Studies on chlorophyllase of Chlorella protothecoides III. Purification and catalytic properties

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Chlorophyllase was extracted from green cells of Chlorella protothecoides by n-butanol treatment and purified 600-fold, as measured by enzyme activity in chlorophyll a hydrolysis, by ammonium sulfate precipitation, chromatography on TEAE-cellulose column and gel filtration with Sephadex G-200. At each purification step the following activities were compared : hydrolyses of chlorophyll a and methyl chlorophyilide a, methanolysis of chlorophyll a and transphythylation of methyl chlorophyllide a to chlorophyll a. The ratio of activities of chlorophyll a hydrolysis to chlorophyll a methanolysis changed on purification and partial inactivation by heat, PCMB and phytol, as well as by varying the reaction temperature, thus suggesting that the two reactions are not catalyzed by a single enzyme. In contrast, the activity ratio of chlorophyll a methanolysis to transphytylation of methyl chlorophyllide a remained unaltered, indicating that these reactions can be forward and backward reactions catalyzed by one enzyme. Results of kinetic studies also indicated that the chlorophyllase of Chlorella protothecoides consists of at least two enzymes. One enzyme catalyzes chlorophyll a hydrolysis and the other, chlorophyll a methanolysis and the reverse reaction, transphytylation of methyl chlorophyllide a.
日本植物生理学会の論文