Peroxidase-catalysed oxidation of chlorophyll by hydrogen peroxide |
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Authors: | Albert Huff |
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Affiliation: | Plant Sciences Department, University of Arizona, Tucson, AZ 85721, U.S.A. |
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Abstract: | Chlorophyll is effectively bleached by H2O2 in the presence of certain phenols and peroxidase (EC 1.11.1.7) extracted from acetone powders of orange flavedo (Citrus sinensis). Optimal conditions for chlorophyll: hydrogen peroxide oxidoreductase include: pH, 5.9; [H2O2] 222 μM; ionic strength 0.11. A phenol is required and resorcinol is the most effective. Catechol and hydroquinone are inhibitory. Chlorophyll a, chlorophyllide a, and chlorophyll b all have similar Vmax but Km for chlorophyll a is about one-third that of chlorophyll b, while the Km for chlorophyllide a is about one-half that of chlorophyll a. Pheophytin a was much less reactive than chlorophyll a, and Mg2+ included in the reaction system did not affect rates of pheophytin destruction. |
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Keywords: | Rutaceae orange catabolism chlorophyll peroxidase chlorophyll: hydrogen peroxide oxidoreductase. |
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