title: Mass spectrometric fragmentation of cyclic peptides belonging to the polymyxin and colistin antibiotics studied by ion trap and quadrupole/orthogonal-acceleration time-of-flight technology.
abstract: Electrospray ionization linked to quadrupole/orthogonal-acceleration time-of-flight (Q/oaTOF) and ion trap equipment was used to study the fragmentation behavior of the linear side-chain cyclized peptides of the polymyxin B and E antibiotics. This study exemplifies both the benefits and the drawbacks of mass spectrometric techniques for the determination of the sequence of such complex linear side-chain cyclized peptides. Q/oaTOF accurate mass measurements did not help sufficiently to assign the product ions observed in the product ion spectra. An ion trap mass spectrometer providing MS(n) capability was used to eliminate ambiguities encountered with a single MS/MS approach. The complex fragmentation behavior of these compounds of well-established structure is described which could be useful for structural characterization of unknown substances related to polymyxin B and E in the future.
authors.affiliation: Laboratorium voor Farmaceutische Chemie en Analyse van Geneesmiddelen, Katholieke Universiteit Leuven, Faculteit Farmaceutische Wetenschappen, E. Van Evenstraat 4, B-3000 Leuven, Belgium.
authors.forename: Cindy
authors.initials: C
authors.lastname: Govaerts
authors.forename: Jef
authors.initials: J
authors.lastname: Rozenski
authors.forename: Jennifer
authors.initials: J
authors.lastname: Orwa
authors.forename: Eugène
authors.initials: E
authors.lastname: Roets
authors.forename: Ann
authors.initials: A
authors.lastname: Van Schepdael
authors.forename: Jos
authors.initials: J
authors.lastname: Hoogmartens
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D003091:Colistin / Q000737:chemistry*; D015394:Molecular Structure; D011113:Polymyxins / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D000900:Anti-Bacterial Agents; D011113:Polymyxins; D003091:Colistin