Microcalorimetry of Protein-Ligand Interactions

Abstract

The energetics of enzymic processes and the interactions responsible for protein behaviour have been central to our discussions so far. Several indirect methods are available for probing the thermodynamics of protein interactions, but the most unambiguous and direct experimental approaches are based on calorimetry. Most reactions have an associated heat effect and, apart from its intrinsic interest in terms of energetics, this heat can serve as a useful general probe of biomolecular processes. My purpose here is to describe the basis and applications of isothermal microcalorimetry to the study of interactions at protein binding sites, illustrating the range of information that may be obtained from such studies. But before doing this, we should perhaps consider the nature of the problem and why an empirical, rather than theoretical approach is necessary.