Crystallization and preliminary X-ray analysis of anti-digoxin antibodies

The Fab fragments of several monoclonal antibodies that bind digoxin and other cardiac glycosides have been screened for crystallization conditions. We have crystallized two of these in forms suitable for X-ray analysis. The anti-digoxin antibody 40-50 in complex with ouabain crystallizes with symmetry consistent with space group C2, with a = 92.6, b = 85.0, c = 73.0 Å and β = 131.7°. This crystal form shows considerable non-isomorphism between crystals. A second anti-digoxin antibody, 49-10, crystallizes with symmetry consistent with space group P2₁2₁2, with a = 95.3, b = 147.1 and c = 76.2 Å.