Infrared Spectroscopic Studies of Plant Photosynthesis

蛋白质动力学在酶机制中扮演着关键但知之甚少的角色。识别促进化学反应的蛋白质结构变化的新方法的发展将对我们对生物催化的理解产生革命性的影响。光合作用反应中心提供了一个生物反应的例子，其中蛋白质动力学在其中发挥重要作用，并且这些反应是光诱导的。因此，光合作用反应可以作为一个模型系统，其中动力学机制可以用激光闪光来同步和启动反应来研究。为了确定在催化中重要的蛋白质结构变化，将对光系统II(PSII)中的放氧复合体(OEC)进行新颖的、时间分辨的光谱研究。PSII由完整的跨膜亚基和外源亚基组成。OEC包含一个四核锰(Mn)簇，并积累了从水中生产氧气所需的四个光子衍生的氧化当量。催化中心的顺序氧化形式被称为锡态，其中n是指存储的氧化当量的数量。氯化物在S的状态循环中扮演着一个重要但尚未完全理解的角色。尽管经过了几十年的研究，但水氧化机理的许多方面仍有待阐明。这些活动的智力价值在于，将产生对蛋白质动力学在催化中的作用的新的基本理解。光合作用的放氧反应负责维持地球上的有氧生命，因此在生物化学中具有内在的重要性。这些反应也是其他涉及分子氧的酶反应的模型。更广泛的影响：这些活动的更广泛影响来自于教学、培训和学习的进步，以及扩大代表不足群体的科学参与。首席调查员有幸培训来自代表性不足群体的个人，包括研究生和本科生。这位首席研究员的几个以前的学生和博士后助理继续在本科生或授予博士学位的机构任教。首席研究人员与在非博士授予机构任教的个人合作，这些个人与首席研究人员共同撰写出版物，这些出版物已广泛传播给科学界。此外，首席研究员是佐治亚理工学院一个新的分子生物物理学培训项目的项目主任，该项目将加强佐治亚理工学院的研究和培训基础设施。这位首席研究员在佐治亚理工学院的本科生和研究生阶段任教，她在这些课程中融入了基于研究和文献的练习。此外，首席调查员还参与了通过科学博览会活动接触社区的活动。下一个资助周期的计划包括，通过接触东南部和亚特兰大地区历史上的黑人机构，扩大研究生和本科生对分子生物物理学研究项目的参与。此外，首席调查员将在夏季通过NSF REU项目招募暑期学生，并在学年通过佐治亚理工学院的研究机会招募学生。

Protein dynamics play a key but poorly understood role in enzymatic mechanisms. The development of new methods to identify protein structural changes that facilitate chemical reactions will have a transformative effect on our understanding of biological catalysis. Photosynthetic reaction centers provide an example of biological reactions in which protein dynamics play an important role and in which the reactions are light-inducible. Therefore, the photosynthetic reactions serve as a model system in which kinetic mechanism can be investigated using laser flashes to synchronize and start reactions. To identify protein structural changes important in catalysis, novel, time-resolved spectroscopic studies of the oxygen-evolving complex (OEC) in photosystem II (PSII) will be conducted. PSII consists both of integral, membrane-spanning subunits and of extrinsic subunits. The OEC contains a tetranuclear manganese (Mn) cluster and accumulates the four photon-derived oxidizing equivalents necessary for oxygen production from water. The sequentially oxidized forms of the catalytic site are called the Sn states, where n refers to the number of oxidizing equivalents stored. Chloride plays an important but not completely understood role in the S state cycle. Despite decades of study, many aspects of the water oxidation mechanism remain to be elucidated. The intellectual merit of these activities is that new fundamental understandings of the role of protein dynamics in catalysis will result. The photosynthetic oxygen-evolving reactions are responsible for the maintenance of aerobic life on earth and thus are of intrinsic importance in biological chemistry. These reactions also serve as a model of other enzymatic reactions involving molecular oxygen. BROADER IMPACTS:The broader impact of these activities results from the advancement of teaching, training, and learning, as well as from broadening the scientific participation of underrepresented groups. The principal investigator has had the privilege of training individuals from underrepresented groups, including both graduate and undergraduate students. Several of the principal investigator's former students and postdoctoral associates have gone on to teach at undergraduate or Ph.D.-granting institutions. The principal investigator has collaborations with individuals who teach at non-Ph.D. granting institutions, and these individuals are co-authors with the principal investigator on publications, which have been broadly disseminated to the scientific community. In addition, the principal investigator is program director for a new Georgia Tech Molecular Biophysics training program, which will enhance the infrastructure for research and training at Georgia Tech. The principal investigator teaches at both the undergraduate and graduate levels at Georgia Tech, and she incorporates research and literature-based exercises in these courses. Further, the principal investigator has been involved in outreach to the community through science fair activities. Plans for the next funding cycle include broadening graduate and undergraduate student involvement in the Molecular Biophysics research program by outreach to historically black institutions in the Southeast and Atlanta area. Also, the principal investigator will recruit summer students through the NSF REU program in the summer and through Georgia Tech research opportunities during the academic year.