Studies of the Primary Reactions of Bacterial Photosynthesis

伍德伯里博士建议研究初始 细菌光合反应中心的电子传递。 特别感兴趣的是进一步了解 蛋白质基质在调节热动力学过程中的作用 光合电子传递的动力学参数。 到 为此，伍德伯里博士将利用定向 诱变以改变反应中心附近的氨基酸 辅因子和瞬态光谱来分析动力学， 氧化还原活性辅因子间电子转移热力学 以及鉴定重要的中间体 参与了这一反应。 提出了若干具体项目。 一种是使用定点突变来研究 研究了氢键作用对聚乙烯氧化还原性能的影响。 初始电子供体，然后确定改变的效果 这个重要的电子转移热力学参数 机制 伍德伯里博士将执行大部分快速光谱分析 在这个项目中，突变体是由艾伦设计和构建的 还有威廉姆斯。 另一个项目涉及比较电子 反应中心从不同生物体的转移机制， 反应中心之间的DNA序列交换区域 这些生物的基因。 在蛋白质骨架的水平上， 反应中心具有近二重旋转对称性。 然而，存在于两侧的氨基酸大部分是 不同. 结果是电子转移非常 不对称，几乎完全发生在两个 可能的途径，即使存在两种途径， 相同的辅助因子。 这将通过交换区域进行研究 双方之间进行光谱分析， 方向，动力学和中间态参与初始 电子转移 %%% 该项目有两个更广泛的目标。 一是 了解光合作用过程中太阳能的转换， 这也是本实验室的一大兴趣。 基本上所有的 生物体所使用的能量最终来自这个来源， 对这一过程的机械性理解 可用于开发分子器件， 比能量输入（这就是反应中心的真正含义）。 第二，反应中心提供了一个很好的实验室， 研究辅因子-蛋白质相互作用的学科。 有 一些蛋白质-发色团系统，其中反应机制可以 在飞秒的时间尺度上进行了如此详细的探测 （其包括分子运动的时间尺度）。 这里 同样，从这些研究中获得的信息可以用于 多种分子器件的合理设计， 了解非常广泛的蛋白质介导的化学 反应.

Dr. Woodbury proposes to investigate the mechanism of initial electron transfer in bacterial photosynthetic reaction centers. Particular interests lie in furthering the understanding of the role that the protein matrix plays in modulating the thermodynamic and kinetic parameters of photosynthetic electron transfer. To this end, Dr. Woodbury will utilize a combination of directed mutagenesis to alter the amino acids near the reaction center cofactors and transient spectroscopy to assay the kinetics and thermodynamics of electron transfer between redox active cofactors as well as to identify the mechanistically important intermediates involved in this reaction. Several specific projects are proposed. One involves the use of site-directed mutagenesis to investigate the effect of hydrogen bonding on the redox properties of the initial electron donor and then to determine the effect of changing this important thermodynamic parameter on the electron transfer mechanism. Dr. Woodbury will perform most of the fast spectroscopy in this project; the mutants were designed and constructed by Allen and Williams. Another project involves comparing the electron transfer mechanisms of reaction centers from different organisms by exchanging regions of DNA sequence between the reaction center genes of these organisms. At the level of the protein backbone, the reaction center has a near two fold-rotational symmetry. However, the amino acids present on the two sides are largely different. The result is that electron transfer is very asymmetric, occurring almost exclusively down one of the two possible pathways, even though two pathways exist with chemically identical cofactors. This will be studied by exchanging regions between the two sides and performing spectroscopic analysis of the direction, kinetics and intermediate states involved in initial electron transfer. %%% There are two broader goals of the project. First, an understanding of solar energy conversion during photosynthesis is itself a major interest of this laboratory. Essentially all of the energy used by living organisms ultimately comes from this source, and a mechanistic understanding of this process could be very useful in the development of molecular devices that require a specific energy input (which is what a reaction center really is). Second, the reaction center provides an excellent laboratory for the study of cofactor-protein interactions in general. There are few protein-chromophore systems where reaction mechanism can be probed in such detail on time scales as short as femtoseconds (which encompasses the time scale of molecular motion). Here again, the information obtained from these studies can be used in the rational design of many types of molecular devices and in the understanding of a very wide range of protein-mediated chemical reactions.