Reaction Rate Math
The rate at which molecules interact to form a bound complex is called the association rate; conversely the rate at which a bound complex breaks down into constituent parts is called the dissociation rate.
The affinity of this binding is:
affinity constant: KA = 1 / KD = kon / koff
Binding is reversible, with a dissociation constant of:
dissociation constant: KD = 1 / KA = koff / kon