Infrared Spectroscopic Studies of Plant Photosynthesis

蛋白质动力学在酶机制中起着关键但知之甚少的作用。开发新方法来识别促进化学反应的蛋白质结构变化，将对我们对生物催化的理解产生变革性影响。光合反应中心提供了一个生物反应的例子，其中蛋白质动力学发挥重要作用，其中的反应是光诱导的。因此，光合反应作为一个模型系统，其中动力学机制可以使用激光闪光同步和启动反应进行研究。为了确定蛋白质结构的变化，重要的催化，新的，时间分辨光谱研究的光系统II（PSII）中的放氧复合物（OEC）将进行。PSII由完整的跨膜亚基和外源亚基组成。OEC含有一个四核锰（Mn）簇，并积累了从水中产生氧气所必需的四种光子衍生的氧化当量。催化位点的顺序氧化形式称为Sn态，其中n是指储存的氧化当量的数量。氯化物在S态循环中起着重要但尚未完全理解的作用。尽管经过了几十年的研究，水氧化机制的许多方面仍有待阐明。这些活动的智力价值在于，将导致对蛋白质动力学在催化中的作用的新的基本理解。光合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。这些反应也作为其他涉及分子氧的酶促反应的模型。更广泛的影响：这些活动的更广泛的影响来自于教学，培训和学习的进步，以及扩大代表性不足的群体的科学参与。主要研究者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。主要研究者的几个以前的学生和博士后同事已经继续在本科或博士学位任教。授予机构。主要研究者与在非博士学位教学的个人合作。这些人与主要研究员共同撰写出版物，这些出版物已在科学界广泛传播。此外，首席研究员是一个新的格鲁吉亚技术分子生物物理学培训计划的项目主任，该计划将加强格鲁吉亚技术研究和培训的基础设施。主要研究者在格鲁吉亚理工学院教授本科和研究生课程，她在这些课程中融入了研究和基于文献的练习。此外，首席研究员还通过科学展览活动参与了社区外联活动。下一个资助周期的计划包括扩大研究生和本科生参与分子生物物理学研究计划，通过与东南部和亚特兰大地区历史上的黑人机构进行联系。此外，首席研究员将通过NSF REU计划在夏季和通过格鲁吉亚技术研究机会在学年期间招募暑期学生。

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.