title: The application of negative ion electrospray mass spectrometry for the sequencing of underivatized disulfide-containing proteins: insulin and lysozyme.
abstract: Negative ion electrospray mass spectra of the peptides produced by tryptic and chymotrypsin digests of bovine insulin, and from the tryptic digest of lysozyme identify at least 80% of the sequences of these proteins. In particular, negative ion mass spectrometry identifies and positions disulfide moieties, and is the method of choice for identifying this post-translational modification in these two proteins. Intramolecular disulfide functionality is identified by the fragmentation [(M - H)(-)- H(2)S(2)](-) in a digest peptide, and CID of that fragment anion provides amino acid sequencing information. Digest peptides containing an intermolecular disulfide structure undergo facile and diagnostic cleavages. Each cleavage produces a peptide fragment from which CID MS/MS data provide sequencing information.
authors.affiliation: Department of Chemistry, The University of Adelaide, South Australia, 5005, Australia.
authors.forename: Hayley J
authors.initials: HJ
authors.lastname: Andreazza
authors.forename: John H
authors.initials: JH
authors.lastname: Bowie
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D004220:Disulfides / Q000737:chemistry*; D007328:Insulin / Q000737:chemistry*; D008969:Molecular Sequence Data; D009113:Muramidase / Q000737:chemistry*; D020539:Sequence Analysis, Protein; D021241:Spectrometry, Mass, Electrospray Ionization; D014357:Trypsin / Q000378:metabolism
chemical_list: D004220:Disulfides; D007328:Insulin; D009113:Muramidase; D014357:Trypsin