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MO: Molekülphysik

MO 12: Biomolecules I

MO 12.6: Vortrag

Freitag, 4. März 2005, 15:30–15:45, HU 2091

Analysis of isolated extended beta-sheet model systems in the gas phase — •M. Gerhards, H. Fricke, and A. Gerlach — Institut für Physikalische Chemie I, H.-Heine Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf

Proteins have a well defined three dimensional structure which is essential for their function. An important secondary structure element is the β-sheet. We investigate isolated peptides and peptide clusters with β-sheet binding motifs in molecular beam experiments. The chosen combined IR and UV spectroscopic methods are mass-, isomer-, and state-selective yielding an IR spectrum for each individual isomer. With our new developed nanosecond narrow band-width and high power IR laser we are able to obtain spectra in the complete region from 1000 to 4000 cm-1. By investigating isolated clusters we would like to answer the questions (a) what are the driving forces of peptides to form either inter- or intramolecular hydrogen-bonds and (b) how strong are the individual hydrogen bonds of a β-sheet structure. Our group has started with the investigations of smaller β-sheet models containing clusters of protected amino acids (phe, trp, tyr). We now present results both on the larger isolated tri- and tetrapeptides and on the extended β-sheet models formed by the clusters of the tri- and tetrapeptides. These are the largest peptide aggregates investigated up to now with the chosen highly selective spectroscopic methods.