电子顺磁共振在生物，化学中的应用（从系综到单分子）

发布时间：2018-12-10 09:04

【摘要】：电子顺磁共振(ESR),是一种强大的研究含有未成对物质电子结构和动力学信息的谱学方法。目前,ESR技术在生物化学领域中得到了广泛应用,如解析含有过渡金属离子的单分子磁体的构象与功能,金属蛋白酶结构和催化机理,自由基相关的电子传递过程,稳定自由基的结构与动力学等。由于探测手段的限制,传统顺磁共振一般需要有109个电子自旋的系综样品才能探测到信号。近年来,随着技术手段的提升以及对微观世界探索的深入,人们逐渐向单分子水平直接观测迈进。与之相随,磁共振领域也在向微观磁共振发展,目前,基于NV的微观自旋磁共振技术日趋成熟,甚至达到了单分子单自旋的探测水平。我们正在通过这一新兴的磁共振技术,探索其在生物体系中的应用。我们的目标是在研究生物体系系综磁共振效应的同时,能够通过基于NV的磁探测技术,将自旋信号逐个提取出来,解析其结构与动力学信息,既把握其整体效应,又不忘其个体特征。我们围绕这一目标,展开了相关科研工作。本论文主要介绍我们完成的3个相关工作：1.在系综平台上,我们探索了漆酶催化邻苯二酚的反应机理。我们发现了漆酶可以导致酚类物质的开环,而且该过程是一自由基反应过程,通过顺磁共振谱学方法,我们推测出了一个可能的反应途径。通过机理的研究,我们推断漆酶可能会导致棉酚脱毒,而实验证实确实有脱毒效应。这可能会对拓展棉花的应用提供很大的帮助。2.在系综平台上,我们完成了苯乙炔及其衍生物和亚磷酸二乙酯反应机理的研究。我们发现了在铜铁双金属体系下,苯乙炔和亚磷酸二乙酯可以合成p-羰基磷酸酯。通过ESR自旋捕获技术,确认了其自由基反应途径。这是一高效环保的化学反应,产物在化学合成领域,生物学领域均有应用前景。3.我们完成了系综探测氮氧自由基标记的蛋白质,了解了其系综下性质的同时,我们利用基于NV的磁共振技术,首个观测到室温下的单分子的电子顺磁谱图,并就其单个分子的ESR信号的特征做了深入分析。这是电子顺磁共振从系综水平跨到单分子水平的重要标志性实验。并且已经初步应用到了生物体系中,解析了其部分结构和动力学信息。
[Abstract]:Electron paramagnetic resonance (EPR) (ESR), is a powerful spectroscopic method for studying the electronic structure and kinetic information of unpaired matter. At present, ESR technology has been widely used in the field of biochemistry, such as the analysis of the conformation and function of monolayer magnets containing transition metal ions, the structure and catalytic mechanism of metalloproteinases, and the electron transport processes related to free radicals. Structure and kinetics of stable free radicals. Conventional paramagnetic resonance usually requires 109 electron spin ensemble samples to detect signals due to the limitation of detection methods. In recent years, with the improvement of technology and the exploration of microcosm, people are moving towards direct observation at single molecule level. Along with it, the magnetic resonance field is also developing to the micro magnetic resonance. At present, the micro spin magnetic resonance technology based on NV is becoming more and more mature, and even reaches the level of single molecule single spin detection. We are exploring its application in biological systems through this new magnetic resonance technology. Our goal is to study the ensemble magnetic resonance effect of biological systems, and at the same time, we can extract the spin signal one by magnetic detection based on NV, and analyze its structure and dynamics information. And not forget its individual characteristics. We have carried out related scientific research work around this goal. This paper mainly introduces three related works that we have accomplished: 1. On the ensemble platform, we explored the mechanism of laccase catalyzed catechol reaction. We found that laccase can lead to the ring opening of phenols, and this process is a free radical reaction process. By means of paramagnetic resonance spectroscopy, we speculate a possible reaction pathway. Through the study of mechanism, we infer that laccase may lead to gossypol detoxification, and it is proved that laccase does have detoxification effect. This may provide a great help to expand the application of cotton. 2. The reaction mechanism of phenylacetylene and its derivatives with diethyl phosphite was studied on the ensemble platform. It was found that p-carbonyl phosphate could be synthesized from phenylacetylene and diethyl phosphite in copper-iron bimetallic system. The free radical reaction pathway was confirmed by ESR spin trapping technique. This is a highly efficient and environmentally friendly chemical reaction, the products in the chemical synthesis field, biological field have application prospects. 3. We have completed the ensemble detection of nitrogen-oxygen free radical labeled proteins, and we have obtained the first electron paramagnetic spectra of a single molecule at room temperature using magnetic resonance technique based on NV. The characteristics of the ESR signal of its single molecule are analyzed in depth. This is an important landmark experiment of electron paramagnetic resonance from ensemble level to monolayer level. And it has been applied to biological system, and some structural and kinetic information have been analyzed.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O482.533

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