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Chlorophyllase
Chlorophyllase (klawr-''uh''-fil-eys)〔(chlorophyllase - Definitions from Dictionary.com )〕 is the key enzyme in chlorophyll metabolism. It is a membrane protein that is commonly known as Chlase (, ''CLH'') and systematically known as chlorophyll chlorophyllidohydrolase. Chlorophyllase can be found in the chloroplast, thylakoid membrane and etioplast of at least higher plants such as ferns, mosses, brown and red algae and diatoms. Chlase is the catalyst for the hydrolysis of chlorophyll to produce chlorophyllide (also called Chlide) and phytol. It is also known to function in the esterification of Chlide and transesterification. The enzyme functions optimally at pH 8.5 and 50°C.
==Role of chlorophyllase in chlorophyll breakdown==
Of high importance to all photosynthetic organisms is chlorophyll, and so, its synthesis and breakdown are closely regulated throughout the entire life cycle of the plant. Chlorophyll breakdown is most evident in seasonal changes as the plants lose their green color in the autumn; it is also evident in fruit ripening, leaf senescence and flowering. In this first step, chlorophyllase initiates the catabolism of chlorophyll to from chlorophyllide. Chlorophyll degradation occurs in the turnover of chlorophyll, as well as in the event of cell death caused by injuries, pathogenic attack, and other external factors.
Chlorophyllase’s role is two-fold as it functions in both de-greening processes, such as autumnal coloration, and is also thought to be involved in turnover and homeostasis of chlorophylls. Chlorophyllase catalysis of the initial step of chlorophyll breakdown is important for plant development and survival. The breakdown serves as a prerequisite in the detoxification of the potentially phototoxic chlorophyll and chlorophyll intermediates as it accompanies leaf senescence to non-fluorescent catabolites. Rapid degradation of chlorophyll and its intermediates is therefore necessary to prevent cell damage due to the potential phototoxicity of chlorophyll.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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