The FVIII C2 domain/G99 F_ABinterface. (A) Direct molecular contacts between the G99 CDR region and C2 domain residue Lys2227; pink: fVIII C2 domain, dark green: G99 heavy chain, light green: G99 light chain. (B) Direct molecular contacts between the G99 light chain and the C2 domain 2222-2228 loop; pink: fVIII C2 domain, light green: G99 light chain. (C) Direct molecular contacts between the G99 heavy chain and the C2 domain residues 2273-2282; pink: fVIII C2 domain, dark green: G99 heavy chain. (D,E) Electrostatic surface potentials for the G99 epitope on the fVIII C2 domain (D) and the variable region of the G99 F_AB (D); blue: positive charge, red: negative charge. The surface potentials were calculated with APBS at surface potential values of ±5 kT/e, and the surfaces were displayed in PyMol.