Asparagine
Encyclopedia
Asparagine is one of the 20 most common natural amino acid
s on Earth
. It has carboxamide
as the side-chain's functional group
. It is not an essential amino acid
. Its codons are AAU and AAC.
A reaction between asparagine and reducing sugar
s or reactive carbonyl
s produces acrylamide
(acrylic amide) in food when heated to sufficient temperature. These products occur in baked goods such as French fries, potato chips, and roasted coffee.
and Pierre Jean Robiquet
(then a young assistant) from asparagus
juice, in which it is abundant — hence, the name they chose for that new matter — becoming the first amino acid to be isolated. The characteristic smell observed in the urine
of individuals after their consumption of asparagus
is attributed to various metabolic byproducts of asparagine.
A few years later, in 1809, Pierre Jean Robiquet again identified, this time from liquorice root, a substance with properties he qualified as very similar to those of asparagine, that Plisson in 1828 identified as asparagine itself.
s, with an extra methylene group, have more conformational entropy and thus are less useful in this regard.
Asparagine also provides key sites for N-linked glycosylation
, modification of the protein chain with the addition of carbohydrate chains.
, which means that it can be synthesized from central metabolic pathway intermediates in humans and is not required in the diet. Asparagine is found in:
enzyme. The enzyme transfers the amino group from glutamate to oxaloacetate producing α-ketoglutarate and aspartate. The enzyme asparagine synthetase
produces asparagine, AMP
, glutamate, and pyrophosphate
from aspartate, glutamine
, and ATP
. In the asparagine synthetase reaction, ATP is used to activate aspartate, forming β-aspartyl-AMP. Glutamine
donates an ammonium group, which reacts with β-aspartyl-AMP to form asparagine and free AMP.
. L-asparaginase hydrolyzes the amide group to form aspartate and ammonium. A transaminase converts the aspartate to oxaloacetate, which can then be metabolized in the citric acid cycle
or gluconeogenesis
.
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s on Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
. It has carboxamide
Carboxamide
In organic chemistry carboxamides are functional groups with the general structure R-CO-NH2 with R as an organic substituent.Two amino acids, asparagine and glutamine, have a carboxamide group in them....
as the side-chain's functional group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
. It is not an essential amino acid
Essential amino acid
An essential amino acid or indispensable amino acid is an amino acid that cannot be synthesized de novo by the organism , and therefore must be supplied in the diet.-Essentiality vs. conditional essentiality in humans:...
. Its codons are AAU and AAC.
A reaction between asparagine and reducing sugar
Reducing sugar
A reducing sugar is any sugar that either has an aldehyde group or is capable of forming one in solution through isomerisation. This functional group allows the sugar to act as a reducing agent, for example in the Tollens' test or Benedict's test.-Chemistry:...
s or reactive carbonyl
Carbonyl
In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups....
s produces acrylamide
Acrylamide
Acrylamide is a chemical compound with the chemical formula C3H5NO. Its IUPAC name is prop-2-enamide. It is a white odourless crystalline solid, soluble in water, ethanol, ether, and chloroform. Acrylamide is incompatible with acids, bases, oxidizing agents, iron, and iron salts...
(acrylic amide) in food when heated to sufficient temperature. These products occur in baked goods such as French fries, potato chips, and roasted coffee.
History
Asparagine was first isolated in 1806, under a crystalline form, by French chemists Louis Nicolas VauquelinLouis Nicolas Vauquelin
Nicolas Louis Vauquelin , was a French pharmacist and chemist.-Early life:Vauquelin was born at Saint-André-d'Hébertot in Normandy, France. His first acquaintance with chemistry was gained as laboratory assistant to an apothecary in Rouen , and after various vicissitudes he obtained an introduction...
and Pierre Jean Robiquet
Pierre Jean Robiquet
Pierre Jean Robiquet was a French chemist, who laid founding work in identifying amino acids, the fundamental bricks of proteins, through recognizing the first of them, asparagin, in 1806, in the take up of the industry of industrial dyes, with the identification of alizarin in 1826, and in the...
(then a young assistant) from asparagus
Asparagus
Asparagus officinalis is a spring vegetable, a flowering perennialplant species in the genus Asparagus. It was once classified in the lily family, like its Allium cousins, onions and garlic, but the Liliaceae have been split and the onion-like plants are now in the family Amaryllidaceae and...
juice, in which it is abundant — hence, the name they chose for that new matter — becoming the first amino acid to be isolated. The characteristic smell observed in the urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
of individuals after their consumption of asparagus
Asparagus
Asparagus officinalis is a spring vegetable, a flowering perennialplant species in the genus Asparagus. It was once classified in the lily family, like its Allium cousins, onions and garlic, but the Liliaceae have been split and the onion-like plants are now in the family Amaryllidaceae and...
is attributed to various metabolic byproducts of asparagine.
A few years later, in 1809, Pierre Jean Robiquet again identified, this time from liquorice root, a substance with properties he qualified as very similar to those of asparagine, that Plisson in 1828 identified as asparagine itself.
Structural function in proteins
Since the asparagine side-chain can form hydrogen bond interactions with the peptide backbone, asparagine residues are often found near the beginning and the end of alpha-helices, and in turn motifs in beta sheets. Its role can be thought as "capping" the hydrogen bond interactions that would otherwise be satisfied by the polypeptide backbone. GlutamineGlutamine
Glutamine is one of the 20 amino acids encoded by the standard genetic code. It is not recognized as an essential amino acid but may become conditionally essential in certain situations, including intensive athletic training or certain gastrointestinal disorders...
s, with an extra methylene group, have more conformational entropy and thus are less useful in this regard.
