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 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(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.