Untersuchungen zum Mechanismus der beta-Hairpin Faltung mittels Kombination von Fluoreszenzspektroskopie und Computersimulation
Final Report Abstract
This project helped establish that the fluorescence quenching process by photoinduced electron transfer between oxazine fluorophores and Tryptophan serves as reliable reporter for conformational dynamics of polypeptides. The signal that is observed originates from fluctuating fluorescence emission mediated by fluorescence quenching interactions that are based on photoinduced-electron transfer (PET). The requirement that fluorophore and quencher need van-der-Waals contact for efficient quenching to occur allows monitoring of short range distance and related structure variations on time scales down to a few nanoseconds using fluorescence correlation spectroscopy (PET-FCS). Precise measurements of end-to-end contact formation rates in unstructured glycine-serine peptides of various lengths, at various solvent viscosities, as function of temperature, and in the presence of molecular crowding agents yielded further insights in conformational dynamics of unstructured polypeptides. We characterized the energetic contribution of the reporter system due to complex formation between dye and tryptophan and found a strong influence on β-hairpin folding in labeled β-hairpins. We could further show that comparative measurements allow quantitative characterization of heterogeneous polypeptide sequences, including β-hairpin and β-turn sequences. The combination of PET-FCS experiments and molecular dynamics computer simulations gave insights into the role that hydrogen bonding between backbone atoms plays for unstructured polypeptide chains.
Publications
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Dynamics of unfolded polypeptide chains in crowded environment studied by fluorescence correlation spectroscopy. J. Mol. Biol. 2007, 365, (3), 856-69
Neuweiler, H.; Löllmann, M.; Doose, S.; Sauer, M.
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Fluorescence quenching by photoinduced electron transfer: a reporter for conformational dynamics of macromolecules. ChemPhysChem 2009, 10, (9-10), 1389-98
Doose, S.; Neuweiler, H.; Sauer, M.
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Dissertation, Fakultät für Physik, Universität Bielefeld, 2010
Marc Löllmann
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Hydrogen-bond driven loop-closure kinetics in unfolded polypeptide chains. PLoS computational biology 2010, 6, (1), e1000645
Daidone, I.; Neuweiler, H.; Doose, S.; Sauer, M.; Smith, J. C.
