A Mathematical Model for Biopanning (Affinity Selection) Using Peptide Libraries on Filamentous Phage

A mathematical model is presented for the process of selection of peptides for binding to a target. The affinity enrichment process commonly known as biopanning relies on subjecting a library of peptides on filamentous phage to a selection for binding to the target immobilized on solid support or in solution. The model is an implementation of the mass-action law to the diverse population of macromolecular assemblies. An analytical solution is presented for the enrichment process. Most parameters in the enrichment formula can be easily determined experimentally. Two examples corresponding to biopanning with epitope libraries and antibody libraries are given. The model allows for an estimation of the contribution of equilibrium and dissociative biopanning to the overall enrichment. The model can be a tool in the evaluation of the role of different biopanning parameters. Its implementation in a spreadsheet makes it possible to perform a computer stimulation of a biopanning experiment.