Information on EC 1.7.6.1 - nitrite dismutase

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The expected taxonomic range for this enzyme is: Rhodnius prolixus

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EC NUMBER
COMMENTARY hide
1.7.6.1
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RECOMMENDED NAME
GeneOntology No.
nitrite dismutase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
3 nitrite + 2 H+ = 2 nitric oxide + nitrate + H2O
show the reaction diagram
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SYSTEMATIC NAME
IUBMB Comments
nitrite:nitrite oxidoreductase
Contains ferriheme b. The enzyme is one of the nitrophorins from the salivary gland of the blood-feeding insect Rhodnius prolixus. Nitric oxide produced induces vasodilation after injection. Nitrophorins 2 and 4 can also catalyse this reaction.
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ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
physiological function
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NP7 inhibits prothrombin activation by blocking phospholipid binding sites for the prothrombinase complex on the surfaces of vesicles and activated platelets. As a NO complex, NP7 inhibits collagen and ADP-induced platelet aggregation and induces disaggregation of ADP-stimulated platelets by an NO-mediated mechanism
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SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
3 nitrite + 2 H+
2 nitric oxide + nitrate + H2O
show the reaction diagram
additional information
?
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NP7 is unique in its ability to bind to negatively charged cell surfaces
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
3 nitrite + 2 H+
2 nitric oxide + nitrate + H2O
show the reaction diagram
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
heme b
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pH OPTIMUM
ORGANISM
UNIPROT
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LITERATURE
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pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
8.72
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calculated from sequence
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SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
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PDB
SCOP
CATH
ORGANISM
UNIPROT
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MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
20600
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x * 20600, calculated from sequence
20966
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x * 20966, MALDI-TOF-MS
20969
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x * 20969, calculated from sequence
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SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
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enzyme tends to form oligomers and precipitates at higher concentration. At concentrations of approximately 0.1-2 mM oligomers are in equilibrium with monomers. The protein oligomerizes preferably in units of trimers, hexamers, and higher oligomeric states of unidentified composition
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Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
crystal structure of nitrophorin 4 at 1.5 A resolution
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protein crystals are obtained using the vapor diffusion method with the conditions containing 3.2 M ammonium phosphate (pH 7.4). X-ray crystallography of NP4 crystals soaked with nitrite reveals the formation of an eta1-N nitro complex
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solid-state NMR analysis. Enzyme tends to form oligomers and precipitates at higher concentration. At concentrations of approximately 0.1-2 mM oligomers are in equilibrium with monomers. The protein oligomerizes preferably in units of trimers, hexamers, and higher oligomeric states of unidentified composition
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pH STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
4 - 5
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the enzyme-NO complex is more stable at pH 4-5 than at physiologic pH. pH. In pH 4.5 sodium acetate buffer, a complex formed by incubation with S-nitroso-N-acetylpenicillamine is stable for several hours at room temperature, is purified by gel filtration chromatography at pH 4.5, and maintains indefinitely at -20°C. Raising the pH of the complex solution by adding concentrated Tris-HCl, pH 7.5 results in dissociation of the complex over a period of 10-15 min
714157
7.5
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the enzyme-NO complex is more stable at pH 4-5 than at physiologic pH. pH. In pH 4.5 sodium acetate buffer, a complex formed by incubation with S-nitroso-N-acetylpenicillamine is stable for several hours at room temperature, is purified by gel filtration chromatography at pH 4.5, and maintains indefinitely at -20°C. Raising the pH of the complex solution by adding concentrated Tris-HCl, pH 7.5 results in dissociation of the complex over a period of 10-15 min
714157
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TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
45
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truncated mutant enzyme NP7(DELTA1-3) shows marked decay above 45°C. Wild-type nitrophorin 7, in contrast, is comparatively stable, and does not experience a marked signal decrease of activity at temperatures below 52 °C
52
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truncated mutant enzyme NP7(DELTA1-3) shows marked decay above 45°C. Wild-type nitrophorin 7, in contrast, is comparatively stable, and does not experience a marked signal decrease of activity at temperatures below 52 °C
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GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
NP7 is unstable when lyophilized
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the N-terminus of NP7 significantly stabilizes the protein fold
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
the NP7 protein is obtained as inclusion bodies and is denatured, refolded, and reconstituted with heme as described for other nitrophorins. The refolded reconstituted protein is purified by a two-step procedure
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expressed in Escherichia coli
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expressed in Escherichia coli BL21(DE3)
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expressed in Escherichia coli BL21(DE3); expressed in Escherichia coli BL21(DE3)
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expression in Escherfichia coli
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expression in Escherichia coli
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expression in Escherichia coli BL21. Expression and reconstitution method for NP7 that yields sufficient amounts of pure protein for extensive characterization
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
K149A
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using 3:1 phosphatidylcholine:phosphatidylserine vesicles, binding is reduced by a factor of three from that observed with wild-type protein, suggesting that this region does play an important role in phospholipid binding
additional information
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truncated mutant enzyme NP7(DELTA1-3) lacking the 0Met-Leu-Pro-Gly3 sequence, shows marked decay above 45°C. Wild-type nitrophorin 7, in contrast, is comparatively stable, and does not experience a marked signal decrease of activity at temperatures below 52°C
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LINKS TO OTHER DATABASES (specific for EC-Number 1.7.6.1)
ExplorEnz
ExPASy
KEGG
MetaCyc
SABIO-RK
NCBI: PubMed, Protein, Nucleotide, Structure, Genome, OMIM
IUBMB Enzyme Nomenclature
PROSITE Database of protein families and domains
SYSTERS
Protein Mutant Database
InterPro (database of protein families, domains and functional sites)