The occurrence and properties of dihydrofolate reductase in pea seedlings

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概要

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• Dihydrofolate reductase (E.C. 1.5.1.3) was found in pea seedlings and was partially purified by treatments with ammonium sulfate, protamine sulfate and by DEAE-cellulose column chromatography. Some properties of the enzyme were investigated. Optimum pH for the reaction was 6.5. In the enzyme reaction, FAH_2 and NADPH_2 were specifically required. MICHAELIS constants for FAH_2 and NADPH_2 were 4.3 × 10^<-6> M and 4.0 × 10^<-5> M, respectively. Folate antagonists such as aminopterin, methotrexate and pyrimethamine were potent inhibitors of this enzyme. Enzyme activity was almost completely inhibited at a concentration of 10^<-7> M of aminopterin and methotrexate and 10^<-6> M of pyrimethamine. Growth of germinating pea seeds was inhibited by aminopterin, methotrexate and pyrimethamine, and it recovered significantly with a tetrahydro-derivative of folate, CF, but not with dihydrofolic or folic acid. These results suggest that growth inhibition of pea seedlings by these antagonists is due to inhibition of dihydrofolate reductase in seedlings.

• 日本植物生理学会の論文

著者

• IWAI KAZUO

  Research Institute for Food Science, Kyoto University

• Iwai Kazuo

  Research Institute For Food Science Kyoto University

• SUZUKI NOBORU

  Research Institute for Food Science, Kyoto University

• Suzuki Noboru

  Research Institute For Food Science Kyoto University

関連論文

• Biosynthesis of folic acid compounds in plants VI. The occurrence and properties of the dihydrofolate-synthesizing enzyme in pea seedlings
• THE DISTRIBUTION OF FROMYLTETRAHYDROFOLATE SYNTHETASE IN PLANTS, AND THE PURIFICATION AND PROPERTIES OF THE ENZYME FROM PEA SEEDLINGS
• The occurrence and properties of methenyltetrahydrofolate cyclohydrolase in plants
• The occurrence and properties of dihydrofolate reductase in pea seedlings

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