Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 67: Competition for the Gerhard Ertl Young Investigator Award

O 67.4: Talk

Thursday, March 14, 2013, 12:00–12:30, H45

Controlling the Conformation of Peptides and Proteins on Solid Surfaces in Ultrahigh Vacuum — •Stephan Rauschenbach — Max-Planck-Institute for Solid State Reseach, Stuttgart

The hierarchical self-assembly of functional proteins through folding is a versatile and robust approach to generate functional nanoscale structures. It can, however, not be mimicked outside of biological systems.

We developed an electrospray ion beam deposition (ES-IBD) system capable of depositing nonvolatile molecules including proteins and polypeptides on surfaces in ultrahigh vacuum (UHV). In this environment we study their structure and electronic properties with resolution at the atomic level using scanning tunneling microscopy (STM).

We show that the structure of polypeptides adsorbed on a surface can be controlled on several length scales, using features unique to ES-IBD. Bradykinin, a short peptide of 9 amino acids (AA) folds into an equilibrium structure, influenced by the molecule-substrate interaction. Long polypeptide chains (unfolded cytochrome-c, 104 AA) do not reach an thermal equilibrium, but instated fold randomly, perfectly following polymer statistics in two dimensions (2d). In this case, ES-IBD allows us to select the mechanical properties of the gas phase ion before deposition and steer the structure on the surface between extended chains for high charge states and refolded 2d-random coils for low charge states.

This result shows that ES-IBD combined with high resolution UHV STM, opens the door to conformational control of 2d polypeptides and its application to rationally fold functional nanostructures at surfaces.