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Information on EC 1.1.99.35 - soluble quinoprotein glucose dehydrogenase
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1.1.99.35 soluble quinoprotein glucose dehydrogenaseIUBMB Comments
Soluble periplasmic enzyme containing PQQ as prosthetic group, bound to a calcium ion. Electron acceptor is not known. It is assayed with Wurster's Blue or phenazine methosulfate. It has negligible sequence or structure similarity to other quinoproteins. It catalyses an exceptionally high rate of oxidation of a wide range of aldose sugars, including D-glucose, galactose, arabinose and xylose, and also the disaccharides lactose, cellobiose and maltose. It has been described only in Acinetobacter calcoaceticus.
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Word Map
- 1.1.99.35
- calcoaceticus
-
acinetobacter
- aldose
- pqqh2
-
electrodes
-
pqq-containing
-
tautomerization
-
hydride
-
pqq-dependent
- synthesis
-
stopped-flow
-
beta-anomer
- biofuel production
-
half-reaction
- gluconolactone
- disaccharide
-
electrochemical
-
beta-strands
- energy production
- diagnostics
- biotechnology
The enzyme appears in viruses and cellular organisms
Synonyms
soluble quinoprotein glucose dehydrogenase, soluble pqq-glucose dehydrogenase, soluble pqq-gdh, 
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SYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
2,7,9-tricarboxypyrroloquinoline quinone-dependent glucose dehydrogenase
-
-
GCD
GDH
PQQ-GDH
PQQ-sGDH
PQQGDH
pyrroloquinoline quinone-dependent glucose dehydrogenase
s-GDH
sGDH
soluble PQQ-dependent glucose dehydrogenase
soluble pyrroloquinoline quinone-dependent glucose dehydrogenase
soluble pyrroloquinoline quinone-dependent glucose dehydrogenase
-
-
soluble pyrroloquinoline quinone-dependent glucose dehydrogenase
-
-
-
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
D-glucose + acceptor = D-glucono-1,5-lactone + reduced acceptor
-
-
-
-
D-glucose + acceptor = D-glucono-1,5-lactone + reduced acceptor
ping-pong behaviour and double-substrate inhibition
-
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SYSTEMATIC NAME
IUBMB Comments
D-glucose:acceptor oxidoreductase
Soluble periplasmic enzyme containing PQQ as prosthetic group, bound to a calcium ion. Electron acceptor is not known. It is assayed with Wurster's Blue or phenazine methosulfate. It has negligible sequence or structure similarity to other quinoproteins. It catalyses an exceptionally high rate of oxidation of a wide range of aldose sugars, including D-glucose, galactose, arabinose and xylose, and also the disaccharides lactose, cellobiose and maltose. It has been described only in Acinetobacter calcoaceticus.
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
2-deoxy-D-glucose + oxidized 2,6-dichlorophenolindophenol
2-deoxy-D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
3-O-methyl-D-glucose + oxidized 2,6-dichlorophenolindophenol
3-O-methyl-D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
cellobiose + N-methylphenazonium methylsulfate
cellobiono-1,5-lactone + reduced N-methylphenazonium methylsulfate
-
-
-
-
?
cellobiose + oxidized 2,6-dichlorophenolindophenol
? + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-allose + N-methylphenazonium methylsulfate
D-allono-1,5-lactone + reduced N-methylphenazonium methylsulfate
-
-
-
-
?
D-allose + oxidized 2,6-dichlorophenolindophenol
D-allono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
D-fucose + oxidized 2,6-dichlorophenolindophenol
D-fucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-galactose + N-methylphenazonium methylsulfate
D-galactono-1,5-lactone + reduced N-methylphenazonium methylsulfate
-
30% activity compared to D-glucose
-
-
?
D-galactose + oxidized 2,6-dichlorophenolindophenol
D-galactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
D-galactose + oxidized N-methylphenazonium methyl sulfate
D-galactono-1,5-lactone + reduced N-methylphenazonium methyl sulfate
-
-
-
-
?
D-glucose + 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
D-glucose + dimethyl((6-methyl-7-((4-nitrosophenyl)amino)-1H-imidazo[1,2-b]pyrazol-1-yl)methyl)phosphine oxide
D-glucono-1,5-lactone + reduced dimethyl((6-methyl-7-((4-nitrosophenyl)amino)-1H-imidazo[1,2-b]pyrazol-1-yl)methyl)phosphine oxide
-
-
-
?
