Information on EC 5.1.3.30 - D-psicose 3-epimerase

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
5.1.3.30
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RECOMMENDED NAME
GeneOntology No.
D-psicose 3-epimerase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
D-psicose = D-fructose
show the reaction diagram
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SYSTEMATIC NAME
IUBMB Comments
D-psicose 3-epimerase
The enzyme is highly specific for D-psicose and shows very low activity with D-tagatose (cf. EC 5.1.3.31, D-tagatose 3-epimerase). The enzyme from the bacterium Clostridium scindens requires Mn2+ [1], whereas the enzymes from the bacteria Clostridium cellulolyticum [2,5], Clostridium sp. BNL1100 [3], and Clostridium bolteae [4] require Co2+ as optimum cofactor. The enzyme from Ruminococcus sp. [6] is not dependent on the presence of metal ions, but its activity is enhanced by Mn2+.
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
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UniProt
Manually annotated by BRENDA team
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-
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Manually annotated by BRENDA team
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
D-fructose
D-psicose
show the reaction diagram
D-psicose
D-fructose
show the reaction diagram
D-tagatose
D-sorbose
show the reaction diagram
additional information
?
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Fe3+
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at 1 mM increases enzymatic activity by 30%
additional information
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
Cu2+
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leads to protein aggregation and thus drastically decreased activity
Ni2+
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leads to protein aggregation and thus drastically decreased activity
Zn2+
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leads to protein aggregation and thus drastically decreased activity
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
40.1 - 549
D-fructose
2 - 227.6
D-psicose
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
55.9 - 63570
D-fructose
40.45 - 1827
D-psicose
kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.275 - 8.72
D-fructose
117
0.84 - 64.5
D-psicose
2077
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5.5 - 8.5
pH 5.5: about 50% of maximal activity, pH 8.5: about 40% of maximal activity
5.5 - 9
pH 5.5: about 66% of maximal activity, pH 9.0: about 65% of maximal activity
TEMPERATURE RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
35 - 70
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35C: about 50% of maximal activity, 70C: about 65% of maximal activity
35 - 75
35C: about 45% of maximal activity, 75C: about 55% of maximal activity
40 - 70
50 - 75
50C: about 50% of maximal activity, 75C: about 70% of maximal activity
50 - 70
50C: about 50% of maximal activity, 70C: about 55% of maximal activity
pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5.02
calculated from sequence
PDB
SCOP
CATH
ORGANISM
UNIPROT
Agrobacterium fabrum (strain C58 / ATCC 33970)
Agrobacterium fabrum (strain C58 / ATCC 33970)
Clostridium cellulolyticum (strain ATCC 35319 / DSM 5812 / JCM 6584 / H10)
Clostridium cellulolyticum (strain ATCC 35319 / DSM 5812 / JCM 6584 / H10)
Clostridium cellulolyticum (strain ATCC 35319 / DSM 5812 / JCM 6584 / H10)
Clostridium cellulolyticum (strain ATCC 35319 / DSM 5812 / JCM 6584 / H10)
Clostridium cellulolyticum (strain ATCC 35319 / DSM 5812 / JCM 6584 / H10)
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
32000
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4 * 32000, SDS-PAGE
33015
4 * 33015, calculated from sequence
33356
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4 * 33356, calculated from sequence
34000
4 * 34000, SDS-PAGE
130000
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gel filtration
132000
139000
gel filtration
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
tetramer
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
sitting drop method. The crystal structure of the apoenzyme and the enzyme in complex with substrates or products (D-psicose, D-fructose, D-tagatose and D-sorbose). From the complex structures of the enzyme with D-psicose and D-fructose, the enzyme has much more interactions with D-psicose than D-fructose by forming more hydrogen bonds between the substrate and the active site residues. Accordingly, based on these ketohexosebound complex structures, a C3-O3 proton-exchange mechanism for the conversion between D-psicose and D-fructose is proposed. These results provide a clear idea for the deprotonation/protonation roles of E150 and E244 in catalysis
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pH STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5.5
4C, 2 h, about 30% loss of activity
728603
6 - 7.5
after incubation at 4 C for 2 h, more than 90% of the residual activity is retained at pH values ranging from of 6.07.5
726795
6 - 9
4C, 2 h, more than 80% of initial activity remains
727229
7.5 - 8
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4C, 2 h, stable
727652
7.5
4C, 2 h, less than 5% loss of activity
728603
8
4C, 2 h, about 10% loss of activity
728603
8.5 - 9
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4C, 2 h, 10% loss of activity
727652
8.5
4C, 2 h, about 10% loss of activity
728603
9
4C, 2 h, about 20% loss of activity
728603
TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
45
in the absence of Co2+, the activity is very stable below 45 C but decreases at temperatures above 50 C with increasing reaction times. When incubated with 0.4 mM Co2+, the half-lives (t1/2) of the enzyme are extended
64.4
apparent melting temperature
65
1 h, about 80% loss of activity
additional information
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the thermostability of the enzyme is enhanced by the addition of Mn2+
GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
Mn2+ improves the structural stability during both heat- and urea-induced unfolding
the enzyme is extremely thermostable in the presence of Co2+ but readily inactivated without metal ion
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ORGANIC SOLVENT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
Ni-affinity chromatography
nickel-affinity chromatography
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expressed in Escherichia coli
expressed with a C-terminal 6His-tag in Escherichia coli
expression in Escherichia coli
APPLICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
synthesis