Microbead display by in vitro compartmentalisation: selection for binding using flow cytometry

In vitro compartmentalisation in an emulsion was used to physically link proteins to the DNA that encodes them via microbeads. These microbeads can be selected for catalysis, or, as demonstrated here, for binding. Genes encoding a peptide containing an epitope (haemagglutinin) were enriched to near purity from a 10(6)-fold excess of genes encoding a different peptide by two rounds of selection using flow cytometry, indicating similar to 1000-fold enrichment per round. Single beads can be isolated using How sorting and the single gene on the bead amplified by polymerase chain reaction. Hence, the entire process can be performed completely in vitro. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.