D-glucose + N-methylphenazonium methylsulfate
D-glucono-1,5-lactone + reduced N-methylphenazonium methylsulfate
-
100% activity
-
-
?
D-glucose + osmium polymer
D-glucono-1,5-lactone + reduced osmium polymer
-
-
-
-
?
D-glucose + oxidized 2,6-dichlorophenol-indophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenol-indophenol
-
-
-
-
?
D-glucose + oxidized 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
D-glucose + oxidized N-methylphenazonium methyl sulfate
D-glucono-1,5-lactone + reduced N-methylphenazonium methyl sulfate
-
-
-
-
?
D-lyxose + N-methylphenazonium methylsulfate
D-lyxono-1,5-lactone + reduced N-methylphenazonium methylsulfate
-
-
-
-
?
D-lyxose + oxidized 2,6-dichlorophenolindophenol
D-lyxono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-mannose + N-methylphenazonium methylsulfate
D-mannono-1,5-lactone + reduced N-methylphenazonium methylsulfate
-
-
-
-
?
D-mannose + oxidized 2,6-dichlorophenolindophenol
D-mannono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
D-ribose + N-methylphenazonium methylsulfate
D-ribono-1,5-lactone + reduced N-methylphenazonium methylsulfate
-
5% activity compared to D-glucose
-
-
?
D-ribose + oxidized 2,6-dichlorophenolindophenol
? + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-xylose + N-methylphenazonium methylsulfate
D-xylono-1,5-lactone + reduced N-methylphenazonium methylsulfate
-
14% activity compared to D-glucose
-
-
?
D-xylose + oxidized 2,6-dichlorophenolindophenol
D-xylono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
D-xylose + oxidized N-methylphenazonium methyl sulfate
D-xylono-1,5-lactone + reduced N-methylphenazonium methyl sulfate
-
-
-
-
?
L-arabinose + N-methylphenazonium methylsulfate
L-arabinono-1,5-lactone + reduced N-methylphenazonium methylsulfate
-
-
-
-
?
L-arabinose + oxidized 2,6-dichlorophenolindophenol
L-arabinono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
lactose + 1-(N,N-dimethylamine)-4-(4-morpholine)benzene
lactono-1,5-lactone + reduced 1-(N,N-dimethylamine)-4-(4-morpholine)benzene
-
-
-
?
lactose + N,N'-dimethyl-4,4'-azopyridinium methyl sulfate
lactono-1,5-lactone + reduced N,N'-dimethyl-4,4'-azopyridinium methyl sulfate
-
-
-
?
lactose + N-methylphenazonium methylsulfate
lactono-1,5-lactone + reduced N-methylphenazonium methylsulfate
-
4% activity compared to D-glucose
-
-
?
lactose + oxidized 2,6-dichlorophenol-indophenol
? + reduced 2,6-dichlorophenol-indophenol
-
-
-
-
?
lactose + oxidized 2,6-dichlorophenolindophenol
lactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
lactose + oxidized N-methylphenazonium methyl sulfate
4-O-beta-D-galactopyranosyl-D-glucono-1,5-lactone + reduced N-methylphenazonium methyl sulfate
-
-
-
-
?
maltose + acceptor
maltono-1,5-lactone + reduced acceptor
-
-
-
?
maltose + N-methylphenazonium methylsulfate
maltono-1,5-lactone + reduced N-methylphenazonium methylsulfate
-
12% activity compared to D-glucose
-
-
?
maltose + oxidized 2,6-dichlorophenolindophenol
maltono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
melibiose + N-methylphenazonium methylsulfate
melibiono-1,5-lactone + reduced N-methylphenazonium methylsulfate
-
5% activity compared to D-glucose
-
-
?
melibiose + oxidized 2,6-dichlorophenolindophenol
? + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
2-deoxy-D-glucose + oxidized 2,6-dichlorophenolindophenol
2-deoxy-D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
2-deoxy-D-glucose + oxidized 2,6-dichlorophenolindophenol
2-deoxy-D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
4% of the activity with D-glucose
-
-
?
3-O-methyl-D-glucose + oxidized 2,6-dichlorophenolindophenol
3-O-methyl-D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
3-O-methyl-D-glucose + oxidized 2,6-dichlorophenolindophenol
3-O-methyl-D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
81% of the activity with D-glucose
-
-
?
D-allose + oxidized 2,6-dichlorophenolindophenol
D-allono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-allose + oxidized 2,6-dichlorophenolindophenol
D-allono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
47% of the activity with D-glucose
-
-
?
