Ellis D J, Berge T, Edwardson J M, Henderson R M
Department of Pharmacology, University of Cambridge, United Kingdom.
Microsc Res Tech. 1999 Mar 1;44(5):368-77. doi: 10.1002/(SICI)1097-0029(19990301)44:5<368::AID-JEMT9>3.0.CO;2-K.
The origin of contrast in atomic force microscopy (AFM) lies in the probe's response to forces between itself and the sample. These forces most commonly result from changes in height as the tip is scanned over the surface, but can also originate in properties inherent in the sample. These have been exploited as further means of contrast and have spawned an array of similar imaging techniques, such as chemical force microscopy, magnetic force microscopy, and frictional force microscopy. All of these techniques use AFM as an extremely sensitive gauge to map forces at discrete sites on the surface. A natural extension of this approach is to map forces in an array, in order to create a force map. AFM can be used in aqueous or fluid environments, thus allowing the exploration of forces in biological systems under physiologically relevant conditions. By immobilizing one half of an interacting pair of proteins onto the tip and the other half onto the substrate, it is possible to investigate the electrostatic and hydrophobic interactions between them. We employed these techniques to examine the interaction between a pair of proteins of known affinity that are involved in exocytosis (NSF and alpha-SNAP) and separately to demonstrate how two-dimensional force mapping can be applied to the nuclear envelope to identify nuclear pore complexes.
原子力显微镜（AFM）中的对比度起源于探针自身与样品之间作用力的响应。这些力最常见的是在探针扫描样品表面时由于高度变化而产生的，但也可能源于样品固有的特性。这些特性已被用作进一步的对比度手段，并催生了一系列类似的成像技术，如化学力显微镜、磁力显微镜和摩擦力显微镜。所有这些技术都将AFM用作极其灵敏的测量工具，以绘制表面离散位置处的力。这种方法的自然延伸是绘制阵列中的力，以创建力图谱。AFM可用于水性或流体环境，从而能够在生理相关条件下探索生物系统中的力。通过将一对相互作用蛋白质中的一半固定在探针上，另一半固定在基底上，可以研究它们之间的静电和疏水相互作用。我们运用这些技术来研究参与胞吐作用的一对已知亲和力的蛋白质（NSF和α-SNAP）之间的相互作用，并分别展示二维力图谱如何应用于核膜以识别核孔复合体。
