Structure of the Anti-C60 Fullerene Antibody Fab Fragment: Structural Determinants of Fullerene Binding.

The structure of the anti-C fullerene antibody Fab fragment (FabC) was solved by X-ray crystallography. The computer-aided docking of C into the antigen-binding pocket of FabC showed that binding of C to FabC is governed by the enthalpy and entropy; namely, by π-π stacking interactions with aromatic residues of the antigen-binding site and reduction of the solvent-accessible area of the hydrophobic surface of C. A fragment of the mobile CDR H3 loop located on the surface of FabC interferes with C binding in the antigen-binding site, thereby resulting in low antibody affinity for C. The structure of apo-FabC has been deposited with pdbid 6H3H.