title: Dihydropteridine reductase and tetrahydropterin in Crithidia fasciculata cells.
abstract: Dihydropteridine reductase was found in extracts of Crithidia fasciculata and was demonstrated by the fact that the enzyme required both quinonoid-dihydropterin and NADH as substrates. 7,8-Dihydropterin and dihydrofolate failed to serve as substrates; tetrahydropterin was formed as the reaction product. The molecular weight of the enzyme was estimated to be about 55 000 by Sephadex G-100 gel filtration. NADH was more effective than NADPH as substrate for the enzyme. Tetrahydropterin (1.35 nmol tetrahydrobiopterin equivalents/g cells) was also detected in C. fasciculata.
mesh_terms: D000630:Aminopterin / Q000494:pharmacology; D000818:Animals; D003421:Crithidia / Q000378:metabolism*; D004093:Dihydropteridine Reductase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008727:Methotrexate / Q000494:pharmacology; D008970:Molecular Weight; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D011622:Pterins / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D011622:Pterins; C025101:quinoid-dihydro-6-methylpterin; D009243:NAD; C011552:tetrahydropterin; D004093:Dihydropteridine Reductase; D009247:NADH, NADPH Oxidoreductases; D000630:Aminopterin; D008727:Methotrexate