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Infrared spectra of charge‐solvated versus salt‐bridge conformations of glycine‐, serine‐, and cysteine‐Ca 2+ complexes
Author(s) -
Corral Inés,
Lamsabhi Al Mokhtar,
Mó Otilia,
Yáñez Manuel
Publication year - 2011
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.23169
Subject(s) - chemistry , cysteine , serine , infrared multiphoton dissociation , infrared spectroscopy , glycine , infrared , dication , dissociation (chemistry) , crystallography , zwitterion , amino acid , ion , molecule , organic chemistry , biochemistry , physics , optics , enzyme
The structure, relative stability, and anharmonic vibrational frequencies of the most stable complexes between glycine, serine, and cysteine with Ca 2+ have been calculated by means of DFT approaches. The global minimum of the potential energy surface for glycine‐Ca 2+ complex corresponds to the salt‐bridge (SB) form, whereas for serine‐ and cysteine‐Ca 2+ complexes is a charge‐solvated (CS) structure in which the metal dication is bound to the carbonyl group of the acidic function, the amino group and the OH (SH) group of the alcohol (enethiol) function. The energy gap between the CS global minimum and the SB form decreases significantly on going from serine to cysteine. Hence, for the latter both CS and SB forms could coexist in the gas phase mainly at high temperatures. Anharmonicity effects are lower than 10%, and do not affect significantly the assignment of the fundamental vibrational modes. The calculated infrared spectra of the SB and CS forms of glycine‐, serine‐, and cysteine‐Ca 2+ complexes show very distinctive characteristics, which should permit to unambiguously characterize them by IR multiphoton dissociation (IRMPD) techniques. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012