Pyruvic acid - Misplaced Pages

Pyruvic acid (CH₃COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate base, CH₃COCOO, is an intermediate in several metabolic pathways throughout the cell.

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

Pyruvic acid supplies energy to 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.

Chemistry

In 1834, Théophile-Jules Pelouze distilled tartaric acid and isolated glutaric acid and another unknown organic acid. Jöns Jacob Berzelius characterized this other acid the following year and named pyruvic acid because it was distilled using heat. The correct molecular structure was deduced by the 1870s.

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, 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

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Pyruvate is an important chemical compound in biochemistry. It is the output of the 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 (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 tricarboxylic 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 (and in carp). Pyruvate from glycolysis is converted by fermentation to lactate using the enzyme lactate dehydrogenase and the coenzyme NADH in lactate fermentation, or to acetaldehyde (with the enzyme pyruvate decarboxylase) 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.

Pyruvic acid production by glycolysis

In the last step of 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		pyruvic acid

	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.

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|alt=Glycolysis and Gluconeogenesis edit]] Glycolysis and Gluconeogenesis edit

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 + P_i

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

Environmental chemistry

Pyruvic acid is an abundant carboxylic acid in secondary organic aerosols.

Uses

Pyruvate is sold as a weight-loss supplement, though credible science has yet to back this claim. 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.

There is also in vitro as well as in vivo evidence in hearts that pyruvate improves metabolism by NADH production stimulation and increases cardiac function.

Notes

^ Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 748. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
Dawson, R. M. C.; et al. (1959). Data for Biochemical Research. Oxford: Clarendon Press.
Fox, Stuart Ira (2011). Human Physiology (12th ed.). McGraw=Hill. p. 146.
Ophardt, Charles E. "Pyruvic Acid - Cross Roads Compound". Virtual Chembook. Elmhurst College. Archived from the original on July 31, 2018. Retrieved April 7, 2017.
Thomson, Thomas (1838). "Chapter II. Of fixed acids Section". Chemistry of organic bodies, vegetables. London: J. B. Baillière. p. 65. Retrieved December 1, 2010.
Berzelius, J. (1835). "Ueber eine neue, durch Destillation von Wein-und Traubensäure erhaltene Säure". Annalen der Pharmacie. 13 (1): 61–63. doi:10.1002/jlac.18350130109.
"Pyruvic acid". Journal of the Chemical Society, Abstracts. 34: 31. 1878. doi:10.1039/CA8783400019.
"Pyruvic Acid". ChemSpider. Royal Society of Chemistry. Retrieved 21 April 2017.
Howard, J. W.; Fraser, W. A. "Pyruvic Acid". Organic Syntheses. 4: 63; Collected Volumes, vol. 1, p. 475.
^ 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.
Aren van Waarde; G. Van den Thillart; Maria Verhagen (1993). "Ethanol Formation and pH-Regulation in Fish". Surviving Hypoxia. CRC Press. pp. 157–170. hdl:11370/3196a88e-a978-4293-8f6f-cd6876d8c428. ISBN 0-8493-4226-0.
Guzman, Marcelo I.; Eugene, Alexis J. (2021-09-01). "Aqueous Photochemistry of 2-Oxocarboxylic Acids: Evidence, Mechanisms, and Atmospheric Impact". Molecules. 26 (17): 5278. doi:10.3390/molecules26175278. PMC 8433822. PMID 34500711.
Onakpoya, I.; Hunt, K.; Wider, B.; Ernst, E. (2014). "Pyruvate supplementation for weight loss: a systematic review and meta-analysis of randomized clinical trials". Crit. Rev. Food Sci. Nutr. 54 (1): 17–23. doi:10.1080/10408398.2011.565890. PMID 24188231. S2CID 20241217.
Jaimes, R. III (Jul 2015). "Functional response of the isolated, perfused normoxic heart to pyruvate dehydrogenase activation by dichloroacetate and pyruvate". Pflügers Arch. 468 (1): 131–42. doi:10.1007/s00424-015-1717-1. PMC 4701640. PMID 26142699.
Hermann, H. P.; Pieske, B.; Schwarzmüller, E.; Keul, J.; Just, H.; Hasenfuss, G. (1999-04-17). "Haemodynamic effects of intracoronary pyruvate in patients with congestive heart failure: an open study". Lancet. 353 (9161): 1321–1323. doi:10.1016/s0140-6736(98)06423-x. ISSN 0140-6736. PMID 10218531. S2CID 25126646.

