Recently, smart chemical modification of native antibodies attracts attention for various purposes, e.g. producing antibody-drug conjugates (ADCs) and fluorescent-labelling, because traditional random reactions between active esters and several unspecific Lys residues sometimes impede antibody performance due to modifications at undesired position. Thus, many site-specific modification strategies are reported (1). Under these circumstances, our group created CCAP (chemical conjugation by affinity peptide) method in 2019 exploiting affinity peptides against human IgG. This method enabled modification at very specific Lys residues in the hinge moiety of the antibody (2,3). Furthermore, based on this methodology, AJICAP method has been established (4). All these methods adopt specially designed “CCAP reagents” consisting of three moieties: payload, affinity peptide, and active ester. By mixing such reagents and native antibody, CCAP reagent containing affinity peptides is site-specifically attached to the antibody via a covalent bond formed between active ester and the specific Lys residues of the antibody.
Here we will discuss novel tCAP reagents containing payload, active ester, and affinity peptide in this order for payload “transfer”. By mixing tCAP reagents and native antibodies, payload such as Ac-Lys(N3)-Gly-Gly was efficiently transferred to the IgG antibodies. Moreover, because self-activatable latent active ester structure was adopted, long shelf life as the reagent was also achieved. Such robust technology for modification of IgG antibodies would be important toward further industrial and pharmaceutical applications.
1) Yamada K, and Ito Y., ChemBioChem, 20, 2019: 2729-2737.
2) Kishimoto S, et al., Bioconjugate Chemistry 30, 2019: 698–702.
3) Mori S, et al., The Journal of Biochemistry, 169, 2021: 35-42
4) Yamada K, et al., Angewandte Chemie International Edition, 58, 2019: 5592–97.