Information on EC 3.2.1.196 - limit dextrin alpha-1,6-maltotetraose-hydrolase

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
3.2.1.196
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RECOMMENDED NAME
GeneOntology No.
limit dextrin alpha-1,6-maltotetraose-hydrolase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
Hydrolysis of (1->6)-alpha-D-glucosidic linkages to branches with degrees of polymerization of three or four glucose residues in limit dextrin.
show the reaction diagram
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
glycogen degradation I
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SYSTEMATIC NAME
IUBMB Comments
glycogen phosphorylase-limit dextrin maltotetraose-hydrolase
This bacterial enzyme catalyses a reaction similar to EC 3.2.1.33, amylo-alpha-1,6-glucosidase (one of the activities of the eukaryotic glycogen debranching enzyme). However, while EC 3.2.1.33 removes single glucose residues linked by 1,6-alpha-linkage, and thus requires the additional activity of 4-alpha-glucanotransferase (EC 2.4.1.25) to act on limit dextrins formed by glycogen phosphorylase (EC 2.4.1.1), this enzyme removes maltotriose and maltotetraose chains that are attached by 1,6-alpha-linkage to the limit dextrin main chain, generating a debranched limit dextrin without a need for another enzyme.
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
-
-
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Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
malfunction
metabolism
physiological function
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
amylopectin + H2O
maltose
show the reaction diagram
beta-cyclodextrin-alpha-1,6-linked maltopentaose + H2O
beta-cyclodextrin + maltopentaose
show the reaction diagram
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-
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?
beta-cyclodextrin-alpha-1,6-linked maltotetraose + H2O
beta-cyclodextrin + maltotetraose
show the reaction diagram
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-
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?
beta-cyclodextrin-alpha-1,6-linked maltotriose + H2O
beta-cyclodextrin + maltotriose
show the reaction diagram
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-
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?
G3-beta-cyclodextrin + H2O
?
show the reaction diagram
G4-beta-cyclodextrin + H2O
?
show the reaction diagram
glycogen + H2O
maltose + ?
show the reaction diagram
phosphorylase-limit dextrin
maltodextrin + ?
show the reaction diagram
phosphorylase-limit dextrin + H2O
?
show the reaction diagram
soluble starch + H2O
maltose + ?
show the reaction diagram
additional information
?
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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
phosphorylase-limit dextrin
maltodextrin + ?
show the reaction diagram
phosphorylase-limit dextrin + H2O
?
show the reaction diagram
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.15
beta-cyclodextrin-alpha-1,6-linked maltotetraose
pH 7, 37°C
1.5
beta-cyclodextrin-alpha-1,6-linked maltotriose
pH 7, 37°C
1.51
G3-beta-cyclodextrin
in 50 mM sodium phosphate buffer (pH7.0) at 37°C
0.15
G4-beta-cyclodextrin
in 50 mM sodium phosphate buffer (pH7.0) at 37°C
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
41.7
beta-cyclodextrin-alpha-1,6-linked maltotetraose
Escherichia coli
P15067
pH 7, 37°C
38
beta-cyclodextrin-alpha-1,6-linked maltotriose
Escherichia coli
P15067
pH 7, 37°C
38
G3-beta-cyclodextrin
Escherichia coli
P15067
in 50 mM sodium phosphate buffer (pH7.0) at 37°C
41.7
G4-beta-cyclodextrin
Escherichia coli
P15067
in 50 mM sodium phosphate buffer (pH7.0) at 37°C
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
76000
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x * 76000, His6-tagged enzyme, SDS-PAGE
78956
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x * 78956, calculated from amino acid sequence
110000
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4 * 110000, His6-tagged enzyme, SDS-PAGE
417000
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native enzyme, gel filtration
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
homotetramer
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
hanging drop vapor diffusion method, using 0.2 M sodium citrate, 47% (v/v) MPD, 4% (v/v) PEG 3350, and HEPES (pH 8.0) buffer; hanging drop vapor diffusion method, using 0.2 M sodium citrate, 47% (w/v) 2-methyl-2,4-pentanediol, 4% (w/v) PEG 3350, and HEPES (pH 8.0) buffer
to 2.25 A resolution. Structure reveals a monomer consisting of three major domains with high structural similarity to the subunit of TreX, the oligomeric bifunctional glycogen debranching enzyme from Sulfolobus. In the overlapping substrate binding groove, conserved residues Leu270, Asp271, and Pro208 block the cleft, yielding a shorter narrow GlgX cleft compared to that of TreX. Residues 207-213 form a unique helical conformation that is observed in both GlgX and TreX, possibly distinguishing GDEs from isoamylases and pullulanases
TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
95
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the His6-tagged enzyme is inactivated by incubation at 95°C for 10 min
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
HisTrap column chromatography and Superdex 200 gel filtration
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Ni-NTA agarose column chromatography
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Ni-NTA column chromatography and Superdex 200 gel filtration; Ni-NTA column chromatography and Superdex 200 gel filtration
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expressed in Escherichia coli BL21AI cells
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expressed in Escherichia coli ER2566 cells
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expressed in Escherichia coli MC1061 cells; expressed in Escherichia coli MC1061 cells
expressed in the glgX mutant of Synechocystis elongatus PCC 7942
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EXPRESSION
ORGANISM
UNIPROT
LITERATURE
maximum gene transcription is observed after 5 min of incubation with seed exudates (50.29fold) whereas in the presence of naringenin a 2.88fold increase is observed after 8 h of incubation