References

Cody, G. D.; Boctor, N. Z.; Filley, T. R.; Hazen, R. M.; Scott, J. H.; Sharma, A.; Yoder, H. S. Jr (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. S2CID 14911449.

External links

Pyruvic acid mass spectrum

v t e Glycolysis metabolic pathway
Glucose Hexokinase ATP ADP Glucose 6-phosphate Glucose-6-phosphate isomerase Fructose 6-phosphate Phosphofructokinase-1 ATP ADP Fructose 1,6-bisphosphate Fructose-bisphosphate aldolase Dihydroxyacetone phosphate + + Glyceraldehyde 3-phosphate Triosephosphate isomerase 2 × Glyceraldehyde 3-phosphate 2 × Glyceraldehyde-3-phosphate dehydrogenase NAD+ P_i NADH + H NAD+ P_i NADH + H 2 × 1,3-Bisphosphoglycerate 2 × Phosphoglycerate kinase ADP ATP ADP ATP 2 × 3-Phosphoglycerate 2 × Phosphoglycerate mutase 2 × 2-Phosphoglycerate 2 × Phosphopyruvate hydratase (enolase) H₂O H₂O 2 × Phosphoenolpyruvate 2 × Pyruvate kinase ADP ATP 2 × Pyruvate 2 ×

Glycolysis metabolic pathway

Glucose

Hexokinase

ATP ADP

Glucose 6-phosphate

Glucose-6-phosphate
isomerase

Fructose 6-phosphate

Phosphofructokinase-1

ATP ADP

Fructose 1,6-bisphosphate

Fructose-bisphosphate
aldolase

Dihydroxyacetone phosphate

Glyceraldehyde 3-phosphate

Triosephosphate
isomerase

2 × Glyceraldehyde 3-phosphate

2 ×

Glyceraldehyde-3-phosphate
dehydrogenase

NAD+ P_i NADH + H

2 × 1,3-Bisphosphoglycerate

2 ×

Phosphoglycerate kinase

ADP ATP

2 × 3-Phosphoglycerate

2 ×

Phosphoglycerate mutase

2 × 2-Phosphoglycerate

2 ×

Phosphopyruvate
hydratase (enolase)

H₂O

2 × Phosphoenolpyruvate

2 ×

Pyruvate kinase

ADP ATP

2 × Pyruvate

2 ×

Amino acid metabolism metabolic intermediates

K→acetyl-CoA

lysine→	Saccharopine Allysine α-Aminoadipic acid 2-Oxoadipic acid Glutaryl-CoA Glutaconyl-CoA Crotonyl-CoA β-Hydroxybutyryl-CoA
leucine→	β-Hydroxy β-methylbutyric acid β-Hydroxy β-methylbutyryl-CoA Isovaleryl-CoA α-Ketoisocaproic acid β-Ketoisocaproic acid β-Ketoisocaproyl-CoA β-Leucine β-Methylcrotonyl-CoA β-Methylglutaconyl-CoA β-Hydroxy β-methylglutaryl-CoA
tryptophan→alanine→	N′-Formylkynurenine Kynurenine Anthranilic acid 3-Hydroxykynurenine 3-Hydroxyanthranilic acid 2-Amino-3-carboxymuconic semialdehyde 2-Aminomuconic semialdehyde 2-Aminomuconic acid Glutaryl-CoA

G→pyruvate→
citrate

glycine→
serine→

3-Phosphoglyceric acid

G→glutamate→
α-ketoglutarate

histidine→	Urocanic acid Imidazol-4-one-5-propionic acid Formiminoglutamic acid Glutamate-1-semialdehyde
proline→	1-Pyrroline-5-carboxylic acid
arginine→	Agmatine Ornithine Citrulline Cadaverine Putrescine
other	cysteine+glutamate→glutathione: γ-Glutamylcysteine

G→propionyl-CoA→
succinyl-CoA

valine→	α-Ketoisovaleric acid Isobutyryl-CoA Methacrylyl-CoA 3-Hydroxyisobutyryl-CoA 3-Hydroxyisobutyric acid 2-Methyl-3-oxopropanoic acid
isoleucine→	2,3-Dihydroxy-3-methylpentanoic acid 2-Methylbutyryl-CoA Tiglyl-CoA 2-Methylacetoacetyl-CoA
methionine→	generation of homocysteine: S-Adenosyl methionine S-Adenosyl-L-homocysteine Homocysteine conversion to cysteine: Cystathionine α-Ketobutyric acid + Cysteine
threonine→	α-Ketobutyric acid
propionyl-CoA→	Methylmalonyl-CoA