Ligand-binding studies: old beliefs and new strategies.

Ligand-binding studies remain a very popular technique among many experimentalists. As far as equilibrium experiments are concerned, saturation and displacement curves are commonly performed for simplicity, convenience or for the sake of tradition. However, alternative protocols, such as 'mixed'-type protocols or multiligand experiments, are also possible. Indeed, there are cases where kinetic experiments, usually considered a 'second-choice' experiment, might have a superior resolving power compared to equilibrium ones. A combination of equilibrium and kinetic experiments might be a powerful solution to overcome limits and shortcomings of each specific technique and is discussed in this issue by G. Enrico Rovati. Thus, a careful choice of the design, a protocol optimization and a computerized analysis of the data can yield a dramatic improvement in the precision of the parameter estimation over more conventional approaches.