Patent ID: 7672786

Claim:
A homogeneous method for selecting a fraction of ligands from a mixture of potential ligands having similar electrophoretic mobility and different binding parameters wherein said selected ligands bind to a target with a desired range of ligand-target complex-formation binding parameters, said complex-formation binding parameters being selected from the equilibrium dissociation constant of the complex, the bimolecular rate constant of the formation of the complex and the unimolecular rate constant of the dissociation of the complex, the method comprising: a) selecting the desired range of the ligand-target complex-formation binding parameters; b) using the desired range of the ligand-target complex-formation binding parameters to determine an incubation time, target concentration, and time window for collecting a fraction containing ligands that bind to the target within the desired range of ligand-target complex-formation binding parameters; c) preparing a sample comprising ligands, target and complexes by incubating the mixture of the ligands and the target, for the incubation time and the target concentration determined in b) where the sample is incubated inside or outside a capillary that is part of a capillary electrophoresis instrument and the capillary is filled with an electrophoresis run buffer solution free of the ligands or ligand-target complexes prior to introduction of the sample; d) if the sample is incubated outside the capillary, introducing the sample into the capillary; e) subjecting the sample to capillary electrophoresis under non-equilibrium conditions optimized to separate the ligands from the complexes and not to separate the ligands from each other; and f) collecting the fraction containing ligands that bind to the target within the desired range of ligand-target complex-formation binding parameters eluting from the capillary in the time window determined in b) said fractions comprising the selected ligands in the form of separated intact ligand-target complexes and/or ligands dissociated from the complexes.