Exploring buffer space for molecular interactions

The interaction of two molecules binding to each other is described by two rate parameters, the association rate parameter k(a) and the dissociation rate parameter k(d). Under standardized conditions these kinetic parameters can be determined by analysis of their interaction in an affinity-based biosensor system, such as BIACORE(R) 3000. The association rate describes the collision frequency and the attraction between two molecules and the dissociation rate describes the stability of the molecular complex. By comparing the affinity of different molecules (calculated as the quotient of the association rate parameter and the dissociation rate parameter), an estimation of specificity can be obtained. For dissociation, two different aspects can be considered-the practical aspect, where one is interested in separating the two molecules, and the informative aspect, where one is interested in the reasons for the dissociation event. This review focuses on a method that was designed to solve the practical problem of regeneration, but eventually produced a considerable amount of information about the interactions themselves.