title: Ultraviolet photodissociation of carboxylate-derivatized peptides in a quadrupole ion trap.
abstract: The fragmentation patterns obtained by ultraviolet photodissociation (UVPD) and collision-induced dissociation (CID) in a quadrupole ion trap mass spectrometer were compared for peptides modified at their C-termini and at acidic amino acids. Attachment of Alexa Fluor 350 or 7-amino-4-methyl-coumarin chromophores at the C-terminal and acidic residues enhances the UV absorptivity of the peptides and all fragment ions that retain the chromophore, such as the y ions that contain the chromophore-modified C-terminus. Whereas CID results in the formation of the typical array of mainly y-type and a/b-type fragment ions, UVPD produces predominantly a/b-type ions with greatly reduced abundances of y ions. Immonium ions, mostly ones from aromatic or basic amino acids, are also observed in the low m/z range upon UVPD. UVPD of peptides containing two chromophore moieties (with one at the C-terminus and another at an acidic residue) results in even more efficient photodissociation at the expense of the annihilation of almost all diagnostic b and y ions containing the chromophore.
authors.affiliation: Department of Chemical Engineering, University of Texas at Austin, 1 University Station A5300, Austin, TX 78712, USA.
authors.forename: Byoung Joon
authors.initials: BJ
authors.lastname: Ko
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Brodbelt
mesh_terms: D000595:Amino Acid Sequence; D001372:Aza Compounds / Q000737:chemistry; D002234:Carbodiimides / Q000737:chemistry; D049408:Luminescent Agents / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D010455:Peptides / Q000737:chemistry* / Q000528:radiation effects*; D055668:Photochemical Processes; D020539:Sequence Analysis, Protein / Q000379:methods; D014230:Triazoles / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: C518491:1-ethyl-3-(3-(diethylamino)propyl)carbodiimide; D001372:Aza Compounds; D002234:Carbodiimides; D049408:Luminescent Agents; D010455:Peptides; D014230:Triazoles; C435757:1-hydroxy-7-azabenzotriazole