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Cytochemical demonstration of 5-formyl tetrahydrofolate cyclodehydrase and 5,10-methenyl tetrahydrofolate cyclohydrolase activity. 1977

F Tzortzatou

The enzyme 5-formyl tetrahydrofolate cyclodehydrase plays an important role in the conversion of 5-formyl tetrahydrofolate to 5,10-methenyl tetrahydrofolate. A second enzyme, cyclohydrolase, converts 5,10-methenyl tetrahydrofolate to 10-formyl tetrahydrofolate. These folate derivatives play a significant part in the biosynthesis of purines. A method has been devised for the cytochemical demonstration of 5-formyl tetrahydrofolate cyclodehydrase and 5,10-methenyl tetrahydrofolate cyclohydrolase activity which uses 5-formyl tetrahydrofolate or 5,10-methenyl tetrahydrofolate as substrate respectively, blocking possible interferences by other enzymes, and allows the nonenzymatic reduction of nitro-blue tetrazolium by 5,10-methenyl tetrahydrofolate formed by the action of the cyclodehydrase on the substrate 5-formyl tetrahydrofolate, and by 10-formyl tetrahydrofolate formed by the action of cyclohydrolase on the substrate 5,10-methenyl tetrahydrofolate, thus revealing intracellular sites of enzyme activity. The methods appear to show only intracellular localization of the blue formazan deposits of reduced tetrazolium. The distribution of positivity in cells of human blood and bone marrow is described.

UI MeSH Term Description Entries
D008025 Ligases A class of enzymes that catalyze the formation of a bond between two substrate molecules, coupled with the hydrolysis of a pyrophosphate bond in ATP or a similar energy donor. (Dorland, 28th ed) EC 6. Ligase,Synthetases,Synthetase
D008727 Methotrexate An antineoplastic antimetabolite with immunosuppressant properties. It is an inhibitor of TETRAHYDROFOLATE DEHYDROGENASE and prevents the formation of tetrahydrofolate, necessary for synthesis of thymidylate, an essential component of DNA. Amethopterin,Methotrexate Hydrate,Methotrexate Sodium,Methotrexate, (D)-Isomer,Methotrexate, (DL)-Isomer,Methotrexate, Dicesium Salt,Methotrexate, Disodium Salt,Methotrexate, Sodium Salt,Mexate,Dicesium Salt Methotrexate,Hydrate, Methotrexate,Sodium, Methotrexate
D001853 Bone Marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Marrow,Red Marrow,Yellow Marrow,Marrow, Bone,Marrow, Red,Marrow, Yellow
D001854 Bone Marrow Cells Cells contained in the bone marrow including fat cells (see ADIPOCYTES); STROMAL CELLS; MEGAKARYOCYTES; and the immediate precursors of most blood cells. Bone Marrow Cell,Cell, Bone Marrow,Cells, Bone Marrow,Marrow Cell, Bone,Marrow Cells, Bone
D002729 Chloromercuribenzoates Chloride and mercury-containing derivatives of benzoic acid.
D002955 Leucovorin The active metabolite of FOLIC ACID. Leucovorin is used principally as an antidote to FOLIC ACID ANTAGONISTS. Calcium Leucovorin,Citrovorum Factor,Folinic Acid,N(5)-Formyltetrahydrofolate,5-Formyltetrahydrofolate,5-Formyltetrahydropteroylglutamate,Calcium Folinate,Folinic Acid-SF,Leucovorin, (D)-Isomer,Leucovorin, (DL)-Isomer,Leucovorin, (R)-Isomer,Leucovorin, Calcium (1:1) Salt,Leucovorin, Calcium (1:1) Salt, (DL)-Isomer,Leucovorin, Calcium (1:1) Salt, Pentahydrate,Leucovorin, Monosodium Salt,Leukovorin,Leukovorum,Wellcovorin,5 Formyltetrahydrofolate,5 Formyltetrahydropteroylglutamate,Acid, Folinic,Factor, Citrovorum,Folinate, Calcium,Folinic Acid SF,Leucovorin, Calcium,Monosodium Salt Leucovorin
D005575 Formyltetrahydrofolates Tetrahydrofolates which are substituted by a formyl group at either the nitrogen atom in the 5 position or the nitrogen atom in the 10 position. N(5)-Formyltetrahydrofolate is leucovorin (citrovorum factor) while N(10)-formyltetrahydrofolate is an active coenzyme which functions as a carrier of the formyl group in a number of enzymatic reactions. Formyltetrahydrofolic Acids,N(10)-Formyltetrahydrofolate
D006651 Histocytochemistry Study of intracellular distribution of chemicals, reaction sites, enzymes, etc., by means of staining reactions, radioactive isotope uptake, selective metal distribution in electron microscopy, or other methods. Cytochemistry
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000619 Aminohydrolases

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