RUI: The Use of Anion Inhibitors to Investigate the Role of Chloride in Oxygen Evolution by Photosystem II of Higher Plants

本项目将探讨氯化物对高等植物分子氧形成的重要性。所有呼吸的生命形式都需要氧气，它是光合作用中将光能转化为化学能的副产品。因此，氧气的产生是维持地球上生命的最重要的生化反应之一。氧是由光系统II中一簇锰离子的水氧化形成的，这是一种膜结合蛋白复合体。这种催化需要氯作为辅助因子。本项目将采用的方法是描述阴离子通过与功能氯竞争来抑制析氧活性的作用。抑制剂的研究对于指出正常功能的特征是有价值的。利用菠菜光系统ii富集膜，分析了F-、N3-、I-、NO2-和NO3-等阴离子抑制剂对酶析氧活性的影响。这些结果将与阴离子对锰簇和其他氧化还原活性中心的电子顺磁共振（EPR）谱的影响进行比较。还将进行研究，以确定某些阴离子与氯化物本身和溴化物一起作为析氧活化剂的特性。这些实验将有助于在分子水平上解释阴离子抑制剂的作用。由于该项目将在一所以本科生为主的大学进行，因此该项目将为初级研究人员提供实验室经验，预计这将影响他们的职业选择。

The importance of chloride for the formation of molecular oxygen by higher plants will be investigated in this project. Oxygen, which is required by all respiring life forms, is evolved as a byproduct of the conversion of light energy into chemical energy during photosynthesis. The production of oxygen is therefore among the most important biochemical reactions for the support of life on earth. Oxygen is formed by the oxidation of water at a cluster of manganese ions in Photosystem II, a membrane-bound protein complex. Chloride is required as a cofactor for this catalysis. The approach to be taken in this project will be to characterize the action of anions that inhibit oxygen evolution activity by competing with functional chloride. Inhibitor studies are valuable in pointing out the characteristics of normal function. Using photosystem II-enriched membranes from spinach, the effects of anion inhibitors such as F-, N3-, I-, NO2-, and NO3- on the enzyme kinetics of oxygen evolution activity will be analyzed. These results will be compared with the effects of the anions on the electron paramagnetic resonance (EPR) spectra of the manganese cluster and other redox active centers. Studies will also be undertaken to characterize some of the anions as activators of oxygen evolution along with chloride itself and bromide. These experiments will facilitate the interpretation of the effects of the anion inhibitors at a molecular level. Since this project will be carried out at a primarily undergraduate university, this project will provide beginning researchers with laboratory experience, which is expected to influence their career choices.