Chloride peroxidase

Chloride peroxidase (EC 1.11.1.10) is a family of enzymes that catalyzes the chlorination of organic compounds. This enzyme combines the inorganic substrates chloride and hydrogen peroxide to produce the equivalent of Cl⁺, which replaces a proton in hydrocarbon substrate:

R-H + Cl⁻ + H₂O₂ + H⁺ → R-Cl + 2 H₂O

Many organochlorine compounds are biosynthesized in this way.

This enzyme belongs to the family of oxidoreductases, specifically those acting on a peroxide as acceptor (peroxidases). The systematic name of this enzyme class is chloride:hydrogen-peroxide oxidoreductase. This enzyme is also called chloroperoxidase. It employs one cofactor which may be either heme or vanadium.^[1]

The heme-containing chloroperoxidase (CPO) exhibits peroxidase, catalase and cytochrome P450-like activities in addition to catalyzing halogenation reactions.^[2] Despite functional similarities with other heme enzymes, the structure of CPO is unique, which folds into a tertiary structure dominated by eight helical segments. The catalytic acid base, required to cleave the peroxide O-O bond, is glutamic acid rather than histidine as in horseradish peroxidase.

Structural studies

As of late 2007, 30 structures have been solved for this class of enzymes, with PDB accession codes 1A7U, 1A88, 1A8Q, 1A8S, 1A8U, 1BRT, 1CPO, 1IDQ, 1IDU, 1QHB, 1QI9, 1VNC, 1VNE, 1VNF, 1VNG, 1VNH, 1VNI, 1VNS, 2CIV, 2CIW, 2CIX, 2CIY, 2CIZ, 2CJ0, 2CJ1, 2CJ2, 2CPO, 2J18, 2J19, and 2J5M.

References

↑ Butler, Alison; Carter-Franklin, Jayme N. (2004). "The role of vanadium bromoperoxidase in the biosynthesis of halogenated marine natural products". Natural Product Reports 21 (1): 180–8. doi:10.1039/b302337k. PMID 15039842. (this paper also discussed chloroperoxidases.
↑ Poulos TL, Sundaramoorthy M, Terner J (1995). "The crystal structure of chloroperoxidase: a heme peroxidase--cytochrome P450 functional hybrid". Structure 3 (12): 1367–1377. doi:10.1016/S0969-2126(01)00274-X. PMID 8747463.

Other reading

Hager LP, Hollenberg PF, Rand-Meir T, Chiang R, Doubek D (1975). "Chemistry of peroxidase intermediates". Ann. N. Y. Acad. Sci. 244: 80–93. doi:10.1111/j.1749-6632.1975.tb41524.x. PMID 1056179.
Morris DR, Hager LP (1966). "Chloroperoxidase. I. Isolation and properties of the crystalline glycoprotein". J. Biol. Chem. 241 (8): 1763–8. PMID 5949836.
Theiler R, Cook JC, Hager LP and Siuda JF (1978). "Halohydrocarbon synthesis by homoperoxidase". Science 202 (4372): 1094–1096. doi:10.1126/science.202.4372.1094. PMID 17777960.

Oxidoreductases: peroxidases (EC 1.11)

1.11.1.1-14	Catalase Cytochrome c peroxidase Eosinophil peroxidase Glutathione peroxidase GPX 1 2 3 4 5 6 7 8 Horseradish peroxidase Lactoperoxidase Myeloperoxidase Thyroid peroxidase Deiodinase Iodothyronine deiodinase Iodotyrosine deiodinase

1.11.1.15 (peroxiredoxin)	1 2 3 4 5 6

Proteins: enzymes

Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis Enzyme kinetics Lineweaver–Burk plot Michaelis–Menten kinetics

Regulation	Allosteric regulation Cooperativity Enzyme inhibitor

Classification	EC number Enzyme superfamily Enzyme family List of enzymes

Types	EC1 Oxidoreductases(list) EC2 Transferases(list) EC3 Hydrolases(list) EC4 Lyases(list) EC5 Isomerases(list) EC6 Ligases(list)

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