【摘要】 电子顺磁共振是唯一能原位、无损地直接跟踪未配对电子及其动态传递的物理方法.本文简要综述了该方法在线粒体呼吸链研究中的应用,并探讨和展望了基于金刚石氮-空位色心传感器的单分子磁共振的应用.更多还原

【Abstract】 Aerobic respiration is the indispensable physiology of higher organism living on earth, since the required energy for biological activities is supplied mainly by this metabolism. It is well established that mitochondria plays an important role in converting the stable chemical energy stored in foods into the active and utilizable energy supplying to life activities. Upon the process, the energy conversion is carried out by the respiratory electron transport chain, which consists of five distinct and coupled protein complexes（termed complex Ⅰ-Ⅴ） embedded in the mitochondria intima. Among them, complex Ⅰ（NADH-ubiquinone oxidoreductase）, Ⅲ（cytochrome bc1） and Ⅳ（cytochrome c oxidase） are the electron-coupled proton-pumping enzymes. Except for the complex Ⅴ（i.e., ATP synthase）, each complex has several redox cofactors to promote the electron transfer within themselves, and the transfer from complex Ⅰ and Ⅱ to complex Ⅲ is shuttled by membrane-embedded ubiquinones, from complex Ⅲ to Ⅳ by the soluble cytochrome c. When the reductive electron is donated by the initial donors NADH or FADH2 to the final acceptor molecular oxygen O₂, a transmembrane proton motive force is formed simultaneously. The latter is the driving force for the ATP synthesis via ATP synthase with a ratio of three protons per ATP. All the aforementioned processes are also known as oxidative phosphorylation, and the arrangement of the electron carriers therein is called as respiratory electron transport chain. In the stepwise electron relay, these carriers undergo the redox changes, giving rise to the respective paramagnetic and diamagnetic spin states. These single-electron relays are prone to the electron paramagnetic resonance spectroscopy（EPR）, which is a powerful and noninvasive technique to monitor the unpaired electron in situ. As shown in the overwhelming literatures, EPR technique has been adopted to reveal the electron transfer pathway in different biological activities. Herein, the application of EPR to study the dynamic electron transfer in mitochondria is reviewed briefly. However, this conventional application required rather high concentration of the active center at a level of 1-10μmol/L. Actually, most of the intermediates of the electron carriers are very active and short-life. In the human body, only a few tissues can accumulate such required concentration of paramagnetic substances, e.g., in blood, heart and liver. For the past decade, a more sensitive single-molecule magnetic resonance technique based on the nitrogen-vacancy（NV） center of diamond has been developing dramatically. In principle, this advanced EPR technique requires the less sample or concentration, even down to the single biomolecule, and provides the time-resolved dynamic information. Lately, the studies of single-biomolecule EPR at room temperature or in aqueous solution have been reported consecutively in single protein（MAD2/mitotic arrest deficient-2） and single DNA（tethered DNA duplexes）. Finally, a perspective of single-biomolecule magnetic resonance technique is given for the further study on mitochondrion and relative physiological activities. The single molecule EPR technique is also helpful to unveil the other specific information of biological processes, for example, drug screening, personalized medicine and other major applications.更多还原