Why is it important to understand the kinetics of my binding interaction?
The affinity or Equilibrium Constant (KD) describes the strength of binding and measured at equilibrium
The kinetics describes the rates of complex formation (ka) and complex decay (kd).
The figure below shows simulated SPR data for a binding interaction with an affinity or Equilibrium Constant (KD) of 1nM but with different kinetics.
The Equilibrium Constant is derived from the dissociation rate constant divided by the association rate constant.
KD = kd / ka
1nM = 1e-2 s-1 / 1e7 M-1 s-1
1nM = 1e-3 s-1 / 1e6 M-1 s-1
1nM = 1e-4 s-1 / 1e5 M-1 s-1
1nM = 1e-5 s-1 / 1e4 M-1 s-1
The figure below shows simulated data using the association and dissociation rates for a 1nM Equilibrium binding constant.
Knowing the kinetics of a molecular interaction is important for understanding the biological processes behind the interaction. In addition ranking therapeutic agents according to their kinetics and in particular their dissociation constant is important during structure activity relationships. The figure below shows a series of peptidomimetic compounds that bind to the SH2 containing adapter protein Grb2. This work was performed in the PCL in collaboration with Dr. Terry Burke (Laboratory of Chemical Biology, NCI).