Influence of Side Chain Restriction and NH --- p Interaction on the b-Turn Folding Modes of Dipeptides Incorporating Phenylalanine Cyclohexane Derivatives

  1. Jiménez, A.I. 2
  2. Cativiela, C. 2
  3. Gómez-Catalán, J. 1
  4. Pérez, J.J. 1
  5. Aubry, A. 3
  6. París, M. 45
  7. Marraud, M. 4
  1. 1 Universitat Politècnica de Catalunya
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    Universitat Politècnica de Catalunya

    Barcelona, España

    ROR https://ror.org/03mb6wj31

  2. 2 Universidad de Zaragoza
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    Universidad de Zaragoza

    Zaragoza, España

    ROR https://ror.org/012a91z28

  3. 3 University of Lorraine
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    University of Lorraine

    Nancy, Francia

    ROR https://ror.org/04vfs2w97

  4. 4 Lab. of Macromolec. Phys. Chemistry, UMR-7568 CNRS-INPL, ENSIC, BP 451, 54001 Nancy, France
  5. 5 Universidad de La Rioja
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    Universidad de La Rioja

    Logroño, España

    ROR https://ror.org/0553yr311

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Revista:
Journal of the American Chemical Society

ISSN: 0002-7863

Año de publicación: 2000

Volumen: 122

Número: 24

Páginas: 5811-5821

Tipo: Artículo

DOI: 10.1021/JA993568K SCOPUS: 2-s2.0-0037548464 GOOGLE SCHOLAR

Otras publicaciones en: Journal of the American Chemical Society

Repositorio institucional: lock_openAcceso abierto Editor

Resumen

We have synthesized the model dipeptides Piv-L-Pro-c6Phe-NH(i)pr, incorporating each of the two cis cyclohexane analogues of phenylalanine: (S,S)- and (R,R)-1-amino-2-phenylcyclohexanecarboxylic acid. Their structural analysis has been carried out in solution by 1H NMR and FTIR absorption spectroscopy and in the solid state by X-ray diffraction. In weakly polar chlorinated solvents, the (S,S)c6Phe-containing dipeptide mainly accommodates a type I β-turn, whereas the (R,R) residue shows a greater propensity to βII-folding. This behavior does not differ significantly from that exhibited by the analogous dipeptides containing L- and D-Phe. However, the L-Pro-L-Phe sequence has been shown to undergo a βI-to-βII transition in the presence of a strong solvating medium, such as DMSO, or in the crystalline state. Interestingly, Piv-L-Pro-(S,S)c6PheNH(i)pr, incorporating its cyclohexane analogue with χ1 fixed at +60°, retains the βI-folded structure under these conditions. Theoretical calculations, supported by the experimental data, indicate that a c6Phe-NH to aromatic π-orbitals interaction has an important influence on the observed β-folding preferences.