Cm. Staschen et Ld. Homer, EXPERIMENTAL-DESIGN AND ESTIMATION OF PARAMETERS IN COMPLEX RADIOLIGAND BINDING SYSTEMS, Journal of pharmacokinetics and biopharmaceutics, 24(6), 1996, pp. 589-609
A computer was used to simulate data from typical radioligand binding
experiments with a 2-site competitive-allosteric model of a receptor.
The 4 equilibrium parameters of this model cannot be estimated by fitt
ing the model to equilibrium data. Data from simulations of associatio
n experiments give satisfactory estimates of the 9 competitive-alloste
ric model parameters, From the kinetic parameters, equilibrium constan
ts may be calculated. Combining data from equilibrium simulations with
data from association simulations provided estimates of the model par
ameters with smaller standard deviations. A further improvement in des
ign was shown possible by including simulated experiments in which rec
eptor was preincubated with inhibitor before adding ligand. This impro
vement was documented using Monte Carlo replications of parameter esti
mates using competing experimental designs. Replications also revealed
certain biases in the parameter estimates and could provide a means o
f estimating those biases when parameter estimates are made using expe
rimental rather than simulated data. Simulations offer a powerful tool
in planning experiments designed to estimate kinetic parameters of a
receptor system. This is especially true with complex systems that may
require pooling data from different kinds of experiments in order to
estimate the kinetic parameters.