Chloride peroxidase

Chloride peroxidase (EC 1.11.1.10) is an enzyme that catalyzes the chlorination

2 RH + 2 Cl^- + H₂O₂ 2 RCl + 2 H₂O

The 3 substrates of this enzyme are a hydrogen containing molecule (RH), chloride ion, and hydrogen peroxide, whereas its two products are a corresponding chloride compound and water.

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 vanadia.

Chloroperoxidase (CPO), the heme containing enzyme, exhibits peroxidase, catalase and cytochrome P450-like activities in addition to catalyzing halogenation reactions^[1]. 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

• 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.