A close look at proteins: submolecular resolution of two- and three-dimensionally folded cytochrome c at surfaces.

Zhitao Deng, Nicha Thontasen, Nikola Malinowski, Gordon Rinke, Ludger Harnau, Stephan Rauschenbach, Klaus Kern

Max-Planck-Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.

Nano letters 2012 May 9

filter terms:

Imaging of individual protein molecules at the single amino acid level has so far not been possible due to the incompatibility of proteins with the vacuum environment necessary for high-resolution scanning probe microscopy. Here we demonstrate electrospray ion beam deposition of selectively folded and unfolded cytochrome c protein ions on atomically defined solid surfaces in ultrahigh vacuum (10(-10) mbar) and achieve unprecedented resolution with scanning tunneling microscopy. On the surface folded proteins are found to retain their three-dimensional structure. Unfolded proteins are observed as extended polymer strands displaying submolecular features with resolution at the amino acid level. On weakly interacting surfaces, unfolded proteins refold into flat, irregular patches composed of individual molecules. This suggests the possibility of two-dimensionally confined folding of peptides of an appropriate sequence into regular two-dimensional structures as a new approach toward functional molecular surface coatings.

Citation

Zhitao Deng, Nicha Thontasen, Nikola Malinowski, Gordon Rinke, Ludger Harnau, Stephan Rauschenbach, Klaus Kern. A close look at proteins: submolecular resolution of two- and three-dimensionally folded cytochrome c at surfaces. Nano letters. 2012 May 9;12(5):2452-8