IMPROVEMENTS IN ATOMIC-FORCE MICROSCOPY PROTOCOLS FOR IMAGING FIBROUSPROTEINS

Myosin is one of the main structural components of biological systems and due to its unique shape is easily recognized. This makes it an ide al subject for the development of preparation techniques for atomic fo rce microscopy (AFM) of other fibrous proteins. Myosin. prepared using a glycerol/ mica deposition technique, has been imaged using contact mode as well as the newly developed tapping mode AFM in liquid. Improv ed resolution using the tapping mode under propanol has allowed us to resolve the similar to 7 nm half-repeat of the coiled-coil a-helix of the myosin tail. Myosin has also been imaged under aqueous conditions. We have also imaged the elastic muscle protein, titin, prepared in a similar fashion. Titin is easily deformed, making contact mode imaging in aqueous conditions a destructive process. However, by using tappin g mode AFM in liquid it has been possible to image titin under aqueous conditions without damage to the molecules at a resolution equivalent to contact mode in propanol. Using tapping mode AFM in liquid it may be possible to follow protein interactions. (C) 1996 American Vacuum S ociety.