Aspartic acid

For the artificial sweetener, see aspartame.

Aspartic acid (symbol Asp or D;^[4] the ionic form is known as aspartate), is an α-amino acid that is used in the biosynthesis of proteins.^[5] The L-isomer of aspartic acid is one of the 22 proteinogenic amino acids, i.e., the building blocks of proteins. D-aspartic acid is one of two D-amino acids commonly found in mammals.^[6][7] Apart from a few rare exceptions, D-aspartic acid is not used for protein synthesis but is incorporated into some peptides and plays a role as a neurotransmitter/neuromodulator.^[6]

Aspartic acid

Skeletal formula of L-aspartic acid
Ball-and-stick model Space-filling model
Names
IUPAC name Trivial: Aspartic acid Systematic: 2-Aminobutanedioic acid
Other names Aminosuccinic acid Asparagic acid Asparaginic acid[1]
Identifiers
CAS Number	L: 56-84-8 Y D/L: 617-45-8 Y D: 1783-96-6 Y
3D model (JSmol)	L: Interactive image D: Interactive image L Zwitterion: Interactive image L Deprotonated zwitterion (aspartate): Interactive image
ChEBI	L: CHEBI:17053 Y D/L: CHEBI:22660 Y D: CHEBI:17364 Y
ChEMBL	L: ChEMBL274323 Y
ChemSpider	L: 5745 Y D/L: 411 Y D: 75697 Y
DrugBank	L: DB00128 Y
ECHA InfoCard	100.000.265
EC Number	L: 200-291-6
KEGG	D/L: C16433 Y
PubChem CID	L: 5960 D/L: 424 D: 83887
UNII	L: 30KYC7MIAI Y D/L: 28XF4669EP Y D: 4SR0Q8YD1X Y
CompTox Dashboard (EPA)	L: DTXSID7022621
InChI InChI=1S/C4H7NO4/c5-2(4(8)9)1-3(6)7/h2H,1,5H2,(H,6,7)(H,8,9)/t2-/m0/s1 Y Key: CKLJMWTZIZZHCS-REOHCLBHSA-N Y D/L: Key: CKLJMWTZIZZHCS-UHFFFAOYSA-N D: Key: CKLJMWTZIZZHCS-UWTATZPHSA-N
SMILES L: C([C@@H](C(=O)O)N)C(=O)O D/L: C(C(C(=O)O)N)C(=O)O D: C([C@H](C(=O)O)N)C(=O)O L Zwitterion: C(C(C(=O)[O-])[NH3+])C(=O)O L Deprotonated zwitterion (aspartate): C(C(C(=O)[O-])[NH3+])C(=O)[O-]
Properties
Chemical formula	C4H7NO4
Molar mass	133.103 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[2]
Acidity (pKa)	1.99 (α-carboxyl; H2O) 3.90 (side chain; H2O) 9.90 (amino; H2O)[3]
Conjugate base	Aspartate
Magnetic susceptibility (χ)	-64.2·10−6 cm3/mol
Hazards
NFPA 704 (fire diamond)	1 1 0
Supplementary data page
Aspartic acid (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Aspartic acid ball and stick model spinning

Like all other amino acids, aspartic acid contains an amino group and a carboxylic acid. Its α-amino group is in the protonated –NH⁺
₃ form under physiological conditions, while its α-carboxylic acid group is deprotonated −COO⁻ under physiological conditions. Aspartic acid has an acidic side chain (CH₂COOH) which reacts with other amino acids, enzymes and proteins in the body.^[5] Under physiological conditions (pH 7.4) in proteins the side chain usually occurs as the negatively charged aspartate form, −COO⁻.^[5] It is a non-essential amino acid in humans, meaning the body can synthesize it as needed. It is encoded by the codons GAU and GAC.

In proteins aspartate sidechains are often hydrogen bonded to form asx turns or asx motifs, which frequently occur at the N-termini of alpha helices.

Aspartic acid, like glutamic acid, is classified as an acidic amino acid, with a pK_a of 3.9; however, in a peptide this is highly dependent on the local environment, and could be as high as 14.

