Relationship between ligand binding and conformational change of macromolecules in the two-state allosteric model

The relationship between the binding function $\text{Y}$ and the state function $\text{R}$ of an oligomeric protein has been analysed for the general two-state allosteric model. It is shown that this relation is determined by the numerical values of the inherent parameters of the model. The shape of the function $\text{Y}\text{= f (}\text{R}\text{)}$ can therefore be strictly concave, strictly convex or inverse sigmoidal according to the conditions. In the two-state allosteric model only a dimeric protein can display a linear relationship between $\text{Y}$ and $\text{R}$.In the paper general criteria for the estimation of the state function $\text{R}$ from experimentally obtained conformational parameters are discussed.