A kinetic model for a biopanning process considering antigen desorption and effective antigen concentration on a solid phase

A phage display library is a powerful tool for screening ligands such as an tibodies and peptides that specifically recognize a target. In this study, we established a kinetic model describing the affinity selection process of phage display libraries and verified the model experimentally. Desorption of target molecules from a solid phase and orientation of the epitopes of a dsorbed target molecules are taken into account in this model. The ratio of the effective antigen density to the total antigen density was estimated t o be 0.0127(+/-)0.0018 when bovine pancreatic ribonuclease A (RNase A) adso rbed on polystyrene beads was recognized by an anti-RNase A single-chain Fv phage antibody. The model can faithfully describe the recovery of the phag e antibody in a round of biopanning based on the effective concentration of RNase A on the beads, the desorption rate constant of RNase A from the bea ds, the dissociation constant and dissociation rate constant of the phage a ntibody from RNase A, and the time for blocking, equilibrium and washing in the biopanning process. A recommended biopanning protocol based on the mod el is also described.