Chlorophyll Metabolism in Higher Plants VI. Involvement of Peroxidase in Chlorophyll Degradation

概要

論文の詳細を見る
The following phenolics were found to be essential for peroxidase-dependent chlorophyll bleaching: 2,4-dichlorophenol (DCP), p-coumaric acid (HCA), phenol, p-hydroxyphenylacetic acid, p-hydroxybenzoic acid, p-hydroxyacetophenone, resorcinol and umbelliferone. Most of them are monophenols with electron-attracting groups at the p-position. The short-lived radicals generated by horseradish peroxidase (HRP)-phenolics-H_2O_2 reaction might be involved in this reaction. Tobacco leaf enzyme preparation with peroxidase activity for guaiacol could also degrade chlorophyll with such phenolics. In addition, tobacco leaf methanol extract could substitute for chlorophyll bleaching as an electron donor in the absence of phenolics. In place offer H_2O_2, the glycolate-glycolate oxidase (GOX) system could degrade chlorophyll in [peroxidase + phenolics] -dependent bleaching. This chlorophyll bleaching system was inhibited by peroxidase inhibitors, radical scavengers, reducing reagents, and carotenoids. Ascorbate and glutathione stopped chlorophyll bleaching with GSSG reductase and NADPH. The role of ascorbate and glutathione in peroxidase activity for controlling the chlorophyll degradation rate is discussed.