DEVELOPMENT OF METHODS OF SINGLE FREQUENCY 2D IR

University Of Pennsylvania, Philadelphia PA

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Abstract

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This Core is the continuation of the original 2D IR experiments on vibrators associated with peptides. Major goals are: - Refinement of 2D IR procedures in order to more fully integrate them into biomedical research by advancing and simplifying the methodology of echo spectroscopy to more rapidly expose proximities and other properties of peptide amide groups in water and membrane environments. - Significant improvements of the contrast in the crossed polarization method to facilitate the acquisition of cross peak maps over a broad frequency range that exposes coupling and proximities between peptide modes. - Development of more robust 2D IR experiment by introducing phase plates, diffractive optics, phase measurement and deformable mirror pulse shaping into the 2D IR apparatus. - Developments of 2D IR measurements of anharmonicities and their structure sensitivities, angular distributions and couplings representative of protein secondary structures in different solvents and comparisons with those found in gases and molecular dynamics simulations. - Development of approaches for obtaining structure from 2D IR of C(alpha)-D modes to provide the protocols and theoretical underpinning of the hydrophobic stabilization of transmembrane peptides. - Systematic evaluation of 2D IR spectra after 13C=18O or 13C=16O replacement of all C=O groups of some small peptides and tryptophan zippers aimed at generating a solid basis for the prediction of amide spectra, the zero order mode frequencies and their delocalization. - 2D IR and linear IR experiments aimed at structure determination and delocalization of modes in a broad set of examples in different environments including isotopomers of parallel and antiparallel sheets, soluble and membrane bound peptides and helices, aggregates of amyloid peptides and isotopomers of 13C=18O in unusual (non-commercially available as isotopomers) amino acids such as aspartic acid, serine, glutamic acid and lysine.