STATISTICAL THERMODYNAMICS OF LIGAND-BINDING TO GIANT MACROMOLECULES

A statistical thermodynamic model for ligand binding to giant respiratory macromolecules, such as molluscan hemocyanins, is proposed. The model complies with the fundamental structural organization of this class of proteins. It assumes that each morphological unit functions as the element of a one-dimensional Ising lattice, so that conformational transitions occurring upon ligand binding may be propagated to the whole macromolecule through nearest-neighbour interactions. An application of the model to the analysis of oxygen equilibria of the β-hemocyanin of Helix pomatia is presented and its general properties are discussed in connection with other models. © 1990 Societá Italiana di Fisica.