title: Site-Specific Dynamics of β-Sheet Peptides with (D) Pro-Gly Turns Probed by Laser-Excited Temperature-Jump Infrared Spectroscopy.
abstract: 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) PGKTYTEV(D) PGOKILQ-NH2 ) is stabilized by the turn sequences, whereas the β-hairpin (SWTVE(D) PGKYTYK-NH2 ) 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.
authors.affiliation: Department of Chemistry, University of Konstanz, 78457, Konstanz, Germany), Fax: (+49) 7531-88-3139.
authors.forename: Alexander
authors.initials: A
authors.lastname: Popp
authors.affiliation: Department of Chemistry, University of Konstanz, 78457, Konstanz, Germany), Fax: (+49) 7531-88-3139.
authors.forename: David
authors.initials: D
authors.lastname: Scheerer
authors.affiliation: Department of Pharmacy and Health Management, Jiangsu Food and Pharmaceutical Science College, 4 E. Meicheng Rd., Huai'an, Jiangsu Province, 223003, P. R. China.
authors.forename: Heng
authors.initials: H
authors.lastname: Chi
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor St., Chicago, Illinois, 60607-7061, USA.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Keiderling
authors.affiliation: Department of Chemistry, University of Konstanz, 78457, Konstanz, Germany), Fax: (+49) 7531-88-3139. Karin.Hauser@uni-konstanz.de.
authors.forename: Karin
authors.identifier: 0000-0003-0546-9038
authors.initials: K
authors.lastname: Hauser
mesh_terms: D005998:Glycine / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D007834:Lasers; D010455:Peptides / Q000737:chemistry*; D011392:Proline / Q000737:chemistry*; D013055:Spectrophotometry, Infrared / Q000379:methods*; D013696:Temperature
chemical_list: D010455:Peptides; D011392:Proline; D005998:Glycine
keywords: IR spectroscopy; conformational dynamics; peptides; protein folding; temperature jump