SPECTROSCOPIC STUDIES OF LIGHT DRIVEN ELECTRON TRANSFER

光驱动电子转移的光谱研究

• 批准号: 2634676
• 负责人: BRIDGETTE ANNE BARRY
• 金额: $ 21.49万
• 依托单位: UNIVERSITY OF MINNESOTA
• 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 1999-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2634676
• 关键词: active sites; conformation; electron spin resonance spectroscopy; electron transport; infrared spectrometry; manganese; oxidation reduction reaction; photochemistry; photosynthetic reaction centers; photosystem; protein structure function; site directed mutagenesis; stable isotope; tyrosine

The overall goal of this proposal is to develop a more detailed understanding of the molecular basis of biological electron transfer. Electron transfer is of central importance in all biological redox reactions and in energy conversion in the mitochondria and chloroplast, but the role that protein and cofactor structural changes play in these processes is just beginning.to be,elucidated. The spectroscopic studies to be described here will identify structural changes that accompany function in an electron transfer protein; the model system to be employed is the photosynthetic oxygen evolving complex, photosystem II. The factors that influence the efficiency of electron transfer after light absorption are likely to be important in other redox reactions, and photosynthetic proteins provide a unique and useful model system, since the reactions can be controlled by light. Moreover, photosystem II contains three redox active tyrosine residues. Therefore, photosystem Il provides an excellent system for studies of the factors that control the function of redox active amino acids. Redox active amino acids are now known to be present in-several enzymes, including prostaglandin H synthase, ribonucleotide reductase, galactose oxidase, and cytochrome c peroxidase. In photosystem II, one of the redox active tyrosines, Z, is oxidized by the primary donor and is reduced by the manganese cluster, which is the catalytic site of water oxidation. A second tyrosine, D, forms a stable radical of unknown function. The third redox active tyrosine, M, was discovered in my laboratory during the previous grant period, and its role in electron transfer is still under investigation. In this proposal, I describe experiments that bill elucidate the environmental factors that control the function of these redox active tyrosines. The experiments will utilize the spectroscopic techniques of EPR and reaction induced (difference) infrared in conjunction with isotopic labeling and site directed mutagenesis. There are three specific aims: (A) to investigate the protein factors that control the function of the redox active tyrosines, D and Z; (B) to investigate the structure, location, and kinetics of redox active tyrosine, M; (C) to isolate mutants that can be used for isotopic labeling of amino acids and prosthetic groups, such as chlorophyll and plastoquinone.

本提案的总体目标是制定一个更详细的 了解生物电子转移的分子基础。 电子转移在所有生物氧化还原反应中具有中心重要性 线粒体和叶绿体中的反应和能量转换， 但蛋白质和辅因子结构变化在这些过程中所起的作用 过程只是beginning.to被阐明。光谱研究， 将识别伴随功能的结构变化 在电子转移蛋白质中;所采用的模型系统是 光合放氧复合体，即光系统II。的因素 影响光吸收后电子转移效率的因素有 可能在其他氧化还原反应中很重要， 蛋白质提供了一个独特的和有用的模型系统，因为反应可以 被光线控制。 此外，光系统II含有三个氧化还原活性酪氨酸残基。 因此，光系统II提供了一个很好的系统，用于研究 控制氧化还原活性氨基酸功能的因素。氧化还原 现在已知活性氨基酸存在于几种酶中， 包括前列腺素H合酶、核糖核苷酸还原酶、半乳糖 氧化酶和细胞色素C过氧化物酶。在光系统II中， 活性酪氨酸Z被初级供体氧化，并被还原， 锰簇，这是水氧化的催化位点。一 第二酪氨酸D形成未知功能的稳定自由基。第三 氧化还原活性酪氨酸，M，是在我的实验室中发现的， 以前的补助金期间，其在电子转移中的作用仍在 调查在这个建议中，我描述了比尔·盖茨的实验， 阐明控制这些功能的环境因素， 氧化还原活性酪氨酸。实验将利用光谱学 EPR技术和反应诱导（差）红外技术 结合同位素标记和定点诱变。 有三个具体目标：（A）研究蛋白质因素， 控制氧化还原活性酪氨酸D和Z的功能;（B）以 研究氧化还原活性的结构、位置和动力学 酪氨酸，M;（C）分离可用于同位素标记的突变体 氨基酸和辅基，如叶绿素和 质体醌