Reductases nitrite reductase

NITRATE REDUCTASE NITRITE REDUCTASE PHENOL HYDROXYLASE PROLINE DEHYDROGENASE PUTRESCINE OXIDASE PYRUVATE OXIDASE SALICYLATE 1-MONOOXYGENASE SUCCINATE DEHYDROGENASE SULFITE REDUCTASE XANTHINE OXIDASE Falling ball viscometry,... 

R)-2-METHYLMALATE DEHYDRATASE NICOTINATE DEHYDROGENASE NITRATE REDUCTASE NITRITE REDUCTASE PHENYLALANINE MONOOXYGENASE PROLYL 3-HYDROXYLASE PROLYL 4-HYDROXYLASE PROTOCATECHUATE 3,4-DIOXYGENASE PROTOCATECHUATE 4,5-DIOXYGENASE RIESKE IRON-SULFUR PROTEIN RUBREDOXIN... 

These include nitrite and trimethylammonium oxide. Nitrite undergoes a six-electron reduction to give ammonia in a reaction catalyzed by a nitrite reductase. Nitrite reductase activity with lactate and formate has been reported, although other donors may support the reduction of nitrite. It should be noted that at least three pathways in E. coli exist for the reduction of nitrite. 

Nitrite reductase (dissimilatory) Nitric oxide reductase Nitrous oxide reductase Nitrite reductase Hydroxylamine oxidase Nitrite oxioreductase Hydroxylamine reductase Hydroxylamine oxioreductase... 

Nitrous oxide reductase Nitrate reductase + nitrite reductase + nitric oxide reductase... 

Complex heme proteins which contain redox centers other than just electron transfer hemes are normally associated with enzymatic catalysis. In this section, we will refer to some of the best studied complex heme proteins sulfite reductase, nitrite reductase, formate dehydrogenase, fumarate reductase and rubredoxin-oxygen oxidoreductase. 

See also The Nitrogen Cycle, Nitrogen Fixation, Utilization of Ammonia, Dimethylsulfoxide Reductase, Nitrite Reductase, Siroheme, Ferredoxin, Figure 20.2... 

The blue copper center in cupredoxins is also found in multidomain, multicopper enzymes " such as ascorbate oxidase (AO), laccase (Lc), human ceruloplasmin (Cp), " and a subfamily of copper-containing nitrite reductase. Nitrite reductase (NiR) catalyzes reduction of nitrite (N(32 ) to nitric oxide (NO), a step in the biological dinitrification cycle. Two distinct types of NIR are known multiheme NiR (see Chapter 8.29) and multicopper NiR. The multicopper... 

Each step of the denitrification pathway is catalyzed by a distinct enzyme, nitrogen oxide reductase (nitrate reductase, nitrite reductase, nitric oxide reductase, and nitrous oxide reductase), that transfers electrons from the chain to the particular intermediate. Thermodynamically, in the absence of oxygen, nitrogen oxides are the most preferred electron acceptors by facultative bacterial groups. The role of nitrogen oxides in regulating organic matter decomposition has been discussed in earlier chapters (see Chapter 5). 

Enzymatic electrochemical biosensors are based on immobilized enzymes, whose products can be electrochemically measured after degradation of the substrate at the surface of the biosensor. Many different types of enzymatic biosensors have been developed for environmental monitoring of pesticides, phenols, heavy metals, nitrate, formaldehyde and sulfur oxide, etc. Commonly used enzymes include but are not limited to organophosphorus hydrolase (OPH), AChE, butyrylcholi-nesterase (BChE), horseradish peroxidase (HRP), tyrosinase (phenol oxidases), nitrate reductase, nitrite reductase, formaldehyde dehydrogenase (FDH), and sulfite oxidase (SO). 

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