Oxidation-reduction behavior of the heme c and heme d moieties of Pseudomonas aeruginosa nitrite reductase and the formation of an oxygenated intermediate at heme d1.
Dithionite reduced the heme c moiety of Pseudomonas nitrite reductase almost instantaneously, whereas the spectral change of heme d proceeded in two steps, requiring at least 15 min for completion. The final spectrum coincided well with that obtained by anaerobic reduction with ascorbate, during which a quasi oxidation-reduction equilibrium was established between the two heme groups. The difference in apparent redox potential was calculated to be 24 mV, heme d being more negative. When the enzyme was supplemented with a reductant and molecular oxygen, an oxygenated intermediate appeared at the heme d moiety.
D001205:Ascorbic Acid / Q000494:pharmacology; D002374:Catalase / Q000494:pharmacology; D004227:Dithionite / Q000494:pharmacology; D006418:Heme / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009572:Nitrite Reductases / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D011550:Pseudomonas aeruginosa / Q000201:enzymology*; D013053:Spectrophotometry
D004227:Dithionite; D006418:Heme; D002374:Catalase; D009247:NADH, NADPH Oxidoreductases; D009572:Nitrite Reductases; D001205:Ascorbic Acid