Atomic force microscopic observation of surface structure of purified protein molecules in vitro
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维普
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目的 以课题组纯化获得的蛋白样本为观察对象,对比原子力显微镜(atomic force microscope,AFM)及扫描电子显微镜(scanning electron microscope,SEM)的观察结果,并总结AFM观察生物大分子的主要问题和解决方法.方法 将蛋白样本使用PBS稀释至15 nmol·L-1,分别固定于载玻片、硅片和云母片上烘干,制成固相观察样本,SEM样本在观察前镀铂,使用AFM及SEM观察蛋白质表面结构,计算样本高度,对比结果差异.结果 带正电的蛋白样本在观察时由于AFM探针的斥力会向右偏移;云母片能很好地消除蛋白正电荷从而避免样本移动;PBS能为蛋白样本提供良好的稳定环境,但PBS盐结晶会干扰探针运行和成像清晰度;SEM样本需要镀铂后观察,无法达到AFM的精度.结论 使用AFM和SEM均可在体外环境直接观察蛋白质结构,AFM能提供更高精度的观察结果;在蛋白样本稳定性允许的情况下首选超纯水为溶剂载体,乙醇等挥发性液体也可作为溶剂载体,AFM的应用可为药理学生物大分子互作研究提供一新途径.
Aim To compare the observation results of atomic force microscopy(AFM)and scanning electron microscopy(SEM),and to summarize the main problems and solutions of AFM in observing biological macromolecules,using the observa-tion subjects of protein samples purified by our research group.Methods The protein samples were diluted to 15 nmol·L-1 with PBS,fixed on glass slides,silicon wafers,and mica sheets,dried,and made into solid-phase observation samples.SEM sam-ples were plated with platinum before observation.The surface structures of proteins were observed using AFM and SEM,sample heights were calculated,and differences in results were com-pared.Results Protein samples with positive charges tended to shift to the right during observation due to the repulsion of the AFM probe;mica sheets could effectively eliminate the positive charge of proteins to avoid sample movement;PBS provided a stable environment for protein samples,but the crystallization of PBS salts interfered with probe operation and imaging clarity;SEM samples needed to be plated with platinum before observa-tion and could not achieve the precision of AFM.Conclusions Both AFM and SEM can directly observe protein structures in vitro,with AFM providing higher precision results;when protein sample stability permits,ultrapure water is preferred as the sol-vent carrier,and volatile liquids such as ethanol can also serve as solvent carriers.The application of AFM offers a new approach for pharmacological studies on interactions between biological macromolecules.
atomic force microscopyscanning electron micro-scopereceptor structureprotein structures in vitroultrastruc-turemica carrier
维普
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