ISSN:
1052-9306
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
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 γ-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.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bms.1200230504
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