2iar
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(New page: 200px<br /><applet load="2iar" size="450" color="white" frame="true" align="right" spinBox="true" caption="2iar, resolution 1.9Å" /> '''Crystal structure of ...)
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Revision as of 10:05, 21 November 2007
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Crystal structure of squid ganglion DFPase W244H mutant
Overview
BACKGROUND: Phosphotriesterases (PTE) are enzymes capable of detoxifying, organophosphate-based chemical warfare agents by hydrolysis. One subclass, of these enzymes comprises the family of diisopropylfluorophosphatases, (DFPases). The DFPase reported here was originally isolated from squid, head ganglion of Loligo vulgaris and can be characterized as squid-type, DFPase. It is capable of hydrolyzing the organophosphates, diisopropylfluorophosphate, soman, sarin, tabun, and cyclosarin. RESULTS:, Crystals were grown of both the native and the selenomethionine-labeled, enzyme. The X-ray crystal structure of the DFPase from Loligo vulgaris has, been solved by MAD phasing and refined to a crystallographic R value of, 17.6% at a final resolution of 1.8 A. Using site-directed mutagenesis, we, have structurally and functionally characterized essential residues in the, active site of the enzyme. CONCLUSIONS: The crystal structure of the, DFPase from Loligo vulgaris is the first example of a structural, characterization of a squid-type DFPase and the second crystal structure, of a PTE determined to date. Therefore, it may serve as a structural model, for squid-type DFPases in general. The overall structure of this protein, represents a six-fold beta propeller with two calcium ions bound in a, central water-filled tunnel. The consensus motif found in the blades of, this beta propeller has not yet been observed in other beta propeller, structures. Based on the results obtained from mutants of active-site, residues, a mechanistic model for the DFP hydrolysis has been developed.
About this Structure
2IAR is a Single protein structure of sequence from Loligo vulgaris with CA as ligand. Active as Diisopropyl-fluorophosphatase, with EC number 3.1.8.2 Full crystallographic information is available from OCA.
Reference
Crystal structure of diisopropylfluorophosphatase from Loligo vulgaris., Scharff EI, Koepke J, Fritzsch G, Lucke C, Ruterjans H, Structure. 2001 Jun;9(6):493-502. PMID:11435114
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