Making chemistry selectable by linking it to infectivity.

The link between recognition and replication is fundamental to the operation of the immune system. In recent years, modeling this process in a format of phage-display combinatorial libraries has afforded a powerful tool for obtaining valuable antibodies. However, the ability to readily select and isolate rare catalysts would expand the scope of library technology. A technique in which phage infection controlled the link between recognition and replication was applied to show that chemistry is a selectable process. An antibody that operated by covalent catalysis to form an acyl intermediate restored phage infectivity and allowed selection from a library in which the catalyst constituted 1 in 10(5) members. Three different selection approaches were examined for their convenience and generality. Incorporating these protocols together with well known affinity labels and mechanism-based inactivators should allow the procurement of a wide range of novel catalytic antibodies.