Crystallization and preliminary X-ray crystallographic data of a histidine-binding protein from Escherichia coli

Histidine-binding protein, purified from periplasmic space of Escherichia coli K12, has been crystallized in a form suitable for X-ray analysis. Crystals of average size 0.3 mm × 0.15 mm × 0.15 mm have been grown by the hanging-drop method, with ammonium sulfate as precipitant. The space group is I4 122, with the unit cell dimensions a = b= 119.1 A ̊ ; c= 151.8 A ̊ ; V m = 2.7 A ̊ 3/dalton . There appear to be two protein subunits of molecular weight 25,000 each in the asymmetric unit.