Hydration of L-Tyrosine in aqueous medium. An experimental and theoretical study by mixed quantum mechanical/molecular mechanics methods

C. D. CONTRERAS; A.E. LEDESMA; H. E. LANÚS; J. ZINCZUK; S. A. BRANDÁN

VIBRATIONAL SPECTROSCOPY

ELSEVIER SCIENCE BV

Año: 2011 vol. 57 p. 108 - 115

0924-2031

Quantum mechanical/molecular mechanics (QM/MM) calculations were carried out in order to study the theoretical structures of L-Tyrosine in both gas phase and in aqueous solution and observe the changes that occur on the structural and vibrational properties in two phases. Therefore, the molecule was charac-terized by infrared and Raman spectroscopy in solid phase and aqueous solution. Optimized geometries and relative stabilities for the zwitterion L-Tyrosine derivatives have been calculated taking into account the solvent effects by using the self-consistent reaction field (SCRF) theory. For a complete assignment of the IR and Raman spectra of L-Tyrosine in solid and aqueous solution phases, density functional theory (DFT) calculations were combined with Pulay’s scaled quantum mechanical force field (SQMFF) method-ology in order to fit the theoretical wavenumber values to the experimental ones. A good agreement between theoretical and available experimental results is found L-Tyrosine in both gas phase and in aqueous solution and observe the changes that occur on the structural and vibrational properties in two phases. Therefore, the molecule was charac-terized by infrared and Raman spectroscopy in solid phase and aqueous solution. Optimized geometries and relative stabilities for the zwitterion L-Tyrosine derivatives have been calculated taking into account the solvent effects by using the self-consistent reaction field (SCRF) theory. For a complete assignment of the IR and Raman spectra of L-Tyrosine in solid and aqueous solution phases, density functional theory (DFT) calculations were combined with Pulay’s scaled quantum mechanical force field (SQMFF) method-ology in order to fit the theoretical wavenumber values to the experimental ones. A good agreement between theoretical and available experimental results is found