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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1a7u

E.C. namechloride peroxidase
SpeciesStreptomyces aureofaciens (Bacteria)
E.C. Number (IntEnz) 1.11.1.10
CSA Homologues of 1a7u1a8u,1bro,1brt,
CSA Entries With UniProtID O31168
CSA Entries With EC Number 1.11.1.10
PDBe Entry 1a7u
PDBSum Entry 1a7u
MACiE Entry M0248

Literature Report

IntroductionChloroperoxidase is a member of the non-haem type haloperoxidases. Haloperoxidases catalyse the halogenation of organic compounds in the presence of halide ions and peroxides such as hydrogen peroxide. They are named after the most electronegative halide they are able to oxidise.
MechansimThe mechanism uses the very common Ser/His/Asp triad. Histidine deprotonates serine, which initiates a nucleophilic attack on the carboxylate carbon of the substrate. The oxyanion collapses, eliminating a water molecule with concomitant deprotonation of histidine. Histidine then deprotonates the hydrogen peroxide substrate, which initiates a nucleophilic attack on the carbonyl carbon of the enzyme-substrate intermediate. The oxyanion collapses, eliminating serine with concomitant deprotonation of histidine. A chloride ion initiates a nucleophilic attack on the peroxointermediate in a substitution reaction, regenerating the carboxylic acid and producing the hypochlorous acid intermediate. The hypochlorous acid then halogenates the alkane.
Reaction

Catalytic Sites for 1a7u

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
SerA9899macie:sideChainSerine is the nucleophilic residue. It is covalently bound to the intermediate in the first stages of the reaction.
HisA257258macie:sideChainActs as a general acid/base throughout the reaction.
AspA228229macie:sideChainStabilises the positive charge on His257 when it is protonated.
PheA3233macie:mainChainAmideForms part of the oxyanion hole to stabilise negatively charged tetrahedral transition states.
MetA99100macie:mainChainAmideForms part of the oxyanion hole to stabilise negatively charged tetrahedral transition states.

Literature References

Notes:
Hofmann B
Structural investigation of the cofactor-free chloroperoxidases.
J Mol Biol 1998 279 889-900
PubMed: 9642069
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