Crystallization of DsbA, an Escherichia coli protein required for disulphide bond formation in vivo.

DsbA is a 21 kDa protein that facilitates disulphide bond formation and is required for the correct folding and stability of a number of exported proteins in Escherichia coli. Crystals of oxidized DsbA have been obtained from polyethylene glycol 8000 (20 to 25%), 0.1 M-cacodylate buffer (pH 6.5) and 1% 2-methyl-2,4-pentanediol. Oxidation of the protein is critical for reproducibly obtaining high quality crystals. The resulting crystals diffract to 2 A and belong to the monoclinic space group C2 with cell dimensions a = 117.5 A, b = 65.0 A, c76.3 A, beta = 126.3 degrees with two molecules in the asymmetric unit.