Screening of peptide ligands that bind to the Fc region of IgG using peptide array and its application to affinity purification of antibody

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• Screening of peptides that bind to IgG was obtained using a peptide array.
• The identified peptides (NKFRGKYK and NARKFYKG) recognized Fc region of human IgG.
• Affinity purification of IgG was performed from cell culture medium with 83% purity.

Small peptides have attracted great interest for affinity purification since they are more stable, less immunogenic, and less expensive compared to protein ligands. In this study, screening of peptides that has affinity to Fc region of IgG was investigated from amino acid sequence of the IgG Fcγ receptor, which is well known as one of the IgG-Fc binding proteins, using a spot-synthesized peptide array. High affinity octamer peptides, NKFRGKYK and NARKFYKG, for mouse IgG were obtained by amino acid substitution assays. Both peptides also recognized human IgG-Fc. The association constants for human IgG-Fc were 8.9 × 106 (NKFRGKYK) and 6.5 × 106 M−1 (NARKFYKG). Purity of the human IgG-Fc from cell culture medium using the peptide immobilized resins was 83% for NKFRGKYK and 68% for NARKFYKG. These peptide ligands were used for the purification of monoclonal antibody (MAb) from cell culture supernatants. The yields obtained for the antibody were found to be 69% and 80% for NKFRGKYK and NARKFYKG, respectively. The residual DNA and host cell protein reduction obtained by these peptides resin were in the range of 4.2 and 1.3 log reduction value (LRV) (NKFRGKYK), 3.9 and 1.5LRV (NARKFYKG), respectively, comparable to those reported for Protein A. Therefore, it was indicated that the screened NKFRGKYK and NARKFYKG peptide would be useful as affinity purification ligands for IgG.