Figure 2.

Design of AF1 antibody sublibrary for affinity maturation that targets naturally diverse and solvent-exposed CDR sites with mutations that are common in human antibodies.A, sites in heavy (H2) and light (L1 and L3) chain CDRs for mutagenesis were identified based on their solvent exposure, diversity in human antibodies, and compatibility with sets of mutations most commonly observed in human antibodies. The wild-type residues at each site (boxed in red) were included in the library, and the average frequency (%) of each residue observed at each site in human antibodies is color coded. Some of the most common residues in human antibodies were not sampled because they are incompatible with degenerate codons encoding the wild-type residue and other favorable residues. Residues in black and bold text were sampled at each site. B, summary of the designed antibody library at 11 CDR sites that includes the wild-type residue and 3 to 5 mutations that aim to sample combinations of residues most commonly observed in human antibodies. The color codes are green for polar residues, red for negatively charged residues, black for hydrophobic residues, and purple for cysteine residues.