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Site‐Specific Dynamics of β‐Sheet Peptides with D Pro–Gly Turns Probed by Laser‐Excited Temperature‐Jump Infrared Spectroscopy
Author(s) -
Popp Alexander,
Scheerer David,
Chi Heng,
Keiderling Timothy A.,
Hauser Karin
Publication year - 2016
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201501089
Subject(s) - microsecond , temperature jump , chemistry , beta sheet , spectroscopy , folding (dsp implementation) , infrared spectroscopy , turn (biochemistry) , raman spectroscopy , crystallography , peptide , molecular dynamics , infrared , stereochemistry , computational chemistry , physics , organic chemistry , optics , biochemistry , electrical engineering , quantum mechanics , engineering
Turn residues and side‐chain interactions play an important role for the folding of β‐sheets. We investigated the conformational dynamics of a three‐stranded β‐sheet peptide ( D P D P) and a two‐stranded β‐hairpin (WVYY– D P) by time‐resolved temperature‐jump ( T ‐jump) infrared spectroscopy. Both peptide sequences contain D Pro–Gly residues that favor a tight β‐turn. The three‐stranded β‐sheet (Ac‐VFITS D PG KTYTEV D PG OKILQ–NH 2 ) is stabilized by the turn sequences, whereas the β‐hairpin (SWTVE D PG KYTYK–NH 2 ) folding is assisted by both the turn sequence and hydrophobic cross‐strand interactions. Relaxation times after the T ‐jump were monitored as a function of temperature and occur on a sub‐microsecond time scale, D P D P being faster than WVYY– D P. The Xxx– D Pro tertiary amide provides a detectable IR band, allowing us to probe the dynamics site‐specifically. The relative importance of the turn versus the intrastrand stability in β‐sheet formation is discussed.