title: Affinity constants for small molecules from SPR competition experiments.
abstract: Direct assay of small molecules by SPR in general is troublesome and at least tedious procedures have to be applied. Competition experiments offer an attractive alternative. A small ligand known to bind to the analyte is immobilized on an SPR sensor surface, and the binding of the larger analyte in the presence of compounds under investigation in a concentration range is assayed. The resulting inhibition curves of the equilibrium SPR signal as function of the compound concentration can be analyzed to yield thermodynamic binding constants for the interaction in solution between analyte and the compounds under investigation. An additional advantage of this method is that series of compounds can be analyzed using the same sensor surface, so there is no immobilization needed for each compound. An adaptation of the method to analyze interactions with bivalent analytes (e.g., antibodies) is also included. Some observed different affinities in solution compared to that on the SPR surface are discussed.
authors.affiliation: Department of Medicinal Chemistry and Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Utrecht, The Netherlands.
authors.forename: Nico J
authors.initials: NJ
authors.lastname: de Mol
mesh_terms: D000906:Antibodies / Q000032:analysis / Q000378:metabolism; D001667:Binding, Competitive; D004353:Drug Evaluation, Preclinical; D008024:Ligands; D046911:Macromolecular Substances / Q000032:analysis / Q000378:metabolism; D015203:Reproducibility of Results; D012996:Solutions; D020349:Surface Plasmon Resonance / Q000295:instrumentation / Q000379:methods*; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D000906:Antibodies; D008024:Ligands; D046911:Macromolecular Substances; D012996:Solutions