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Nitrite oxidoreductase (NOR or NXR) is an enzyme involved in nitrification.It is the last step in the process of aerobic ammonia oxidation, which is carried out by two groups of nitrifying bacteria: ammonia oxidizers such as Nitrosospira, Nitrosomonas, and Nitrosococcus convert ammonia to nitrite, while nitrite oxidizers such as Nitrobacter and Nitrospira oxidize nitrite to nitrate.
For example, nitrifying bacteria such as Nitrobacter oxidize nitrite to nitrate, which releases sufficient energy to pump protons and generate ATP, but not enough to produce NADH directly. [64] As NADH is still needed for anabolic reactions, these bacteria use a nitrite oxidoreductase to produce enough proton-motive force to run part of the ...
Oxygen is required in both ammonia and nitrite oxidation, meaning that both nitrosifying and nitrite-oxidizing bacteria are aerobes. As in sulfur and iron oxidation, NADH for carbon dioxide fixation using the Calvin cycle is generated by reverse electron flow, thereby placing a further metabolic burden on an already energy-poor process.
The conversion of nitrite to nitrate is facilitated by nitrite-oxidizing bacteria. The genus Nitrobacter is widely distributed in both aquatic and terrestrial environments. [ 2 ] Nitrifying bacteria have an optimum growth between 77 and 86 °F (25 and 30 °C), and cannot survive past the upper limit of 120 °F (49 °C) or the lower limit of 32 ...
Many species of nitrifying bacteria have complex internal membrane systems that are the location for key enzymes in nitrification: ammonia monooxygenase (which oxidizes ammonia to hydroxylamine), hydroxylamine oxidoreductase (which oxidizes hydroxylamine to nitric oxide - which is further oxidized to nitrite by a currently unidentified enzyme ...
The systematic name of this enzyme class is ammonium-hydroxide:NAD(P)+ oxidoreductase. Other names in common use include nitrite reductase (reduced nicotinamide adenine dinucleotide , (phosphate)) , NADH-nitrite oxidoreductase , NADPH-nitrite reductase , assimilatory nitrite reductase , nitrite reductase [NAD(P)H2] , and NAD(P)H2:nitrite ...
Nitrate reductase (NADH) (EC 1.7.1.1, assimilatory nitrate reductase, NADH-nitrate reductase, NADH-dependent nitrate reductase, assimilatory NADH: nitrate reductase, nitrate reductase (NADH 2), NADH 2: nitrate oxidoreductase) is an enzyme with systematic name nitrite: NAD + oxidoreductase.
In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor. This group of enzymes usually utilizes NADP+ or NAD+ as cofactors.