title: Gas-phase chemistry of the negative ions of fully-protected peptides by high-resolution electrospray ionization tandem mass spectrometry.
abstract: Fully-protected C-terminal free peptides can be conveniently analyzed by high-resolution electrospray tandem mass spectrometry (ESI-MS/MS) in a quadrupole quadrupole time-of-flight tandem hybrid mass spectrometer, operated in the negative (-) ionizaionization mode. The unusual choice of negative ions in mass spectrometry applications to peptide analysis was needed to obtain exhaustive sequence and structural data. The low-energy collision-induced dissociation (CID) experiments provided, in fact, tandem mass spectra displaying highly diagnostic fragments with a good signal-to-noise ratio. The method is applied to segments of porcine calcitonin (Cal), Cal (1016, 1), Cal (1724, 2) and Cal (2528, 3) whose [M H]- deprotonated molecular ions provided low-energy CID mass spectra which allow the evaluation either of the primary structure of the peptide and of the location of the side-chain protective groups. ESI (+) MS can be conveniently used, in the high resolution mode, to achieve precise information on the elemental composition of the examined peptides.
authors.affiliation: Dipartimento di Chimica, Università della Calabria, via Pietro Bucci cubo 12/C, I-87030, Arcavacata di Rende (CS), Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Napoli
authors.forename: Leonardo
authors.initials: L
authors.lastname: Di Donna
authors.forename: Giovanni
authors.initials: G
authors.lastname: Sindona
authors.forename: Elena
authors.initials: E
authors.lastname: Urso
mesh_terms: D000818:Animals; D002116:Calcitonin / Q000737:chemistry*; D005740:Gases; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry*; D010449:Peptide Mapping / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013552:Swine
chemical_list: D005740:Gases; D010446:Peptide Fragments; D002116:Calcitonin