶绿素。 我们将测试三个假设：（A）酪氨酰基自由基自旋密度以构象敏感的序列依赖性方式离域到肽/蛋白酰胺键中;（13）电子转移连接的质子转移区分光系统II（PSID）中的氧化还原活性酪氨酸;以及（C）叶绿素互变异构状态的差异导致PSII和光系统I（PSI）中主要chl供体之间的中点电位差异。 为了解决这些问题，电子顺磁共振光谱，傅立叶变换红外光谱，和瞬态动力学将被使用。在合作的努力，电子自旋回波包络调制和密度泛函理论也将采用。 蛋白质中的长距离电子转移涉及作为催化中间体的氧化还原活性辅基对之间的逐步电子转移反应。这些辅基包括共价和非共价结合的辅因子，如血红素、脱镁叶绿素和chl，以及氨基酸侧链。该研究项目的一个重要长期目标是确定这些氧化还原中间体的结构和环境变化如何影响电子转移速率。本提案的总体目标是阐明在PSII和PSI的中点电位和电子转移的控制是重要的结构和环境因素。这里所描述的光谱研究将提供有关光合反应中心电子转移机制的新信息。影响电子转移反应效率的因素可能在其他酶促氧化还原反应中很重要，光合蛋白提供了一个独特而有用的模型系统，因为反应可以通过光来控制。