Rotational Spectrum of Tryptophan

Abstract

The rotational spectrum of the natural amino acid tryptophan has been observed for the first time using a combination of laser ablation, molecular beams, and Fourier transform microwave spectroscopy. Independent analysis of the rotational spectra of individual conformers has conducted to a definitive identification of two different conformers of tryptophan, with one of the observed conformers never reported before. The analysis of the 14 N nuclear quadrupole coupling constants is of particular significance since it allows discrimination between structures, thus providing structural information on the orientation of the amino group. Both observed conformers are stabilized by an O-H · · · N hydrogen bond in the side chain and a N-H · · · π interaction forming a chain that reinforce the strength of hydrogen bonds through cooperative effects.

Torsiflex: an automatic generator of torsional conformers. Application to the twenty proteinogenic amino acids

“…From the experimental point of view, the studies by modern techniques as the laser ablation molecular-beam Fourier transform microwave (LA-MB-FTMW) carried out at cryogenic temperatures are contributing to reveal the intrinsic properties of pAAs in the absence of an interacting environment [38][39][40][41][42][43][44][45][46][47].…”

The Rotational Spectrum of Tyrosine

“…Its applicability to aromatic amino acids was first tested in phenylglycine 34 and latter applied to the studies of Phe 35 and Trp. 36 Significant photofragmentation was detected and consequently our experimental setup was modified trying to minimize it. Shorter laser pulses (30 picosecond length pulse) and shorter wavelengths (Nd:YAG 355nm) have been recently implemented in our new instrumentation 36,37 in order to minimize photofragmentation processes.…”

“…36 Significant photofragmentation was detected and consequently our experimental setup was modified trying to minimize it. Shorter laser pulses (30 picosecond length pulse) and shorter wavelengths (Nd:YAG 355nm) have been recently implemented in our new instrumentation 36,37 in order to minimize photofragmentation processes. In the context of our ongoing investigation of the conformational panorama of amino acids using rotational spectroscopy, we report in this paper the first rotational study of the proteogenic aromatic amino acid tyrosine.…”