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 i s injected The concentration of one of the components is fixed, and th e concentration of the other one is varied during a series of experime nts. The presence of both species in the capillary causes a large back ground signal. Two negative peaks will appear in the electropherogram. The migration times of the negative peaks reflect the fractions of th e free and bound components in the mixture, and depends on the concent ration in the buffer. This shift can be used to construct a binding cu rve from which the association parameters can be estimated. Nearly the whole system is saturated with the interacting components, so that lo sses due to wall adsorption are less detrimental. (C) 1997 Elsevier Sc ience B.V.