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Title: The conformational behavior and H-bond structure of asparagine: a theoretical and experimental matrix-isolation FT-IR study
Authors: Boeckx, Bram ×
Maes, Guido #
Issue Date: May-2012
Publisher: North-Holland Pub. Co.
Series Title: Biophysical Chemistry vol:165-166 pages:62-73
Article number: 10.1016/j.bpc.2012.03.006
Abstract: Due to the high importance of the structural properties of peptides, the conformational behavior of one of their elementary building blocks, asparagine, has been investigated in this work. Matrix-isolation FT-IR spectroscopy is a suitable technique to investigate the intrinsic properties of small molecules. Asparagine has been subjected to matrix-isolation FT-IR spectroscopy supported with DFT and MP2 calculations. DFT optimization of asparagine resulted in 10 stable conformations with ∆E(DFT)<10 kJ.mol(-1). Compared to a previous study, one new conformation has been revealed. Further optimization at the MP2/6-31++G** level resulted in seven conformations with ∆E(MP)<10 kJ.mol(-1). A conformation containing the three intramolecular H-bonds, i.e. C=O(sc)…HN(bb), C=O(bb)…HN(sc) and OH(bb)…N(bb) appeared to be the most stable one at both levels despite the large negative entropy contribution due to these 3 H-bonds. At the sublimation temperature of 353 K, the DFT method predicts four and the MP2 method six conformations to be present in the experimental matrix-isolation spectrum. These conformations have different intramolecular H-bonds, which has allowed to identify at least 4 low energy conformations in the FT-IR spectrum. Detailed comparison between theory and experiment resulted in a mean frequency deviation of 7.6 cm(-1).
URI: 
ISSN: 0301-4622
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Translational Genetics (Vesalius Research Center) (+)
Quantum Chemistry and Physical Chemistry Section
× corresponding author
# (joint) last author

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