Figure 2.

Orientations of Tyr^H33 and hapten in the 48G7 germ line and mature antibody–hapten complexes. Orientations are taken from representative structures of the appropriate antibody–hapten complex trajectories. Hydrogen bonds are indicated by dashed lines. (A) Germ line antibody–hapten complex. The carboxyl end of the hapten is ideally oriented to form a hydrogen bond with the hydroxyl of Tyr^H33. (B) Mature antibody–hapten complex. Hydrogen bonding is not possible between Tyr^H33 and the newly positioned carboxyl end of the hapten. However, Tyr^H33 has shifted toward the phosphonate moiety to enable the formation of a strong hydrogen bond between its hydroxyl and one of the phosphonyl oxygens. Produced with the midasplus graphics program (26).