Enzymatic Degradation of Chlorophyll inChenopodium album

摘要

The breakdown of chlorophyll (Chi) in crude extracts ofChenopodium album(white goose foot) in the dark was examined. Derivatives of pheophorbideαwere formed when Chiαor chlorophyllideαwas 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 MgCl2. Analysis by high-performance thin-layer chromatography (HPTLC) and liquid chromatography (HPLC) showed that the appearance of chlorophyllideα, pheophorbideα132-hydroxychlorophyllideαand pyropheophorbideαwas accompanied by a concomitant decrease in levels of ChiαThe formation of 132-hydroxychloro-phyllideαwas not clearly an enzymatic reaction and requires further examination. It appears that Chlαis degraded in a crude extract ofC. albumvia the following enzymatically catalyzed reactionsChla→-phytylchlorophyllidea→-Mgpheophorbidea  →-COOC