title: Hydration of amino acids: FTIR spectra and molecular dynamics studies.
abstract: The hydration of selected amino acids, alanine, glycine, proline, valine, isoleucine and phenylalanine, has been studied in aqueous solutions by means of FTIR spectra of HDO isotopically diluted in H2O. The difference spectra procedure and the chemometric method have been applied to remove the contribution of bulk water and thus to separate the spectra of solute-affected HDO. To support interpretation of obtained spectral results, molecular dynamics simulations of amino acids were performed. The structural-energetic characteristic of these solute-affected water molecules shows that, on average, water affected by amino acids forms stronger and shorter H-bonds than those in pure water. Differences in the influence of amino acids on water structure have been noticed. The effect of the hydrophobic side chain of an amino acid on the solvent interactions seems to be enhanced because of the specific cooperative coupling of water strong H-bond chain, connecting the carboxyl and amino groups, with the clathrate-like H-bond network surrounding the hydrocarbon side chain. The parameter derived from the spectral data, which corresponds to the contributions of the population of weak hydrogen bonds of water molecules which have been substituted by the stronger ones in the hydration sphere of amino acids, correlated well with the amino acid hydrophobicity indexes.
authors.affiliation: Department of Physical Chemistry, Chemical Faculty, Gdańsk University of Technology, Narutowicza 11/12, 80-233, Gdańsk, Poland. aneta.panuszko@pg.gda.pl.
authors.forename: Aneta
authors.initials: A
authors.lastname: Panuszko
authors.affiliation: Department of Physical Chemistry, Chemical Faculty, Gdańsk University of Technology, Narutowicza 11/12, 80-233, Gdańsk, Poland.
authors.forename: Beata
authors.initials: B
authors.lastname: Adamczak
authors.affiliation: Department of Physical Chemistry, Chemical Faculty, Gdańsk University of Technology, Narutowicza 11/12, 80-233, Gdańsk, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Czub
authors.affiliation: Department of Physical Chemistry, Chemical Faculty, Gdańsk University of Technology, Narutowicza 11/12, 80-233, Gdańsk, Poland.
authors.forename: Emilia
authors.initials: E
authors.lastname: Gojło
authors.affiliation: Department of Physical Chemistry, Chemical Faculty, Gdańsk University of Technology, Narutowicza 11/12, 80-233, Gdańsk, Poland.
authors.forename: Janusz
authors.initials: J
authors.lastname: Stangret
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D014867:Water
keywords: Amino acids; Aqueous solutions; FTIR spectroscopy; Hydration; Hydrophobicity index; Molecular dynamics