Folding of a heterogeneous β-hairpin peptide from temperature-jump 2D IR spectroscopy
Author(s)Jones, Kevin C.; Peng, C. S.; Tokmakoff, A.
MetadataShow full item record
We provide a time- and structure-resolved characterization of the folding of the heterogeneous β-hairpin peptide Tryptophan Zipper 2 (Trpzip2) using 2D IR spectroscopy. The amide I′ vibrations of three Trpzip2 isotopologues are used as a local probe of the midstrand contacts, β-turn, and overall β-sheet content. Our experiments distinguish between a folded state with a type I′ β-turn and a misfolded state with a bulged turn, providing evidence for distinct conformations of the peptide backbone. Transient 2D IR spectroscopy at 45 °C following a laser temperature jump tracks the nanosecond and microsecond kinetics of unfolding and the exchange between conformers. Hydrogen bonds to the peptide backbone are loosened rapidly compared with the 5-ns temperature jump. Subsequently, all relaxation kinetics are characterized by an observed 1.2 ± 0.2-μs exponential. Our time-dependent 2D IR spectra are explained in terms of folding of either native or nonnative contacts from a common compact disordered state. Conversion from the disordered state to the folded state is consistent with a zip-out folding mechanism.
DepartmentMassachusetts Institute of Technology. Department of Chemistry
Proceedings of the National Academy of Sciences
National Academy of Sciences (U.S.)
Jones, K. C., C. S. Peng, and A. Tokmakoff. “Folding of a heterogeneous -hairpin peptide from temperature-jump 2D IR spectroscopy.” Proceedings of the National Academy of Sciences 110, no. 8 (February 19, 2013): 2828-2833.
Final published version