title: NMR studies of the antibody-bound conformation of a carbohydrate-mimetic peptide.
abstract: Transferred nuclear Overhauser enhancement (TRNOE) experiments have been performed at 800 MHz to investigate the bound conformation of the hexapeptide DRPVPY, a functional molecular mimic of the group A Streptococcus cell-wall polysaccharide. The hexapeptide binds to the monoclonal antibody SA-3, mimicking the branched trisaccharide repeating unit, L-Rha-alpha-(1 --> 2)-(D-GlcNAc-beta-(1 --> 3))-alpha-L-Rha (Rha, rhamnose; GlcNAc, N-acetylglucosamine). The peptide adopts a tight turn conformation with close contacts between the side chains of valine and tyrosine. Relaxation network editing experiments (QUIET-NOESY) were used to confirm the validity of the observed contacts and to evaluate the presence of spin diffusion pathways. Saturation transfer difference (STD-NMR) experiments with selective saturation of protein resonances revealed enhancements of many of the peptide resonances due to close contacts between the peptide and the protein within the antibody combining site.
authors.affiliation: Departments of Chemistry and of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Johnson
authors.forename: Archimede
authors.initials: A
authors.lastname: Rotondo
authors.forename: B Mario
authors.initials: BM
authors.lastname: Pinto
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D001666:Binding Sites, Antibody; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry; D008024:Ligands; D051379:Mice; D018716:Molecular Mimicry; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D009842:Oligopeptides / Q000737:chemistry* / Q000276:immunology; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D011135:Polysaccharides, Bacterial / Q000737:chemistry* / Q000276:immunology; D011485:Protein Binding / Q000276:immunology; D011487:Protein Conformation; D013297:Streptococcus pyogenes; D013816:Thermodynamics
chemical_list: D000911:Antibodies, Monoclonal; D007140:Immunoglobulin Fab Fragments; D008024:Ligands; D009842:Oligopeptides; D010446:Peptide Fragments; D011135:Polysaccharides, Bacterial; C102511:cell wall polysaccharide, Streptococcus