"Light triggered β-hairpin folding and unfolding"T. E. Schrader, W. J. Schreier, T. Cordes, F. O. Koller, G. Babitzki, R. Denschlag, C. Renner, S.-L. Dong, M. Löweneck, L. Moroder, P. Tavan, and W. Zinth
Proc. Natl. Acad. Sci. USA 104 (2007) 15729-15734.
A light-switchable peptide is transformed with ultrashort pulses from a β-hairpin to an unfolded hydrophobic cluster and vice versa.
The structural changes are monitored by mid-IR probing. Instantaneous normal mode analysis with a Hamiltonian combining density functional theory with molecular mechanics is used to interpret the absorption transients. Illumination of the β-hairpin state triggers an unfolding reaction that visits several intermediates and reaches the unfolded state within a few nanoseconds. In this unfolding reaction to the equilibrium hydrophobic cluster conformation, the system does not meet significant barriers on the
free-energy surface. The reverse folding process takes much longer because it occurs on the time scale of 30 μs. The folded state has
a defined structure, and its formation requires an extended search for the correct hydrogen-bond pattern of the β-strand.
BMO authors (in alphabetic order):
Photoswitchable model peptides and their conformational dynamics
Peptide and protein folding
QM/MM hybrid descriptions of solutes in complex solvents