Vibrational spectroscopy and DFT calculations of the di-amino acid peptide L-aspartyl-L-glutamic acid in the zwitterionic state

Nighat Kausar, Trevor J. Dines, Babur Z. Chowdhry, Bruce D. Alexander

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    13 Citations (Scopus)

    Abstract

    Solid state IR and Raman as well as aqueous solution state Raman spectra are reported for the linear di-amino acid peptide L-aspartyl-L-glutamic acid (L-Asp-L-Glu); the solution state Raman spectrum has also been obtained for the N,O-deuterated derivative. SCF-DFT calculations at the B3-LYP/cc-pVDZ level established that the structure and vibrational spectra of L-Asp-L-Glu can be interpreted using a model of the peptide with ten hydrogen-bonded water molecules, in conjunction with the conductor-like polarizable continuum solvation method. The DFT calculations resulted in the computation of a stable zwitterionic structure, which displays trans-amide conformation. The vibrational spectra were computed at the optimised molecular geometry, enabling normal coordinate analysis, which yielded satisfactory agreement with the experimental IR and Raman data. Computed potential energy distributions of the normal modes provided detailed vibrational assignments.

    Original languageEnglish
    Pages (from-to)6389-6400
    Number of pages12
    JournalPhysical Chemistry Chemical Physics
    Volume11
    Issue number30
    DOIs
    Publication statusPublished - 2009

    Keywords

    • POLARIZABLE CONTINUUM MODEL
    • SOLVATION FREE-ENERGIES
    • RAMAN-SPECTRA
    • INFRARED-SPECTRA
    • RESONANCE
    • DIPEPTIDES
    • MOLECULES
    • HYDROGEN
    • DENSITY
    • IR

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