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Ligand-Receptor Binding Kinetics
Watch ligands diffuse, bind, and unbind in real time. Tune kon, koff, concentration, and competition between two ligands.
Law of mass action: R + L ⇌ RL with rate dRL/dt = kon[R][L] − koff[RL]. At steady state, KD = koff/kon and occupancy θ = [L]/(KD+[L]) (hyperbolic). Competition: two ligands compete for the same site; the apparent KD for each is raised by the other. Mean dwell time τbound = 1/koff can be measured from single-molecule experiments. The animated dots represent individual ligand molecules diffusing and colliding with membrane receptors (orange squares).