Two-Step Strategy for Alteration of Immunoglobulin Specificity by In Vitro Mutagenesis

A two-step strategy for changing the specificity of antibodies (Abs) is presented, which we have used to change the specificity of an Ab from 11-deoxycortisol (11-DOC) to cortisol (CS). Two kinds of in vitro mutagenesis are utilized in this protocol: first, mutations are introduced at restricted positions in the complementarity-determining regions (CDRs) by site-directed mutagenesis; second, mutations are introduced into the entire V-coding regions by random mutagenesis.