title: A reduced pyridine nucleotides-diaphorase activity associated to the assimilatory nitrite reductase complex from Neurospora crassa.
abstract: The Neurospora crassa assimilatory NAD(P)H-nitrite reductase complex has associated a NAD(P)H-diaphorase activity. 1. This NAD(P)H-diaphorase activity can use either mammalian cytochrome c, 2,6--dichlorophenol-indophenol, ferricyanide, or menadione as electron acceptor from the reduced pyridine nucleotides, and requires flavin adenine dinucleotide for maximal activity. 2. It is inhibited by p-hydroxymercuribenzoate, 1 muM, and it is unaffected by cyanide, sulfite, or arsenite at concentrations which completely inhibit the NAD(P)H-nitrite reductase activity. 3. Flavin adenine dinucleotide specifically protects the NAD(P)H-diaphorase activities, but not the NAD(P)H-nitrite reductase activities, against thermal inactivation. 4. In vitro preincubation of the Neurospora crassa nitrite reductase complex with reduced pyridine nucleotides plus flavin adenine dinucleotide inactivates the NAD(P)H-nitrite reductase activities, but does not affect the NAD(P)H-diaphorase activities, indicating that this nitrite reductase inactivation occurs in the part of the enzyme that contain the nitrite reducing center.
mesh_terms: D003579:Cytochrome Reductases / Q000037:antagonists & inhibitors / Q000302:isolation & purification; D004355:Drug Stability; D005486:Flavin Mononucleotide; D005182:Flavin-Adenine Dinucleotide; D006358:Hot Temperature; D009097:Multienzyme Complexes; D009247:NADH, NADPH Oxidoreductases; D009491:Neurospora / Q000201:enzymology*; D009492:Neurospora crassa / Q000201:enzymology*; D009572:Nitrite Reductases / Q000037:antagonists & inhibitors / Q000302:isolation & purification
chemical_list: D009097:Multienzyme Complexes; D005182:Flavin-Adenine Dinucleotide; D005486:Flavin Mononucleotide; D009247:NADH, NADPH Oxidoreductases; D003579:Cytochrome Reductases; D009572:Nitrite Reductases