title: Oxidative degradation of cis- and trans-1,4-polyisoprenes and vulcanized natural rubber with enzyme-mediator systems.
abstract: Oxidative degradation of cis- and trans-1,4-polyisoprenes by two types of enzyme-mediator systems, lipoxygenase/linoleic acid and horseradish peroxidase/1-hydroxybenzotriazole, was investigated at 37 degrees C in aqueous media and analyzed by gel permeation chromatography. Lipoxygenase and horseradish peroxidase activate their substrates, linoleic acid and 1-hydroxybenzotriazole, respectively, for scission of main chains of both 1,4-polyisoprenes. Molecular weights of 1,4-polyisoprenes decreased during the treatment under both enzyme-mediator systems, and the depolymerization was completely inhibited by the addition of butylated hydroxytoluene. When the enzyme or the mediator from a reaction system was omitted, depolymerization did not progress, indicating that the scission of polymer chain is induced by the radicals generated only in the presence of both enzyme and mediator. Fenton reagent with linoleic acid was also effective against the degradation of both 1,4-polyisoprenes. Vulcanized natural rubber latex gloves were treated under these three methods, and surface degradation with hole formation was observed with a scanning electron micrograph.
authors.affiliation: Polymer Chemistry Laboratory, RIKEN Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Enoki
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Doi
authors.forename: Tadahisa
authors.initials: T
authors.lastname: Iwata
mesh_terms: D002850:Chromatography, Gel; D045782:Hemiterpenes; D006735:Horseradish Peroxidase / Q000737:chemistry; D007840:Latex; D019787:Linoleic Acid / Q000737:chemistry; D015227:Lipid Peroxidation; D008084:Lipoxygenase / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D010084:Oxidation-Reduction; D011095:Polyethylenes / Q000737:chemistry*; D012408:Rubber / Q000737:chemistry*; D014230:Triazoles / Q000737:chemistry
chemical_list: D045782:Hemiterpenes; D007840:Latex; D011095:Polyethylenes; D014230:Triazoles; C455100:1,4-polyisoprene; D012408:Rubber; D019787:Linoleic Acid; C011852:1-hydroxybenzotriazole; D006735:Horseradish Peroxidase; D008084:Lipoxygenase