INTERACTION OF SPIN LABELS WITH TRANSITION METALS

自旋标记与过渡金属的相互作用

• 批准号: 6489940
• 负责人: Gareth R Eaton
• 金额: $ 20.81万
• 依托单位: UNIVERSITY OF DENVER (COLORADO SEMINARY)
• 依托单位国家: 美国
• 财政年份: 1977
• 资助国家: 美国
• 起止时间: 1977-07-01 至 2004-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6489940
• 关键词: bacterial proteins; bioengineering /biomedical engineering; biophysics; chemical models; chemical structure; crystallization; dipole moment; electron spin resonance spectroscopy; free radicals; heavy metals; heme; intermolecular interaction; iron; magnetism; membrane channels; method development; molecular dynamics; myoglobin; nitrogen oxides; receptor; relaxation spectrometry; siderophores; statistics /biometry; structural biology; temperature

The overall goal of the proposed research is to develop, validate, and apply electron paramagnetic resonance (EPR) methodology for measuring distances in biological systems. EPR studies can be performed in disordered solids or in solutions and even in whole cells. EPR is particularly important for characterizing membrane-bound proteins that are difficult to crystallize. The sites to be studied by EPR can be naturally-occurring metal ions or radicals, or spin labels or metals attached at selected locations introduced by site-directed mutagenesis. Even a few measurements of longer distances can provide key information to define the three-dimensional structure of a large protein or assembly of proteins. The larger magnetic moment of an unpaired electron than of a nuclear spin permits measurement of longer distances by EPR than by nuclear magnetic resonance (NMR). The emphasis of the proposed research is on pulsed EPR methods to determine distances longer than about 20 Angstroms, which is approximately the upper limit for EPR methods based on continuous wave lineshapes. We propose to use the distance-dependent changes in electron spin relaxation rates to determine the distance between a rapidly relaxing electron spin such as iron(III) and a nitroxyl spin label. These methods will be calibrated with spin-labeled variants of metmyoglobin of known structure. The X-ray crystal structure of the iron transport protein, iron protein A, did not define the binding site of the iron siderophore, iron enterobactin. We propose to use our pulse techniques to determine the location of the iron binding site. Our model predicts that experiments at lower microwave frequency will permit measurements of longer distances than are accessible at 9.2 GHz and we propose to test that prediction by performing measurements at 2.5 GHz. Current pulsed EPR measurements of distances are performed at cryogenic temperatures. We will test the feasibility of measurements in fluid solution. For doubly spin-labeled samples of human carbonic anhydrase II, T4 lysozyme, and iron protein A we propose to develop and test pulsed methods to determine spin-spin distances greater than about 20 Angstroms.

拟议研究的总体目标是开发、验证和应用电子顺磁共振（EPR）方法来测量生物系统中的距离。 EPR 研究可以在无序固体或溶液中甚至整个细胞中进行。 EPR 对于表征难以结晶的膜结合蛋白尤其重要。 EPR 要研究的位点可以是天然存在的金属离子或自由基，也可以是通过定点诱变引入的附着在选定位置的自旋标签或金属。即使是一些较长距离的测量也可以提供关键信息来定义大型蛋白质或蛋白质组装的三维结构。不成对电子的磁矩比核自旋的磁矩大，因此 EPR 比核磁共振 (NMR) 能够测量更长的距离。拟议研究的重点是脉冲 EPR 方法，以确定超过约 20 埃的距离，这大约是基于连续波线形的 EPR 方法的上限。我们建议利用电子自旋弛豫率随距离的变化来确定快速弛豫电子自旋（例如铁（III））和硝酰基自旋标记之间的距离。这些方法将用已知结构的高铁肌红蛋白的自旋标记变体进行校准。铁转运蛋白（铁蛋白 A）的 X 射线晶体结构没有确定铁铁载体（铁肠杆菌素）的结合位点。我们建议使用脉冲技术来确定铁结合位点的位置。我们的模型预测，在较低微波频率下进行的实验将允许测量比在 9.2 GHz 下可达到的距离更长的距离，并且我们建议通过在 2.5 GHz 下执行测量来测试该预测。当前的脉冲 EPR 距离测量是在低温下进行的。我们将测试流体溶液中测量的可行性。对于人碳酸酐酶 II、T4 溶菌酶和铁蛋白 A 的双自旋标记样品，我们建议开发和测试脉冲方法以确定大于约 20 埃的自旋距离。

项目成果

Electron spin echo envelope modulation evidence for carbonate binding to iron(III) and copper(II) transferrin and lactoferrin.

碳酸盐与铁 (III) 和铜 (II) 转铁蛋白和乳铁蛋白结合的电子自旋回波包络调制证据。

• 发表时间: 1990
• 期刊: The Journal of biological chemistry
• 作者: Eaton,SS;Dubach,J;Eaton,GR;Thurman,G;Ambruso,DR
• 通讯作者: Ambruso,DR

Electron spin-lattice relaxation rates for high-spin Fe(III) complexes in glassy solvents at temperatures between 6 and 298 K.

6 至 298 K 温度下玻璃状溶剂中高自旋 Fe(III) 配合物的电子自旋晶格弛豫率。

• DOI: 10.1006/jmre.2000.2047
• 发表时间: 2000
• 期刊: Journal of magnetic resonance (San Diego, Calif. : 1997)
• 作者: Zhou,Y;Bowler,BE;Eaton,GR;Eaton,SS
• 通讯作者: Eaton,SS

Electron spin-lattice relaxation in radicals containing two methyl groups, generated by gamma-irradiation of polycrystalline solids.

含有两个甲基的自由基中的电子自旋晶格弛豫，由多晶固体的伽马辐射产生。

• DOI: 10.1016/s1090-7807(02)00013-7
• 发表时间: 2002
• 期刊: Journal of magnetic resonance (San Diego, Calif. : 1997)
• 作者: Harbridge,JamesR;Eaton,SandraS;Eaton,GarethR
• 通讯作者: Eaton,GarethR

Electron-electron spin-spin interaction in spin-labeled low-spin methemoglobin.

自旋标记的低自旋高铁血红蛋白中的电子-电子自旋-自旋相互作用。

• DOI: 10.1016/s0006-3495(95)80436-4
• 发表时间: 1995
• 期刊: Biophysical journal
• 影响因子: 3.4
• 作者: Budker,V;Du,JL;Seiter,M;Eaton,GR;Eaton,SS
• 通讯作者: Eaton,SS

Comparison of electron paramagnetic resonance methods to determine distances between spin labels on human carbonic anhydrase II.

比较电子顺磁共振方法以确定人碳酸酐酶 II 上自旋标记之间的距离。

• DOI: 10.1016/s0006-3495(01)76254-6
• 发表时间: 2001
• 期刊: Biophysical journal
• 影响因子: 3.4
• 作者: Persson,M;Harbridge,JR;Hammarström,P;Mitri,R;Mårtensson,LG;Carlsson,U;Eaton,GR;Eaton,SS
• 通讯作者: Eaton,SS