title: Polysaccharide degradation by Fenton reaction--or peroxidase-generated hydroxyl radicals in isolated plant cell walls.
abstract: The formation of hydroxyl radicals (OH*) by peroxidase was confirmed by EPR spectroscopy using ethanol/alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone as a spin-trapping system specific of OH*. The effect of OH*, generated either non-enzymatically with the Fenton reaction (H(2)O(2) + Fe(2+)) or with horseradish peroxidase in the presence of O(2) and NADH, on cell walls isolated from maize (Zea mays) coleoptiles or soybean (Glycine max) hypocotyls was investigated. OH* produced by these reactions attack polysaccharides in the wall, demonstrated by the release of a heterogeneous mixture of polymeric breakdown products into the incubation medium. The peroxidase-catalyzed degradation of cell-wall polysaccharides can be inhibited by KCN and superoxide radical (O(2)*) or OH* scavengers. These data support the hypothesis that OH*, produced by cell-wall peroxidases in vivo, act as wall-loosening agents in plant extension growth.
authors.affiliation: Albert-Ludwigs-Universität Freiburg, Institut für Biologie II, Schänzlestr 1, D-79104 Freiburg, Germany.
authors.forename: Carmen
authors.initials: C
authors.lastname: Schweikert
authors.forename: Anja
authors.initials: A
authors.lastname: Liszkay
authors.forename: Peter
authors.initials: P
authors.lastname: Schopfer
mesh_terms: D002473:Cell Wall / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D006735:Horseradish Peroxidase / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D006878:Hydroxides / Q000378:metabolism; D017665:Hydroxyl Radical / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D018384:Oxidative Stress; D011134:Polysaccharides / Q000378:metabolism*; D013025:Glycine max / Q000378:metabolism; D013997:Time Factors; D003313:Zea mays / Q000378:metabolism
chemical_list: C045076:Fenton's reagent; D006878:Hydroxides; D011134:Polysaccharides; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; D007501:Iron; D006735:Horseradish Peroxidase