CRYSTALLIZATION OF DSBC, THE DISULFIDE BOND ISOMERASE OF ESCHERICHIA-COLI

DsbC is a 2 x 23 kDa soluble dimeric protein molecule involved in prot ein disulfide bond formation in the E. coli periplasm, primarily catal yzing disulfide bond rearrangements. Crystals of both the native and s elenomethione protein suitable for structure determination were obtain ed using the hanging-drop vapour-diffusion method. The best crystals w ere obtained using 18-22% (v/v) polyethylene glycol 550 monomethyl eth er in 100 mM Tris-HCl (pH 8.9). Seeding methods were used to produce l arge crystals diffracting to 2 Angstrom resolution, and the detergent n-octyl-beta-glucoside was used to improve crystal quality. Significan t variation in cell dimensions and crystal order was observed. Cell di mensions obtained for frozen crystals were in the range a = 58.8(0.3), b = 78.9(0.5), c = 95.2 (5.0) Angstrom. The lattice is orthorhombic a nd systematic absences indicate that the space group is P2(1)2(1)2(1).