The one-letter code D for aspartate was assigned arbitrarily,^[8] with the proposed mnemonic asparDic acid.^[9]

Discovery

Aspartic acid was first discovered in 1827 by Auguste-Arthur Plisson and Étienne-Ossian Henry^[10][11] by hydrolysis of asparagine, which had been isolated from asparagus juice in 1806.^[12] Their original method used lead hydroxide, but various other acids or bases are now more commonly used instead.^{[citation needed]}

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.^[13] 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.^{[citation needed]}

Synthesis

Biosynthesis

In the human body, aspartate is most frequently synthesized through the transamination of oxaloacetate. The biosynthesis of aspartate is facilitated by an aminotransferase enzyme: the transfer of an amine group from another molecule such as alanine or glutamine yields aspartate and an alpha-keto acid.^[5]

Chemical synthesis

Industrially, aspartate is produced by amination of fumarate catalyzed by L-aspartate ammonia-lyase.^[14]

Racemic aspartic acid can be synthesized from diethyl sodium phthalimidomalonate, (C₆H₄(CO)₂NC(CO₂Et)₂).^[15]

Metabolism

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.^[16] 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 has many other biochemical roles. It is a metabolite in the urea cycle^[17] 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 a hydrogen acceptor in a chain of ATP synthase. Dietary L-aspartic acid has been shown to act as an inhibitor of Beta-glucuronidase, which serves to regulate enterohepatic circulation of bilirubin and bile acids.^[18]

Interactive pathway map

Click on genes, proteins and metabolites below to link to respective articles.^{[§ 1]}

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Glycolysis and Gluconeogenesis edit

1. The interactive pathway map can be edited at WikiPathways: "GlycolysisGluconeogenesis_WP534".

Neurotransmitter

Aspartate (the conjugate base of aspartic acid) stimulates NMDA receptors, though not as strongly as the amino acid neurotransmitter L-glutamate does.^[19] Aspartate is the "A" in NMDA (N-methyl-D-aspartate receptor).

Applications & market

In 2014, the global market for aspartic acid was 39.3 thousand short tons (35.7 thousand tonnes)^[20] or about $117 million annually.^[21] The three largest market segments include the U.S., Western Europe, and China. Current applications include biodegradable polymers (polyaspartic acid), low calorie sweeteners (aspartame), scale and corrosion inhibitors, and resins.^{[citation needed]}

Superabsorbent polymers

One area of aspartic acid market growth is biodegradable superabsorbent polymers (SAP), and hydrogels.^[22] Around 75% of superabsorbent polymers are used in disposable diapers and an additional 20% is used for adult incontinence and feminine hygiene products. Polyaspartic acid, the polymerization product of aspartic acid, is a biodegradable substitute to polyacrylate.^[22][23][24]

Additional uses

In addition to SAP, aspartic acid has applications in the fertilizer industry, where polyaspartate improves water retention and nitrogen uptake.^[25]

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, and does not need to be present in the diet. In eukaryotic cells, roughly 1 in 20 amino acids incorporated into a protein is an aspartic acid,^[26] and accordingly almost any source of dietary protein will include aspartic acid. Additionally, aspartic acid is found in:

• Dietary supplements, either as aspartic acid itself or salts (such as magnesium aspartate)
• The sweetener aspartame, which is made from an aspartic acid and phenylalanine

See also

• Aspartate transaminase
• Polyaspartic acid
• Sodium polyaspartate, a synthetic polyamide

