title: NMR line shapes and multi-state binding equilibria.
abstract: Biological function of proteins relies on conformational transitions and binding of specific ligands. Protein-ligand interactions are thermodynamically and kinetically coupled to conformational changes in protein structures as conceptualized by the models of pre-existing equilibria and induced fit. NMR spectroscopy is particularly sensitive to complex ligand-binding modes-NMR line-shape analysis can provide for thermodynamic and kinetic constants of ligand-binding equilibria with the site-specific resolution. However, broad use of line shape analysis is hampered by complexity of NMR line shapes in multi-state systems. To facilitate interpretation of such spectral patterns, I computationally explored systems where isomerization or dimerization of a protein (receptor) molecule is coupled to binding of a ligand. Through an extensive analysis of multiple exchange regimes for a family of three-state models, I identified signature features to guide an NMR experimentalist in recognizing specific interaction mechanisms. Results show that distinct multi-state models may produce very similar spectral patterns. I also discussed aggregation of a receptor as a possible source of spurious three-state line shapes and provided specific suggestions for complementary experiments that can ensure reliable mechanistic insight.
authors.affiliation: Department of Chemistry, Marquette University, PO Box 1881, Milwaukee, WI 53201, USA. evgueni.kovriguine@mu.edu
authors.forename: Evgenii L
authors.initials: EL
authors.lastname: Kovrigin
mesh_terms: D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D012984:Software; D013816:Thermodynamics
chemical_list: D008024:Ligands; D011506:Proteins