Structure and Function of the Oxygen Evolving Complex of Photosystem II

从光系统II中去除许多调节蛋白 （PSII）导致含有七种蛋白质的制剂 能够光诱导氧释放的亚基 活动 与此同时，这些净化程序改变了 氧的析出和电子转移的性质， PSII。 这些实验将确定 电子转移活性的变化。 研究将 进行定量的色素含量和 PSII中的质体醌。 去除28 kDa 叶绿素结合蛋白可以诱导 对除草剂敏感的醌的光还原; 将检查这种蛋白质的性质， 其他已知的叶绿素结合蛋白以及 以确定其在调节除草剂结合中的作用， 醌光还原 进一步调查将评估 几种PSII相关蛋白在提供 结合外源多肽的位点和尝试 以确定低分子量肽是否 与PSII共同纯化的是 活动。% 光系统II（PSII）催化光驱动的4-电子 将水氧化成分子氧。 使用相对 简单的生物化学方法允许从植物中分离PSII， 叶绿体的类囊体膜。 非离子型的应用 洗涤剂到这些膜片上允许分离 更简单的制剂， 多肽，但同时保留氧气 进化活动。 从PSII中去除各种多肽 诱导电子转移活性的改变， 这些改变的修复被证明有助于发现 氧释放反应的新辅因子。 本研究 将推断出一组选定的角色， 未表征的多肽，当从PSII中除去时， 引起电子转移活性变化。 还将 确定低分子量多肽是否与 PSII制剂在电子 转移活动。*

Removal of a number of regulatory proteins from photosystem II (PSII) results in a preparation containing seven protein subunits which is capable of light-induced oxygen evolution activity. At the same time, these purification routines alter the properties of oxygen evolution and electron transfer in PSII. These experiments will determine the origins of the changes in electron transfer activity. Studies will be conducted to quantify the contents of pigments and plastoquinone in PSII during purification. Removal of a 28 kDa chlorophyll-binding protein can be shown to induce alterations to herbicide-sensitive photoreduction of quinones; the properties of this protein will be examined to place it in the context of other known chlorophyll binding proteins as well as to determine its role in regulation of herbicide binding and quinone photoreduction. Additional investigations will assess the roles of several PSII-associated proteins in providing sites for the binding of extrinsic polypeptides and attempts will be made to determine whether low molecular weight peptides which copurify with PSII are essential components of activity.%%% Photosystem II (PSII) catalyzes the light-driven 4-electron oxidation of water to molecular oxygen. The use of relatively simple biochemical procedures permit the isolation of PSII from thylakoid membranes of chloroplasts. Application of non-ionic detergents to these membrane sheets permits the isolation of simpler preparations which contain reduced numbers of polypeptides, but which at the same time retain oxygen evolution activity. Removal of various polypeptides from PSII induces alterations to electron transfer activity, and the repair of these alterations has proven useful in discovering new cofactors for the oxygen evolving reaction. This research will deduce the roles of a selected set of largely uncharacterized polypeptides which, upon removal from PSII, induce changes to electron transfer activity. It will also be determined whether low molecular weight polypeptides associated with PSII preparations play significant roles in electron transfer activity.***