Cooperativity liganded interfaces

Fig. 7. Schematic illustration of free energy assignments for three different types of interactions. The examples illustrate the situation existing for folded, unfolded, and one partially folded intermediate. For hydrophobic interfaces, partially folded intermediates always include an extra term Ag corresponding to the solvent exposure of protein regions that have not undergone unfolding. The unfolded state lacks this uncompensated exposure term. For a bonded or liganded interface, cooperative behavior is created when the unfolding of either domain results in the disruption of the bonded interface or the dissociation of the ligand molecule. [Reprinted from Freire el al. (1991)].

A model used to explain cooperativity on the basis of ligand-induced changes in conformation that may or may not alter the subunit-subunit interfaces of oligomeric enzymes and receptors. This model has also been referred to as the Adair-Koshland-Nemethy-Filmer model (AKNF model), the induced-fit model, and the sequential model. 

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