1.2.5.1: pyruvate dehydrogenase (quinone)
This is an abbreviated version!
For detailed information about pyruvate dehydrogenase (quinone), go to the full flat file.
Word Map on EC 1.2.5.1
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1.2.5.1
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corynebacterium
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glutamicum
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flavoprotein
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fed-batch
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thiamin
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acetohydroxyacid
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transaminase
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volumetric
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2-ketoisovalerate
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isomeroreductase
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l-valine
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ilvbncd
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dihydroxyacid
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l-lactate
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transhydrogenase
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pta-acka
- 1.2.5.1
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corynebacterium
- glutamicum
- flavoprotein
-
fed-batch
- thiamin
-
acetohydroxyacid
- transaminase
-
volumetric
- 2-ketoisovalerate
-
isomeroreductase
- l-valine
-
ilvbncd
-
dihydroxyacid
- l-lactate
-
transhydrogenase
-
pta-acka
Reaction
Synonyms
EC 1.2.2.2, ECPOX, POX, poxB, POXEC, pqo, pyruvate (quinone) dehydrogenase, pyruvate oxidase, pyruvate oxidase B, pyruvate:quinone oxidoreductase, pyruvate:ubiquinone-8-oxidoreductase, ubiquinione-dependent pyruvate oxidase, ubiquinone-dependent pyruvate oxidase
ECTree
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KM Value
KM Value on EC 1.2.5.1 - pyruvate dehydrogenase (quinone)
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additional information
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the rate of decarboxylation of pyruvate to form CO2, and hydroxyethylthiamine diphosphate for both activated and unactivated forms of the enzyme is identical within experimental error. The pseudo-first order rate constant for the decarboxylation step is 60-80 per s. The pseudo-first order rate of oxidation of hydroxyethylthiamine diphosphate and concomitant enzyme-bound flavin reduction with unactivated enzyme is 2.85 per s and increases 145fold for lipid-activated enzyme to 413 per s and 61fold for the proteolytically activated enzyme to 173 per s. The rate of oxidation of enzyme-FADH is very fast for both unactivated and activated enzyme, being 1041 per s and 645 per s, respectively. The FAD reduction step is the rate-limiting step in the overall reaction for unactivated enzyme. Alternatively, the rate-limiting step in the overall reaction with the activated enzyme shifts to one of the partial steps in the decarboxylation reaction
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additional information
additional information
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the unactivated form of enzyme is markedly hysteretic. At low substrate concentration, there is an initial acceleration in enzyme turnover due to slow interconversion between two forms of the enzyme, one with low turnover and one which rapidly turns over. During turnover, even in the absence of lipid activators, some of the enzyme converts to the rapid-turnover form. This slow interconversion precludes a steady state from being established. Lipid activators shift the equilibrium to favor the rapid turnover form of the enzyme. Once the enzyme is locked into an activated conformation, the hysteresis is no longer observed. Activation results in both increased rates of electron transfer into and out of the flavin
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