A FOKKER-PLANCK DESCRIPTION OF MULTIVALENT INTERACTIONS

A dynamic model is presented which uses a mean first passage time to c haracterize multivalent binding as the continuum limit of a one-step s tochastic process. The use of a stochastic model instead of a model ba sed on rate equations permits consideration of fluctuations in the num ber of bonds formed. The importance of fluctuations to the problem of multivalent interactions, especially low affinity interactions, is dis cussed. Assumptions for the theory are based on data in which liposome s were used as a model system for multivalency. The data suggest a lin ear sequential process of bond rupture, and thus a high degree of coop erativity in the microscopic events associated with multivalent liposo mal binding.