title: Electronic transitions of protonated and deprotonated amino acids in aqueous solution in the region 145-300 nm studied by attenuated total reflection far-ultraviolet spectroscopy.
abstract: The electronic transitions of 20 naturally occurring amino acids in aqueous solution were studied with attenuated total reflection far-ultraviolet (ATR-FUV) spectroscopy in the region from 145 to 300 nm. From the measured ATR spectra of sample solutions, the FUV absorption spectra attributed to the amino acids were separated from the intense solvent absorption by using a modified Kramers-Kronig transformation method. The FUV absorption spectra of the amino acids reflect the protonation states of the backbone and side-chain structures. The contributions of the side chains to the spectra were also examined from the difference spectra subtracting the corresponding Gly spectrum from each spectrum. The observed spectra were compared mostly with the electronic transition studies of the molecular fragments of the amino acids in gas phase. The FUV spectra of the amino acids exhibited the intra- and intermolecular electronic interactions of the solute-solute as well as the solute-solvent, and those are essential factors to elucidate UV photochemical processes of the amino acids in aqueous solution.
authors: National Food Research Institute, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-8642, Japan.
authors: Takeyoshi
authors: T
authors: Goto
authors: Akifumi
authors: A
authors: Ikehata
authors: Yusuke
authors: Y
authors: Morisawa
authors: Yukihiro
authors: Y
authors: Ozaki
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D005740:Gases; D006863:Hydrogen-Ion Concentration; D011522:Protons; D012996:Solutions; D012997:Solvents; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D014867:Water / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D005740:Gases; D011522:Protons; D012996:Solutions; D012997:Solvents; D014867:Water