Fast dynamics of HP35 for folded and urea-unfolded conditions.
The changes in fast dynamics of HP35 with a double CN vibrational dynamics label (HP35-P(2)) as a function of the extent of denaturation by urea were investigated with two-dimensional infrared (2D IR) vibrational echo spectroscopy. Cyanophenylalanine (PheCN) replaces the native phenylalanine at two residues in the hydrophobic core of HP35, providing vibrational probes. NMR data show that HP35-P(2) maintains the native folded structure similar to wild type and that both PheCN residues share essentially the same environment within the peptide. A series of time-dependent 2D IR vibrational echo spectra were obtained for the folded peptide and the increasingly unfolded peptide. Analysis of the time dependence of the 2D spectra yields the system's spectral diffusion, which is caused by the sampling of accessible structures of the peptide under thermal equilibrium conditions. The structural dynamics become faster as the degree of unfolding is increased.
Department of Chemistry, Stanford University, Stanford, California 94305, USA.
Jean K
JK
Chung
Megan C
MC
Thielges
Stephen R
SR
Lynch
Michael D
MD
Fayer
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D008840:Microfilament Proteins / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D058767:Protein Unfolding; D014508:Urea / Q000737:chemistry
D008840:Microfilament Proteins; C026615:villin; D014508:Urea