title: Elucidation of some fragmentations of small peptides using sequential mass spectrometry on a hybrid instrument.
abstract: Sequential daughter-ion-scanning analyses of small peptides have been performed using a hybrid tandem instrument of BEqQ configuration. Precursor ions are selected by B and allowed or induced (by high-energy collisional activation) to decompose in the region preceding E. Decoupling of E from the accelerating voltage permits the selection of the first-generation daughter ion whilst retaining appropriate float voltages for the quadrupole assemblies. The daughter ion selected by E is further subjected to low-energy collisional-activation dissociation (CAD) in q and the fragment-ion spectrum is obtained by scanning Q. The sequential daughter-ion-scanning technique has been used to establish that 'internal' fragments of the types, (AY') and (BY'), are formed via initial Y-type cleavage. Fragmentation of a protonated peptide (angiotensin III) by loss of the C-terminal amino acid residue, yielding a (B'n + OH) ion, is reported for the first time. This process is analogous to that previously described for metal-cationized peptides.
authors.affiliation: Center for Experimental Therapeutics, Baylor College of Medicine, Houston, Texas 77030.
authors.forename: G C
authors.initials: GC
authors.lastname: Thorne
authors.forename: S J
authors.initials: SJ
authors.lastname: Gaskell
mesh_terms: D000804:Angiotensin II / Q000737:chemistry; D000805:Angiotensin III / Q000737:chemistry; D004743:Enkephalin, Leucine / Q000737:chemistry; D004744:Enkephalin, Methionine / Q000737:chemistry; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods; D010446:Peptide Fragments / Q000737:chemistry*
chemical_list: D010446:Peptide Fragments; D000804:Angiotensin II; D000805:Angiotensin III; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine