Crystallization and preliminary X-ray analysis of a recombinant Fab fragment in complex with 17 beta-oestradiol

The recombinant Fab fragment of the anti-17 beta -oestradiol antibody 57-2 has been a target for several protein-engineering experiments. A method for production, purification and crystallization of the Fab fragment alone (ap o form) and in complex with the major female sex hormone 17 beta -oestradio l is reported here. Diffracting apo-form crystals were only obtained with m icroseeding; crystals of the Fab- steroid complex were produced by co-cryst allization in the presence of oestradiol and cross-seeding with the apo-for m crystals. The crystals were grown using vapour-diffusion methods with res ervoir solutions containing 10-14% PEG 4000 or 8-12% PEG 8000 and Tris-HCl buffer at high pH (9.0-9.5). Both the apo and complex crystals belong to sp ace group P2(1)2(1)2(1) and diffract to 2.0 Angstrom resolution. High-resol ution X-ray data sets suitable for structure determination were collected f rom flash-cooled crystals using 25% glycerol as the cryoprotectant.