Pyruvic acid

Pyruvic acid
IUPAC name 2-oxopropanoic acid
Other names α-ketopropionic acid; acetylformic acid; pyroracemic acid; Pyr
Identifiers
CAS number	127-17-3 Y
PubChem	1060
ChemSpider	1031 Y
UNII	8558G7RUTR Y
DrugBank	DB00119
KEGG	C00022 N
ChEBI	CHEBI:32816 Y
ChEMBL	CHEMBL1162144 Y
Jmol-3D images	Image 1
SMILES O=C(C(=O)O)C
InChI InChI=1S/C3H4O3/c1-2(4)3(5)6/h1H3,(H,5,6) Y Key: LCTONWCANYUPML-UHFFFAOYSA-N Y
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
Related keto-acids, carboxylic acids	acetic acid glyoxylic acid oxalic acid propionic acid acetoacetic acid
Related compounds	propionaldehyde glyceraldehyde methylglyoxal sodium pyruvate
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Pyruvic acid (CH₃COCOOH) is an organic acid, a ketone, as well as 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 lactic acid when oxygen is lacking (fermentation).

Chemistry

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

Pyruvate is an important chemical compound in biochemistry. It is the output of the anaerobic 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. 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

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
	ADP	ATP
	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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Glycolysis and Gluconeogenesis edit

1. ↑ The interactive pathway map can be edited at WikiPathways: "GlycolysisGluconeogenesis_WP534". 

Decarboxylation to acetyl CoA

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

pyruvate	pyruvate dehydrogenase complex		acetyl-CoA
	CoA + NAD+	CO2 + NADH + H+

Carboxylation to oxaloacetate

Carboxylation by pyruvate carboxylase produces oxaloacetate.

pyruvate	pyruvate carboxylase		oxaloacetate
	ATP + CO2	ADP + Pi

Transamination to alanine

Transamination by alanine transaminase produces alanine.

pyruvate	alanine transaminase		alanine
	glutamate	α-ketoglutarate
	glutamate	α-ketoglutarate

Reduction to lactate

Reduction by lactate dehydrogenase produces lactate.

pyruvate	lactate dehydrogenase		lactate
	NADH	NAD+
	NADH	NAD+

Uses

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

• Pyruvate scale

Notes

References

• Cody, G. D.; Boctor, N. Z.; Filley, T. R.; Hazen, R. M.; Scott, J. H.; Sharma, A.; Yoder Jr, H. S. (2000). "Primordial Carbonylated Iron-Sulfur Compounds and the Synthesis of Pyruvate". Science 289 (5483): 1337–1340. Bibcode:2000Sci...289.1337C. doi:10.1126/science.289.5483.1337. PMID 10958777. 

Wikimedia Commons has media related to Pyruvic acid.

v t e Glycolysis Metabolic Pathway

Glucose Hexokinase Glucose 6-phosphate Glucose-6-phosphate isomerase Fructose 6-phosphate phosphofructokinase-1 Fructose 1,6-bisphosphate Fructose-bisphosphate aldolase ATP ADP ATP ADP Dihydroxyacetone phosphate Glyceraldehyde 3-phosphate Triosephosphate isomerase Glyceraldehyde 3-phosphate Glyceraldehyde-3-phosphate dehydrogenase 1,3-Bisphosphoglycerate NAD+ + Pi NADH + H+ + 2 2 Phosphoglycerate kinase 3-Phosphoglycerate Phosphoglycerate mutase 2-Phosphoglycerate Phosphopyruvate hydratase(Enolase) Phosphoenolpyruvate Pyruvate kinase Pyruvate ADP ATP H2O ADP ATP 2 2 2 2 M: MET mt, k, c/g/r/p/y/i, f/h/s/l/o/e, a/u, n, m k, cgrp/y/i, f/h/s/l/o/e, au, n, m, epon m (A16/C10), i (k, c/g/r/p/y/i, f/h/s/o/e, a/u, n, m)