title: A blue protein as an inactivating factor for nitrite reductase from Alcaligenes faecalis strain S-6.
abstract: A blue protein with a molecule weight of 12,000 containing 1 atom of type I Cu2+ was purified and crystallized from a denitrifying bacterium, Alcaligenes faecalis strain S-6, as an inactivating factor for copper-containing nitrite reductase of the same organism. Inactivation of the enzyme occurred when the enzyme was incubated aerobically with a catalytic amount of the blue protein in the presence of reducing agents such as cysteine and ascorbate. The blue protein acts as a direct electron donor for the enzyme to catalyze the reduction of nitrite, but in the absence of nitrite, the enzyme-reduced blue protein system reacts with oxygen to produce H2O2. A suicide inactivation mechanism of the enzyme due to this H2O2 production is proposed.
mesh_terms: D000421:Alcaligenes / Q000201:enzymology*; D000596:Amino Acids / Q000032:analysis; D001426:Bacterial Proteins; D003300:Copper / Q000032:analysis; D003545:Cysteine; D004578:Electron Spin Resonance Spectroscopy; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008667:Metalloproteins / Q000302:isolation & purification / Q000494:pharmacology*; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors*; D009572:Nitrite Reductases / Q000037:antagonists & inhibitors*; D010084:Oxidation-Reduction; D010100:Oxygen; D013057:Spectrum Analysis
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D008667:Metalloproteins; C017079:mauC protein, Methylobacterium extorquens; D003300:Copper; D006861:Hydrogen Peroxide; D009247:NADH, NADPH Oxidoreductases; D009572:Nitrite Reductases; D003545:Cysteine; D010100:Oxygen