PULSED EPR STUDIES OF BIOLOGICAL MANGANESE CLUSTERS

生物锰簇的脉冲 EPR 研究

• 批准号: 2734736
• 负责人: R David Britt
• 金额: $ 15.73万
• 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 2001-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2734736
• 关键词: calcium ion; catalase; chloride ion; electron spin resonance spectroscopy; enzyme structure; manganese; metal complex; photosystem; synthetic protein; tyrosine

We propose to utilize pulsed EPR methods to study the structure and function of the tetranuclear Mn cluster of Photosystem II (PS II) of plant photosynthesis and the Mn catalase enzyme. Specifically, the techniques of electron spin echo envelope modulation (ESEEM) and electron spin echo - electron nuclear double resonance (ESE-ENDOR) will be utilized to detect nuclear spin transitions of magnetic nuclei within and in close proximity to these multinuclear Mn clusters. High frequency ESE-ENDOR will be utilized to measure the 55Mn spin transitions of the biological Mn clusters and of synthetic model compounds of known structure. Oriented PS ll membranes and single crystals of PS ll will be studied for enhanced resolution. These experiments will provide new knowledge about the structure of this essential catalytic site. The protein ligation to the Mn clusters in PS H and catalase will be explored. The binding of substrate and inhibitor molecules will be characterized. For the PS ll Mn cluster, experiments will be per- formed to characterize the roles of Ca2+ and Cl-, which are essential cofactors in the oxygen evolution chemistry. Experiments will be performed to test the hypothesis that photosynthetic oxygen evolution occurs with a metalloradical mechanism, involving both the Mn cluster and tyrosine Yz. Parallel polarization EPR signals will be used to detect integer spin signals of the Mn clusters.

我们建议使用脉冲EPR方法来研究其结构