Resolution and Reconstitution of Photosystem I in Cyanobacteria and Higher Plants: Molecular Biological and Physicochemical Studies

9723661戈尔贝克。 这项工作的目的是了解导致高量子产率和高热力学效率的光化学自由能转换的I型（铁硫）光合反应中心的分子机制。 为了实现这种水平的理解有关的中间电子受体A1，结合叶绿醌的配体是否一个或两个叶绿醌途径是利用电子转移，如果它是可能的，以操纵氨基酸，使醌与改变氧化还原电位可以交换到网站，必须确定。 关于FA和FB的突变体的问题包括使用取代的芳基硫醇盐来改变铁硫簇合物的中点电位，使用硫醇化的紫精衍生物作为电子转移的动力学探针，以及使用具有不同系链长度的紫精衍生物来研究距离对电子转移速率的影响。 通过PsaM的低分子量多肽PsaE的工作包括通过PsaE的可能的电子转移途径的测量，以及PsaF，PsaI，PsaJ，PsaK或PsaM是否提供从藻胆体吸收的光的能量溢出的链接。 本论文的总体目标是研究蓝藻和植物中光系统I反应中心的结构、功能和组织。 有机化学合成，定点诱变和光谱表征，包括时间分辨光学和EPR的组合，将被用来探测这些问题。 ***

9723661 Golbeck. The aim of this work is to understand the molecular mechanisms which lead to the high quantum yield and high thermodynamic efficiency of light-to-chemical free energy conversion in Type I (iron-sulfur) photosynthetic reaction centers. To achieve this level of understanding about the intermediate electron acceptor A1, the ligands which bind the phylloquinone whether one or both of the phylloquinone pathways is utilized in electron transfer, and if it is possible to manipulate the amino acids so that quinones with altered redox potentials can be exchanged into the site, must be determined. The issues regarding the mutants of FA and FB include using substituted aryl thiolates to modify the midpoint potentials of the iron-sulfur clusters, using thiolated viologen derivatives to function as kinetic probes of electron transfer, and using viologen derivatives with different tether lengths to investigate the effect of distance on electron transfer rate. The work on the low molecular mass polypeptides PsaE through PsaM includes measurements of a possible electron transfer pathway through PsaE, and whether the PsaF, PsaI, PsaJ, PsaK or PsaM provide links for energy spillover from light absorbed by phycobilisomes. The overall goal of this work is to study the structure, function and organization of the photosystem I reaction center in cyanobacteria and plants. A combination of organic chemical synthesis, site-directed mutagenesis and spectroscopic characterization including time-resolved optical and EPR, will be employed to probe these issues. ***