title: Interactions of alpha- and beta-avoparcin with bacterial cell-wall receptor-mimicking peptides studied by electrospray ionization mass spectrometry.
abstract: Solution phase affinity constants of the glycopeptide antibiotic alpha- and beta-avoparcin, with a range of bacterial cell-wall receptor-mimicking model peptides, were determined by a relatively new method: affinity electrospray ionization mass spectrometry (ESI-MS). This method is relatively efficient and allows the parallel determination of several affinity constants in mixtures of antibiotics and receptors. The determined binding constants for alpha- and beta-avoparcin were compared with those of the related glycopeptide antibiotic vancomycin. The solution phase binding affinities of alpha- and beta-avoparcin on one hand, and vancomycin on the other, were found to be in the same order, at least for the range of receptor-mimicking peptides studied. However, beta-avoparcin displayed slightly higher binding affinities than alpha-avoparcin, particularly for strong binding receptor-mimicking peptides. The evidence that alpha- and beta-avoparcin and vancomycin are structurally similar, combined with the present data revealing their similar affinity for bacterial cell-wall receptor-mimicking peptides, supports the hypothesis that the appearance of vancomycin-resistant enterococci (VRE) might be linked to the widespread use of avoparcin.
authors.affiliation: Department of Biomolecular Mass Spectrometry Bijvoet, Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: van de Kerk-van Hoof
authors.forename: A J
authors.initials: AJ
authors.lastname: Heck
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism*; D001419:Bacteria / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D001667:Binding, Competitive; D002473:Cell Wall / Q000737:chemistry; D006020:Glycopeptides; D008024:Ligands; D013058:Mass Spectrometry / Q000379:methods*; D009842:Oligopeptides / Q000378:metabolism*; D014640:Vancomycin / Q000737:chemistry / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D006020:Glycopeptides; D008024:Ligands; D009842:Oligopeptides; D014640:Vancomycin; C016249:avoparcin