Information on EC 1.14.99.55 - lytic starch monooxygenase

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
1.14.99.55
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RECOMMENDED NAME
GeneOntology No.
lytic starch monooxygenase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
starch + reduced acceptor + O2 = D-glucono-1,5-lactone-terminated malto-oligosaccharides + short-chain malto-oligosaccharides + acceptor + H2O
show the reaction diagram
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SYSTEMATIC NAME
IUBMB Comments
starch, hydrogen-donor:oxygen oxidoreductase (D-glucosyl C1-hydroxylating)
The enzyme cleaves starch in an oxidative manner. It releases fragments of starch with a D-glucono-1,5-lactone at the reducing end. The initially formed alpha-D-glucono-1,5-lactone at the reducing end of the shortend amylose chain quickly hydrolyses spontaneously to the aldonic acid. In vitro ascorbate has been found to be able to serve as reducing agent. The enzyme contains copper at the active site.
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
physiological function
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enzyme acts in synergy with glycoside hydrolase, beta-amylase, largely enhancing maltose release from retrograded starch by beta-amylase. The largest enhancements are obtained under specific conditions using the reducing cofactor cysteine, the presence of LPMO enhances the release of maltose by beta-amylase by 100fold
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
amylopectin + ascorbic acid + O2
malto-aldonic acids + dehydroascorbate
show the reaction diagram
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-
?
starch + AH2 + O2
aldonic acid-terminated malto-oligosaccharides + A + H2O
show the reaction diagram
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?
starch + cysteine + O2
malto-oligosaccharide aldonic acid + cystine + H2O
show the reaction diagram
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C1-oxidized maltooligosaccharides with a degree of polymerization from DP5 to DP13, unmodified oligosaccharide species are not observed
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?
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
amylopectin + ascorbic acid + O2
malto-aldonic acids + dehydroascorbate
show the reaction diagram
Q7SCE9
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-
?
starch + AH2 + O2
aldonic acid-terminated malto-oligosaccharides + A + H2O
show the reaction diagram
Q7SCE9
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?
COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
additional information
cellobiose dehydrogenase may serve as the physiologic electron donor. In the presence of cellobiose dehydrogenase and cellobiose the enzyme activity is comparable to that with excess ascorbate.
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
amylose
beta-cyclodextrin
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
cellobiose dehydrogenase
cellobiose dehydrogenase may serve as the physiologic electron donor. In the presence of cellobiose dehydrogenase and cellobiose the enzyme activity is comparable to that with excess ascorbate.
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
30860
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calculated from amino acid sequence
41000
calculated from amino acid sequence
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
POSTTRANSLATIONAL MODIFICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
methylation
the enzyme contains a methylated N-terminal histidine
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
homology modeling of structure
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crystals grown in areservoir containing 0.14 M calcium chloride, 0.07 M sodium acetate, pH 4.6, 14% v/v isopropanol and 30% v/v glycerol
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structure with an ordered zinc-bound active site, at 1.65 A resolution, and three structures from crystals soaked with maltooligosaccharides in solutions devoid of zinc ions, at resolutions of up to 1.10 A
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TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
70
melting temperature
70.9
melting temperature
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
amylose resin column, followed by a size exclusion column
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expression in Pichia pastoris
EXPRESSION
ORGANISM
UNIPROT
LITERATURE
LPMO13A and LPMO13B are among the most abundant proteins in the culture supernatants upon growth on starches, concomitant with secretion of several redoxactive enzymes; LPMO13A and LPMO13B are among the most abundant proteins in the culture supernatants upon growth on starches, concommitant with secretion of several redoxactive enzymes