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Kinetically Trapped Liquid-State Conformers of a Sodiated Model Peptide Observed in the Gas Phase.
Schneider, Markus; Masellis, Chiara; Rizzo, Thomas; Baldauf, Carsten.
Afiliação
  • Schneider M; Theory Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6, D-14195 Berlin, Germany.
  • Masellis C; Laboratoire de Chimie Physique Moléculaire, EPFL SB ISIC LCPM, Ecole Polytechnique Fédérale de Lausanne , Station 6, CH-1015 Lausanne, Switzerland.
  • Rizzo T; Laboratoire de Chimie Physique Moléculaire, EPFL SB ISIC LCPM, Ecole Polytechnique Fédérale de Lausanne , Station 6, CH-1015 Lausanne, Switzerland.
  • Baldauf C; Theory Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft , Faradayweg 4-6, D-14195 Berlin, Germany.
J Phys Chem A ; 121(36): 6838-6844, 2017 Sep 14.
Article em En | MEDLINE | ID: mdl-28831801
ABSTRACT
We investigate the peptide AcPheAla5LysH+, a model system for studying helix formation in the gas phase, in order to fully understand the forces that stabilize the helical structure. In particular, we address the question of whether the local fixation of the positive charge at the peptide's C-terminus is a prerequisite for forming helices by replacing the protonated C-terminal Lys residue by Ala and a sodium cation. The combination of gas-phase vibrational spectroscopy of cryogenically cooled ions with molecular simulations based on density-functional theory (DFT) allows for detailed structure elucidation. For sodiated AcPheAla6, we find globular rather than helical structures, as the mobile positive charge strongly interacts with the peptide backbone and disrupts secondary structure formation. Interestingly, the global minimum structure from simulation is not present in the experiment. We interpret that this is due to high barriers involved in rearranging the peptide-cation interaction that ultimately result in kinetically trapped structures being observed in the experiment.

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Revista: J Phys Chem A Assunto da revista: QUIMICA Ano de publicação: 2017 Tipo de documento: Article País de afiliação: Alemanha

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Revista: J Phys Chem A Assunto da revista: QUIMICA Ano de publicação: 2017 Tipo de documento: Article País de afiliação: Alemanha