Crystallization and preliminary X-ray analysis of the complex between a mouse Fab fragment and a single IgG-binding domain from streptococcal protein G

The Fab fragment of a mouse immunoglobulin G1, complexed with a single IgG-binding domain from streptococcal protein G, has been crystallized in a form suitable for analysis by X-ray diffraction. The needle-shaped crystals were grown from polyethylene glycol 4000 using vapour diffusion methods and diffract to 2.3 Å resolution. The space group is P212121 (a = 64.5 Å, b = 70.5 Å and c = 120.1 Å), with one Fab-protein G domain complex in the asymmetric unit. Solution of the three-dimensional structure of the complex will permit a detailed analysis of the molecular interactions between protein G and the Fab portion of IgG.