title: Dissecting coherent vibrational spectra of small proteins into secondary structural elements by sensitivity analysis.
abstract: The response of proteins to sequences of femtosecond infrared pulses provides a multidimensional view into their equilibrium distribution of structures and snapshot pictures of fast-triggered dynamical events. Analyzing these experiments requires advanced computational tools for assigning regions in the resulting multi-dimensional correlation plots to specific secondary-structure elements and their couplings. A differential sensitivity analysis technique based on a perturbation of the local (real space) Hamiltonian is developed to achieve that goal. Application to the amide I region of a small globular protein reveals regions associated with the alpha-helix, beta-sheet, and their coupling. Comparison of signals generated in different directions shows that the double-quantum-coherence signal has a higher sensitivity to the couplings compared with the single-quantum-coherence (photon echo) technique.
authors.affiliation: Department of Chemistry, University of California, Irvine, CA 92697-2025, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhuang
authors.forename: Darius
authors.initials: D
authors.lastname: Abramavicius
authors.forename: Shaul
authors.initials: S
authors.lastname: Mukamel
mesh_terms: D007259:Infrared Rays; D015394:Molecular Structure; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods; D014732:Vibration
chemical_list: D011506:Proteins