Vacancy affinity capillary electrophoresis, a new method for measuring association constants

A new method to determine association constants, the vacancy affinity capillary electrophoretic (VACE) method is described. The capillary is filled with a mixture of the interacting components and neat buffer is injected The concentration of one of the components is fixed, and the concentration of the other one is varied during a series of experiments. The presence of both species in the capillary causes a large background signal. Two negative peaks will appear in the electropherogram. The migration times of the negative peaks reflect the fractions of the free and bound components in the mixture, and depends on the concentration in the buffer. This shift can be used to construct a binding curve from which the association parameters can be estimated. Nearly the whole system is saturated with the interacting components, so that losses due to wall adsorption are less detrimental. (C) 1997 Elsevier Science B.V.