15min:
ROTATIONAL SPECTRA OF PHENYLALANINE, TIROSINE AND TRYPTOPHAN.

S. MATA, C. PEREZ, M. E. SANZ, S. BLANCO, J. C. LÓPEZ AND J. L. ALONSO, Grupo de Espectroscopía Molecular (GEM), Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, E-47005 Valladolid, Spain.

The rotational spectra of the aromatic natural amino acids phenylalanine, tyrosine and tryptophan have been investigated by Laser Ablation Molecular Beam Fourier transform Microwave Spectroscopy LA-MB-FTMW. The spectra of two rotamers of phenylalanine have been detected in the supersonic expansion. Both forms are stabilized by a chain of intramolecular hydrogen bonds O-H cdotsN-H cdots pi, being the carboxylic group in cis configuration. One conformer of tyrosine, which only differs from phenylalanine in a -OH group in para position, has been also characterized. Preliminary results on the rotational spectrum of tryptophan are presented.