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Catalytic Site Atlas

CSA LITERATURE entry for 1cv2

E.C. namehaloalkane dehalogenase
SpeciesPseudomonas paucimobilis (Sphingomonas paucimobilis)
E.C. Number (IntEnz) 3.8.1.5
CSA Homologues of 1cv2There are 24 Homologs
CSA Entries With UniProtID P51698
CSA Entries With EC Number 3.8.1.5
PDBe Entry 1cv2
PDBSum Entry 1cv2
MACiE Entry 1cv2

Literature Report

IntroductionThe Haloalkane dehalogenase LinB, found in bacteria, catalyses the degradation of a wide variety of cyclic halogenoalkenes, thus is important in the degradation of the toxic compound 1,2,3,4,5,6-hexachlorocyclohexane. Thus study of the enzyme is important in understanding how bacteria are able to degrade xenobiotics and how pollutants can be detoxified using microorganisms. The enzyme is part of the alpha-beta hydrolase family and shows sequence and structural homology with a wide variety of haloalkane dehalogenases with different specificities.
MechansimThe reaction proceeds via initial nucleophilic attack by Asp 108 on the electrophilic carbon atom leading to the loss of a chloride ion from the molecule and the formation of a covalent enzyme intermediate. This SN-2 step proceeds via a pentavalent carbon transition state, stabilised by Trp 109. Hydrolysis of this intermediate then follows, with a water molecule activated by the His 272 Glu 132 diad, to replace the chloride ion with an OH group on the substrate.
Reaction

Catalytic Sites for 1cv2

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
HisA272272macie:sideChainActs as general acid base to deprotonate water, thus activating water so its lone pair can attack the covalent enzyme intermediate.
TrpA109109macie:sideChainThe nitrogen atom of the ring is able to form favourable contacts with the trigonal bipyramidal transition state.
GluA132132macie:sideChainActs to modify the pKa of His 272 so that it remains in the correct protonation state for its role in catalysis.
AspA108108macie:sideChainActs as nucleophile on the electrophilic carbon atom to form a covalent enzyme intermediate which is hydrolysed to give the product.

Literature References

Notes:
Marek J
Crystal structure of the haloalkane dehalogenase from Sphingomonas paucimobilis UT26.
Biochemistry 2000 39 14082-14086
PubMed: 11087355
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