Ligand binding interaction energies

Table 1. Average ligand-surrounding interaction energies, electrostatic corrections and observed binding free energies (kcal/mol) for the eight thrombin inhibitors (from Ref. 46). b...

Figure 3. Free energy diagram for ligand binding interactions to an MWC dimer. Note that the relative stability of the To to Rq alters the ligand saturation curve as shown in each graph. The energy changes between each R-state are equivalent because each ligand binding interaction has the same equilibrium constant.

Figure 5. Free energy diagrams showing the salient differences between the Monod and Koshland models. The MWC model is a two-state model with equivalent ligand binding interactions (indicated here by the equal spacing between Rq and Rb states and between RLi and RL2 states). In the KNF model, the amount of energy released determines whether binding will be independent or show negative or positive cooperativity.

Isothermal titration calorimetry (ITC) is almost the ultimate titration methodology in that this technique is based entirely upon titration of heat energy and then deconvolution of this information into equilibrium binding constant information. However, the real beauty of this technique is that it engages directly with the thermodynamics of receptor-ligand binding interactions. 

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