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Compact Folding of Isolated Four‐Residue Neutral Peptide Chains: H‐Bonding Patterns and Entropy Effects
Author(s) -
Plowright Richard J.,
Gloaguen Eric,
Mons Michel
Publication year - 2011
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.201001023
Subject(s) - chemistry , enthalpy , molecule , folding (dsp implementation) , entropy (arrow of time) , residue (chemistry) , spectroscopy , crystallography , peptide , stereochemistry , thermodynamics , organic chemistry , biochemistry , physics , quantum mechanics , electrical engineering , engineering
The intrinsic folding of isolated neutral tetrapeptides is investigated by IR‐UV double‐resonance laser spectroscopy coupled to quantum chemistry (DFT‐D) calculations. Laser‐desorbed jet‐cooled Ac‐(Ala) 3 ‐Phe‐NH 2 as well as two other related four‐residue molecules are shown to fold according to the same 14‐7L‐X‐10II′‐7L compact, β‐hairpin‐like backbone pattern, leading to a remarkable closed daisy chain of H‐bonds along the molecule. Thermodynamic calculations confronted to the abundances observed show that these laser‐desorbed peptides are best described by a finite conformational temperature (typically ca. 300–450 K), which suggests that not only enthalpy but also entropy effects play an important role in selecting these structures within this temperature range.