Information on EC 3.2.2.2 - inosine nucleosidase

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The expected taxonomic range for this enzyme is: Eukaryota, Bacteria, Archaea

EC NUMBER
COMMENTARY hide
3.2.2.2
-
RECOMMENDED NAME
GeneOntology No.
inosine nucleosidase
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
inosine + H2O = D-ribose + hypoxanthine
show the reaction diagram
-
-
-
-
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
hydrolysis of N-glycosyl bond
-
-
-
-
PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
adenosine nucleotides degradation I
-
-
Purine metabolism
-
-
purine metabolism
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-
SYSTEMATIC NAME
IUBMB Comments
inosine ribohydrolase
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CAS REGISTRY NUMBER
COMMENTARY hide
9030-95-9
-
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
strain 0
-
-
Manually annotated by BRENDA team
subsp. Kurstaki
UniProt
Manually annotated by BRENDA team
-
-
-
Manually annotated by BRENDA team
Jerusalem artichoke
-
-
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
physiological function
-
isoform NSH2 acts during the late phase of senescence and supports inosine breakdown
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
1-methylguanosine + H2O
1-methylguanine + D-ribose
show the reaction diagram
-
-
-
-
?
1-N2-ethenoguanosine + H2O
1-N2-ethenoguanine + D-ribose
show the reaction diagram
-
-
-
-
?
1-N2-isopropenoguanosine + H2O
1-N2-isopropenoguanine + D-ribose
show the reaction diagram
-
-
-
-
?
5-methyluridine + H2O
D-ribose + 5-methyluracil
show the reaction diagram
-
-
-
-
?
6-mercaptopurine riboside + H2O
6-mercaptopurine + D-ribose
show the reaction diagram
7-methylguanosine + H2O
7-methylguanine + D-ribose
show the reaction diagram
-
-
-
-
?
8-azainosine + H2O
8-azahypoxanthine + D-ribose
show the reaction diagram
-
-
-
-
?
adenosine + H2O
adenine + D-ribose
show the reaction diagram
adenosine + H2O
D-ribose + adenine
show the reaction diagram
guanosine + H2O
D-ribose + guanine
show the reaction diagram
guanosine + H2O
guanine + D-ribose
show the reaction diagram
inosine + H2O
D-ribose + hypoxanthine
show the reaction diagram
inosine + H2O
hypoxanthine + D-ribose
show the reaction diagram
purine riboside + H2O
purine + D-ribose
show the reaction diagram
-
nebularine
-
?
uridine + H2O
D-ribose + uracil
show the reaction diagram
-
-
-
-
?
xanthosine + H2O
D-ribose + hypoxanthine
show the reaction diagram
-
-
-
-
?
xanthosine + H2O
xanthine + D-ribose
show the reaction diagram
additional information
?
-
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
inosine + H2O
hypoxanthine + D-ribose
show the reaction diagram
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
2'-deoxyguanosine
-
competitive
2'-methylguanosine
-
competitive
6-mercaptopurine riboside
-
-
adenine
adenosine
-
competitive
ATP
-
binds to I1- and I2-site, noncompetitive inhibition, ligand exclusion model
Co2+
-
24.2% residual activity at 0.1 M using inosine as substrate, 25.8% residual activity at 0.1 M using guanosine as substrate, 33.3% residual activity at 0.1 M using adenosine as substrate
Cu2+
-
10.6% residual activity at 0.1 M using inosine as substrate, 9.67% residual activity at 0.1 M using guanosine as substrate, complete inhibition at 0.1 M using adenosine as substrate
Fe2+
-
60.6% residual activity at 0.1 M using inosine as substrate, 54.8% residual activity at 0.1 M using guanosine as substrate, 66.6% residual activity at 0.1 M using adenosine as substrate
guanine
-
competitive
hypoxanthine
Mg2+
-
62.1% residual activity at 0.1 M using inosine as substrate, 74.2% residual activity at 0.1 M using guanosine as substrate, 75% residual activity at 0.1 M using adenosine as substrate
NaCN
-
60.6% residual activity at 0.1 M using inosine as substrate, 38.7% residual activity at 0.1 M using guanosine as substrate, 41.6% residual activity at 0.1 M using adenosine as substrate
nucleoside diphosphates
-
less effective inhibitor compared to nucleoside triphosphates, non competitive inhibition
nucleoside monophosphates
-
slight inhibition or no effect
nucleoside triphosphates
-
most potent inhibitor, non competitive inhibition
Theobromine
-
at alkaline pH
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.06 - 0.7
adenosine
0.0027 - 0.16
guanosine
0.0025 - 1.4
Inosine
0.44
methyluridine
-
pH and temperature not specified in the publication
0.8
uridine
-
pH and temperature not specified in the publication
1.2 - 1.69
Xanthosine
additional information
additional information
-
kinetics
-
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
3.8
adenosine
Sulfolobus solfataricus
-
-
29.1
guanosine
Sulfolobus solfataricus
-
-
23.3 - 48.9
Inosine
IC50 VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.0015
2'-deoxyguanosine
Lupinus luteus
-
pH 4.8
0.0036
2'-methylguanosine
Lupinus luteus
-
pH 4.8
0.021
adenosine
Lupinus luteus
-
pH 4.8
0.0097
guanine
Lupinus luteus
-
pH 4.8
0.06
Mn2+
Lupinus luteus
-
pH 4.8
0.06
Zn2+
Lupinus luteus
-
pH 4.8
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
0.00275
-
substrate: inosine
9.25
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pH 4.8
14.5
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purified recombinant enzyme, substrate inosine
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
4.7 - 5.5
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-
7
-
substrate: xanthosine
8
-
around pH 8
9
-
substrate: inosine
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
TEMPERATURE RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
70 - 100
high activity
105 - 115
-
105C: maximal activity, 115C: 50% of maximal activity
pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5.92
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estimated
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
34000
-
2 * 34000 Da, SDS-PAGE, predicted: 34325 Da/subunit, intersubunit disulfide bond
62000
-
gel filtration
80000
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gel filtration
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
homodimer
monomer
-
1 * 80000, SDS-PAGE
TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
50 - 60
-
the enzyme shows 68.18%, 45.45% and 28.78% residual activities for inosine hydrolysis after 4 min, 6 min, and 8 min of incubation, respectively, at 50C. The enzyme is completely inactivated after 10 min at 50C and 4 min at 60C
90
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100% activity after 1h, apparent melting temperature: 107C
100
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half-live 45 min
105
-
half-live 30 min
110
-
half-live 15 min
GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
hydrolysis activity for inosine, guanosine and adenosine is highest in citrate-phosphate buffer
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STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
-20C, tolerates repeated freeze-thawing
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-25C, highly stable at deep-freeze conditions
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-5C, in citrate-phosphate buffer (pH 4.0), the enzyme retains 100%, 95.7%, 93,6% and 82.9% activity for inosine hydrolysis after 24 h, 48 h, 72 h and 120 h of incubation, respectively
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4C, highly stable
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
highly purified, 233fold
-
partial purification
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
URH1, DNA and amino acid sequence determination and analysis, expression in Escherichia coli, functional complementation of a yeast mutant, expression in transgenic Arabidopsis thaliana mutant plants under control of the CaMV 35S promoter
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information