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1s0y
From Proteopedia
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'''The structure of trans-3-chloroacrylic acid dehalogenase, covalently inactivated by the mechanism-based inhibitor 3-bromopropiolate at 2.3 Angstrom resolution''' | '''The structure of trans-3-chloroacrylic acid dehalogenase, covalently inactivated by the mechanism-based inhibitor 3-bromopropiolate at 2.3 Angstrom resolution''' | ||
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[[Category: Poelarends, G J.]] | [[Category: Poelarends, G J.]] | ||
[[Category: Whitman, C P.]] | [[Category: Whitman, C P.]] | ||
| - | [[Category: | + | [[Category: Covalent modification]] |
| - | [[Category: | + | [[Category: Dehalogenase]] |
| - | [[Category: | + | [[Category: Dehalogenation mechanism]] |
| - | [[Category: | + | [[Category: Inhibition]] |
| - | [[Category: | + | [[Category: Malonyl inhibitor]] |
| - | [[Category: | + | [[Category: Michael addition]] |
| - | [[Category: | + | [[Category: Tautomerase family]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 08:09:32 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 05:09, 3 May 2008
The structure of trans-3-chloroacrylic acid dehalogenase, covalently inactivated by the mechanism-based inhibitor 3-bromopropiolate at 2.3 Angstrom resolution
Overview
Isomer-specific 3-chloroacrylic acid dehalogenases function in the bacterial degradation of 1,3-dichloropropene, a compound used in agriculture to kill plant-parasitic nematodes. The crystal structure of the heterohexameric trans-3-chloroacrylic acid dehalogenase (CaaD) from Pseudomonas pavonaceae 170 inactivated by 3-bromopropiolate shows that Glu-52 in the alpha-subunit is positioned to function as the water-activating base for the addition of a hydroxyl group to C-3 of 3-chloroacrylate and 3-bromopropiolate, whereas the nearby Pro-1 in the beta-subunit is positioned to provide a proton to C-2. Two arginine residues, alphaArg-8 and alphaArg-11, interact with the C-1 carboxylate groups, thereby polarizing the alpha,beta-unsaturated acids. The reaction with 3-chloroacrylate results in the production of an unstable halohydrin, 3-chloro-3-hydroxypropanoate, which decomposes into the products malonate semialdehyde and HCl. In the inactivation mechanism, however, malonyl bromide is produced, which irreversibly alkylates the betaPro-1. CaaD is related to 4-oxalocrotonate tautomerase, with which it shares an N-terminal proline. However, in 4-oxalocrotonate tautomerase, Pro-1 functions as a base participating in proton transfer within a hydrophobic active site, whereas in CaaD, the acidic proline is stabilized in a hydrophilic active site. The altered active site environment of CaaD thus facilitates a previously unknown reaction in the tautomerase superfamily, the hydration of the alpha,beta-unsaturated bonds of trans-3-chloroacrylate and 3-bromopropiolate. The mechanism for these hydration reactions represents a novel catalytic strategy that results in carbon-halogen bond cleavage.
About this Structure
1S0Y is a Protein complex structure of sequences from Pseudomonas pavonaceae. Full crystallographic information is available from OCA.
Reference
The X-ray structure of trans-3-chloroacrylic acid dehalogenase reveals a novel hydration mechanism in the tautomerase superfamily., de Jong RM, Brugman W, Poelarends GJ, Whitman CP, Dijkstra BW, J Biol Chem. 2004 Mar 19;279(12):11546-52. Epub 2003 Dec 29. PMID:14701869 Page seeded by OCA on Sat May 3 08:09:32 2008
