Everything about Pyruvate totally explained
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Pyruvic acid (CH
3COCO
2H) is an
alpha-keto acid. Pyruvate plays an important role in biochemical processes. The
carboxylate anion of pyruvic acid is known as
pyruvate.
Chemistry
Pyruvic acid is a colorless liquid with a smell similar to that of
acetic acid. It is
miscible with water, and soluble in
ethanol and
diethyl ether. In the laboratory, pyruvic acid may be prepared by heating a mixture of
tartaric acid and
potassium hydrogen sulfate, or by the hydrolysis of
acetyl cyanide, formed by reaction of
acetyl chloride with
potassium cyanide:
» CH
3COCl + KCN → CH
3COCN
CH
3COCN → CH
3COCOOH
Biochemistry
Pyruvate is an important
chemical compound in
biochemistry. It is the output of the aerobic metabolism of
glucose known as
glycolysis. One molecule of
glucose breaks down into two molecules of pyruvate, which are then used to provide further energy, in one of two ways. Pyruvate is converted into
acetyl-coenzyme A, which is the main input for a series of reactions known as the
Krebs cycle. Pyruvate is also converted to
oxaloacetate by an
anaplerotic reaction which replenishes Krebs cycle intermediates; alternatively, the oxaloacetate is used for
gluconeogenesis. These reactions are named after
Hans Adolf Krebs, the biochemist awarded the 1953
Nobel Prize for physiology, jointly with
Fritz Lipmann, for research into metabolic processes. The cycle is also called the
citric acid cycle, because citric acid is one of the intermediate compounds formed during the reactions.
If insufficient oxygen is available, the acid is broken down
anaerobically, creating
lactic acid in animals and
ethanol in plants. Pyruvate from glycolysis is converted by
anaerobic respiration to
lactate using the
enzyme lactate dehydrogenase and the
coenzyme NADH in lactate
fermentation, or to
acetaldehyde and then to ethanol in alcoholic fermentation.
Pyruvate is a key intersection in the network of
metabolic pathways. Pyruvate can be converted to
carbohydrates via
gluconeogenesis, to
fatty acids or energy through
acetyl-CoA, to the
amino acid alanine and to
ethanol. Therefore it unites several key metabolic processes.
The pyruvic acid derivative
bromopyruvic acid is being studied for potential cancer treatment applications by researchers at
Johns Hopkins University in ways that would support the
Warburg hypothesis on the cause(s) of cancer.
Pyruvate production by glycolysis
In
glycolysis,
phosphoenolpyruvate (PEP) is converted to pyruvate by
pyruvate kinase. This reaction is strongly exergonic and irreversible; in
gluconeogenesis it takes two enzymes,
pyruvate carboxylase and
PEP carboxykinase to catalyze the reverse transformation of pyruvate to PEP. The arrow indicating a reverse reaction in the Figure below is incorrect.
Pyruvate decarboxylation to acetyl CoA
Pyruvate decarboxylation by the
pyruvate dehydrogenase complex produces
acetyl-CoA.
Pyruvate carboxylation to oxaloacetate
Carboxylation by the
pyruvate carboxylase produces
oxaloacetate.
Transamination by the alanine aminotransferase
Reduction to lactate
Reduction by the
lactate dehydrogenase produces
lactate.
Origin of life
Current evolutionary theory on the
origin of life posits that the first organisms were anaerobic because the atmosphere of prebiotic Earth was almost devoid of oxygen. As such, requisite biochemical materials must have preceded life and recent experiments indicate that pyruvate can be synthesized
abiotically. In vitro,
iron sulfide at sufficient pressure and temperature
catalyzes the formation of pyruvate. Thus, argues
Günter Wächtershäuser, the mixing of iron-rich crust with hydrothermal vent fluid is suspected of providing the fertile basis for the formation of life.
Further Information
Get more info on 'Pyruvate'.
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