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Solvation Phenomena of a Tetrapeptide in Water/Trifluoroethanol and Water/Ethanol Mixtures: A Diffusion NMR, Intermolecular NOE, and Molecular Dynamics Study

2002; American Chemical Society; Volume: 124; Issue: 26 Linguagem: Inglês

10.1021/ja0259335

1943-2984

Marco Fioroni, Dolores Díaz, Klaus Burger, Stefan Berger,

Advanced NMR Techniques and Applications

Solvation of a tetrapeptide, NAc-Ser-Phe-Val-Gly-OMe (1), in water and in water/alcohol mixtures with 2,2,2-trifluoroethanol (TFE)/water or ethanol (ETH)/water has been studied by diffusion NMR and intermolecular NOE measurements. The experimental results were compared with those obtained from detailed Molecular Dynamics (MD) calculations. Independently, all three methods revealed preferential solvation on the surface of the peptide by TFE in the water/TFE mixtures, but not by ETH in the water/ETH mixtures. The MD calculations show that the TFE concentration coating the peptide is higher than that in the bulk, while for ethanol, the concentration is nearly equal to that in the bulk. Calculated site-specific preferential solvation data between TFE, ETH, and water with the different peptide groups have been compared with the NMR data and shown to be in general agreement with the experimental facts.