title: Manipulating the fragmentation patterns of phosphopeptides via gas-phase boron derivatization: determining phosphorylation sites in peptides with multiple serines.
abstract: Trivalent boron species readily react with protonated phosphopeptides to give addition products with the loss of boron ligands. In the present study, trimethoxyborane (TMB), diisopropoxymethylborane (DIPM), and diethylmethoxyborane (DEMB) were allowed to react with four phosphopeptides, VsSF, LSsF, LsGASA, and VSGAsA (lower-case s indicates phosphoserine). Each of the phosphopeptides contains one serine that is phosphorylated and one that is not. Under collision-activated dissociation (CAD) conditions, the boron-derivatized peptides give fragmentation patterns that differ significantly from that of the protonated phosphopeptide. The patterns vary, depending on the number of labile (i.e., alkoxy) ligands on the boron. In general, boron derivatization increases the yield of phosphate-containing sequence ions, but dramatic effects are only seen with certain reagent/peptide combinations. However, the suite of reagents provides a means of altering and increasing the information content of phosphopeptide CAD spectra.
authors.affiliation: Department of Chemistry and Biochemistry, San Francisco State University, CA 94132, USA. sgronert@sfsu.edu
authors.forename: Scott
authors.initials: S
authors.lastname: Gronert
authors.forename: Kathy H
authors.initials: KH
authors.lastname: Li
authors.forename: Mizue
authors.initials: M
authors.lastname: Horiuchi
mesh_terms: D000465:Algorithms; D001665:Binding Sites; D001896:Boron Compounds / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D005740:Gases / Q000737:chemistry; D010446:Peptide Fragments / Q000032:analysis / Q000737:chemistry; D044367:Phase Transition; D010748:Phosphopeptides / Q000032:analysis* / Q000737:chemistry*; D010766:Phosphorylation; D011485:Protein Binding; D012694:Serine / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D001896:Boron Compounds; D005740:Gases; D010446:Peptide Fragments; D010748:Phosphopeptides; D012694:Serine