RUI: Biophysical and Electron Paramagnetic Resonance Studies: Energetics of the Oxygen-Evolving Complex and New Curricula for Undergraduates

[600925] Haddy本研究的主要目的是从能量学的角度来表征高等植物进化氧复合体（OEC）中锰团簇的氧化态变化。这将通过监测两个电子顺磁共振（EPR）信号来实现，一个是g=2时的多线信号，另一个是g=4时的宽信号，这两个信号与其中一个氧化态S2有关。此外，在g=4.8处存在与S1相关的均匀自旋EPR信号，即S2之前的状态，将通过并行模式检测确认并随后用于监测S1。具体研究目标包括：确认S2信号在g=4时（指定S2-g=4）的状态先于S2多线信号（S2-mult）的状态；确定S1与S2-g=4、S2-g=4与S2-mult、S2-mult与S2后态S3之间的活化能垒；确定S1、S2-g=4和S2-mult相关态的相对自由能；并研究了氨抑制剂存在时的能垒和相对自由能。为了实现这些目标，S2信号的大小，如果存在S1信号，将在一系列的平衡和动力学实验中在一定的照明温度范围内进行测量。其大小将与每个州的人口有关。建议的教育活动与化学系目前发展生物化学专业的计划一致。培养目标包括：开设一学期的生物化学实验课程；作为第二学期导论课程的一部分的一系列关于生物物理学的讲座；以及一套供本科生实验室使用的EPR实验。本科生的EPR实验将包括一些在生物化学中有应用的实验，这些实验目前在化学教育文献中没有。% % %

9600925 Haddy The primary research goal is to characterize the oxidation state changes of the manganese cluster of the oxygen evolving complex (OEC) of higher plants in terms of energetics. This will be carried out by monitoring two electron paramagnetic resonance (EPR) signals, a multiline signal at g=2 and a broad signal at g=4, associated with one of the oxidation states, S2. In addition, the presence of an even spin EPR signal at g=4.8 associated with S1, the state preceding S2, will be confirmed using parallel mode detection and subsequently used to monitor S1. The specific research objectives include: confirmation that the state associated with the S2 signal at g=4 (designated S2-g=4) precedes the state associated with the S2 multiline signal (S2-mult); determination of the activation energy barriers between the states associated with S1 and S2-g=4, S2-g=4 and S2-mult, and S2-mult and S3, the state that follows S2; determination of the relative free energies of the states associated with S1, S2-g=4, and S2-mult; and investigation of the energy barriers and relative free energies in the presence of the inhibitor ammonia. To achieve these objectives, the magnitudes of the S2 signals and if present the S1 signal will be measured in a series of equilibrium and kinetics experiments performed over a range of illumination temperatures. The magnitudes will be related to the population in each state. The educational activities proposed are in accord with the Chemistry Department's current plans to develop a concentration or major in biochemistry. The education objectives include the development of: a one-semester biochemistry laboratory course; a series of lectures on biophysical topics to be given as part of the second semester introductory course; and a set of EPR experiments for use in undergraduate laboratories. The EPR experiments for undergraduates will include some that have applications in biochemistry and are not presently available in the chemical education literature. %%%