To measure the rate constants, known concentrations of receptor and ligand are mixed in solution and the quantity of free receptor is repeatedly measured over time as the solution phase reaction occurs. The time course of the free receptor depletion is then fit with a standard bimolecular rate equation.
(4)	dLR/dt = k∙R∙L - K∙k∙RL
where K * k has been substituted for k .