Ligand binding to transiently accessible sites: mechanisms for varying apparent binding rates.

摘要: Many biological processes are characterized by models where ligand has continuous access to binding sites. Use-dependent such as ion channel blockade appear represent a class of site is transient and dependent on conformation (state). (Alternatively, the existence proper for might be transient.) We assume takes place only with that accessible or in bindable conformation. For channels, responds local chemical electrical stimulation. The stimulus amplitude determines mixture channels inaccessible When equilibrium achieved rapidly relation binding, then can considered result an apparent rate determined true modified fraction With repetitive stimulation, model extended setting rates repetitively switch response induced variation states. resulting theoretical description provides means relating parameters those obtained under conditions In particular: (1) piecewise exponential; (2) envelope measured at each pulse train varies exponentially linearly specific rates; (3) steady state degree saturation equilibria.