Fig. 1: Binding kinetics of ligelizumab or omalizumab on recombinant human IgE. | Nature Communications

Fig. 1: Binding kinetics of ligelizumab or omalizumab on recombinant human IgE.

From: The mechanistic and functional profile of the therapeutic anti-IgE antibody ligelizumab differs from omalizumab

Fig. 1

a, b Association and dissociation of ligelizumab (a) and omalizumab (b) Fab fragments to human recombinant Sus11-IgE by SPR. Each color refers to an individual measurement cycle. Curves were fitted (black dashed) using a 1:1 langmuir binding model. c Wildtype C328 and mutant C335 IgE-Fc3-4. d, e Binding of wt C328 IgE-Fc3-4 (d) and mut C335 IgE-Fc3-4 variants (e) to ligelizumab IgG by SPR. f Binding of wt C328 IgE-Fc3-4 or mut C335 IgE-Fc3-4 to ligelizumab IgG by ELISA (technical duplicates as mean ± SEM). g, h Binding of wt C328 IgE-Fc3-4 (g) and mut C335 IgE-Fc3-4 (h) to omalizumab IgG by SPR. i Binding of wt C328 IgE-Fc3-4 or mut C335 IgE-Fc3-4 to omalizumab IgG by ELISA (technical duplicates as mean ± SEM). j–m Crystal structure of ligelizumab single chain Fv (scFV) bound to wt C328 IgE-Fc3-4 (PDB ID: 6UQR). IgE-Fc3-4 dimer in surface representation (white and light gray). Ligelizumab epitope residues shown in blue. The ligelizumab scFv is shown in cartoon format (light orange and wheat). 90˚ rotations with perpendicular (j) and parallel (k) view to IgE-Fc twofold axis. l, m Contact interface between ligelizumab VH and VL CDR loops with the two IgE Cε3 domains. l Orientation along the IgE twofold axis. m Orientation from the side of the VH:IgE-Fc interaction. Ligelizumab VH domain interaction is centered around IgE residues R419, M430 and Q417. Ligelizumab residue W31 packs into a pocket on IgE, with additional HCDR1 residues (Y32 and W33) forming interactions that straddle the central R419/M430/Q417 site. Interactions of the VL domain with IgE are limited and located adjacent to residue N394. n Structure of omalizumab bound to IgE-Fc (PDB ID: 5HYS41) oriented as in k. Omalizumab is shown in ribbon format with heavy chains (violet) and light chains (magenta). IgE is shown in surface format with interface residues (magenta). o Overlap of ligelizumab and omalizumab epitopes. Residues unique to omalizumab interactions (magenta) and unique to ligelizumab are (blue) and those that interact with both antibodies (violet) are shown. Source data are provided as Source Data file.

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