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This enzyme forms part of the chlorophyll degradation pathway, and is found in higher plants and in algae. In higher plants it participates in de-greening processes such as fruit ripening, leaf senescence, and flowering. The enzyme exists in two forms: type 1 is induced by senescence whereas type 2 is constitutively expressed [1,2]. The enzyme is highly specific for pheophorbide as substrate (with a preference for pheophorbide?a?over pheophorbide?b) as other chlorophyll derivatives such as protochlorophyllide?a, pheophytin?a?and?c, chlorophyll?a?and?b, and chlorophyllide?a?cannot act as substrates [2]. Another enzyme, called pheophorbide demethoxycarbonylase (PDC), produces pyropheophorbide?a?from pheophorbide?a?without forming an intermediate although the precise reaction is not yet known [1]. |
