title: Gas phase hydrogen/deuterium exchange reactions of peptide ions in a quadrupole ion trap mass spectrometer.
abstract: Hydrogen/deuterium exchange reactions of protonated and sodium cationized peptide molecules have been studied in the gas phase with a MALDI/quadrupole ion trap mass spectrometer. Unit-mass selected precursor ions were allowed to react with deuterated ammonia introduced into the trap cell by a pulsed valve. The reactant gas pressure, reaction time, and degree of the internal excitation of reactant ions were varied to explore the kinetics of the gas phase isotope exchange. Protonated peptide molecules exhibited a high degree of reactivity, some showing complete exchange of all labile hydrogen atoms. On the contrary, peptide molecules cationized with sodium exhibited only very limited reactivity, indicating a vast difference between the gas phase structures of the two ions.
authors.affiliation: Johns Hopkins University School of Medicine, Department of Pharmacology, Baltimore, Maryland 21205, USA.
authors.forename: I A
authors.initials: IA
authors.lastname: Kaltashov
authors.forename: V M
authors.initials: VM
authors.lastname: Doroshenko
authors.forename: R J
authors.initials: RJ
authors.lastname: Cotter
mesh_terms: D002412:Cations; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003903:Deuterium / Q000737:chemistry* / Q000378:metabolism; D006096:Gramicidin / Q000737:chemistry / Q000378:metabolism; D006859:Hydrogen / Q000737:chemistry* / Q000378:metabolism; D008962:Models, Theoretical; D010446:Peptide Fragments / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D002412:Cations; D010446:Peptide Fragments; D006096:Gramicidin; D006859:Hydrogen; D012964:Sodium; D003903:Deuterium