Müller D J, Fotiadis D, Scheuring S, Müller S A, Engel A
M.E. Muller-Institute for Microscopic Structural Biology, Biozentrum, University of Basel, Basel, Switzerland.
Biophys J. 1999 Feb;76(2):1101-11. doi: 10.1016/S0006-3495(99)77275-9.
To achieve high-resolution topographs of native biological macromolecules in aqueous solution with the atomic force microscope (AFM) interactions between AFM tip and sample need to be considered. Short-range forces produce the submolecular information of high-resolution topographs. In contrast, no significant high-resolution information is provided by the long-range electrostatic double-layer force. However, this force can be adjusted by pH and electrolytes to distribute the force applied to the AFM tip over a large sample area. As demonstrated on fragile biological samples, adjustment of the electrolyte solution results in a local reduction of both vertical and lateral forces between the AFM tip and proteinous substructures. Under such electrostatically balanced conditions, the deformation of the native protein is minimized and the sample surface can be reproducibly contoured at a lateral resolution of 0.6 nm.
要使用原子力显微镜（AFM）获得水溶液中天然生物大分子的高分辨率形貌图，需要考虑AFM探针与样品之间的相互作用。短程力产生高分辨率形貌图的亚分子信息。相比之下，长程静电双层力不会提供显著的高分辨率信息。然而，这种力可以通过pH值和电解质进行调节，以便将施加在AFM探针上的力分布在较大的样品区域。正如在脆弱的生物样品上所展示的那样，调节电解质溶液会导致AFM探针与蛋白质亚结构之间的垂直力和侧向力局部降低。在这种静电平衡条件下，天然蛋白质的变形最小化，并且可以以0.6纳米的横向分辨率对样品表面进行可重复的轮廓描绘。
