Title :
structure of the Fab fragment from F124, a monoclonal antibody specific for hepatitis B surface antigen
Abstract :
- The crystal structure of the Fab fragment from the monoclonal anti-preS2 antibody F124 (IgG1 ,kappa) has been solved by molecular replacement and refined at 3 .0 A resolution
- The Fab crystallizes with two independent molecules in the asymmetric unit
- F124 recognizes an epitope contained within the preS2 segment between residues 120 and 132 of the surface antigen of hepatitis B virus
- The antibody shows a high affinity for the glycan N-linked to Asn123 , but it also cross-reacts with the non-glycosylated peptide fragment 120-132
- Although crystallization was performed in the presence of an eightfold excess of the cross-reactive peptide , no evidence for the ligand was found in the antigen-binding site , which is close to a neighbouring molecule in the crystal lattice
- The antigen-binding site has a groove-like topology which is modulated with pocket-like cavities
- It is characterized by a large number of tyrosine and aspartate residues
- The importance of germ-line mutations at the binding site is discussed