Pulsed EPR Studies of Biological Manganese Clusters

生物锰簇的脉冲 EPR 研究

• 批准号: 6766001
• 负责人: R David Britt
• 金额: $ 23.39万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-07-01 至 2005-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6766001
• 关键词: catalase; chemical structure function; electron nuclear double resonance spectroscopy; electron spin resonance spectroscopy; enzyme structure; lipoxygenase; manganese; photosystem; structural biology; superoxide dismutase; tyrosine

We will employ advanced EPR methods to study the structure and function of the tetranuclear manganese cluster of the Photosystem II oxygen evolving complex. Multifrequency CW and pulsed EPR and ENDOR experiments will be used to characterize the physical and electronic structures of the S state intermediates (S0, S1, S2, S3) of the oxygen evolving cycle. ENDOR and ESEEM experiments using PSII particles incorporating 2H- and 19F-labelled tyrosine will determine the distance between the YZ tyrosine and the Mn cluster in oxygen-evolving PSII particles. ESEEM and multifrequency ENDOR experiments will investigate details of substrate, substrate analog, and inhibitor binding to the Mn cluster at different S states, as well as the proximity of essential cofactors Ca2+ and Cl-. The role of the 17, 23, and 33kDa extrinsic polypeptides in limiting access of larger substrate analogs and inhibitors to the Mn cluster will be explored. Other ESEEM and multifrequency ENDOR experiments will investigate the amino acid ligation of the cluster at various S states. Parallel mode and high frequency EPR, along with ESEEM and ENDOR, will be used to detect and characterize signals from Mn cluster assembly intermediates and cluster reduction products. Studies of synthetic Mn model clusters of known structure will allow us to correlate EPR/ENDOR derived properties with known structural elements. We will also characterize the structures of interesting Mn complexes that serve as "spectral models" for the PSII Mn cluster. Finally, we will target the mononuclear Mn enzymes, Mn superoxide dismutase and Mn lipoxygenase, and the dinuclear Mn enzyme, Mn catalase, for study with our advanced EPR methods.

我们将利用先进的EPR方法研究光系统II放氧复合体的四核锰簇的结构和功能。用多频连续波、脉冲EPR和Endor实验表征了S态中间体(S0、S1、S2、S3)的物理结构和电子结构。Endor和ESEEM实验使用含有2H和19F标记的酪氨酸的PSII颗粒，将确定放氧PSII颗粒中YZ酪氨酸和锰团簇之间的距离。ESEEM和多频Endor实验将研究底物、底物类似物和抑制剂在不同S状态下与Mn团簇结合的细节，以及基本辅因子Ca+和Cl-的接近程度。将探索17、23和33 kDa外源多肽在限制较大底物类似物和抑制剂对MN簇的访问中的作用。其他ESEEM和多频Endor实验将研究该团簇在不同S状态下的氨基酸连接。并行模式和高频EPR，以及ESEEM和Endor，将被用于检测和表征来自Mn团簇组装中间体和团簇还原产物的信号。对已知结构的合成锰模型簇的研究将使我们能够将EPR/Endor衍生性质与已知的结构元素关联起来。我们还将描述有趣的锰络合物的结构，这些络合物可以作为PSII锰团簇的“光谱模型”。最后，我们将以单核锰酶，锰超氧化物歧化酶和锰脂肪氧合酶，以及双核锰酶，锰过氧化氢酶为目标，用我们先进的EPR方法进行研究。