位置定向自旋标记——电子顺磁共振技术在蛋白质结构研究中的应用

Application of site-directed spin labeling combined with electron paramagnetic resonance to protein structure studies

位置定向的自旋标记（SDSL）技术结合电子顺磁共振（EPR）波谱技术成为检测蛋白质结构的有力工具。目前SDSL正经历快速发展的应用阶段。本文主要讨论SDSL-EPR技术在蛋白质二级和三级结构的检测中的应用。主要包括自旋标记物侧链易趋性（accessibility）和运动性的改变，膜蛋白位形图，静电势，膜蛋白在膜表面的位置定向，残基间距离以及时间分辨结构改变的研究。这些改变可以在毫秒和纳秒范围内得到检测，从而实现蛋白在行使功能时构象改变的检测。该方法对蛋白分子的大小没有限制，样品量可以很少，有时50-100皮摩尔（pmol）即可。所有这些特点使得SDSL可以在蛋白质结构和动力学研究中得到广泛应用。

Site-directed spin labeling （SDSL） combined with electron paramagnetic resonance （EPR） spectroscopy is a powerful tool for detecting structure of proteins. Application of SDSL is experiencing a stage of rapid evolution. In this review the application of SDSL-EPR to determining secondary and tertiary structure of proteins, such as the changes in the mobility and solvent accessibility of the spin labeled side chains, membrane protein topography, electrostatic potentials, and the orientation of proteins at membrane surfaces, inter-residue distances and time-resolved changes in protein is illustrated. These events can be monitored in the millisecond or nanosecond time-scale, making it possible to follow structural changes during functioning. There is no upper limit to the size of proteins investigated, and sometimes only 50 - 100 picomoles（pmol） of protein ore required. These features make site-directed spin labeling an attractive approach for the study of structure and dynamics of a wide range of systems.