TAILIEUCHUNG - Báo cáo Y học: Production and chemiluminescent free radical reactions of glyoxal in lipid peroxidation of linoleic acid by the ligninolytic enzyme, manganese peroxidase

Glyoxal is a key compound involved in glyoxal oxidase (GLOX)-dependent production of glyoxylate, oxalate and H2O2 by lignin-degrading basidiomycetes. In this paper, we report that glyoxal was produced from a metabolite of ligninolytic fungi, linoleic acid, by manganese peroxidase (MnP)-dependent lipid peroxidation. In the absence of the parent substrate of linoleic acid, the dialdehyde was oxidized by MnP and Mn(III) chelate to start free radical reactions with emission of chemiluminescence at 700– 710 nm. . | Eur. J. Biochem. 268 6114-6122 2001 FEBS 2001 Production and chemiluminescent free radical reactions of glyoxal in lipid peroxidation of linoleic acid by the ligninolytic enzyme manganese peroxidase Takashi Watanabe1 Nobuaki Shirai2 Hitomi Okada1 Yoichi Honda1 and Masaaki Kuwahara1 1 Laboratory of Biomass Conversion Wood Research Institute Kyoto University Gokasho Uji Japan 2 Industrial Research Center of Shiga Prefecture Ritto Kamitoyama Japan Glyoxal is a key compound involved in glyoxal oxidase GLOX -dependent production of glyoxylate oxalate and H2O2 by lignin-degrading basidiomycetes. In this paper we report that glyoxal was produced from a metabolite of ligninolytic fungi linoleic acid by manganese peroxidase MnP -dependent lipid peroxidation. In the absence of the parent substrate of linoleic acid the dialdehyde was oxidized by MnP and Mn III chelate to start free radical reactions with emission of chemiluminescence at 700710 nm. The spectroscopic profile of the light emission is distinguishable from a singlet oxygen b triplet carbonyls from dioxetane and a-hydroxyperoxyl radicals and c biacyl triplet formed by the coupling of two acyl radicals. The photon emission of glyoxal by MnP was activated by co-oxidation of tartrate. The MnP-dependent oxidation of glyoxal in tartrate buffers continued for 10 days without addition of exogenous H2O2. The importance of these results is discussed in relation to the free radical chemistry of lignin biodegradation by wood rot fungi. Keywords Manganese peroxidase lipid peroxidation Ceriporiopsis subvermispora acyl radical. Lignin biodegradation by white rot fungi is an extracellular chemical event generating free radicals. Lignin-degrading enzymes lignin peroxidase LiP manganese peroxidase MnP and laccase Lac play a key role in generating free radicals from lignin and oxidizable fungal metabolites such as oxalate glyoxylate malonate hydroquinones and aryl alcohols. Due to the participation of peroxidases in the lignin .

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