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Probing the γ‐Turn in a Short Proline Dipeptide Chain
Author(s) -
Cabezas Carlos,
Varela Marcelino,
Alonso José L.
Publication year - 2013
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201300250
Subject(s) - rotational spectroscopy , chemistry , intramolecular force , dipeptide , conformational isomerism , turn (biochemistry) , hydrogen bond , quadrupole , spectroscopy , crystallography , nuclear magnetic resonance , stereochemistry , molecule , peptide , atomic physics , organic chemistry , physics , biochemistry , quantum mechanics
The small peptide derived from proline, N ‐acetyl‐prolinamide (Ac‐Pro‐NH 2 ), has been investigated using a combination of Fourier transform microwave spectroscopy with laser ablation. Spectral signatures belonging to only one conformer have been detected in the supersonic expansion. Rotational constants and nuclear quadrupole coupling constants of the two 14 N nuclei have been used in the characterization of a γ‐turn structure in the gas phase, which is stabilized by a CO⋅⋅⋅HN intramolecular hydrogen bond closing a seven‐membered ring. A methyl group internal rotation barrier of 354 cm −1 has been determined from the analysis of the A–E splittings.