A density functional study of some physical properties of carnosine (N-β-alanyl-L-histidine)

Equilibrium geometries, harmonic vibrational frequencies, electronic transition energies, and NMR chemical shifts are calculated for different structures of carnosine (N-beta-alanyl-L-histidine) as a further step in the physical characterization of that molecule. The calculations are performed using the generalized gradient approximation to the density functional theory. Solvent effects are implicitly accounted for. Although total energy results indicate that zwitterionic species are more stable than neutral ones, the comparison of calculated properties with experimental geometric parameters and chemical shifts seems to favor the neutral species. The calculated electronic transition energies and harmonic vibrational frequencies suggest that both the electronic and vibrational spectra could be used to determine the nature of the carnosine species under study. (C) 2002 Elsevier Science B.V. All rights reserved.