title: Discrimination between peptide O-sulfo- and O-phosphotyrosine residues by negative ion mode electrospray tandem mass spectrometry.
abstract: Unambiguous differentiation between isobaric sulfated and phosphorylated tyrosine residues (sTyr and pTyr) of proteins by mass spectrometry is challenging, even using high resolution mass spectrometers. Here we show that upon negative ion mode collision-induced dissociation (CID), pTyr- and sTyr-containing peptides exhibit entirely different modification-specific fragmentation patterns leading to a rapid discrimination between the isobaric covalent modifications using the tandem mass spectral data. This study reveals that the ratio between the relative abundances of [M-H-80](-) and [M-H-98](-) fragment ions in ion-trap CID and higher energy collision dissociation (HCD) spectra of singly deprotonated +80 Da Tyr-peptides can be used as a reliable indication of the Tyr modification group nature. For multiply deprotonated +80 Da Tyr-peptides, CID spectra of sTyr- and pTyr-containing sequences can be readily distinguished based on the presence/absence of the [M-nH-79]((n-1)-) and [M-nH-79-NL]((n-1)-) (n=2, 3) fragment ions (NL=neutral loss).
authors.affiliation: Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany. m.edelson-averbukh@qmul.ac.uk
authors.forename: Marina
authors.initials: M
authors.lastname: Edelson-Averbukh
authors.forename: Andrej
authors.initials: A
authors.lastname: Shevchenko
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Pipkorn
authors.forename: Wolf D
authors.initials: WD
authors.lastname: Lehmann
mesh_terms: D007477:Ions / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D019000:Phosphotyrosine / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D007477:Ions; D010455:Peptides; D019000:Phosphotyrosine; C005662:tyrosine O-sulfate; D014443:Tyrosine