title: Purification and properties of a unique flavin-containing chloroperoxidase from the capitellid polychaete Notomastus lobatus.
abstract: A unique flavin-containing chloroperoxidase from the marine worm Notomastus lobatus was purified to homogeneity. This enzyme is composed of two dissociable protein moieties, a flavoprotein and a heme protein, in 1:1 molar ratio. The flavoprotein (Mr = 120,000) consists of four identical subunits having Mr of 30,000, and contains FAD. The heme protein (Mr = 54,000) is composed of two copies each of two non-identical subunits (Mr = 15, 500 and 11, 500) and contains ferriheme. The native N. lobatus chloroperoxidase (Mr = 174,000) therefore has a structure of alpha 4 beta 2 gamma 2. Neither the flavoprotein nor the heme protein alone has detectable chloroperoxidase activity but readily associate to form fully active enzyme. This enzyme is capable of oxidizing Cl-, Br-, and I- with optimum pH values of 4.5, 5.0, and 4.5, respectively, at 440 microM H2O2 and has halide-independent catalase activity in the absence of organic substrate. The enzyme can halogenate a wide variety of aromatic compounds, including phenol, from which it produces 4-bromophenol, 2,4-dibromophenol, and 2,4,6-tribromophenol. The same compounds are found in N. lobatus. The N. lobatus chloroperoxidase is the first haloperoxidase to be purified to homogeneity from a marine polychaete, the first reported to contain flavin, and has several unusual physical and catalytic properties. This chloroperoxidase appears to represent a new class of haloperoxidases.
authors.affiliation: Department of Biological Sciences, University of South Carolina, Columbia 29208.
authors.forename: Y P
authors.initials: YP
authors.lastname: Chen
authors.forename: D E
authors.initials: DE
authors.lastname: Lincoln
authors.forename: S A
authors.initials: SA
authors.lastname: Woodin
authors.forename: C R
authors.initials: CR
authors.lastname: Lovell
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002711:Chloride Peroxidase / Q000302:isolation & purification* / Q000378:metabolism; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D005415:Flavins / Q000032:analysis; D005420:Flavoproteins / Q000302:isolation & purification / Q000378:metabolism; D006420:Hemeproteins / Q000302:isolation & purification / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D011077:Polychaeta / Q000201:enzymology*; D013053:Spectrophotometry
chemical_list: D000596:Amino Acids; D005415:Flavins; D005420:Flavoproteins; D006420:Hemeproteins; D046911:Macromolecular Substances; D002711:Chloride Peroxidase