In-source CID of guanosine: gas phase ion-molecule reactions.
In-source collision induced dissociation was applied to access second generation ions of protonated guanosine. The in-source gas-phase behavior of [BH2]+-NH3 (m/z 135, C5H3N4O+) was investigated. Adduct formation and reactions with available solvent molecules (H2O and CH3OH) were demonstrated. Several addition/elimination sequences were observed for this particular ion and solvent molecules. Dissociation pathways for the newly formed ions were developed using a QqTOF mass spectrometer, permitting the assignment of elemental compositions of all product ions produced. Reaction schemes were suggested arising from the ring-opened intermediate of the protonated base moiety [BH2]+, obtained from fragmentation of guanosine. The mass spectral data revealed that the in-source CH3OH-reaction product underwent more complex fragmentations than the comparable ion following reaction with H2O. A rearrangement and a parallel radical dissociation pathway were discerned. Apart from the mass spectrometric evidence, the fragmentation schemes are supported by density functional theory calculations, in which the reaction of the ring-opened protonated guanine intermediate with CH3OH and a number of subsequent fragmentations were elaborated. Additionally, an in-source transition from the ring-opened intermediate of protonated guanine to the ring-opened intermediate of protonated xanthine was suggested. For comparison, a low-energy collision induced dissociation study of xanthosine was performed. Its dissociation pathways agreed with our assumption.
Tuytten
Robin
R
Department of Chemistry, Nucleoside Research and Mass Spectrometry Unit and Center for Proteomics and Mass Spectrometry, University of Antwerp, Groenenborgelaan 171, B-2020, Antwerp, Belgium.
Lemière
Filip
F
Department of Chemistry, Nucleoside Research and Mass Spectrometry Unit and Center for Proteomics and Mass Spectrometry, University of Antwerp, Groenenborgelaan 171, B-2020, Antwerp, Belgium. filip.lemiere@ua.ac.be.
Esmans
Eddy L
EL
Department of Chemistry, Nucleoside Research and Mass Spectrometry Unit and Center for Proteomics and Mass Spectrometry, University of Antwerp, Groenenborgelaan 171, B-2020, Antwerp, Belgium.
Herrebout
Wouter A
WA
Department of Chemistry, Cryospectroscopy, University of Antwerp, Antwerp, Belgium.
van der Veken
Benjamin J
BJ
Department of Chemistry, Cryospectroscopy, University of Antwerp, Antwerp, Belgium.
Dudley
Ed
E
Biochemistry Group, School of Biological Sciences and Biomolecular Analysis Mass Spectrometry Facility, University of Wales, Swansea, UK.
Newton
Russell P
RP
Biochemistry Group, School of Biological Sciences and Biomolecular Analysis Mass Spectrometry Facility, University of Wales, Swansea, UK.
Witters
Erwin
E
Department of Biology, Laboratory for Plant Biochemistry and Center for Mass Spectrometry and Proteomics, University of Antwerp, Antwerp, Belgium.
D003198:Computer Simulation; D005740:Gases / Q000737:chemistry*; D006151:Guanosine / Q000737:chemistry*; D007477:Ions / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D044367:Phase Transition
D005740:Gases; D007477:Ions; D006151:Guanosine