Crystallization and preliminary X-ray crystallographic analysis of DFPase from Loligo vulgaris

'Squid-type' diisopropylØuorophosphatases (DFPases), a subclass of the phosphotriesterases, are enzymes capable of hydrolysing organophosphorus nerve agents. To date, no three-dimensionalstructure of a `squid-type' DFPase is known. Here, the crystallization of the DFPase originally isolated from head ganglion of the squid Loligo vulgarisis reported. The protein has been heterologously expressed in Escherichia coli, purified to homogeneity and subsequently crystallized. The protein crystals belong to space group P212121, with unit-cell parametersa= 43.1,b= 82.1,c= 86.6 Å and one monomer per asymmetric unit. Under cryoconditions (120 K) the crystals diffracted beyond 2.0 Å using a Cu rotating-anode X-raygenerato