Pyruvic acid (CH
3COCOOH) is an
organic acidAn organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids whose acidity is associated with their carboxyl group -COOH. Sulfonic acids, containing the group -SO
2OH, are relatively stronger acids. The relative stability of the...
. It is also a
ketoneIn organic chemistry, a ketone is a type of compound that features a carbonyl group bonded to two other carbon atoms, i.e., R3CCO-CR3 where R can be a variety of atoms and groups of atoms...
, as well as being the simplest alpha-keto acid. The carboxylate (COOH) ion (anion) of pyruvic acid, CH
3COCOO
-, is known as
pyruvate, and is a key intersection in several metabolic pathways. It can be made from
glucoseGlucose , a monosaccharide also known as - grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology. The living cell uses it as a source of energy and metabolic intermediate...
through
glycolysisGlycolysis is the metabolic pathway that converts glucose, C
6H
12O
6, into pyruvate, C
3H
6O
3-...
, supplies energy to living cells in the
citric acid cycleThe citric acid cycle — also known as the tricarboxylic acid cycle , the Krebs cycle, or more rarely, the Szent-Györgyi-Krebs cycle — is a series of enzyme-catalysed chemical reactions, which is of central importance in all living cells that use oxygen as part of cellular respiration...
, and can also be converted to carbohydrates via gluconeogenesis, to fatty acids or energy through acetyl-CoA, to the amino acid alanine and to ethanol.
Pyruvic acid is a colorless liquid with a smell similar to that of
acetic acidAcetic acid, CH
3COOH, also known as ethanoic acid, is an organic acid which gives vinegar its sour taste and pungent smell. It is a weak acid, in that it is only partially dissociated acid in aqueous solution...
.
Pyruvic acid (CH
3COCOOH) is an
organic acidAn organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids whose acidity is associated with their carboxyl group -COOH. Sulfonic acids, containing the group -SO
2OH, are relatively stronger acids. The relative stability of the...
. It is also a
ketoneIn organic chemistry, a ketone is a type of compound that features a carbonyl group bonded to two other carbon atoms, i.e., R3CCO-CR3 where R can be a variety of atoms and groups of atoms...
, as well as being the simplest alpha-keto acid. The carboxylate (COOH) ion (anion) of pyruvic acid, CH
3COCOO
-, is known as
pyruvate, and is a key intersection in several metabolic pathways. It can be made from
glucoseGlucose , a monosaccharide also known as - grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology. The living cell uses it as a source of energy and metabolic intermediate...
through
glycolysisGlycolysis is the metabolic pathway that converts glucose, C
6H
12O
6, into pyruvate, C
3H
6O
3-...
, supplies energy to living cells in the
citric acid cycleThe citric acid cycle — also known as the tricarboxylic acid cycle , the Krebs cycle, or more rarely, the Szent-Györgyi-Krebs cycle — is a series of enzyme-catalysed chemical reactions, which is of central importance in all living cells that use oxygen as part of cellular respiration...
, and can also be converted to carbohydrates via gluconeogenesis, to fatty acids or energy through acetyl-CoA, to the amino acid alanine and to ethanol.
Chemistry
Pyruvic acid is a colorless liquid with a smell similar to that of
acetic acidAcetic acid, CH
3COOH, also known as ethanoic acid, is an organic acid which gives vinegar its sour taste and pungent smell. It is a weak acid, in that it is only partially dissociated acid in aqueous solution...
. It is miscible with water, and soluble in
ethanolEthanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug, best known as the type of alcohol found in alcoholic beverages and in modern thermometers. Ethanol is one of the oldest recreational drugs...
and
diethyl etherDiethyl ether, also known as ether, ethyl ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic odor. It is the most common member of a class of chemical compounds known generically as ethers. It is an isomer of butanol...
. In the laboratory, pyruvic acid may be prepared by heating a mixture of
tartaric acidTartaric acid is a white crystalline diprotic organic acid. It occurs naturally in many plants, particularly grapes, bananas, and tamarinds, and is one of the main acids found in wine. It is added to other foods to give a sour taste, and is used as an antioxidant. Salts of tartaric acid are known...
and
potassium hydrogen sulfatePotassium bisulfate is the potassium salt of bisulfate anion, with the molecular formula KHSO4. This compound is commonly used in the conversion of tartrates to bitartrates in wine...
, by the oxidation of
propylene glycolPropylene glycol, known also by the systematic name propane-1,2-diol, is an organic compound , with a faintly sweet taste, and is a colorless, nearly odorless, clear, viscous liquid that is hygroscopic and miscible with water, acetone, and chloroform...
by a strong oxidizer (eg.
potassium permanganatePotassium permanganate is the inorganic chemical compound KMnO
4, a water soluble salt consisting of equal mole amounts of potassium and permanganate ions. This salt, formerly known as permanganate of potash or Condy's crystals is a strong oxidizing agent...
or
bleachA bleach is a chemical that removes colors or whitens, often via oxidation. Common chemical bleaches include household "chlorine bleach", a solution of approximately 3–6% sodium hypochlorite , and "oxygen bleach", which contains hydrogen peroxide or a peroxide-releasing compound such as sodium...
