STRUCTURE & FUNCTION OF PHOTOSYNTHETIC REACTION CENTERS

结构

• 批准号: 6384993
• 负责人: GEORGE FEHER
• 金额: $ 46.46万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 1976
• 资助国家: 美国
• 起止时间: 1976-05-10 至 2004-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6384993
• 关键词: Chlamydomonas; X ray crystallography; atomic force microscopy; binding sites; bioenergetics; complementary DNA; computer simulation; cytochrome c; dielectric property; electron density; electron nuclear double resonance spectroscopy; electron spin resonance spectroscopy; electron transport; hydrogen bond; molecular dynamics; mutant; photosynthesis; photosynthetic bacteria; photosynthetic reaction centers; photosystem; protein binding; protein structure function; protonation; site directed mutagenesis; structural biology

In the broadest sense, our objective is to understand biological processes and phenomena in terms of physical mechanisms, i.e. on a molecular level. The main problem addressed in this proposal deals with the conversion of electromagnetic energy (light) into chemical energy, i.e. photosynthesis. This process is mediated by an integral membrane protein - pigment complex called the reaction center (RC). Our work focuses on the structural aspects of the RC from the photosynthetic bacterium Rb. sphaeroides and the structural implications on the function of the RC. The mechanisms of electron and proton transfers that take place in the RC are of general importance in all living systems. For instance, the processes that take place in mitochondria (in mammalian cells) can be viewed as the reverse process of photosynthesis utilizing similar mechanisms. Thus, the understanding of electron and proton transfer mechanisms should lead to a deeper understanding of the molecular basis of some metabolic deficiencies. The fields and methodologies used in this proposal are interdisciplinary, ranging from physics to chemistry and molecular biology. Consequently, different techniques and tools are used in our work, e.g. computational methods, X-ray crystallography, optical spectroscopy, magnetic resonance (EPR, ENDOR), protein chemistry and recombinant DNA techniques. The specific problems addressed are: The three-dimensional structure of native and mutant RCs from the photosynthetic bacterium Rb. sphaeroides and the structure of the transient RC-cyt c2 complex. These studies are being pursued by X-ray crystallography, complemented by magnetic resonance techniques. The mechanisms of two electron transfer reactions: k(1)AB(Q-AQB->QAQ-B) and k(2)AB (Q-AQ-B+H+->Q(QBH)-), as well as the protonation of the secondary quinone, QB, are being studied by kinetic optical spectroscopy and site-directed mutagenesis.

从最广泛的意义上讲，我们的目标是从物理机制（即分子水平）来理解生物过程和现象。该提案解决的主要问题涉及电磁能（光）转化为化学能，即光合作用。这个过程是由称为反应中心（RC）的完整膜蛋白-色素复合物介导的。我们的工作重点是光合细菌 Rb 的 RC 的结构。球状体及其对 RC 功能的结构影响。 RC 中发生的电子和质子转移机制对于所有生命系统都具有普遍重要性。例如，线粒体（哺乳动物细胞）中发生的过程可以被视为利用类似机制的光合作用的逆过程。因此，对电子和质子转移机制的了解应该有助于更深入地了解某些代谢缺陷的分子基础。该提案中使用的领域和方法是跨学科的，从物理学到化学和分子生物学。因此，我们的工作中使用了不同的技术和工具，例如计算方法、X 射线晶体学、光谱学、磁共振（EPR、ENDOR）、蛋白质化学和重组 DNA 技术。解决的具体问题是： 光合细菌 Rb 的天然和突变 RC 的三维结构。球状体和瞬时 RC-cyt c2 复合物的结构。这些研究正在通过 X 射线晶体学进行，并辅以磁共振技术。两个电子转移反应的机理：k(1)AB(Q-AQB->QAQ-B)和k(2)AB(Q-AQ-B+H+->Q(QBH)-)，以及仲醌 QB 的质子化正在通过动力学光谱和定点诱变进行研究。