D-galactose + oxidized 2,6-dichlorophenolindophenol
D-galactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-galactose + oxidized 2,6-dichlorophenolindophenol
D-galactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
11% of the activity with D-glucose
-
-
?
D-galactose + oxidized 2,6-dichlorophenolindophenol
D-galactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
about 13% activity compared to D-glucose
-
-
?
D-galactose + oxidized 2,6-dichlorophenolindophenol
D-galactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
about 13% activity compared to D-glucose
-
-
?
D-glucose + 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-glucose + 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-glucose + 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-glucose + 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-glucose + acceptor
D-glucono-1,5-lactone + reduced acceptor
-
-
-
-
?
D-glucose + acceptor
D-glucono-1,5-lactone + reduced acceptor
-
-
-
?
D-glucose + oxidized 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-glucose + oxidized 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
?
D-glucose + oxidized 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
100% activity
-
-
?
D-glucose + oxidized 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
100% activity
-
-
?
D-glucose + phenazine methosulfate
D-glucono-1,5-lactone + reduced phenazine methosulfate
-
-
-
-
?
D-glucose + phenazine methosulfate
D-glucono-1,5-lactone + reduced phenazine methosulfate
-
-
-
-
?
D-glucose + phenazine methosulfate
D-glucono-1,5-lactone + reduced phenazine methosulfate
-
-
-
-
?
D-glucose + phenazine methosulfate
D-glucono-1,5-lactone + reduced phenazine methosulfate
-
-
-
-
?
D-mannose + oxidized 2,6-dichlorophenolindophenol
D-mannono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-mannose + oxidized 2,6-dichlorophenolindophenol
D-mannono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
13% of the activity with D-glucose
-
-
?
D-mannose + oxidized 2,6-dichlorophenolindophenol
D-mannono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
about 11% activity compared to D-glucose
-
-
?
D-xylose + oxidized 2,6-dichlorophenolindophenol
D-xylono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
D-xylose + oxidized 2,6-dichlorophenolindophenol
D-xylono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
7% of the activity with D-glucose
-
-
?
D-xylose + oxidized 2,6-dichlorophenolindophenol
D-xylono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
about 9% activity compared to D-glucose
-
-
?
lactose + oxidized 2,6-dichlorophenolindophenol
? + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
lactose + oxidized 2,6-dichlorophenolindophenol
? + reduced 2,6-dichlorophenolindophenol
-
61% of the activity with D-glucose
-
-
?
lactose + oxidized 2,6-dichlorophenolindophenol
lactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
lactose + oxidized 2,6-dichlorophenolindophenol
lactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
61% of the activity with D-glucose
-
-
?
lactose + oxidized 2,6-dichlorophenolindophenol
lactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
about 50% activity compared to D-glucose
-
-
?
maltose + oxidized 2,6-dichlorophenolindophenol
? + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
maltose + oxidized 2,6-dichlorophenolindophenol
? + reduced 2,6-dichlorophenolindophenol
-
61% of the activity with D-glucose
-
-
?
maltose + oxidized 2,6-dichlorophenolindophenol
maltono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
-
?
maltose + oxidized 2,6-dichlorophenolindophenol
maltono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
61% of the activity with D-glucose
-
-
?
maltose + oxidized 2,6-dichlorophenolindophenol
maltono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
about 70% activity compared to D-glucose
-
-
?
additional information
?
-
-
kinetic mechanism of sGDH consists of (a) step(s) in which a fluorescing intermediate is formed, and a subsequent, irreversible step, determining the overall rate of the reductive half-reaction. The pH optimum determined for glucose oxidation appears to be 7.0, implying that reoxidation of sGDHred is rate-limiting with those electron acceptors displaying a different value under steady-state conditions.
-
-
?
additional information
?
-
-
mechanism comprises general base-catalyzed hydride transfer
-
-
?
additional information
?
-
-
the sequential steps in the mechanism of sGDH must be reversible substrate binding, direct transfer of a hydride ion (reversible or irreversible) from the C1 position of the beta-anomer of glucose to the C5 of PQQ, irreversible, rate-determining tautomerization of the fluorescing, C5-reduced PQQ to PQQH2 and release (or earlier) of the product, D-glucono-delta-lactone, and oxidation of PQQH2 by an electron acceptor. The PQQ-activating Ca2+ greatly facilitates the reactions occurring in the second step. His144 may also play a role in this by acting as a general base catalyst, initiating hydride transfer by abstracting a proton from the anomeric OH group of glucose
-
-
?
additional information
?
