Single proteins observed by atomic force microscopy

Here we discuss the experimental approaches that have allowed high resolution atomic force microscopy (AFM) imaging, and review results that show AFM to be of great interest for biologists, AFM allows single proteins to be imaged under physiologically relevant conditions. The exceptional signal-to- noise ratio and resolution of AFM topographs enables the oligomerization state and characteristic substructures of individual proteins to be resolved. Several examples demonstrate the capabilities of AFM to directly observe single proteins, and their conformational changes, to study protein- protein interactions and to follow the assembly of membrane proteins. We consider the AFM techniques that have allowed high resolution imaging, and review results that show AFM to be a powerful method to analyze biological processes at the level of single molecules