Neutral and zwitterionic glycine.H(2)O complexes: A theoretical and matrix-isolation Fourier transform infrared study.
The H-bond interaction between glycine and H2O has been studied by a combined theoretical (DFT(B3LYP)/6-31++G(**)) and experimental (matrix-isolation FT-IR) methodology. The 1:1 and 1:2 complexes of the most stable conformation (I) of glycine appear to be neutral complexes which have been vibrationally characterized in detail. The higher stoichiometry complexes (glycine).(H2O)n with n larger than 3 are demonstrated to be zwitterionic H-bonded complexes. A set of characteristic IR absorption bands for this zwitterionic structure has been observed in low-temperature Ar matrices. This would be the first experimental IR evidence for proton transfer occurring between the NH2 and COOH groups of amino acids by a H-bonded water molecular channel in isolated conditions.
Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
Riet
R
Ramaekers
Joanna
J
Pajak
Bert
B
Lambie
Guido
G
Maes
D026921:Amino Acid Transport Systems, Neutral / Q000737:chemistry; D001665:Binding Sites; D003198:Computer Simulation; D005998:Glycine / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D011485:Protein Binding; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D055672:Static Electricity; D014867:Water / Q000737:chemistry*
D026921:Amino Acid Transport Systems, Neutral; D014867:Water; D005998:Glycine