expected kon and koff for antibody

Hi all

I've been building software that incorperates more complex models for antiboody binding for use with SPR experiments and I'd like to see what range of values people would expect for antibody kon and koff parameters- so these can be used for the innitial range of parameter estimates and I can check the outputs I already have.

In my literature review I've so far found it much easier to find sources showing the distribution of affinity rather than kon and koff parameters.
(I've included a bar graph of mouse monoclonal affinities from abcam )

Hi,

In general, the antibodies where we are looking for have a low equilibrium dissociation constant (K_D). As you noticed, often only this value is stated and compared. However, the association (k_a) and dissociation rate (k_d) can differ greatly but resulting in the same K_D.

If we take the high affinity antibodies, most of them have a low dissociation rate (e.g. < 10^-4 s^-1). Applications such as an ELISA or pull down assay benefit from a low dissociation rate enabling stringent washing. The association rate can be relatively low because incubation times can be prolonged.

So for initial values I would choose
k_a: 10⁴ M^-1 s^-1
k_d: 10^-5 s^-1

Kind regards
Arnoud

PS: www.researchgate.net/figure/304536910_fi...-grouped-by-antibody

Thanks thats hugely helpful!

In the past people have told me that lower analyte concentrations lead to lower k_on estimates, and higher analyte concentrations lead to higher estimates.

I haven't been able to find any support in the literature for this, is this something other people have seen? Is there any documentation for it?

The association rate constant (k_a) and dissociation rate constant (k_d) are constant! for a certain interaction pair. The association rate/speed is dependent on the analyte concentration.

Thus the concentration of the components does not determine the intrinsic kinetics but does the speed of the kinetics.

Arnoud