标题：THE OCCURRENCE AND PROPERTIES OF METHYLENE-TETRAHYDROFOLATE DEHYDROGENASE IN PEA SEEDLINGS, AND INTRACELLULAR DISTRIBU-TION OF SOME FOLATE-LINKED ENZYMES IN THE PLANT
期刊名称：Journal of Nutritional Science and Vitaminology
印刷版ISSN：0301-4800
电子版ISSN：1881-7742
出版年度：1974
卷号：20
期号：2
页码：89-96
DOI：10.3177/jnsv.20.89
出版社：Center for Academic Publications Japan
摘要：Methylenetetrahydrofolate dehydrogenase (EC 1.5.1.5) which is responsible for the enzymatic convertion of 5, 10-methylene-H4FA to 5, 10-methenyl-H4FA was found in various plant tissues. The enzyme was partially purified from pea seedlings and some of its properties were investigated. The enzyme was purified about 40-fold by fractionation with ammonium sulfate and gel-filtration. The optimum pH was 7.8. 5, 10-Methylene-H4FA and NADP were specifically required in the enzymatic reaction. Their Km values were 3.5×10-4M and 5.1×10-5M, respectively. Intracellular distribution of some folate-linked enzymes, i.e. , methylenetetrahydrofolate dehydrogenase, formyltetrahydrofolate synthetase, methenyltetrahydrofolate cyclohydrolase, and phosphoribosylaminoimidazolecarboxamide formyltransferase, in pea seedlings were investigated. Major portions of these enzymes were located in the soluble fraction, while some activities of these enzymes were significantly detected in mitochondrial or microsomal fraction. A possible pathway for the synthesis and metabolism of folate coenzymes in plants is discussed.
