title: A matrix-assisted laser desorption/ionization compatible reagent for tagging tryptophan residues.
abstract: Chemical tagging of amino acids is an important tool in proteomics analysis, and has been used to introduce isotope labels and mass defect labels into proteolytic peptides by derivatization of cysteine or lysine residues. Here, we present a new reagent with chemical specificity for tryptophan residues. Previously, 2-nitrobenzenesulfenyl chloride has been used as a highly specific reagent for labeling tryptophan residues. We show that this tag undergoes UV dissociation during matrix assisted laser desorption/ionization (MALDI). The multiplicity of photofragments increases the difficulty of characterizing the derivatization products. To overcome this problem, we have synthesized a new reagent, 2-(trifluoromethyl)benzenesulfenyl chloride, which is shown to react quantitatively with tryptophan in peptides and proteins. Most significantly, it exhibits high photostability in MALDI-Fourier transform mass spectrometry analyses.
authors.affiliation: Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Li
authors.forename: Vijay
authors.initials: V
authors.lastname: Gawandi
authors.forename: Adam
authors.initials: A
authors.lastname: Protos
authors.forename: Robert S
authors.initials: RS
authors.lastname: Phillips
authors.forename: I Jonathan
authors.initials: IJ
authors.lastname: Amster
mesh_terms: D001839:Bombesin / Q000032:analysis; D006845:Hydrocarbons, Fluorinated / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D009211:Myoglobin / Q000032:analysis; D010446:Peptide Fragments / Q000032:analysis; D011506:Proteins / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013056:Spectrophotometry, Ultraviolet; D053719:Tandem Mass Spectrometry; D014364:Tryptophan / Q000032:analysis*
chemical_list: C520761:2-(trifluoromethyl)benzenesulfenyl chloride; D006845:Hydrocarbons, Fluorinated; D007202:Indicators and Reagents; D009211:Myoglobin; D010446:Peptide Fragments; D011506:Proteins; D014364:Tryptophan; D001839:Bombesin