), or by the hydrolysis of acetyl cyanide, formed by reaction of
acetyl chlorideAcetyl chloride is an acid chloride derived from acetic acid. It has the formula CH3COCl and it belongs to the class of organic compounds called acyl halides. At room temperature and pressure, it is a clear colorless liquid...
with
potassium cyanidePotassium cyanide is an inorganic compound with the formula KCN. This colorless crystalline compound, similar in appearance to sugar, is highly soluble in water. The vast majority of KCN is used in gold mining followed by use in organic synthesis, and electroplating. Smaller applications include...
:
- CH3COCl + KCN → CH3COCN
- CH3COCN → CH3COCOOH
Biochemistry
Pyruvate is an important
chemical compoundA chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
in
biochemistryBiochemistry is the study of the chemical processes in living organisms. It deals with the structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules....
. It is the output of the anaerobic metabolism of
glucoseGlucose , a monosaccharide also known as - grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology. The living cell uses it as a source of energy and metabolic intermediate...
known as
glycolysisGlycolysis is the metabolic pathway that converts glucose, C
6H
12O
6, into pyruvate, C
3H
6O
3-...
. One molecule of
glucoseGlucose , a monosaccharide also known as - grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology. The living cell uses it as a source of energy and metabolic intermediate...
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 AAcetyl-CoA is an important molecule in metabolism, used in many biochemical reactions. Its main use is to convey the carbon atoms within the acetyl group to the citric acid cycle to be oxidized for energy production. In chemical structure, acetyl-CoA is the thioester between coenzyme A and acetic...
, which is the main input for a series of reactions known as the Krebs cycle. Pyruvate is also converted to oxaloacetate by an
anaplerotic reactionAnaplerotic reactions are those that form intermediates of the Tricarboxylic acid Cycle . In normal function of this cycle for respiration, concentrations of TCA intermediates remain constant; however, many biosynthetic reactions also use these molecules as a substrate...
which replenishes Krebs cycle intermediates; alternatively, the oxaloacetate is used for
gluconeogenesisGluconeogenesis is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids....
. These reactions are named after
Hans Adolf KrebsSir Hans Adolf Krebs was a German born British physician and biochemist. Krebs is best known for his identification of two important metabolic cycles: the urea cycle and the citric acid cycle...
, the biochemist awarded the 1953
Nobel PrizeThe Nobel Prize is a Sweden-based international monetary prize. The award was established by the 1895 will and estate of Swedish chemist and inventor Alfred Nobel. It was first awarded in Physics, Chemistry, Physiology or Medicine, Literature, and Peace in 1901...
for physiology, jointly with Fritz Lipmann, for research into metabolic processes. The cycle is also called the
citric acid cycleThe citric acid cycle — also known as the tricarboxylic acid cycle , the Krebs cycle, or more rarely, the Szent-Györgyi-Krebs cycle — is a series of enzyme-catalysed chemical reactions, which is of central importance in all living cells that use oxygen as part of cellular respiration...
, 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
lactateLactate may refer to:*The act of lactation*A salt or ester of lactic acid...
in animals and
ethanolEthanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug, best known as the type of alcohol found in alcoholic beverages and in modern thermometers. Ethanol is one of the oldest recreational drugs...
in plants and microorganisms. Pyruvate from glycolysis is converted by
anaerobic respirationIn biology, anaerobic respiration is a way for an organism to produce usable energy carriers without the involvement of oxygen; it is respiration without oxygen. Respiration is a redox reaction that processes energy in a form usable by an organism, chiefly the process of producing ATP, the...
to
lactateLactic acid , also known as milk acid, is a chemical compound that plays a role in several biochemical processes. It was first isolated in 1780 by a Swedish chemist, Carl Wilhelm Scheele, and is a carboxylic acid with a chemical formula of C
3H
6O
3...
using the
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at...
lactate dehydrogenaseLactate dehydrogenase is an enzyme present in a wide variety of organisms, including plants and animals.Lactate dehydrogenases exist in four distinct enzyme classes. Two of them are cytochrome c-dependent enzymes with each acting on either D-lactate or L-lactate...
and the coenzyme NADH in lactate
fermentationFermentation is the process of deriving energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. This is in contrast to cellular respiration, where electrons are donated to an exogenous electron acceptor,...
, or to
acetaldehydeAcetaldehyde is an organic chemical compound with the formula CH3CHO or MeCHO. It is a flammable liquid. Acetaldehyde occurs naturally in ripe fruit, coffee, and bread, and is produced by plants as part of their normal metabolism...
and then to ethanol in alcoholic fermentation.
Pyruvate is a key intersection in the network of
metabolic pathway-Cellular respiration:Several distinct but linked metabolic pathways are used by cells to transfer the energy released by breakdown of fuel molecules to ATP...
s. Pyruvate can be converted into
carbohydrateCarbohydrates
[Means "hydrates of carbon"] or saccharides
[The word comes from the Greek σάκχαρον, sákcharon, meaning "sugar").] are the most abundant of the four major classes of biomolecules...
s via
gluconeogenesisGluconeogenesis is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids....
