Crystallization and preliminary X-ray analysis of the periplasmic dipeptide binding protein from Escherichia coli.

The periplasmic dipeptide-binding protein from Escherichia coli has been purified, freed of bound endogenous ligands, and crystallized. Crystals of the protein in complex with added dipeptides have been subjected to X-ray analysis. The crystals grow as hexagonal bipyramids or eye-shaped disks which have the symmetry of space group P6(1). The unit cell dimensions are a = b = 183 A, c = 212 A, and the diffraction pattern extends to 3.2 A resolution with a conventional X-ray source.