Aspartic acid

Aspartic acid

Names
IUPAC names Trivial: Aspartic acid Systematic: 2-Aminobutanedioic acid
Other names Aminosuccinic acid, asparagic acid, asparaginic acid
Identifiers
CAS Number	617-45-8 Y 56-84-8 (L-isomer) N 1783-96-6 (D-isomer) N
ChEBI	CHEBI:22660 Y
ChEMBL	ChEMBL139661 Y
ChemSpider	411 Y
EC Number	200-291-6
Jmol 3D model	Interactive image Interactive image
KEGG	C16433 Y
PubChem	424
UNII	28XF4669EP Y
InChI InChI=1S/C4H7NO4/c5-2(4(8)9)1-3(6)7/h2H,1,5H2,(H,6,7)(H,8,9) Y Key: CKLJMWTZIZZHCS-UHFFFAOYSA-N Y InChI=1/C4H7NO4/c5-2(4(8)9)1-3(6)7/h2H,1,5H2,(H,6,7)(H,8,9) Key: CKLJMWTZIZZHCS-UHFFFAOYAE
SMILES O=C(O)CC(N)C(=O)O C(C(C(=O)O)N)C(=O)O
Properties
Chemical formula	C4H7NO4
Molar mass	133.10 g·mol−1
Appearance	colourless crystals
Density	1.7 g/cm3
Melting point	270 °C (518 °F; 543 K)
Boiling point	324 °C (615 °F; 597 K) (decomposes)
Solubility in water	4.5 g/L
Acidity (pKa)	3.9
Vapor pressure	{{{value}}}
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
N verify (what is YN ?)
Infobox references

Aspartic acid (abbreviated as Asp or D; encoded by the codons [GAU and GAC]) is an ɑ-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated -+NH3 form under biological conditions), an α-carboxylic acid group (which is in the deprotonated –COO- form under biological conditions), and a side chain CH₂COOH, classifying it as a charged(at physiological pH), aliphatic amino acid. It is semi-essential in humans, meaning the body can synthesize it from oxaloacetate.

Asp's L-isomer is one of the 23 proteinogenic amino acids, i.e., the building blocks of proteins. Asp (and glutamic acid) is classified as acidic, with a pK_a of 3.9, however in a peptide this is highly dependent on the local environment (as with all amino acids), and could be as high as 14. Asp is pervasive in biosynthesis.

L-aspartic acid is one of the two main ingredients of the artificial sweetener aspartame, along with L-phenylalanine.

Discovery

Aspartic acid was first discovered in 1827 by Auguste-Arthur Plisson and Étienne Ossian Henry, derived from asparagine, which had been isolated from asparagus juice in 1806, by boiling with a base.

Forms and nomenclature

There are two forms or enantiomers of aspartic acid. The name "aspartic acid" can refer to either enantiomer or a mixture of two. Of these two forms, only one, "L-aspartic acid", is directly incorporated into proteins. The biological roles of its counterpart, "D-aspartic acid" are more limited. Where enzymatic synthesis will produce one or the other, most chemical syntheses will produce both forms, "DL-aspartic acid," known as a racemic mixture.

Metabolism

Aspartate is non-essential in mammals, being produced from oxaloacetate by transamination. It can also be generated from ornithine and citrulline in the urea cycle. In plants and microorganisms, aspartate is the precursor to several amino acids, including four that are essential for humans: methionine, threonine, isoleucine, and lysine. The conversion of aspartate to these other amino acids begins with reduction of aspartate to its "semialdehyde," O₂CCH(NH₂)CH₂CHO. Asparagine is derived from aspartate via transamidation:

-O₂CCH(NH₂)CH₂CO₂- + GC(O)NH₃+ O₂CCH(NH₂)CH₂CONH₃+ + GC(O)O

(where GC(O)NH₂ and GC(O)OH are glutamine and glutamic acid, respectively)

Other biochemical roles

Aspartate is also a metabolite in the urea cycle and participates in gluconeogenesis. It carries reducing equivalents in the malate-aspartate shuttle, which utilizes the ready interconversion of aspartate and oxaloacetate, which is the oxidized (dehydrogenated) derivative of malic acid. Aspartate donates one nitrogen atom in the biosynthesis of inosine, the precursor to the purine bases. In addition, aspartic acid acts as hydrogen acceptor in a chain of ATP synthase.

Interactive pathway map

Click on genes, proteins and metabolites below to link to respective articles.

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File:WP534.png

Glycolysis and Gluconeogenesis edit

Neurotransmitter

Aspartate (the conjugate base of aspartic acid) stimulates NMDA receptors, though not as strongly as the amino acid neurotransmitter L-glutamate does.

Sources

Dietary sources

Aspartic acid is not an essential amino acid, which means that it can be synthesized from central metabolic pathway intermediates in humans. Aspartic acid is found in:

• Animal sources: oysters, luncheon meats, sausage meat, wild game
• Vegetable sources: sprouting seeds, oat flakes, avocado, asparagus, young sugarcane, and molasses from sugar beets.
• Dietary supplements, either as aspartic acid itself or salts (such as magnesium aspartate)
• The sweetener aspartame (brands: NutraSweet, Equal, Canderel, etc.)

Chemical synthesis

Racemic aspartic acid can be synthesized from diethyl sodium phthalimidomalonate, (C₆H₄(CO)₂NC(CO₂Et)₂).

The major disadvantage of the above technique is that equimolar amounts of each enantiomer are made. Using biotechnology it is now possible to use immobilised enzymes to create just one type of enantiomer owing to their stereospecificity.

See also

• Aspartate transaminase
• Polyaspartic acid
• Sodium poly(aspartate), a synthetic polyamide

External links

• GMD MS Spectrum