title: N-terminal derivatization of peptides with isothiocyanate analogues promoting Edman-type cleavage and enhancing sensitivity in electrospray ionization tandem mass spectrometry analysis.
abstract: N-terminal derivatization of peptides with Edman's reagent, phenyl isothiocyanate (PITC), promotes gas-phase Edman cleavage that yields abundant complementary b(1) and y(n-1) ion pairs by tandem mass spectrometry (MS/MS). The formation of b(1) ions can be utilized as a mass tag to enhance the interpretation of MS/MS spectra and increase the confidence of peptide identification during mass spectrometry analysis. Derivatization of tryptic peptides with another isothiocyanate analogue, 4-sulfophenyl isothiocyanate, also produces signature ions resulting from Edman cleavage and facilitates peptide sequencing on linear or branched peptides. The limitation of these derivatizations, however, is reduced MS signal intensities of modified peptides, due presumably to the tags themselves. Here we have demonstrated that several other isothiocyanate analogues bearing basic moieties can derivatize peptides and significantly improve the MS sensitivity of tagged analytes, while promoting Edman fragmentation and maintaining other sequence fragments as well.
authors.affiliation: Biotechnology Core Facility Branch, Division of Scientific Resources, National Center for Preparedness, Detection, and Control of Infectious Disease, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia 30333, USA. dov2@cdc.gov
authors.forename: Dongxia
authors.initials: D
authors.lastname: Wang
authors.forename: Sunan
authors.initials: S
authors.lastname: Fang
authors.forename: Robert M
authors.initials: RM
authors.lastname: Wohlhueter
mesh_terms: D001557:Benzenesulfonates / Q000737:chemistry*; D007287:Inorganic Chemicals; D017879:Isothiocyanates / Q000737:chemistry*; D008956:Models, Chemical; D010455:Peptides / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry
chemical_list: D001557:Benzenesulfonates; D007287:Inorganic Chemicals; D017879:Isothiocyanates; D010455:Peptides; C015308:4-isothiocyanatobenzenesulfonate