nitrite reductase (NO-forming) activity
Definition
Target type: molecularfunction
Catalysis of the reaction: nitric oxide + H2O + ferricytochrome c = nitrite + ferrocytochrome c + 2 H+. [EC:1.7.2.1, MetaCyc:NITRITE-REDUCTASE-CYTOCHROME-RXN]
Nitrite reductase (NO-forming) activity catalyzes the reduction of nitrite (NO2-) to nitric oxide (NO), a crucial step in the nitric oxide cycle. This enzyme is commonly found in bacteria and fungi, where it plays a vital role in nitrogen metabolism and detoxification. The enzymatic mechanism involves the transfer of electrons from a reducing agent, often a reduced cytochrome c or ferredoxin, to nitrite, ultimately leading to the release of NO. The enzyme utilizes a variety of metal cofactors, typically heme or copper, which are essential for the electron transfer process.
The NO produced by nitrite reductase has a wide range of biological functions, including:
* **Signaling:** NO acts as a signaling molecule in various physiological processes, such as vasodilation, neurotransmission, and immune response.
* **Antimicrobial activity:** In some organisms, NO serves as an antimicrobial agent, inhibiting the growth of pathogens.
* **Nitrogen fixation:** In certain bacteria, NO can be further reduced to ammonia (NH3), which is essential for nitrogen fixation.
The regulation of nitrite reductase activity is tightly controlled to ensure proper NO production and prevent detrimental effects. Factors influencing its activity include the availability of nitrite, the redox state of the electron donor, and the presence of specific inhibitors.
Overall, nitrite reductase (NO-forming) activity is a critical enzyme in the nitric oxide cycle, contributing to diverse biological processes through the production of NO. Understanding its molecular function is essential for unraveling the complex roles of NO in various organisms.'
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Proteins (2)
| Protein | Definition | Taxonomy |
|---|---|---|
| Cystathionine beta-synthase | A cystathionine beta-synthase that is encoded in the genome of human. [PRO:DNx, UniProtKB:P35520] | Homo sapiens (human) |
| NADH-cytochrome b5 reductase 3 | An NADH-cytochrome b5 reductase 3 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P00387] | Homo sapiens (human) |
Compounds (10)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| aminooxyacetic acid | (aminooxy)acetic acid : A member of the class of hydroxylamines that is acetic acid substituted at postion 2 by an aminooxy group. It is a compound which inhibits aminobutyrate aminotransferase activity in vivo, resulting in increased levels of gamma-aminobutyric acid in tissues. Aminooxyacetic Acid: A compound that inhibits aminobutyrate aminotransferase activity in vivo, thereby raising the level of gamma-aminobutyric acid in tissues. | amino acid; hydroxylamines; monocarboxylic acid | anticonvulsant; EC 2.6.1.19 (4-aminobutyrate--2-oxoglutarate transaminase) inhibitor; EC 4.2.1.22 (cystathionine beta-synthase) inhibitor; nootropic agent |
| aurintricarboxylic acid | aurintricarboxylic acid : A member of the class of quinomethanes that is 3-methylidene-6-oxocyclohexa-1,4-diene-1-carboxylic acid in which the methylidene hydrogens are replaced by 4-carboxy-3-hydroxyphenyl groups. The trisodium salt is the biological stain 'chrome violet CG' while the triammonium salt is 'aluminon'. Aurintricarboxylic Acid: A dye which inhibits protein biosynthesis at the initial stages. The ammonium salt (aluminon) is a reagent for the colorimetric estimation of aluminum in water, foods, and tissues. | monohydroxybenzoic acid; quinomethanes; tricarboxylic acid | fluorochrome; histological dye; insulin-like growth factor receptor 1 antagonist |
| hypericin | |||
| propylthiouracil | 6-propyl-2-thiouracil : A pyrimidinethione consisting of uracil in which the 2-oxo group is substituted by a thio group and the hydrogen at position 6 is substituted by a propyl group. Propylthiouracil: A thiourea antithyroid agent. Propythiouracil inhibits the synthesis of thyroxine and inhibits the peripheral conversion of throxine to tri-iodothyronine. It is used in the treatment of hyperthyroidism. (From Martindale, The Extra Pharmacopeoia, 30th ed, p534) | pyrimidinethione | antidote to paracetamol poisoning; antimetabolite; antioxidant; antithyroid drug; carcinogenic agent; EC 1.14.13.39 (nitric oxide synthase) inhibitor; hormone antagonist |
| agathisflavone | agathisflavone : A biflavonoid that is obtained by oxidative coupling of two molecules of apigenin resulting in a bond between positions C-6 and C-8 of the two chromene rings. agathisflavone: bis-apigenin coupled at 6 and 8 positions; isolated from the plant Canarium manii; has hepatoprotective activity against carbon tetrachloride-induced hepatotoxicity | biaryl; biflavonoid; hydroxyflavone | antineoplastic agent; antiviral agent; hepatoprotective agent; metabolite |
| cupressuflavone | cupressuflavone : A biflavonoid that is obtained by oxidative coupling of two molecules of apigenin resulting in a bond between positions C-8 of the two chromene rings respectively. Isolated from Cupressus sempervirens and Juniperus occidentalis, it exhibits free radical scavenging and antielastase activities. cupressuflavone: from Cupressus macrocarpa; structure in first source | biflavonoid; hydroxyflavone; ring assembly | EC 3.4.21.37 (leukocyte elastase) inhibitor; metabolite; radical scavenger |
| myricetin | 7-hydroxyflavonol; hexahydroxyflavone | antineoplastic agent; antioxidant; cyclooxygenase 1 inhibitor; food component; geroprotector; hypoglycemic agent; plant metabolite | |
| podocarpusflavone a | podocarpusflavone A: isolated from Podocarpus imbricatus | flavonoid oligomer | |
| rubrolide a | rubrolide A: from Synoicum prunum; structure in first source | ||
| ly 341495 | xanthenes |