Thermodinamic Analysis in Drug-receptor Binding: The A3 Adenosine receptor

Receptor binding thermodynamics is a powerful tool to gain deep insight, at the molecular level, of the events which occur during drug-receptor interactions. This paper deals with the study of the A3 adenosine receptors in the general scenario of all receptors studied so far from this point of view. Thermodynamic parameters, standard free energy (G°), standard enthalpy (H°) and standard entropy (S°) of the A3 adenosine receptor binding equilibrium are reported, discussed and compared with those observed for membrane receptors thermodynamically investigated. As for available thermodynamic data of all G-protein coupled receptors (GPCRs) and ligand-gated ion channels receptors (LGICRs) are reported and discussed in terms of two important physical phenomena, the thermodynamic discrimination and enthalpy-entropy compensation. Thermodynamic data of A3 adenosine receptors will be compared with those obtained in different cell systems for A1, A2A and A2B receptors.