PROBABILITY-DISTRIBUTIONS OF THERMODYNAMIC AFFINITIES FOR HETEROGENEOUS RECEPTOR POPULATIONS

A statistical approach to characterize the thermodynamic affinity dist ributions of heterogeneous receptor populations in terms of stoichiome tric binding constants is presented. The use of stoichiometric density distributions provides a novel description of ligand binding systems. The distributions of stoichiometric constants, T-i(Ki)'s, are obtaine d assuming that the distribution of site constants N(k) is known. It i s found that in the case of heterogeneous systems with multivalent rec eptors, N(k) is an average over all the T-i(Ki)'s even when there are positive or negative site-site interactions. It is seen that in the ab sence or in the presence of site-site interactions the mean and the va riance of the Ki's can be derived from a Scatchard plot. Some of these results are particularly applicable to bivalent heterogeneous antibod y populations and other results are applicable to bivalent heterogeneo us systems with different binding sites. (C) 1998 Academic Press Limit ed.