New computing technology enables researchers to see clearer images of biomolecules by breaking the usual resolution limits of the atomic force microscope (AFM). The method offers a new way of obtaining high quality structural data on biological compounds such as proteins in their natural environment.
While X-ray crystallography and cryo-electron microscopy allow researchers to image biomolecules at the atomic level, these techniques are based on samples that have been crystallized or frozen at ultra-cold temperatures, which can alter the natural shapes of the molecules. With AFM, molecules can be examined under normal physiological conditions, but the images are not as sharp as with the other methods.
A team led by Simon Schuering from Cornell University, USA, has now found a way to improve the quality of AFM images. The strategy, inspired by methods already used in optical microscopy, uses a localization image reconstruction algorithm to process data from multiple scans of individual molecules. It can even be used retrospectively to reveal new details hidden in old AFM data.
The researchers demonstrate the technique and explain that they “could increase the resolution beyond the limits set by the tip radius and dissolve individual amino acid residues on soft protein surfaces under native and dynamic conditions”.
Highlighting another benefit of the technique, Scheuring said on the Weill Cornell Medicince website that using high-resolution AFM to monitor individual molecules as they move between confirmations could help “avoid potentially misleading results when averaging of data from many molecules can occur “.