Site-Selective Lysine Acetylation of Human Immunoglobulin G for Immunoliposomes and Bispecific Antibody Complexes

• DOI: 10.1021/jacs.2c07594
• Publication Date: 2022-09-28T02:11:47Z
• Authors: Dingdong Yuan; Yu Zhang; King Hoo Lim; Stephen King Pong...; Xizi Yang; Yujie Liang; Wilson Chun Yu Lau; Kwan T. Chow; Jiang Xia
• Keywords: Conjugate; Polylysine

Site-selective acetylation of a single lysine residue in protein that reaches acetyltransferase's accuracy, precision, and reliability is challenging. Here, we report peptide-guided, proximity-driven group transfer reaction acetylates residue, Lys 248, the fragment crystallizable region (Fc region) heavy chain human Immunoglobulin G (IgG). An Fc-interacting peptide bound with Fc domain positioned phenolic ester close to which induced nucleophilic resulted an acetyl 248. The proceeded decent yield under physiological condition without need for deglycosylation, unnatural amino acids, or catalysts. Along acetylation, functional moieties such as azide, alkyne, fluorescent molecules, biotin could also be site-selectively installed on allowing IgG's further derivatization. We then synthesized antibody–lipid conjugate constructed antibody-conjugated liposomes (immunoliposomes), targeting HER2-positive (HER2+) cancer cells. built bispecific antibody complex (bsAbC) covalently linking anti-HER2 anti-CD3 antibody. bsAbC showed vitro effector-cell-mediated cytotoxicity at nanomolar concentrations. Compared antibodies (bsAbs), bsAbCs are based native IgGs contain two antigen-binding sites each antigen, twice bsAbs. Altogether, this work reports method site-selective antibodies, highlights facile way IgG functionalization, underscores potential immunotherapy.