Calorimetric methods for interpreting protein—Ligand interactions

Abstract

This chapter discusses the calorimetric methods for interpreting protein-ligand interactions. Calorimetric measurement of protein-ligand binding is considered from two different viewpoints: one is its use in obtaining binding constants, the other is its employment to measure the other thermodynamic parameters of a reaction. Heat uses as a phenomenological signal to indicate the extent to which a ligand-binding site is saturated. Calorimetry merely takes its place among a wide variety of such physically measurable signals whose utility in determining binding constants requires no knowledge of the physical basis of its expression. As such, like other signals (such as difference spectroscopy, fluorescence, H+ titration, and elution gel chromatography), its choice of employment in the measurement of K depends on two kinds of factors, intrinsic factors and the specific system. The enthalpy of a given protein-ligand interaction is a function of ligand concentration, pH, and temperature, as well as the presence of other ligands, ionic strength, and other solvent conditions. © 1995 Elsevier Inc.