title: Kinetic studies of the copper nitrite reductase from Achromobacter cycloclastes and its interaction with a blue copper protein.
abstract: Transient state, burst and steady state kinetics of reactions of the blue copper nitrite reductase (NIR) and blue copper protein from Achromobacter cycloclastes are investigated. The two copper-containing species are reacted with each other and where possible with dithionite, ascorbate and nitrite. Both copper proteins are fully reduced by dithionite with both S2O4(2-) and SO2-. species active. NIR is only partially reduced by ascorbate in an unusual biphasic reaction consistent with complete reduction of type-one copper followed by partial reduction of type-two copper. The rate of reduction of the type-one copper is accelerated using phenazine methosulfate as mediator. Nitrite can oxidize dithionite-reduced NIR but cannot reduce oxidized NIR. Rate constants were determined for all observed reactions.
mesh_terms: D000421:Alcaligenes / Q000201:enzymology*; D001205:Ascorbic Acid / Q000494:pharmacology; D001426:Bacterial Proteins; D004227:Dithionite / Q000494:pharmacology; D007700:Kinetics; D008667:Metalloproteins / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009572:Nitrite Reductases / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008667:Metalloproteins; C017079:mauC protein, Methylobacterium extorquens; D004227:Dithionite; D009247:NADH, NADPH Oxidoreductases; D009572:Nitrite Reductases; C052695:nitrite reductase, copper-containing; D001205:Ascorbic Acid