engleski

Signature of the Conformational Preferences of Small Peptides: a Theoretical Investigation

An extensive computational study of the conformational preferences of N-acetylphenylalaninylamide (NAPA) is reported, including conformational and anharmonic frequency analyses, as well as calculations of excitation energies of the four NAPA conformers lowest in energy. Particular attention is paid to the influence of hydrogen-bonding interactions on the relative stability of the conformers, which was found to be very sensitive upon both, the level of quantum chemical computations, and the anharmonic treatment of molecular vibrations. The assignments of the UV spectral peaks are well supported by the multireference CASSCF/MS-CASPT2 calculations. Upon considering the MP2 and DFT structures, overall energetics, harmonic and anharmonic corrections, we found no conclusive theoretical evidence for the assumed conformational propensity of small model peptides towards extended beta-strand structures.

quantum chemistry; peptide; conformational analysis; IR spectroscopy; UV/Vis spectroscopy; Ab Initio; density functional theory

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