title: A close look at proteins: submolecular resolution of two- and three-dimensionally folded cytochrome c at surfaces.
abstract: 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.
authors.affiliation: Max-Planck-Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
authors.forename: Zhitao
authors.initials: Z
authors.lastname: Deng
authors.forename: Nicha
authors.initials: N
authors.lastname: Thontasen
authors.forename: Nikola
authors.initials: N
authors.lastname: Malinowski
authors.forename: Gordon
authors.initials: G
authors.lastname: Rinke
authors.forename: Ludger
authors.initials: L
authors.lastname: Harnau
authors.forename: Stephan
authors.initials: S
authors.lastname: Rauschenbach
authors.forename: Klaus
authors.initials: K
authors.lastname: Kern
mesh_terms: D045304:Cytochromes c / Q000737:chemistry / Q000378:metabolism*; D020527:Microscopy, Scanning Probe; D017510:Protein Folding; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D045304:Cytochromes c