Acta Crystallographica Section F

Structural Biology and Crystallization Communications

Volume 63, Part 1 (January 2007)

crystallization communications

Acta Cryst. (2007). F63, 42-45 [ doi:10.1107/S1744309106052924 ]

Preliminary time-of-flight neutron diffraction study on diisopropyl fluorophosphatase (DFPase) from Loligo vulgaris

M.-M. Blum, A. Koglin, H. Rüterjans, B. Schoenborn, P. Langan and J. C.-H. Chen

Abstract: The enzyme diisopropyl fluorophosphatase (DFPase) from Loligo vulgaris is capable of decontaminating a wide variety of toxic organophosphorus nerve agents. DFPase is structurally related to a number of enzymes, such as the medically important paraoxonase (PON). In order to investigate the reaction mechanism of this phosphotriesterase and to elucidate the protonation state of the active-site residues, large-sized crystals of DFPase have been prepared for neutron diffraction studies. Available H atoms have been exchanged through vapour diffusion against D₂O-containing mother liquor in the capillary. A neutron data set has been collected to 2.2 Å resolution on a relatively small (0.43 mm³) crystal at the spallation source in Los Alamos. The sample size and asymmetric unit requirements for the feasibility of neutron diffraction studies are summarized.

Keywords: neutron diffraction; DFPase; time-of-flight; phosphotriesterase.