Diisopropylfluorophosphatases (DFPases) are capable of detoxifying chemical warefare agents like diisopropylfluorophosphate (DFP), soman, sarin, tabun, and cyclosarin by hydrolysis. The protein reported here belongs to the subclass of squid-type DFPases and was originally isolated from squid head ganglion of Loligo vulgaris, but in this work we used the protein recombinantely expressed in E. coli. The X-ray crystal structure of this enzyme has been refined to a resolution of 0.85 Å and a crystallographic R-value of 9.42%. Reversible flashcooling improved both, mosaicity and resolution of the crystals considerably. The overall structure of this protein represents a six-bladed ß-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 length could be refined in the solvent region. 45 of the 314 residues have been refined with alternative orientations. Hydrogen atoms have been omitted from these residues. In the residues of the inner ß strands, hydrogen atoms are visible in a normal Fo-Fc difference map of a hydrogen deficient structural model. The 208 most reliable residues, without disorder or reduced occupancy in their sidechains, were finally refined without restraints. The following full matrix refinement cycle for the positional parameters yielded estimated standard deviations (e.s.d.s.) by matrix inversion. The herewith-calculated bond-lengths and bond-esds were used to obtain averaged bond-length, which had been compared to the restraints used in preceding refinement rounds. Also very accurate dimensions for the Ca 2+ coordination polyhedrons could be obtained.
For the first time the technology of a small-size polycapillary lenses manufacturing was proposed. Technique of micro lens certification is considered. Efficiency of simultaneous using of such lenses and micro focus x-ray sources is shown.
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