title: Identification of a copper-sensitive ascorbate peroxidase in the unicellular green alga Selenastrum capricornutum.
abstract: Extracts from the unicellular green alga Selenastrum capricornutum exhibit high superoxide dismutase activity, but only traces of catalase activity. The excess hydrogen peroxide (H2O2) generated by the superoxide dismutase in S. capricornutum may be degraded by a unique peroxidase. This peroxidase has a high specificity for ascorbate as its electron donor. The enzyme has an optimum pH at 8, is insensitive to cyanide and is inhibited by oxine. Addition of low concentrations of copper to algal cultures stimulates the peroxidase activity threefold. This enzymatic system could be used as a sensitive bioindicator for copper in fresh water.
authors.affiliation: Department of Microbiology and Molecular Cell Sciences, University of Memphis, TN 38152-6041, USA.
authors.forename: K R
authors.initials: KR
authors.lastname: Sauser
authors.forename: J K
authors.initials: JK
authors.lastname: Liu
authors.forename: T Y
authors.initials: TY
authors.lastname: Wong
mesh_terms: D060387:Ascorbate Peroxidases; D002374:Catalase / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D000460:Chlorophyta / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D003300:Copper / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology*; D003486:Cyanides / Q000494:pharmacology; D004583:Electrons; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D008670:Metals / Q000494:pharmacology; D015125:Oxyquinoline / Q000633:toxicity; D010544:Peroxidases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D013379:Substrate Specificity; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D003486:Cyanides; D007527:Isoenzymes; D008670:Metals; D015125:Oxyquinoline; D003300:Copper; D006861:Hydrogen Peroxide; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase