Light-triggered β-hairpin folding and unfolding

• DOI: 10.1073/pnas.0707322104
• Publication Date: 2007-09-25T00:59:03Z
• Authors: Tobias E. Schrader; Wolfgang J. Schreier; Thorben Cordes; Florian O. Koller; Galina Babitzki; Robert Denschlag; Christian Renner; Markus Löweneck; Shou-Liang Dong; Luis Moroder; Paul Tavan; Wolfgang Zinth
• Keywords: Folding (DSP implementation)

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 Hamiltonian combining density functional theory molecular mechanics used interpret the absorption transients. Illumination of state triggers unfolding reaction that visits several intermediates reaches within few nanoseconds. In this equilibrium conformation, system does not meet significant barriers on free-energy surface. reverse folding process takes much longer because it occurs time scale 30 μs. folded has defined structure, its formation requires extended search for correct hydrogen-bond pattern β-strand.