, to
fatty acidIn chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail , which is either saturated or unsaturated...
s or energy through
acetyl-CoAAcetyl-CoA is an important molecule in metabolism, used in many biochemical reactions. Its main use is to convey the carbon atoms within the acetyl group to the citric acid cycle to be oxidized for energy production. In chemical structure, acetyl-CoA is the thioester between coenzyme A and acetic...
, to the
amino acidAmino acids are molecules containing an amine group, a carboxylic acid group and one of the twenty R-groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H
2NCHRCOOH, where R is an organic substituent...
alanineAlanine is an α-amino acid with the chemical formula CH3CHCOOH. The L-isomer is one of the 20 proteinogenic amino acids, i.e. the building blocks of proteins. Its codons are GCU, GCC, GCA, and GCG. It is classified as a nonpolar amino acid...
and to
ethanolEthanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug, best known as the type of alcohol found in alcoholic beverages and in modern thermometers. Ethanol is one of the oldest recreational drugs...
. Therefore it unites several key metabolic processes.
The pyruvic acid derivative
bromopyruvic acidBromopyruvic acid, or bromopyruvate, is a synthetic brominated derivative of pyruvic acid. It is being studied as a potential treatment for certain types of cancer...
is being studied for potential cancer treatment applications by researchers at
Johns Hopkins UniversityThe Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university located in Baltimore, Maryland, United States. Johns Hopkins also maintains full-time campuses elsewhere in Maryland, Washington, D.C., Italy, China, and Singapore...
in ways that would support the
Warburg hypothesisWarburg's hypothesis was postulated by the Nobel laureate Otto Heinrich Warburg in 1924. He hypothesized that cancer, malignant growth, and tumor growth are caused by the fact that tumor cells mainly generate energy by non-oxidative breakdown of glucose...
on the cause(s) of cancer.
Pyruvate production by glycolysis
In
glycolysisGlycolysis is the metabolic pathway that converts glucose, C
6H
12O
6, into pyruvate, C
3H
6O
3-...
,
phosphoenolpyruvatePhosphoenolpyruvic acid , or phosphoenolpyruvate as the anion, is an important chemical compound in biochemistry. It has the high-energy phosphate bond found in living organisms, and is involved in glycolysis and gluconeogenesis...
(PEP) is converted to pyruvate by
pyruvate kinasePyruvate kinase is an enzyme involved in glycolysis. It catalyzes the transfer of a phosphate group from phosphoenolpyruvate to ADP, yielding one molecule of pyruvate and one molecule of ATP.-Reaction:The reaction with pyruvate kinase:...
. This reaction is strongly exergonic and irreversible; in
gluconeogenesisGluconeogenesis is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids....
it takes two enzymes,
pyruvate carboxylasePyruvate carboxylase is an enzyme of the ligase class that catalyzes the irreversible carboxylation of pyruvate to form oxaloacetate .It is an important anaplerotic reaction that provides oxaloacetate precursor for the citric acid cycle...
and PEP carboxykinase to catalyze the reverse transformation of pyruvate to PEP.
Pyruvate decarboxylation to acetyl CoA
Pyruvate decarboxylation by the pyruvate dehydrogenase complex produces
acetyl-CoAAcetyl-CoA is an important molecule in metabolism, used in many biochemical reactions. Its main use is to convey the carbon atoms within the acetyl group to the citric acid cycle to be oxidized for energy production. In chemical structure, acetyl-CoA is the thioester between coenzyme A and acetic...
.
Pyruvate carboxylation to oxaloacetate
Carboxylation by the
pyruvate carboxylasePyruvate carboxylase is an enzyme of the ligase class that catalyzes the irreversible carboxylation of pyruvate to form oxaloacetate .It is an important anaplerotic reaction that provides oxaloacetate precursor for the citric acid cycle...
produces oxaloacetate.
Transamination by the alanine aminotransferase
Reduction to lactate
Reduction by the
lactate dehydrogenaseLactate dehydrogenase is an enzyme present in a wide variety of organisms, including plants and animals.Lactate dehydrogenases exist in four distinct enzyme classes. Two of them are cytochrome c-dependent enzymes with each acting on either D-lactate or L-lactate...
produces
lactateLactate may refer to:*The act of lactation*A salt or ester of lactic acid...
.
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, in theory, almost barren of oxygen. As such, requisite biochemical materials must have preceded life. In vitro,
iron sulfideIron sulfide or Iron sulphide may refer to a chemical compound of iron and sulfur with a formula*FeS*FeS2...
at sufficient pressure and temperature catalyzes the formation of pyruvate. Thus, argues
Günter WächtershäuserGünter Wächtershäuser , a German chemist turned patent lawyer, is mainly known for his work on the origin of life, and in particular his iron-sulfur world theory, a theory that life on Earth had hydrothermal origins...
, the mixing of iron-rich crust with hydrothermal vent fluid is suspected of providing the fertile basis for the formation of life.