Enzymatic Degradation of Chlorophyll in Chenopodium album

概要

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The breakdown of chlorophyll (Chl) in crude extracts of Chenopodium album (white goose foot) in the dark was examined. Derivatives of pheophorbide a were formed when Chl a or chlorophyllide a was incubated with depigmented crude extracts. The formation of pheophorbide was completely prevented by heat treatment of extracts, indicating that the reaction was enzymatic, and the presence of a Mg-releasing enzyme, the so called Mg-dechelatase, was postulated. This hypothesis was strongly supported by the observation that the formation of pheophorbide was inhibited by 51% by 10 mM MgCl_2. Analysis by high-performance thin-layer chromatography (HPTLC) and liquid chromatography (HPLC) showed that the appearance of chlorophyllide a, pheophorbide a, 13^2-hydroxychlorophyllide a and pyropheophorbide a was accompanied by a concomitant decrease in levels of Chl a. The formation of 13^2-hydroxychlorophyllide a was not clearly an enzymatic reaction and requires further examination. It appears that Chl a is degraded in a crude extract of C. album via the following enzymatically catalyzed reactions : [chemical formula].
日本植物生理学会の論文