Information on EC 4.2.1.110 - aldos-2-ulose dehydratase

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
4.2.1.110
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RECOMMENDED NAME
GeneOntology No.
aldos-2-ulose dehydratase
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
1,5-anhydro-4-deoxy-D-glycero-hex-3-en-2-ulose = 2-hydroxy-2-(hydroxymethyl)-2H-pyran-3(6H)-one
show the reaction diagram
; second of two consecutive reactions
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-
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1,5-anhydro-D-fructose = 1,5-anhydro-4-deoxy-D-glycero-hex-3-en-2-ulose + H2O
show the reaction diagram
; first of two consecutive reactions
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-
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1,5-anhydro-D-fructose = 2-hydroxy-2-(hydroxymethyl)-2H-pyran-3(6H)-one + H2O
show the reaction diagram
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
dehydration
elimination
-
-
isomerization
ascopyrone M (APM) to microthecin
SYSTEMATIC NAME
IUBMB Comments
1,5-anhydro-D-fructose hydro-lyase (microthecin-forming)
This enzyme catalyses two of the steps in the anhydrofructose pathway, which leads to the degradation of glycogen and starch via 1,5-anhydro-D-fructose [1,2]. Aldose-2-uloses such as 2-dehydroglucose can also act as substrates, but more slowly [1,2,4]. This is a bifunctional enzyme that acts as both a lyase and as an isomerase [2]. Differs from EC 4.2.1.111, which can carry out only reaction (1a), is inhibited by its product and requires metal ions for activity [1].
CAS REGISTRY NUMBER
COMMENTARY hide
101920-80-3
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145266-93-9
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ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
Microthecium sobelii
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-
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Manually annotated by BRENDA team
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-
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Manually annotated by BRENDA team
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-
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Manually annotated by BRENDA team
Polyporus obtusus
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-
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Manually annotated by BRENDA team
Polyporus obtusus AU124PD
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-
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Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
malfunction
removal of two zinc ions at the bottom of two putative active-site clefts in the propeller and the cupin domains leads to loss of enzymatic activity, although the structure of the Zn2+-depleted enzyme is very similar to that of native AUDH
physiological function
the bifunctional enzyme aldos-2-ulose dehydratase/isomerase participates in carbohydrate secondary metabolism, catalyzing the conversion of glucosone and 1,5-D-anhydrofructose to the secondary metabolites cortalcerone and microthecin, respectively
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
1,5-anhydro-D-fructose
2-hydroxy-2-(hydroxymethyl)-2H-pyran-3(6H)-one + H2O
show the reaction diagram
1,5-D-anhydrofructose
microthecin
show the reaction diagram
dehydration reaction most likely follows an elimination mechanism, where Zn2+ acts as a Lewis acid polarizing the C2 oxo group of 1,5-D-anhydrofructose. The reaction intermediate ascopyrone M shows binding of this compound at two different sites, with direct coordination to Zn2+ in the propeller domain and as second sphere ligand of the metal ion in the cupin domain
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-
?
D-glucosone
cortalcerone + H2O
show the reaction diagram
D-xylosone
?
show the reaction diagram
glucosone
cortalcerone + H2O
show the reaction diagram
additional information
?
-
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
1,5-anhydro-D-fructose
2-hydroxy-2-(hydroxymethyl)-2H-pyran-3(6H)-one + H2O
show the reaction diagram
glucosone
cortalcerone + H2O
show the reaction diagram
P84193
2-keto glucose
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-
?
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Mg2+
the enzyme contains a structural Mg2+ located in loop region, metal binding site and structure, overview
Zn2+
the enzyme contains a structural Zn2+ located in loop regions and two zinc ions at the bottom of two putative active-site clefts in the propeller and the cupin domain, respectively. Catalysis is dependent on these two zinc ions, as their specific removal leads to loss of enzymatic activity, metal binding site and structure, overview
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
1,5-anhydro-4-deoxy-D-glycero-hexo-2,3-diulose dihydrate
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4 mM, 50% inhibition when 1,5-anhydro-D-fructose is used as the substrate at 5 mM and pH 5.8
1,5-Anhydro-D-fructose
substrate inhibition to AUDH at a concentration up to 10% (w/v)
microthecin
product inhibition to AUDH at a concentration up to 10% (w/v)
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
5.4
1,5-Anhydro-D-fructose
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
0.02
Polyporus obtusus
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cleared lysate, at pH 6.0 and 25C
9
Polyporus obtusus
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after 450fold purification, at pH 6.0 and 25C
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5
at a pH lower than 5.0, the reaction rate is slower and there is a tendency for increased formation of degradation products (FHMK), at a pH higher than 5.5, there is a tendency for more APT dihydrate formation
5.8
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formation of 1,5-anhydro-4-deoxy-D-glycero-hex-3-en-2-ulose
6.8
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formation of microthecin
additional information
the reaction medium acidifies by itself due to unknown events related to the AUDH catalysed reaction
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
at a pH lower than 5.0, the reaction rate is slower and there is a tendency for increased formation of degradation products (FHMK), at a pH higher than 5.5, there is a tendency for more APT dihydrate formation
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
24
at temperatures higher than 24C there is increased degradation of microthecin
pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5.2 - 5.3
recombinant enzyme, isoelectric focusing
5.46
sequence calculation
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
95000
Polyporus obtusus
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2 * 95000, SDS-PAGE
97400
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x * 97400, SDS-PAGE
98700
2 * 98700, recombinant enzyme, SDS-PAGE, 2 * 98746, sequence calculation, the AUDH subunit consists of three domains, all of beta-structure: the N-terminal domain with a beta-propeller fold, a middle domain containing two cupin folds and a C-terminal lectin domain
98746
2 * 98700, recombinant enzyme, SDS-PAGE, 2 * 98746, sequence calculation, the AUDH subunit consists of three domains, all of beta-structure: the N-terminal domain with a beta-propeller fold, a middle domain containing two cupin folds and a C-terminal lectin domain
200000
Polyporus obtusus
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gel filtration
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
?
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x * 97400, SDS-PAGE
homodimer
additional information
secondary, quarternary, and overall structure analysis, detailed overview
GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
Microthecin is found to be most stable in de-ionized water at a pH around 7.0 and stable in freeze-dried form. Under acidic conditions microthecin is degraded to 2-furyl-2-hydroxymethylketone (FHMK).
ORGANIC SOLVENT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
the best solvent for AUDH-catalysed microthecin reaction is de-ionized water
STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
4C, purified enzyme in 0.1 M sodium phosphate buffer (pH 7.0), several months, the enzyme remains stable
Polyporus obtusus
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
precipitation with 20% (w/v) PEG 4000, DEAE-Sepharose column chromatography, and carboxymethyl-Sepharose column chromatography
Polyporus obtusus
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
gene Audh; ph.chr, expression in Hansenula polymorpha