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

Lugar: New York; Año: 2011 vol. 57 p. 108 - 115

0924-2031

Quantum mechanical/molecular mechanics (QM/MM) calculations were carried out in order to study thetheoretical structures of l-tyrosine in both gas phase and in aqueous solution and observe the changesthat occur on the structural and vibrational properties in two phases. Therefore, the molecule was characterizedby infrared and Raman spectroscopy in solid phase and aqueous solution. Optimized geometriesand relative stabilities for the zwitterion l-tyrosine derivatives have been calculated taking into accountthe solvent effects by using the self-consistent reaction field (SCRF) theory. For a complete assignmentof 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) methodologyin order to fit the theoretical wavenumber values to the experimental ones. A good agreementbetween theoretical and available experimental results is found.