Directed evolution of hydrolytic antibodies in phage-displayed combinatorial libraries

Abstract

This review article describes our strategy for directed evolution of catalytic antibodies in phage-displayed antibody (Fab) libraries. To evolve catalytic antibodies toward higher catalytic activity, we have reconstructed an enzyme-evolutionary process in vitro. Thus, a phage-displayed combinatorial library from a hydrolytic antibody, 6D9, generated by the conventional in vivo method by immunization with transition-state analog (TSA) 5, was screened against a newly devised TSA 7 to optimize the differential affinity for the transition state relative to the ground state. This method provided evolved mutants which exhibited 20-fold higher activity than the parent antibody, 6D9. Structural analysis revealed an advantage of in vitro evolution over in vivo evolution: an induced catalytic residue in the evolved catalytic antibody arises from double mutations in one codon, which rarely occur in somatic hypermutation in the immune response. © 2014 The Chemical Society of Japan.