title: Infrared spectroscopy of fragments from doubly protonated tryptic peptides.
abstract: Most proteins in proteomics are identified from tandem mass spectra of doubly protonated tryptic peptides. Statistical studies indicate that these spectra fall into two distinct classes. IR spectroscopy experiments and DFT calculations performed on model b(2) ions show that peptides producing Class I spectra form protonated oxazolone ions (see figure) and not protonated diketopiperazines as proposed elsewhere.
authors.affiliation: Department of Molecular Biophysics, German Cancer Research Center, Im Neuenheimer Feld 580, Heidelberg, Germany.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Bythell
authors.forename: Undine
authors.initials: U
authors.lastname: Erlekam
authors.forename: Béla
authors.initials: B
authors.lastname: Paizs
authors.forename: Philippe
authors.initials: P
authors.lastname: Maître
mesh_terms: D000595:Amino Acid Sequence; D054659:Diketopiperazines / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D008956:Models, Chemical; D010081:Oxazolone / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D014357:Trypsin / Q000737:chemistry*
chemical_list: D054659:Diketopiperazines; D007477:Ions; D010446:Peptide Fragments; D010081:Oxazolone; D014357:Trypsin