title: Phenyl radical-induced damage to dipeptides.
abstract: Laser-induced acoustic desorption (LIAD) incorporated with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR) has been utilized to investigate phenyl radical-induced damage to dipeptides in the gas phase. On the basis of the product branching ratios measured for the reactions of two different positively charged phenyl radicals with 17 different dipeptides, the overall order of susceptibility to attack of the different sites in the dipeptides was determined to be heteroaromatic side chain approximately = S atom in SCH(3) group > H atom in SH group > H atom in CH group > aromatic side chain > S atom in SH group > NH(2) in side chain > N-terminal NH(2) > COOH in side chain approximately = C-terminal COOH. The amino acid sequence also influences the selectivity of these reactions. As expected, the ability of a phenyl radical to damage dipeptides increases as the electrophilicity of the phenyl radical increases.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Sen
authors.initials: S
authors.lastname: Li
authors.forename: Mingkun
authors.initials: M
authors.lastname: Fu
authors.forename: Steven C
authors.initials: SC
authors.lastname: Habicht
authors.forename: George O
authors.initials: GO
authors.lastname: Pates
authors.forename: John J
authors.initials: JJ
authors.lastname: Nash
authors.forename: Hilkka I
authors.initials: HI
authors.lastname: Kenttämaa
mesh_terms: D004151:Dipeptides / Q000737:chemistry* / Q000528:radiation effects; D005609:Free Radicals; D017665:Hydroxyl Radical; D015394:Molecular Structure; D019800:Phenol / Q000737:chemistry*
chemical_list: D004151:Dipeptides; D005609:Free Radicals; D017665:Hydroxyl Radical; D019800:Phenol