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

The structure of the anti-C-60 fullerene antibody Fab fragment (FabC(60)) was solved by X-ray crystallography. The computer-aided docking of C-60 into the antigen-binding pocket of FabC(60) showed that binding of C-60 to FabC(60) is governed by the enthalpy and entropy; namely, by pi-pi stacking interactions with aromatic residues of the antigen-binding site and reduction of the solvent-accessible area of the hydrophobic surface of C-60. A fragment of the mobile CDR H3 loop located on the surface of FabC(60) interferes with C-60 binding in the antigen-binding site, thereby resulting in low antibody affinity for C-60. The structure of apo-FabC(60) has been deposited with pdbid 6H3H.