FIG 7.

Details of the antigen-antibody interactions in the 2424 and 447-52D Fab/V3 peptide complexes. The color scheme is the same as for Figs. 6A and B. The key residues involved in the antigen-antibody interactions are shown as sticks. (A) Fab 2424/epitope complex. Note that three residues, His^P308, Pro^P313, and Arg^P315, of V3 play key roles in the antigen-antibody interaction: (i) the side chain His^P308 is stacked with that of Tyr^H52 and forms a potential hydrogen bond with Asp^H54, (ii) the side chain of Pro^P313 is stacked with that of Phe^H58, and (iii) the side chain of Arg^P315 is surrounded by three Tyrs and forms a salt bridge with Asp^H100B. (B) 447-52D Fab/epitope complex. Note again that three residues, His^P308, Pro^P313, and Arg^P315, of V3 play key roles in the antigen-antibody interaction.