Bell's expression and the generalized Garg form for forced dissociation of a biomolecular complex

The dissociation of a biomolecular complex under the action of constant force, constant loading rate, and periodic force is studied theoretically. We show that the celebrated Bell expression provides a good approximation for the bond dissociation rate when F/Fc«1, where Fc is the maxima slope of the binding potential along the reaction coordinate. When 1-F/Fc«1 the dissociation rate is better described by a generalized Garg form in which the potential derivative is expanded near Fc. We also show that a constant-force experiment is suitable for extracting the activation energy of the bond, a constant loading experiment is suitable to extract Fc, while time-periodic force can be applied to extract both bond dissociation rates at zero force and Fc.