A straightforward method for measuring binding affinities of ligands to proteins of unknown concentration in biological tissues

Abstract

The equilibrium dissociation constant (K_d) is a quantitative measure of the strength with which a drug binds to its receptor. Methods for determining K_d typically require a priori knowledge of protein concentration or mass. We report a simple dilution method for estimation of K_d using native mass spectrometry which can be applied to protein–ligand complexes involving proteins of unknown concentration, from complex mixtures, including direct tissue sampling.