1pta
From Proteopedia
THREE-DIMENSIONAL STRUCTURE OF PHOSPHOTRIESTERASE: AN ENZYME CAPABLE OF DETOXIFYING ORGANOPHOSPHATE NERVE AGENTS
Structural highlights
Function[OPD_BREDI] Has an unusual substrate specificity for synthetic organophosphate triesters and phosphorofluoridates. All of the phosphate triesters found to be substrates are synthetic compounds. The identity of any naturally occurring substrate for the enzyme is unknown. Has no detectable activity with phosphate monoesters or diesters and no activity as an esterase or protease. It catalyzes the hydrolysis of the insecticide paraoxon at a rate approaching the diffusion limit and thus appears to be optimally evolved for utilizing this synthetic substrate. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedOrganophosphates, such as parathion and paraoxon, constitute the largest class of insecticides currently used in industrialized nations. In addition, many of these compounds are known to inhibit mammalian acetylcholinesterases thereby acting as nerve agents. Consequently, organophosphate-degrading enzymes are of considerable interest in light of their ability to detoxify such compounds. Here we report the three-dimensional structure of such an enzyme, namely, phosphotriesterase, as determined by single crystal X-ray diffraction analysis to 2.1-A resolution. Crystals employed in this investigation belonged to the space group P2(1)2(1)2 with unit cell dimensions of a = 80.3 A, b = 93.4 A, and c = 44.8 A and one molecule per asymmetric unit. The structure was solved by multiple isomorphous replacement with two heavy-atom derivatives and refined to a crystallographic R factor of 18.0%. As observed in various other enzymes, the overall fold of the molecule consists of an alpha/beta barrel with eight strands of parallel beta-pleated sheet. In addition, there are two antiparallel beta-strands at the N-terminus. The molecular model of phosphotriesterase presented here provides the initial structural framework necessary toward understanding the enzyme's broad substrate specificities and its catalytic mechanism. Three-dimensional structure of phosphotriesterase: an enzyme capable of detoxifying organophosphate nerve agents.,Benning MM, Kuo JM, Raushel FM, Holden HM Biochemistry. 1994 Dec 20;33(50):15001-7. PMID:7999757[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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