Information on EC 4.2.1.123 - tetrahymanol synthase

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The enzyme appears in viruses and cellular organisms

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EC NUMBER
COMMENTARY hide
4.2.1.123
-
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RECOMMENDED NAME
GeneOntology No.
tetrahymanol synthase
-
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
tetrahymanol = squalene + H2O
show the reaction diagram
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
hopanoid biosynthesis (bacteria)
-
-
Sesquiterpenoid and triterpenoid biosynthesis
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Biosynthesis of secondary metabolites
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-
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SYSTEMATIC NAME
IUBMB Comments
squalene-tetrahymanol cyclase
The reaction occurs in the reverse direction.
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ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
no activity in Alicyclobacillus acidocaldarius
-
-
-
Manually annotated by BRENDA team
no activity in Bradyrhizobium japonicum
-
-
-
Manually annotated by BRENDA team
no activity in Methylococcus capsulatus
-
-
-
Manually annotated by BRENDA team
no activity in Rhodopseudomonas palustris
-
-
-
Manually annotated by BRENDA team
-
-
-
Manually annotated by BRENDA team
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GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
evolution
metabolism
-
the enzyme converts squalene to tetrahymanol, EC 4.2.1.123, and to hopanol, EC 4.2.1.129, pathway overview
additional information
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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
dihydrosqualene + H2O
euph-7-ene
show the reaction diagram
-
-
-
-
?
squalene + H2O
tetrahymanol
show the reaction diagram
squalene + H2O
tetrahymanol + diplopterol
show the reaction diagram
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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
squalene + H2O
tetrahymanol
show the reaction diagram
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INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
2,3-Iminosqualene
-
effective inhibitor, complete inhibition at 1 mM
4,4,10beta-trimethyltransdecal-3beta-ol
-
25% inhibition at 40 mM
4-chloromercuribenzenesulfonic acid
-
86% inhibition at 5 mM
diethyldicarbonate
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complete inhibition at 5 mM
Digitonin
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solubilization of the cyclase in 8 mg/ml digitonin inactivates the enzyme, its activity can be recovered by complementation of the assay buffer with octylthioglucoside above its critical micellar concentration
Emulgene 911
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solubilization of the cyclase in 1 mg/ml Emulgene 911 inactivates the enzyme
N,N-Dimethyldodecylamine-N-oxide
-
effective inhibitor, complete inhibition at 1 mM
Ro 43-8522
-
effective inhibitor, complete inhibition at 1 mM
Triton X-100
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strong inactivator
Tween 80
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solubilization of the cyclase in 30 mg/ml Tween 80 inactivates the enzyme, its activity can be recovered by complementation of the assay buffer with octylthioglucoside above its critical micellar concentration
additional information
-
the cyclase is not influenced by EDTA concentrations up to 0.1 M, and lodoacetate is not inhibitory at 1 and 5 mM
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.018
squalene
-
pH 7.0, 30°C
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IC50 VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.00003
2,3-Iminosqualene
Tetrahymena thermophila
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pH 7.0, 30°C
0.00005
N,N-Dimethyldodecylamine-N-oxide
Tetrahymena thermophila
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pH 7.0, 30°C
0.00004
Ro 43-8522
Tetrahymena thermophila
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pH 7.0, 30°C
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
105
-
enzyme from homogenate, pH 7.0, 30°C
31280
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enzyme after 297fold purification, pH 7.0, 30°C
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
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LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
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MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
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SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
?
-
x * 72000, SDS-PAGE
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pH STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
4 - 8.5
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the enzyme is not active beyond the pH limits of pH 4.5 and 8.0
714282
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TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
50
-
the enzyme is not active at 50°C
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ORGANIC SOLVENT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
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STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
-80°C, whole cells and particulate material, 6 months, no loss of activity
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6°C, octylthioglucoside-solubilized enzyme, one week, almost complete loss of activity
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
DEAE-trisacryl column chromatography, hydroxyapatite column chromatography, and Mono Q column chromatography
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
phylogenetic analysis
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LINKS TO OTHER DATABASES (specific for EC-Number 4.2.1.123)
ExplorEnz
ExPASy
KEGG
MetaCyc
SABIO-RK
NCBI: PubMed, Protein, Nucleotide, Structure, Genome, OMIM
IUBMB Enzyme Nomenclature
PROSITE Database of protein families and domains
InterPro (database of protein families, domains and functional sites)