Development of tCAP(N3): Affinity Peptide-Aided, pH-Triggered Strategy for Site-Specific Native IgG Modification

Area of Science:

• Bioconjugation Chemistry
• Antibody Engineering
• Chemical Biology

Background:

• Direct modification of native antibodies with affinity peptides is challenging due to peptide interference with antibody function.
• Existing methods often result in blocked antibody-receptor interactions, limiting their therapeutic potential.

Purpose of the Study:

• To develop a novel, traceless chemical conjugation method for site-selective antibody modification.
• To create stable antibody conjugates with preserved biological activity using an affinity peptide.

Main Methods:

• Development of traceless chemical conjugation (tCAP(N3)) using an active ester precursor for spontaneous activation.
• Site-selective transfer of an azide-containing peptide onto Lys248 of native IgG.
• Further modification of azidated IgG with DBCO compounds for conjugation.

Main Results:

• tCAP(N3) allows for stable storage and spontaneous activation under neutral conditions.
• Site-selective azidation of IgG at Lys248 was achieved, yielding divalently azidated IgG.
• The resulting antibody conjugates demonstrated retained Fc receptor binding and antigen recognition comparable to unmodified IgG.

Conclusions:

• tCAP(N3) offers a robust and traceless method for antibody modification with affinity peptides.
• This approach yields antibody conjugates with preserved essential biological functions.
• The developed method holds promise for advancing antibody-based therapeutics and diagnostics.