Crystallization and preliminary X-ray crystallographic studies on a Fab fragment of the mouse anti-human Fas monoclonal antibody HFE7A

The Fas-Fas ligand system is involved in apoptosis. The mouse antihuman Fas monoclonal antibody HFE7A (m-HFE7A) has a potential use in human therapy a gainst autoimmune diseases such as rheumatoid arthritis. Information on the three-dimensional structure is essential for antibody humanization. Crysta ls of an antigen-binding fragment (Fab) of m-HFE7A were obtained by the han ging-drop vapour-diffusion method using sodium citrate as a precipitant and 2-methyl-2,4-pentanediol as an additive. Fast optimization to produce sing le crystals suitable for X-ray analysis was achieved by the streak-seeding technique. The crystals belong to the orthorhombic space group P2(1)2(1)2(1 ), with unit-cell parameters a = 43.4, b = 74.0, c = 133.8 Angstrom. The cr ystals diffract at least to 2.5 Angstrom resolution.