-
-
almost no activity with D-fructose
-
-
?
additional information
?
-
-
no activity with D-glucosamine, L-altrose, L-lyxose, L-talose, L-mannose, D-altrose, D-arabinose, D-talose, L-xylose, L-glucose, L-galactose, L-allose, sucrose, trehalose, and raffinose
-
-
?
additional information
?
-
-
almost no activity with D-fructose
-
-
?
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NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
D-galactose + oxidized 2,6-dichlorophenolindophenol
D-galactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
D-glucose + oxidized 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
D-mannose + oxidized 2,6-dichlorophenolindophenol
D-mannono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
about 11% activity compared to D-glucose
-
-
?
D-xylose + oxidized 2,6-dichlorophenolindophenol
D-xylono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
about 9% activity compared to D-glucose
-
-
?
lactose + oxidized 2,6-dichlorophenolindophenol
lactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
about 50% activity compared to D-glucose
-
-
?
maltose + oxidized 2,6-dichlorophenolindophenol
maltono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
about 70% activity compared to D-glucose
-
-
?
D-galactose + oxidized 2,6-dichlorophenolindophenol
D-galactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
about 13% activity compared to D-glucose
-
-
?
D-galactose + oxidized 2,6-dichlorophenolindophenol
D-galactono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
about 13% activity compared to D-glucose
-
-
?
D-glucose + acceptor
D-glucono-1,5-lactone + reduced acceptor
-
-
-
-
?
D-glucose + acceptor
D-glucono-1,5-lactone + reduced acceptor
-
-
-
?
D-glucose + oxidized 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
-
-
?
D-glucose + oxidized 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
100% activity
-
-
?
D-glucose + oxidized 2,6-dichlorophenolindophenol
D-glucono-1,5-lactone + reduced 2,6-dichlorophenolindophenol
-
100% activity
-
-
?
additional information
?
-
-
almost no activity with D-fructose
-
-
?
additional information
?
-
-
almost no activity with D-fructose
-
-
?
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
pyrroloquinoline quinone
-
soluble isoform sGDH is able to bind two mol of PQQ in one mol of the homodimer with high affinity. The binding reaction is much faster at alkaline pH than at acidic pH and requires the presence of some divalent cations such as Cd2+, Ca2+, Sr2+, or Mn2+. Membrane-bound isoform mGDH binds one mol of PQQ in the monomeric enzyme with a relatively slow reaction process, which has an optimim at acidic pH and in the presence of divalent cations such as Mg2+, Ca2+, Zn2+, Sr2+. Binding of PQQ affects the conformation of both isoforms
pyrroloquinoline quinone
-
the catalytic potential of the cofactor in the enzyme is not determined by its adduct-forming ability but by whether it is or can be activated with Ca2+
pyrroloquinoline quinone
reconstitution mechanism of the enzyme (sGDH) with its two cofactors, i.e., pyrroloquinoline quinone (PQQ) and Ca2+: pyrroloquinoline quinone first binds to apo-sGDH, it strongly impedes the access of Ca2+ to its enclosed position at the bottom of the enzyme binding site, thereby greatly slowing down the reconstitution rate of sGDH. The slow calcium insertion may purposely be accelerated by providing more flexibility to the Ca2+ binding loop through the specific mutation of the calcium-coordinating P248 proline residue, reducing thus the kinetic barrier to calcium ion insertion
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Ca2+
Cd2+
-
or Ca2+, Sr2+, or Mn2+, required for binding of cofactor PQQ in soluble isoform sGDH. Mg2+, or Ca2+, Zn2+, or Sr2+, required for binding of cofactor PQQ in membrane-bound isoform mGDH
Mg2+
-
or Ca2+, Zn2+, or Sr2+, required for binding of cofactor PQQ in membrane-bound isoform mGDH. With Mg2+, 115% of the activity with Ca2+
Mn2+
-
or Ca2+, Sr2+, or Cd2+, required for binding of cofactor PQQ in soluble isoform sGDH. Mg2+, or Ca2+, Zn2+, or Sr2+, required for binding of cofactor PQQ in membrane-bound isoform mGDH
Sr2+
Ca2+
-
or Cd2+, Sr2+, or Mn2+, required for binding of cofactor PQQ in soluble isoform sGDH, 100% activity with Ca2+. Mg2+, or Ca2+, Zn2+, or Sr2+, required for binding of cofactor PQQ in membrane-bound isoform mGDH. 100% activity with Ca2+