Asparagine also provides key sites for N-linked glycosylation
Glycosylation
Glycosylation is the reaction in which a carbohydrate, i.e. a glycosyl donor, is attached to a hydroxyl or other functional group of another molecule . In biology glycosylation refers to the enzymatic process that attaches glycans to proteins, lipids, or other organic molecules...
, modification of the protein chain with the addition of carbohydrate chains.
Dietary sources
Asparagine is not an essential amino acidEssential amino acid
An essential amino acid or indispensable amino acid is an amino acid that cannot be synthesized de novo by the organism , and therefore must be supplied in the diet.-Essentiality vs. conditional essentiality in humans:...
, which means that it can be synthesized from central metabolic pathway intermediates in humans and is not required in the diet. Asparagine is found in:
- Animal sources: dairyDairyA dairy is a business enterprise established for the harvesting of animal milk—mostly from cows or goats, but also from buffalo, sheep, horses or camels —for human consumption. A dairy is typically located on a dedicated dairy farm or section of a multi-purpose farm that is concerned...
, wheyWheyWhey or Milk Serum is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. Sweet whey is manufactured during the making of rennet types of hard cheese like cheddar or Swiss cheese...
, beefBeefBeef is the culinary name for meat from bovines, especially domestic cattle. Beef can be harvested from cows, bulls, heifers or steers. It is one of the principal meats used in the cuisine of the Middle East , Australia, Argentina, Brazil, Europe and the United States, and is also important in...
, poultryPoultryPoultry are domesticated birds kept by humans for the purpose of producing eggs, meat, and/or feathers. These most typically are members of the superorder Galloanserae , especially the order Galliformes and the family Anatidae , commonly known as "waterfowl"...
, eggsEgg (food)Eggs are laid by females of many different species, including birds, reptiles, amphibians, and fish, and have probably been eaten by mankind for millennia. Bird and reptile eggs consist of a protective eggshell, albumen , and vitellus , contained within various thin membranes...
, fishFishFish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, lactalbuminLactalbuminLactalbumin is the albumin contained in milk and obtained from whey. Lactalbumin is found in the milk of many mammals. There are alpha and beta lactalbumins; both contained in milk....
, seafoodSeafoodSeafood is any form of marine life regarded as food by humans. Seafoods include fish, molluscs , crustaceans , echinoderms . Edible sea plants, such as some seaweeds and microalgae, are also seafood, and are widely eaten around the world, especially in Asia... - Plant sources: asparagusAsparagusAsparagus officinalis is a spring vegetable, a flowering perennialplant species in the genus Asparagus. It was once classified in the lily family, like its Allium cousins, onions and garlic, but the Liliaceae have been split and the onion-like plants are now in the family Amaryllidaceae and...
, potatoes, legumes, nutsNut (fruit)A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...
, seedsSEEDSSEEDS is a voluntary organisation registered under the Societies Act of India....
, soy, whole grains
Biosynthesis
The precursor to asparagine is oxaloacetate. Oxaloacetate is converted to aspartate using a transaminaseTransaminase
In biochemistry, a transaminase or an aminotransferase is an enzyme that catalyzes a type of reaction between an amino acid and an α-keto acid. To be specific, this reaction involves removing the amino group from the amino acid, leaving behind an α-keto acid, and transferring it to the...
enzyme. The enzyme transfers the amino group from glutamate to oxaloacetate producing α-ketoglutarate and aspartate. The enzyme asparagine synthetase
Asparagine synthetase
Asparagine synthetase is an enzyme that generates asparagine from aspartate. This amidation reaction is similar to that promoted by glutamine synthetase....
produces asparagine, AMP
Adenosine monophosphate
Adenosine monophosphate , also known as 5'-adenylic acid, is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid and the nucleoside adenosine. AMP consists of a phosphate group, the sugar ribose, and the nucleobase adenine...
, glutamate, and pyrophosphate
Pyrophosphate
In chemistry, the anion, the salts, and the esters of pyrophosphoric acid are called pyrophosphates. Any salt or ester containing two phosphate groups is called a diphosphate. As a food additive, diphosphates are known as E450.- Chemistry :...
from aspartate, glutamine
Glutamine
Glutamine is one of the 20 amino acids encoded by the standard genetic code. It is not recognized as an essential amino acid but may become conditionally essential in certain situations, including intensive athletic training or certain gastrointestinal disorders...
, and ATP
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...
. In the asparagine synthetase reaction, ATP is used to activate aspartate, forming β-aspartyl-AMP. Glutamine
Glutamine
Glutamine is one of the 20 amino acids encoded by the standard genetic code. It is not recognized as an essential amino acid but may become conditionally essential in certain situations, including intensive athletic training or certain gastrointestinal disorders...
donates an ammonium group, which reacts with β-aspartyl-AMP to form asparagine and free AMP.
Degradation
Aspartate is a glucogenic amino acidGlucogenic amino acid
A glucogenic amino acid is an amino acid that can be converted into glucose through gluconeogenesis. This is in contrast to the ketogenic amino acids, which are converted into ketone bodies....
. L-asparaginase hydrolyzes the amide group to form aspartate and ammonium. A transaminase converts the aspartate to oxaloacetate, which can then be metabolized in the citric acid cycle
Citric acid cycle
The citric acid cycle — also known as the tricarboxylic acid cycle , the Krebs cycle, or the Szent-Györgyi-Krebs cycle — is a series of chemical reactions which is used by all aerobic living organisms to generate energy through the oxidization of acetate derived from carbohydrates, fats and...
or gluconeogenesis
Gluconeogenesis
Gluconeogenesis is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids....
.
Function
The nervous system requires asparagine. It also plays an important role in the synthesis of ammonia.Betaine structure