Hydrogen Bonding and Solvation of a Proline-Based Peptide Model in Salt Solutions

The hydrogen bonding of water and water/salt mixtures around the proline-based tripeptide model glycyl-l-prolyl-glycinamide·HCl (GPG-NH ) is investigated here by multi-wavelength UV resonance Raman spectroscopy (UVRR) to clarify the role of ion-peptide interactions in affecting the conformational st...

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Bibliographic Details
Published in:Life (Basel, Switzerland) Switzerland), 2021-08, Vol.11 (8), p.824
Main Authors: Catalini, Sara, Rossi, Barbara, Tortora, Mariagrazia, Foggi, Paolo, Gessini, Alessandro, Masciovecchio, Claudio, Bruni, Fabio
Format: Article
Language:English
Subjects:
Anions
Aqueous solutions
Carbonyl compounds
Carbonyls
Cations
Chemical bonds
Circular dichroism
Dichroism
Equilibrium
Fluoride
Fluorides
Hydration
Hydrogen
Hydrogen bonding
Hydrogen bonds
Investigations
peptide
Peptides
Polypeptides
Proline
Protein folding
Radiation
Raman spectroscopy
Saline solutions
Selectivity
Solvation
Spectrum analysis
UV resonance Raman
Water chemistry
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Summary:The hydrogen bonding of water and water/salt mixtures around the proline-based tripeptide model glycyl-l-prolyl-glycinamide·HCl (GPG-NH ) is investigated here by multi-wavelength UV resonance Raman spectroscopy (UVRR) to clarify the role of ion-peptide interactions in affecting the conformational stability of this peptide. The unique sensitivity and selectivity of the UVRR technique allow us to efficiently probe the hydrogen bond interaction between water molecules and proline residues in different solvation conditions, along with its influence on to isomerism in the hydrated tripeptide. The spectroscopic data suggest a relevant role played by the cations in altering the solvation shell at the carbonyl site of proline , while the fluoride and chloride anions were found to promote the establishment of the strongest interactions on the C=O site of proline. This latter effect is reflected in the greater stabilization of the conformers of the tripeptide in the presence of these specific ions. The molecular view provided by UVRR experiments was complemented by the results of circular dichroism (CD) measurements that show a strong structural stabilizing effect on the β-turn motif of GPG-NH observed in the presence of KF as a co-solute.
ISSN:2075-1729
2075-1729
DOI:10.3390/life11080824