title: Dihydropteridine reductase from Escherichia coli.
abstract: A dihydropteridine reductase from Escherichia coli was purified to apparent homogeneity. It is a dimeric enzyme with identical subunits (Mr 27000) and a free N-terminal group. It can use NADH (Vmax./Km 3.36 s-1) and NADPH (Vmax./Km 1.07 s-1) when 6-methyldihydro-(6H)-pterin is the second substrate, as well as quinonoid dihydro-(6H)-biopterin (Vmax./Km 0.69 s-1), dihydro-(6H)-neopterin (Vmax./Km 0.58 s-1), dihydro-(6H)-monapterin 0.66 s-1), 6-methyldihydro-(6H)-pterin and cis-6,7-dimethyldihydro-(6H)-pterin (Vmax./Km 0.66 s-1) when NADH is the second substrate. The pure reductase has a yellow colour and contains bound FAD. The enzyme also has pterin-independent NADH and NADPH oxidoreductase activities when potassium ferricyanide is the electron acceptor.
authors.affiliation: Department of Biochemistry, John Curtin School of Medical Research, Australian National University, Canberra.
authors.forename: S G
authors.initials: SG
authors.lastname: Vasudevan
authors.forename: D C
authors.initials: DC
authors.lastname: Shaw
authors.forename: W L
authors.initials: WL
authors.lastname: Armarego
mesh_terms: D000595:Amino Acid Sequence; D002852:Chromatography, Ion Exchange; D004093:Dihydropteridine Reductase / Q000302:isolation & purification / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology*; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D007700:Kinetics; D008727:Methotrexate / Q000494:pharmacology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D013379:Substrate Specificity
chemical_list: D009243:NAD; D005182:Flavin-Adenine Dinucleotide; D004093:Dihydropteridine Reductase; D009247:NADH, NADPH Oxidoreductases; D008727:Methotrexate