Pseudomonas denitrificans nitrite reductase

The emerging picture of dissimilatory nitrite reductases as diheme proteins is upset by the P. denitrificans enzyme a nonheme, copper-containing protein of molecular weight 150,000 (4 3). It has been suggested that the strain P. denitrificans is more appropriately classified with the Alcali-genes (see work cited in reference 361), and, if so, we would be less surprised at finding a difference between its reductase and those of the other Pseudomonas strains. 

Nitrite reduction to nitric oxide is catalyzed by dissimilatory nitrite reductase. The enzymes purified from Alcaligenes faecalis (Iwasaki and Matsub-ara, 1971), Pseudomonas aeruginosa (Walker and Nicholas, 1961), andMj-crococcus denitrificans (Newton, 1969) have been shown to contain c d-type cytochrome. The nitrite reductase from Achromobacter cycloclastes does not... 

Heme di (107), which was isolated by Timkovich et al (70) and Chang et al (71) occurs as one of two cofactors in the reductase cytochrome cd. Cytochrome cd participates in the reduction of nitrite to nitrous oxide (N2O) in chemoautotrophic bacteria, such as Pseudomonas aeruginosa, Paracoccus denitrificans, and Thiobacillus denitrificans (13). From recent investigations it seems very likely that cytochrome cdi mediates the nitrite reduction to nitric oxide (NO) and that a second enzyme produces N2O from NO (13). A structure was... 

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