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pyruvate decarboxylase : ウィキペディア英語版 | pyruvate decarboxylase
Pyruvate decarboxylase is a homotetrameric enzyme () that catalyses the decarboxylation of pyruvic acid to acetaldehyde and carbon dioxide in the cytoplasm of prokaryotes, and in the cytoplasm and mitochondria of eukaryotes. It is also called 2-oxo-acid carboxylase, alpha-ketoacid carboxylase, and pyruvic decarboxylase. In anaerobic conditions, this enzyme is part of the fermentation process that occurs in yeast, especially of the ''Saccharomyces'' genus, to produce ethanol by fermentation. Pyruvate decarboxylase starts this process by converting pyruvate into acetaldehyde and carbon dioxide. Pyruvate decarboxylase depends on cofactors thiamine pyrophosphate (TPP) and magnesium. This enzyme should not be mistaken for the unrelated enzyme pyruvate dehydrogenase, an oxidoreductase (), that catalyzes the oxidative decarboxylation of pyruvate to acetyl-CoA. == Yeast ==
In yeast, pyruvate decarboxylase acts independently during anaerobic fermentation and releases the 2-carbon fragment as acetaldehyde plus carbon dioxide. Pyruvate decarboxylase creates the means of CO2 elimination, which the cell dispels. The enzyme is also means to create ethanol, which is used as an antibiotic to eliminate competing organisms.〔; 〕 The enzyme is necessary to help the decarboxylation of alpha-keto acids because there is a build-up of negative charge that occurs on the carbonyl carbon atom in the transition state; therefore, the enzyme provides the suitable environment for TPP and the alpha-keto acid (pyruvate) to meet.〔
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