Pyruvic acid

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Pyruvic acid
Pyruvic-acid-2D-skeletal.png Pyruvic-acid-3D-balls.png
Identifiers
CAS number 127-17-3 YesY
PubChem 1060
ChemSpider 1031 YesY
UNII 8558G7RUTR YesY
DrugBank DB00119
KEGG C00022 N
ChEBI CHEBI:32816 YesY
ChEMBL CHEMBL1162144 YesY
Jmol-3D images Image 1
Properties
Molecular formula C3H4O3
Molar mass 88.06 g/mol
Density 1.250 g/cm³
Melting point 11.8 °C (53.2 °F; 284.9 K)
Boiling point 165 °C (329 °F; 438 K)
Acidity (pKa) 2.50[1]
Related compounds
Other anions pyruvate ion
ion of pyruvic acid
   Pyruvate-3D-balls.png
Related keto-acids, carboxylic acids acetic acid
glyoxylic acid
oxalic acid
propionic acid
acetoacetic acid
Related compounds propionaldehyde
glyceraldehyde
methylglyoxal
sodium pyruvate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Pyruvic acid (CH3COCOOH) is an organic acid, has a carboxylic acid and a ketone functional group, and is the simplest of the alpha-keto acids. The carboxylate (COO) anion of pyruvic acid, its Brønsted–Lowry conjugate base, CH3COCOO, is known as pyruvate, and is a key intersection in several metabolic pathways.

Pyruvic acid can be made from glucose through glycolysis, converted back to carbohydrates (such as glucose) via gluconeogenesis, or to fatty acids through acetyl-CoA. It can also be used to construct the amino acid alanine and be converted into ethanol.

Pyruvic acid supplies energy to living cells through the citric acid cycle (also known as the Krebs cycle) when oxygen is present (aerobic respiration), and alternatively ferments to produce lactate when oxygen is lacking (fermentation).

Chemistry[edit]

In 1834, Théophile-Jules Pelouze distilled both tartaric acid (L-tartaric acid) and racemic acid (a mix of D- and L-tartaric acid) and isolated pyrotartaric acid (methyl succinic acid[2]) and another acid that Jöns Jacob Berzelius characterized the following year and named pyruvic acid.[3] Pyruvic acid is a colorless liquid with a smell similar to that of acetic acid and is miscible with water. In the laboratory, pyruvic acid may be prepared by heating a mixture of tartaric acid and potassium hydrogen sulfate,[4] by the oxidation of propylene glycol by a strong oxidizer (e.g., potassium permanganate or bleach), or by the hydrolysis of acetyl cyanide, formed by reaction of acetyl chloride with potassium cyanide:

CH3COCl + KCN → CH3COCN + KCl
CH3COCN → CH3COCOOH

Biochemistry[edit]

Pyruvate is an important chemical compound in biochemistry. It is the output of the metabolism of glucose known as glycolysis.[5] One molecule of glucose breaks down into two molecules of pyruvate,[5] 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 (also known as the Citric Acid Cycle or Tricarboxylic Acid Cycle). Pyruvate is also converted to oxaloacetate by an anaplerotic reaction, which replenishes Krebs cycle intermediates; also, 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 known as the citric acid cycle or tri-carboxylic 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 lactate in animals and ethanol in plants and microorganisms. Pyruvate from glycolysis is converted by fermentation 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 into 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.

Reference ranges for blood tests, comparing blood content of pyruvate (shown in violet near middle) with other constituents.

Pyruvic acid production by glycolysis[edit]

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.

phosphoenolpyruvate pyruvate kinase pyruvate
Phosphoenolpyruvate wpmp.png   Pyruvate wpmp.png
ADP ATP
Biochem reaction arrow reversible YYYY horiz med.png
ADP ATP
 
  pyruvate carboxylase and PEP carboxykinase

Compound C00074 at KEGG Pathway Database. Enzyme 2.7.1.40 at KEGG Pathway Database. Compound C00022 at KEGG Pathway Database.

Click on genes, proteins and metabolites below to link to respective articles. [§ 1]

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GlycolysisGluconeogenesis_WP534 go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to Entrez go to article go to article go to article go to article go to article go to WikiPathways go to article go to Entrez go to article
|{{{bSize}}}px|alt=Glycolysis and Gluconeogenesis edit|]]
Glycolysis and Gluconeogenesis edit
  1. ^ The interactive pathway map can be edited at WikiPathways: "GlycolysisGluconeogenesis_WP534". 

Decarboxylation to acetyl CoA[edit]

Pyruvate decarboxylation by the pyruvate dehydrogenase complex produces acetyl-CoA.

pyruvate pyruvate dehydrogenase complex acetyl-CoA
Pyruvate wpmp.png   Acetyl-CoA.svg
CoA + NAD+ CO2 + NADH + H+
Biochem reaction arrow forward YYNN horiz med.png
 
 

Carboxylation to oxaloacetate[edit]

Carboxylation by pyruvate carboxylase produces oxaloacetate.

pyruvate pyruvate carboxylase oxaloacetate
Pyruvate wpmp.png   Oxaloacetate wpmp.png
ATP + CO2 ADP + Pi
Biochem reaction arrow forward YYNN horiz med.png
 
 

Transamination to alanine[edit]

Transamination by alanine transaminase produces alanine.

pyruvate alanine transaminase alanine
Pyruvate wpmp.png   L-alanine-skeletal.svg
glutamate α-ketoglutarate
Biochem reaction arrow reversible YYYY horiz med.png
glutamate α-ketoglutarate
 
 

Reduction to lactate[edit]

Reduction by lactate dehydrogenase produces lactate.

pyruvate lactate dehydrogenase lactate
Pyruvate wpmp.png   Lactic-acid-skeletal.svg
NADH NAD+
Biochem reaction arrow reversible YYYY horiz med.png
NADH NAD+
 
 

Uses[edit]

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.[citation needed]

Pyruvate is sold as a weight-loss supplement, though evidence supporting this use is lacking. A systematic review of six trials found a statistically significant difference in body weight with pyruvate compared to placebo. However, all of the trials had methodological weaknesses and the magnitude of the effect was small. The review also identified adverse events associated with pyruvate such as diarrhea, bloating, gas, and increase in low-density lipoprotein (LDL) cholesterol. The authors concluded that there was insufficient evidence to support the use of pyruvate for weight loss.[6]

See also[edit]

Notes[edit]

  1. ^ Dawson, R. M. C. et al., Data for Biochemical Research, Oxford, Clarendon Press, 1959.
  2. ^ Thomson, Thomas (1838). "II. Of fixed acids Section". Chemistry of organic bodies, vegetables. London: J. B. Baillière. p. 65. Retrieved December 1, 2010. 
  3. ^ Thorpe, Sir Thomas Edward (1922). "Glutaric acid". A dictionary of applied chemistry 3. London: Longmans, Green, and Co. pp. 426–427. Retrieved December 1, 2010. 
  4. ^ Organic Syntheses, Coll. Vol. 1, p.475 (1941); Vol. 4, p.63 (1925)
  5. ^ a b Lehninger, Albert L.; Nelson, David L.; Cox, Michael M. (2008). Principles of Biochemistry (5th ed.). New York, NY: W.H. Freeman and Company. p. 528. ISBN 978-0-7167-7108-1. 
  6. ^ Onakpoya I, Hunt K, Wider B, Ernst E. "Pyruvate supplementation for weight loss: a systematic review and meta-analysis of randomized clinical trials.". Critical Reviews in Food Science and Nutrition. Retrieved 26 November 2013. 

References[edit]

External links[edit]