FIG. 2.

The epitope binding sites of antibody 1G9-1C2 (25 μg/ml) were determined with 30 peptides (7 residues each) corresponding to a single-residue frameshift of the 7-residue sequence starting at residue 30 of the sequence identified in AP 87-8 of Fig. 3. For example, peptide 1 was H-DDGDDDG-OH, peptide 2 was H-DGDDDGA-OH, peptide 3 was H-GDDDGAD-OH, etc. Peptides were synthesized simultaneously on a derivatized cellulose sheet (SPOTs; Genosys). SPOT 32 contained H-DDDDDDD-OH and SPOT 33 contained H-EEEEEEE-OH as peptide controls. SPOTs were detected after the strip was incubated in casein-based blocking buffer, incubated in antibody, washed, incubated in secondary β-galactosidase-conjugated antibody, and incubated in Signal Development solution. Epitopes that contained more than 2 terminal Asp residues were recognized.