Crystallization of Enzyme IIB of the Cellobiose-specific Phosphotransferase System of Escherichia coli

Crystals of enzyme IIB of the cellobiose-specific phosphotransferase system have been obtained from 15% polyethylene glycol 4000 using both streak-seeding and macroseeding techniques at 4°. Crystals were grown with the hanging drop method of vapour diffusion. Addition of 2-propanol and benzamidine/HCl proved essential to obtain single crystals suitable for X-ray analysis. The crystals diffract to 1.8 Å resolution and have the monoclinic space group P21, with cell dimensions a = 53.6 Å, b = 31.7 Å, c = 60.0 Å and β = 101.7°. From a self-rotation function it seems likely that there are two molecules in the asymmetric unit related by a non-crystallographic 2-fold axis.