Lysine residues on antibody component (Lys)

Lysine residues on antibody components, specifically the ε-amino groups of lysine side chains, are critical structural elements used as conjugation sites in the development of antibody-drug conjugates (ADCs) (Beck et al., 2017). In a typical IgG1 antibody, there are approximately 80-100 lysine residues, many of which are solvent-accessible and available for chemical modification (Panowski et al., 2014). While they are not therapeutic targets themselves, they serve as the chemical foundation for attaching cytotoxic payloads, fluorophores, or polyethylene glycol (PEG) chains (Lewis Phillips et al., 2008). The use of lysine for conjugation often results in a heterogeneous mixture of drug products with varying drug-to-antibody ratios (DAR) because the reaction is typically non-specific across multiple available lysine sites (Wang et al., 2005). This heterogeneity can influence the pharmacokinetics, efficacy, and safety profile of the resulting therapeutic (Adem et al., 2014). Careful optimization is required to ensure that conjugation does not occur within the complementarity-determining regions (CDRs), which could impair the antibody's ability to bind its intended biological target (Beck et al., 2017).

Other names

Lysine side chainsε-amino groups of lysineAntibody lysine residuesLysine-based conjugation sites

Lysine residues on the antibody scaffold serve as nucleophilic attachment points for electrophilic linker-payload complexes, typically via N-hydroxysuccinimide (NHS) ester chemistry, resulting in the formation of stable amide bonds and the creation of antibody-drug conjugates (ADCs).