Dresden 2006 – wissenschaftliches Programm

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AKB: Biologische Physik

AKB 19: Proteins

AKB 19.1: Vortrag

Mittwoch, 29. März 2006, 16:00–16:15, ZEU 260

Origin of the twisting in β-sheet structures — •Joel Ireta and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195, Berlin

The potential-energy surface of a single-strand β-sheet is studied using density-functional theory in the Perdew, Burke, and Ernzerhof approximation to the exchange-correlation functional. Infinite polyalanine and polyglycine chains are used to model the single-strand β-sheet structure. The potential-energy surface of polyalanine is found to be asymmetric with respect to twisting. This leads to a left-handed twist of few degrees in the structure. However for polyglycine, the potential-energy surface is found to be symmetric. We find that the asymmetry in the potential-energy surface of polyalanine can not be solely attributed to repulsive interactions between the side group, which is absent in polyglycine, and the helix backbone but to the pyramidalization of the nitrogen atom in the peptide bond. Symmetry with respect to twisting in the potential-energy surface of polyalanine is induced when nitrogen pyramidalization is avoided. In a survey throughout the crystallized structures of proteins listed in the protein data bank, we find indeed a left-handed twisting in the β-sheet conformations.