title: Residual native structure in a thermally denatured beta-hairpin.
abstract: We investigate the thermal denaturation of trpzip2 between 15 and 82 degrees C using two-dimensional infrared (2D IR) vibrational spectroscopy, dispersed vibrational echo (DVE) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The FTIR and DVE spectra of trpzip2 show in the amide I region of the spectrum two resonances, which arise primarily from the interstrand coupling between local amide I oscillators along the peptide backbone. The coupling is seen directly in the 2D IR spectra as the formation of cross-peak ridges. Although small shifts of these frequencies occur on heating the sample, the existence of cross-peak ridges at all temperatures indicates that stable hydrogen bond interactions persist between the two beta-strands. These observations indicate a significant amount of native structure in the thermally denatured state of trpzip2.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Adam W
authors.initials: AW
authors.lastname: Smith
authors.forename: Hoi Sung
authors.initials: HS
authors.lastname: Chung
authors.forename: Ziad
authors.initials: Z
authors.lastname: Ganim
authors.forename: Andrei
authors.initials: A
authors.lastname: Tokmakoff
mesh_terms: D006358:Hot Temperature; D011487:Protein Conformation; D011489:Protein Denaturation; D011506:Proteins / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D011506:Proteins