Covalent and non-covalent dissociations of gas-phase complexes of avoparcin and bacterial receptor mimicking precursor peptides studied by collisionally activated decomposition mass spectrometry.
The gas-phase stability and reactivity of non-covalent complexes of avoparcin and bacterial receptor mimicking precursor peptides were probed by electrospray ionization mass spectrometry combined with collisionally activated decomposition (CAD) studies. The order of the gas-phase stabilities of these non-covalent complexes is different from the order of the stabilities of the same complexes in solution. The specific stereoselectivity observed in non-covalent binding in solution is not retained in the gas phase. The presence of a lysine residue in the bacterial receptor mimicking precursor peptides appears to promote the gas-phase stabilities of the antibiotic-peptide complexes. Complexes of avoparcin with receptor peptides containing a lysine residue are stabilized in the gas phase to such an extent that CAD of these non-covalent complexes proceeds through a competition between non-covalent and covalent fragmentation pathways. These results indicate clearly that the use of CAD mass spectra for the quantitative characterization of the stability of non-covalent complexes in solution should be applied with extreme caution.
van der Kerk-van Hoof
A
A
Department of Biomolecular Mass Spectrometry and Bijvoet Center for Biomolecular Research, Department of Chemistry, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.
Heck
A J
AJ
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000493:pharmacokinetics; D001287:Attachment Sites, Microbiological; D006020:Glycopeptides; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D011498:Protein Precursors / Q000737:chemistry* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013816:Thermodynamics
D000900:Anti-Bacterial Agents; D006020:Glycopeptides; D009842:Oligopeptides; D011498:Protein Precursors; C016249:avoparcin