title: Analysis of a bioactive synthetic analogue of tuftsin by tandem mass spectrometry: anomalous fast atom bombardment activated processes.
abstract: Fast atom bombardment (FAB) tandem mass spectrometry has been used to analyse the biologically potent, partially modified retro-inverso (PMRI) synthetic isomer of tuftsin: this compound represents the active peptide of the fraction of gamma-globulin (leukokinin) which binds specifically to blood neutrophilic leukocytes and monocytes. Protonated molecules and fragment ions were collisionally dissociated at low energies in a triple-quadrupole mass spectrometer to yield a complete picture of the reactions that occur in the condensed and in the gas phase. The study shows that, when retro-inversion is within the N-terminal amino acid, charge localization at the basic sites (possibly at the N-terminus) induces a marked decomposition of the molecule, the loss of ammonia being the most favourable fragmentation process. Also, artifacts are formed in the liquid phase via bimolecular reactions promoted by the high-energy beam. The findings indicate that despite the fact that PMRI isomers of this type are stable against exo-peptidases and also stable under acidic conditions, they appear to be labile under conditions where the energy deposition, due to FAB is necessarily high.
authors.affiliation: Dip. di Chimica, Univ. de l'Aquila, Italy.
authors.forename: F
authors.initials: F
authors.lastname: De Angelis
authors.forename: R
authors.initials: R
authors.lastname: Nicoletti
authors.forename: T
authors.initials: T
authors.lastname: Kuster
authors.forename: C W
authors.initials: CW
authors.lastname: Heizmann
authors.forename: M
authors.initials: M
authors.lastname: Pinori
authors.forename: A S
authors.initials: AS
authors.lastname: Verdini
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D008969:Molecular Sequence Data; D016339:Spectrometry, Mass, Fast Atom Bombardment; D014405:Tuftsin / Q000031:analogs & derivatives* / Q000032:analysis*
chemical_list: D014405:Tuftsin