Ca2+
-
study on interconversions of different enzyme species from monomeric apoenzyme to fully reconstituted enzyme, e.g. consisting of dimer with one firmly bound Ca2+ ion, dimer with two PQQ and two extra Ca2+ ions, or substitutes for Ca2+. Dimers consisting of two monomers with one firmly bound Ca2+ ion and dimers consisting of two monomers with one firmly bound Ca2+ ion and with two PQQ and two extra Ca2+ ions are very stable enzyme species regarding monomerization and inactivation by chelator, respectively, the bound Ca2+ being locked up in such a way that it is not accessible to chelator. The two Ca2+ ions required for activation of dimers consisting of two monomers with one firmly bound Ca2+ ion and with two PQQ, are even more firmly bound than the two required for dimerization of monomers and anchoring of PQQ
Ca2+
-
substituting the Ca2+ involved in activation of pyrroloquinoline quinone in soluble GDH by Sr2+ affects the cooperativity effect but not the two turnover rates of the hybrid enzyme for glucose
Ca2+
the enzyme binds three calcium ions per monomer, two of which are located in the dimer interface, crystallization data
Ca2+
calcium is essential for dimerization and PQQ binding
Ca2+
reconstitution mechanism of the enzyme (sGDH) with its two cofactors, i.e., pyrroloquinoline quinone (PQQ) and Ca2+: pyrroloquinoline quinone first binds to apo-sGDH, it strongly impedes the access of Ca2+ to its enclosed position at the bottom of the enzyme binding site, thereby greatly slowing down the reconstitution rate of sGDH. The slow calcium insertion may purposely be accelerated by providing more flexibility to the Ca2+ binding loop through the specific mutation of the calcium-coordinating P248 proline residue, reducing thus the kinetic barrier to calcium ion insertion
Ca2+
the holoenzyme is reconstituted by incubating the apoenzyme in 5 mM MES buffer at pH 6.5 with 1 mM CaCl2 and 0.060 mM pyrroloquinoline quinone for 3 h at room temperature in the dark
Sr2+
-
or Ca2+, Cd2+, or Mn2+, required for binding of cofactor PQQ in soluble isoform sGDH, with Sr2+, 67% of the activity with Ca2+. Mg2+, or Ca2+, Zn2+, or Sr2+, required for binding of cofactor PQQ in membrane-bound isoform mGDH, with Sr2+, 70% of the activity with Ca2+
Sr2+
-
substituting the Ca2+ involved in activation of pyrroloquinoline quinone in soluble GDH by Sr2+ affects the cooperativity effect but not the two turnover rates of the hybrid enzyme for glucose
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INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
lactose
the inhibition of the enzyme by substrate significantly decreases at pH 8.0
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
additional information
additional information
-
under conditions that avoid its masking by sugar-substrate inhibition as much as possible, negative kinetic cooperativity with respect to sugar substrate oxidation is observed. The cooperativity effect dramatically changes the performance of soluble GDH, as reflected by the V2 and K2 values for glucose in phosphate buffer being about 10-fold and 100-fold higher than the V1 and K1 values, respectively. Substituting the Ca2+ involved in activation of pyrroloquinoline quinone in soluble GDH by Sr2+ affects the cooperativity effect but not the two turnover rates of the hybrid enzyme for glucose
-
2 - 3
3-O-methyl-D-glucose
-
recombinant wild-type with R4-tail, pH 7.0
22
3-O-methyl-D-glucose
-
heterodimer wild-type/mutant H168Q, pH 7.0
0.74
D-glucose
pH and temperature not specified in the publication
17.5
D-glucose
-
recombinant enzyme, expression in Pichia pastoris
25
D-glucose
-
recombinant enzyme, expression in Escherichia coli
0.0014
lactose
electron transfer mediator: 1-(N,N-dimethylamine)-4-(4-morpholine)benzene, pH 8.0, temperature not specified in the publication
0.0018
lactose
electron transfer mediator: 1-(N,N-dimethylamine)-4-(4-morpholine)benzene, pH 7.0, temperature not specified in the publication
0.0019
lactose
electron transfer mediator: N,N'-dimethyl-4,4'-azopyridinium methyl sulfate, pH 8.0, temperature not specified in the publication
0.0023
lactose
electron transfer mediator: N,N'-dimethyl-4,4'-azopyridinium methyl sulfate, pH 7.0, temperature not specified in the publication
18.9
lactose
-
recombinant enzyme, expression in Escherichia coli