Asparagine | History | Biosynthesis | Applications....

 Asparagine | History | Biosynthesis | Applications....

ASPARAGINE AMINO ACID

History -

Asparagine was first discovered in 1806 in a crystalline form by French chemists Louis Nicolas Vauquelin and Pierre Jean Robiquet from asparagus juice in which it is abundant, hence the chosen name.

In 1809, Pierre Jean Robiquet identified a substance from liquorice root  with properties which he qualified as very similar to those of asparagines. and which Plisson  identified in 1828 as asparagine itself.

Introduction-

Asparagine is a non-essential amino acid in humans. Asparagine is α-amino acid that is used in the biosynthesis of proteins. Asparagine is a beta-amido derivative of aspartic acid and plays an important role in the biosynthesis of glycoproteins and other proteins. It contains an α- amino group an α-carboxylic acid groups and a side chain carboxamide, classifying it as a polar aliphatic amino acid. A metabolic precursor to aspartate. Asparagine is a nontoxic carrier of residual ammonia to be eliminated from the body. It is non-essential in humans, meaning the body can synthesize it. It is encoded by the codons AAU and AAC.

The reaction between asparagine and reducing sugars and other source of carbonyl produces acrylamide in food when heated to sufficient temperature.

Structure-

Asparagine side-chain can from hydrogen bond interactions with the peptide backbone. Asparagines residues are often found near the alpha-helices as asx turns, asx motifs, amide rings and beta sheets. . Its role can be thought as "capping" the hydrogen bond interactions that would otherwise be satisfied by the polypeptide backbone.

Asparagine also provides key sites for N-linked glycosylation, modification of the protein chain with the addition of carbohydrates chains. Asparagine can be hydroxylated in the HIF1 hypoxia inducible transcription factor. This modification inhibits HIF1 mediated gene activation.

Properties :-

Chemical formula :- C₄H₈N₂O₃

Molar mass :- 132.119 g·mol−1

Appearance :- white crystals

Density :- 1.543 g/cm3

Melting point :- 234 °C (453 °F; 507 K)

Boiling point :- 438 °C (820 °F; 711 K)

Thermodynamic data :- Phase behaviour (solid–liquid–gas)

Sources-

Asparagine is not essential for humans, which means that it can be synthesized from central metabolic pathway intermediates and is not required in the diet.

Asparagine is found in:

·         Animal sources: dairy, whey, beef, sea food, egg, fish

·         Plant sources: asparagus, potatoes, nuts, seed, soy

 

Biosynthesis Pathway

The precursor to asparagine is oxaloacetate. Oxaloacetate is converted to aspartate using a transaminase 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.

 Functions-

Asparagine is used for development and function of the brain.

 It also plays an important role in the synthesis of ammonia.

 Asparagine is also important for protein synthesis during replication of poxviruses.

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