title: Atomic resolution crystal structure of squid ganglion DFPase.
abstract: Diisopropylfluorophosphatases (DFP-ases) are capable of detoxifying chemical warfare agents like diisopropylfluorophosphate (DFP) by hydrolysis. The protein reported here was recombinantely expressed in E. coli. The X-ray crystal structure of this enzyme has been refined to a resolution of 0.85 A and a crystallographic R value of 9.4%. Reversible flash-cooling improved both, mosaicity and resolution of the crystals considerably. The overall structure of this protein represents a six-bladed beta-propeller with two calcium ions bound in a central water filled tunnel. 496 water, 2 glycerol, 2 MES-buffer molecules, and 18 PEG fragments of different lengths could be refined in the solvent region. The 208 most reliable residues, without disorder or reduced occupancy in their side-chains, were finally refined without restraints. A subsequent full-matrix refinement cycle for the positional parameters yielded estimated standard deviations (esds) by matrix inversion. The herewith calculated bond lengths and bond-esds were used to obtain averaged bond lengths, which have been compared to the restraints used in preceding refinement cycles.
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray; D049832:Decapodiformes / Q000201:enzymology; D004950:Esterases / Q000737:chemistry*; D005724:Ganglia / Q000201:enzymology; D008958:Models, Molecular; D044345:Phosphoric Triester Hydrolases; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry; D055672:Static Electricity
chemical_list: D011994:Recombinant Proteins; D004950:Esterases; D044345:Phosphoric Triester Hydrolases; C020061:diisopropyl-fluorophosphatase