Information on EC 3.2.1.B36 - maltose-forming alpha-amylase

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
3.2.1.B36
preliminary BRENDA-supplied EC number
RECOMMENDED NAME
GeneOntology No.
maltose-forming alpha-amylase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
An exo-type maltose-forming alpha-amylase alpha-1,4- and alpha-1,6-glucan hydrolytic activity. It acts on the non-reducing end of the substrate and requires at least a G2 unit at its working site
show the reaction diagram
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ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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UniProt
Manually annotated by BRENDA team
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UniProt
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
evolution
additional information
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
4-nitrophenyl alpha-D-maltohexaoside + H2O
4-nitrophenyl alpha-D-maltotetraoside + maltose
show the reaction diagram
at an early stage of the reaction only maltose and 4-nitrophenol alpha-D-maltotetraoside, but not maltotetraose are observed. Even as the reaction proceeded, maltotetraose does not appear at all
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?
6-O-maltosyl-beta-cyclodextrin + H2O
maltose + beta-cyclodextrin
show the reaction diagram
6-O-maltotetraosyl-beta-cyclodextrin + H2O
2 maltose + beta-cyclodextrin
show the reaction diagram
amylopectin + H2O
maltose + ?
show the reaction diagram
the enzyme only released maltose from polymers such as soluble starch, amylopectin, and glycogen, while maltose is rarely detected from reaction with amylose and pullulan
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?
glycogen + H2O
maltose + ?
show the reaction diagram
the enzyme only released maltose from polymers such as soluble starch, amylopectin, and glycogen, while maltose is rarely detected from reaction with amylose and pullulan
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?
maltopentaose + H2O
2 maltose + D-glucose
show the reaction diagram
maltotetraose + H2O
2 maltose
show the reaction diagram
maltotriose + H2O
maltose + D-glucose
show the reaction diagram
soluble starch + H2O
maltose + ?
show the reaction diagram
the enzyme only released maltose from polymers such as soluble starch, amylopectin, and glycogen, while maltose is rarely detected from reaction with amylose and pullulan
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?
additional information
?
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
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no metal ions
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.3 - 0.7
6-O-maltotetraosyl-beta-cyclodextrin
16.2 - 21.2
maltopentaose
18.2 - 18.8
maltotetraose
4.25 - 8.4
maltotriose
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
25.75 - 30.1
6-O-maltotetraosyl-beta-cyclodextrin
0.0017 - 3.85
maltopentaose
0.0033 - 3.95
maltotetraose
6.35 - 11.45
maltotriose
kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
42.8 - 85.8
6-O-maltotetraosyl-beta-cyclodextrin
42665
0.000078 - 0.24
maltopentaose
272
0.00018 - 0.22
maltotetraose
269
0.76 - 2.7
maltotriose
188
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
6
alpha-1,6-glycosidic linkage hydrolysis
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
4 - 8
pH 4.0: about 50% of maximal activity, pH 8.0: about 70% of maximal activity, alpha-1,6-glycosidic linkage hydrolysis of 6-O-maltotetraosyl-beta-cyclodextrin
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
85
alpha-1,4-glycosidic linkage hydrolysis
90
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assay at
90 - 95
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98
alpha-1,6-glycosidic linkage hydrolysis
TEMPERATURE RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
60 - 95
60°C; about 50% of maximal activity, 60°C: about 60% of maximal activity, alpha-1,4-glycosidic linkage hydrolysis of maltotriose
70
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about 55% of maximal activity
80 - 98
activity at 80°C is about 50% compared to the activity at 98°C, alpha-1,6-glycosidic linkage hydrolysis of 6-O-maltotetraosyl-beta-cyclodextrin
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
70191
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2 * 70191, recombinant enzyme, SDS-PAGE, in the dimeric structure, extensive interactions including Asn185-Gly327, Glu224-Lys241 and Gly327-Asn185 hydrogen bonds and a Glu224-Lys241 salt bridge between two (beta/alpha)7-barrels of the N-domains comprise the dimer associations
260000
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
homotetramer
monomer
additional information
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
purified recombinant selenomethionine-labeled wild-type enzyme, sitting drop vapour diffusion method, mixing of 0.001 ml of 15 mg/ml protein solution with 0.001 ml of reservoir solution consisting of 1.0 M ammonium citrate dibasic, 0.8 M sodium acetate trihydrate pH 4.6, 18°C, X-ray diffraction structure determination and analysis at 1..8 A resolution
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TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
67
melting temperature at pH 4.0
75
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half-life: 254 min
91
melting temperature at pH 5.0
105
melting temperature at pH 6.0
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
recombinant wild-type and mutant enzymes from Escherichia coli strain BL21-CodonPlus(DE3)-RP
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expressed the gene in Escherichia coli
recombinant expression of selenomethionine-labeled wild-type and mutant enzymes in Escherichia coli strain BL21-CodonPlus(DE3)-RP
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
D253N
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site-directed mutagenesis, the mutant shows reduced alpha-1,4- and alpha1,6-hydrolytic activity compared to the wild-type enzyme
E153Q
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site-directed mutagenesis, the mutant shows reduced alpha-1,4- and alpha1,6-hydrolytic activity compared to the wild-type enzyme
E580Q
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site-directed mutagenesis, the mutant shows reduced alpha-1,4- and alpha1,6-hydrolytic activity compared to the wild-type enzyme
F218A
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site-directed mutagenesis, the mutant exhibits 3.5fold icreased alpha-1,4-glucosidic bond hydrolysis compared to the wild-type enzyme
F452A
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site-directed mutagenesis, the mutant shows reduced alpha-1,4- and alpha1,6-hydrolytic activity compared to the wild-type enzyme
W453A
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site-directed mutagenesis, the mutant shows reduced alpha-1,4- and alpha1,6-hydrolytic activity compared to the wild-type enzyme
D253N
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site-directed mutagenesis, the mutant shows reduced alpha-1,4- and alpha1,6-hydrolytic activity compared to the wild-type enzyme
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