Single hydration of the peptide bond: The case of the Vince Lactam

  1. Écija, P. 1
  2. Basterretxea, F.J. 1
  3. Lesarri, A. 2
  4. Millán, J. 3
  5. Castaño, F. 1
  6. Cocinero, E.J. 1
  1. 1 Universidad del País Vasco/Euskal Herriko Unibertsitatea
    info

    Universidad del País Vasco/Euskal Herriko Unibertsitatea

    Lejona, España

    ROR https://ror.org/000xsnr85

  2. 2 Universidad de Valladolid
    info

    Universidad de Valladolid

    Valladolid, España

    ROR https://ror.org/01fvbaw18

  3. 3 Universidad de La Rioja
    info

    Universidad de La Rioja

    Logroño, España

    ROR https://ror.org/0553yr311

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Journal:
Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment & General Theory

ISSN: 1089-5639

Year of publication: 2012

Volume: 116

Issue: 41

Pages: 10099-10106

Type: Article

DOI: 10.1021/JP3072734 SCOPUS: 2-s2.0-84867651356 WoS: WOS:000311872200008 GOOGLE SCHOLAR

More publications in: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment & General Theory

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Abstract

2-Azabicyclo[2.2.1]hept-5-en-3-one (ABH or Vince lactam) and its monohydrated complex (ABH⋯H2O) have been observed in a supersonic jet by Fourier transform microwave spectroscopy. ABH is broadly used in the synthesis of therapeutic drugs, whereas the ABH⋯H2O system offers a simple model to explain the conformational preferences of water linked to a constrained peptidic bond. A single predominant form of the Vince lactam and its singly hydrated complex have been detected, determining the rotational constants, centrifugal distortion constants, and nuclear quadrupole coupling tensor. The monohydrated complex is stabilized by two hydrogen bonds (C=O⋯H-O and N-H⋯O) closing a six-membered ring. The complexation energy has been estimated to be ∼10 kJ mol-1 from experimental results. In addition, the observed structure in the gas phase has been compared with solid-phase diffraction data. The structural parameters and binding energies of ABH⋯H2O have also been compared with similar molecules containing peptide bonds. Ab initio (MP2) and density functional (M06-2X and B3LYP) methods have supported the experimental work, describing the rotational parameters and conformational landscape of the title compound and its singly hydrated complex. © 2012 American Chemical Society.