CONFORMATIONAL CORRECTION MECHANISMS AIDING ANTIGEN RECOGNITION BY A HUMANIZED ANTIBODY

The crystal structure of the complex between hen egg lysozyme and the Fv fragment of a humanized antilysozyme antibody was determined to 2.7 -Angstrom resolution. The structure of the antigen combining site in t he complex is nearly identical to that of the complexed form of the pa rent mouse antibody, D1.3. In cont rast, the combining sites of the un liganded mouse and humanized antilysozymes show moderate conformationa l differences. This disparity suggests that a conformational readjustm ent process linked to antigen binding reverses adverse conformations i n the complementarity determining regions that had been introduced by engineering these segments next to human framework regions in the huma nized antibody.