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| {{STRUCTURE_2o7v| PDB=2o7v | SCENE= }} | | {{STRUCTURE_2o7v| PDB=2o7v | SCENE= }} |
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| '''Carboxylesterase AeCXE1 from Actinidia eriantha covalently inhibited by paraoxon'''
| | ===Carboxylesterase AeCXE1 from Actinidia eriantha covalently inhibited by paraoxon=== |
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| ==Overview==
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| Carboxylesterases (CXEs) are widely distributed in plants, where they have been implicated in roles that include plant defense, plant development, and secondary metabolism. We have cloned, overexpressed, purified, and crystallized a carboxylesterase from the kiwifruit species Actinidia eriantha (AeCXE1). The structure of AeCXE1 was determined by X-ray crystallography at 1.4 A resolution. The crystal structure revealed that AeCXE1 is a member of the alpha/beta-hydrolase fold superfamily, most closely related structurally to the hormone-sensitive lipase subgroup. The active site of the enzyme, located in an 11 A deep hydrophobic gorge, contains the conserved catalytic triad residues Ser169, Asp276, and His306. Kinetic analysis using artificial ester substrates showed that the enzyme can hydrolyze a range of carboxylester substrates with acyl groups ranging from C2 to C16, with a preference for butyryl moieties. This preference was supported by the discovery of a three-carbon acyl adduct bound to the active site Ser169 in the native structure. AeCXE1 was also found to be inhibited by organophosphates, with paraoxon (IC50 = 1.1 muM) a more potent inhibitor than dimethylchlorophosphate (DMCP; IC50 = 9.2 muM). The structure of AeCXE1 with paraoxon bound was determined at 2.3 A resolution and revealed that the inhibitor binds covalently to the catalytic serine residue, with virtually no change in the structure of the enzyme. The structural information for AeCXE1 provides a basis for addressing the wider functional roles of carboxylesterases in plants.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17256879}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17256879 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17256879}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Insecticide]] | | [[Category: Insecticide]] |
| [[Category: Paraoxon]] | | [[Category: Paraoxon]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 10:25:52 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 04:51:54 2008'' |
