Soft X-ray Magnetic Circular Dichroism of Metalloproteins

金属蛋白的软X射线磁圆二色性

• 批准号: 9107312
• 负责人: Stephen Cramer
• 金额: $ 34.95万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-01-01 至 1994-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9107312&HistoricalAwards=false
• 关键词: Soft; ray; Magnetic; Circular; Dichroism

X-ray magnetic circular dichroism (XMCD) is a new experimental technique with tremendous potential for site-specific characterization of metals in clusters and complex proteins. Dr. Cramer proposes to conduct the first-ever XMCD measurements on carefully selected paramagnetic transition metal complexes, and to compare the experimental results with recently developed theoretical simulation programs. XMCD experiments will then be conducted on small proteins with known metal sites, and the results compared with data from other methods such as Mossbauer and EPR. With the experimental and theoretical basis of XMCD established, he will apply the technique to magnetic and structural questions about metal centers in the metalloenzymes nitrogenase, hydrogenase, and photosystem II. To conduct these experiments, he will employ circularly-polarized soft x-rays emitted as synchrotron radiation from electron storage rings such as the National Synchrotron Light Source. Samples will be placed in the strong magnetic field of a superconducting magnet. Photoabsorption will be measured directly by the transmission method on thin films, and indirectly using sample photocurrent or fluorescence detection techniques. Site-specific characterization of metals in nitrogenase, hydrogenase, and photosystem II will allow better understanding and synthetic modelling of their important catalytic activities. The development of this new technique will also provide the bioinorganic community with a new tool for magnetic and site- specific characterization, and the XMCD techniques will be generally applicable to nearly all paramagnetic transition metal complexes.

X射线磁性圆二色谱(XMCD)是一种新的实验技术，在团簇和复杂蛋白质中金属的位置特异性表征方面具有巨大的潜力。克雷默博士建议首次对精心挑选的顺磁性过渡金属络合物进行XMCD测量，并将实验结果与最近开发的理论模拟程序进行比较。XMCD实验将在具有已知金属位点的小蛋白质上进行，并将结果与穆斯堡尔和EPR等其他方法的数据进行比较。在建立了XMCD的实验和理论基础后，他将把这项技术应用于关于金属酶固氮酶、氢酶和光系统II中金属中心的磁性和结构问题。他将使用圆偏振软X射线，作为同步辐射从电子存储环，如国家同步辐射光源。样品将被放置在超导磁体的强磁场中。光吸收将直接通过透射法在薄膜上测量，并使用样品光电流或荧光检测技术间接测量。对固氮酶、氢酶和光系统II中的金属进行特定部位的表征将有助于更好地理解和模拟它们的重要催化活性。这一新技术的发展也将为生物无机界提供一种新的磁性和位置特异性表征工具，XMCD技术将普遍适用于几乎所有顺磁性过渡金属配合物。