Information on EC 4.2.1.122 - tryptophan synthase (indole-salvaging)

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The expected taxonomic range for this enzyme is: Thermotoga maritima

EC NUMBER
COMMENTARY
4.2.1.122
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RECOMMENDED NAME
GeneOntology No.
tryptophan synthase (indole-salvaging)
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
L-serine + indole = L-tryptophan + H2O
show the reaction diagram
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PATHWAY
KEGG Link
MetaCyc Link
tryptophan biosynthesis
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SYSTEMATIC NAME
IUBMB Comments
L-serine hydro-lyase [adding indole, L-tryptophan-forming]
Most mesophilic bacteria have a multimeric tryptophan synthase complex (EC 4.2.1.20) that forms L-tryptophan from L-serine and 1-C-(indol-3-yl)glycerol 3-phosphate via an indole intermediate. This intermediate, which is formed by the alpha subunits, is transferred in an internal tunnel to the beta units, which convert it to tryptophan. In thermophilic organisms the high temperature enhances diffusion and causes the loss of indole. This enzyme, which does not combine with the alpha unit to form a complex, salvages the lost indole back to L-tryptophan. It has a much lower Km for indole than the beta subunit of EC 4.2.1.20.
SYNONYMS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
ORGANISM
COMMENTARY
LITERATURE
SEQUENCE CODE
SEQUENCE DB
SOURCE
GENERAL INFORMATION
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
physiological function
-
TrpB2 acts as an indole rescue protein, which prevents the escape of this costly hydrophobic metabolite from the cell at the high growth temperatures of hyperthermophiles
SUBSTRATE
PRODUCT                      
REACTION DIAGRAM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
(Substrate)
LITERATURE
(Substrate)
COMMENTARY
(Product)
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
L-serine + indole
L-tryptophan + H2O
show the reaction diagram
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-
-
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?
additional information
?
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TrpB2 does not bind to TrpA but is catalytically highly active, has an extremely low Km value for indole
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KM VALUE [mM]
KM VALUE [mM] Maximum
SUBSTRATE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
0.00077
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Indole
-
Km below 0.00077 mM, at 80C, pH not specified in the publication
50.2
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L-serine
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at 80C, pH not specified in the publication
TURNOVER NUMBER [1/s]
TURNOVER NUMBER MAXIMUM[1/s]
SUBSTRATE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
0.46
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Indole
-
at 80C, pH not specified in the publication
0.44
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L-serine
-
at 80C, pH not specified in the publication
kcat/KM VALUE [1/mMs-1]
kcat/KM VALUE [1/mMs-1] Maximum
SUBSTRATE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
0.0006
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Indole
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KCAT_KM below 0.0006 mM, at 80C, pH not specified in the publication
11630
8700
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L-serine
-
at 80C, pH not specified in the publication
12405
MOLECULAR WEIGHT
MOLECULAR WEIGHT MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
61700
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gel filtration
92770
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calculated from amino acid sequence
98000
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sedimentation equilibrium analysis
SUBUNITS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
homodimer
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2 * 46400, calculated from amino acid sequence
Purification/COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
Mono Q column chromatography and Superdex 75 gel filtration
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Cloned/COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
expressed in Escherichia coli BL21(DE3) cells
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