References

1. Budavari, Susan; Co, Merck (1989). "862. Aspartic acid". The Merck Index (11th ed.). Merck. p. 132. ISBN 978-0-911910-28-5.
2. "ICSC 1439 - L-ASPARTIC ACID". inchem.org.
3. Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). CRC Press. pp. 5–89. ISBN 978-1498754286.
4. "Nomenclature and Symbolism for Amino Acids and Peptides". IUPAC-IUB Joint Commission on Biochemical Nomenclature. 1983. Archived from the original on 9 October 2008. Retrieved 5 March 2018.
5. Voet, Donald; Voet, Judith G.; Pratt, Charlotte W. (2016-02-29). Fundamentals of Biochemistry: Life at the Molecular Level. John Wiley & Sons. ISBN 9781118918401. OCLC 910538334.
6. D'Aniello, Antimo (1 February 2007). "d-Aspartic acid: An endogenous amino acid with an important neuroendocrine role". Brain Research Reviews. 53 (2): 215–234. doi:10.1016/j.brainresrev.2006.08.005. PMID 17118457. S2CID 12709991.
7. Huang AS, Beigneux A, Weil ZM, Kim PM, Molliver ME, Blackshaw S, Nelson RJ, Young SG, Snyder SH (March 2006). "D-aspartate regulates melanocortin formation and function: behavioral alterations in D-aspartate oxidase-deficient mice". The Journal of Neuroscience. 26 (10): 2814–9. doi:10.1523/JNEUROSCI.5060-05.2006. PMC 6675153. PMID 16525061.
8. "IUPAC-IUB Commission on Biochemical Nomenclature A One-Letter Notation for Amino Acid Sequences". Journal of Biological Chemistry. 243 (13): 3557–3559. 10 July 1968. doi:10.1016/S0021-9258(19)34176-6.
9. Adoga, Godwin I; Nicholson, Bh (January 1988). "Letters to the editor". Biochemical Education. 16 (1): 49. doi:10.1016/0307-4412(88)90026-X.
10. Plisson, A. (October 1827). "Sur l'identité du malate acide d'althéine avec l'asparagine (1); et sur un acide nouveau" [On the identity of altheine acid malate with asparagine (1); and on a new acid]. Journal de Pharmacie (in French). 13 (10): 477–492.
11. Berzelius JJ, Öngren OG (1839). Traité de chimie (in French). Vol. 3. Brussels: A. Wahlen et Cie. p. 81. Retrieved 25 August 2015.
12. Plimmer R (1912) [1908]. Plimmer R, Hopkins F (eds.). The chemical composition of the proteins. Monographs on Biochemistry. Vol. Part I. Analysis (2nd ed.). London: Longmans, Green and Co. p. 112. Retrieved January 18, 2010.
13. "Nomenclature and symbolism for amino acids and peptides (IUPAC-IUB Recommendations 1983)". Pure and Applied Chemistry. 56 (5): 595–624. 1984. doi:10.1351/pac198456050595..
14. Drauz, Karlheinz; Grayson, Ian; Kleemann, Axel; Krimmer, Hans-Peter; Leuchtenberger, Wolfgang; Weckbecker, Christoph (2006). Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a02_057.pub2. ISBN 978-3-527-30673-2.
15. Dunn MS, Smart BW (1950). "DL-Aspartic Acid". Organic Syntheses. 30: 7; Collected Volumes, vol. 4, p. 55..
16. Lehninger AL, Nelson DL, Cox MM (2000). Principles of Biochemistry (3rd ed.). New York: W. H. Freeman. ISBN 1-57259-153-6.
17. "Biochemistry - Biochemistry". www.varsitytutors.com. Retrieved 2022-02-18.
18. Kreamer, Bill L.; Siegel, Frank L.; Gourley, Glenn R. (Oct 2001). "A novel inhibitor of beta-glucuronidase: L-aspartic acid". Pediatric Research. 50 (4): 460–466. doi:10.1203/00006450-200110000-00007. PMID 11568288.
19. Chen PE, Geballe MT, Stansfeld PJ, Johnston AR, Yuan H, Jacob AL, Snyder JP, Traynelis SF, Wyllie DJ (May 2005). "Structural features of the glutamate binding site in recombinant NR1/NR2A N-methyl-D-aspartate receptors determined by site-directed mutagenesis and molecular modeling". Molecular Pharmacology. 67 (5): 1470–84. doi:10.1124/mol.104.008185. PMID 15703381. S2CID 13505187.
20. "Global Aspartic Acid Market By Application". Grand View Research. Retrieved November 30, 2019.
21. Evans J (2014). Commercial Amino Acids. BCC Research. pp. 101–103.
22. Adelnia, Hossein; Blakey, Idriss; Little, Peter J.; Ta, Hang T. (2019). "Hydrogels Based on Poly(aspartic acid): Synthesis and Applications". Frontiers in Chemistry. 7: 755. Bibcode:2019FrCh....7..755A. doi:10.3389/fchem.2019.00755. ISSN 2296-2646. PMC 6861526. PMID 31799235.
23. Adelnia, Hossein; Tran, Huong D.N.; Little, Peter J.; Blakey, Idriss; Ta, Hang T. (2021-06-14). "Poly(aspartic acid) in Biomedical Applications: From Polymerization, Modification, Properties, Degradation, and Biocompatibility to Applications". ACS Biomaterials Science & Engineering. 7 (6): 2083–2105. doi:10.1021/acsbiomaterials.1c00150. hdl:10072/404497. PMID 33797239. S2CID 232761877.
24. Alford DD, Wheeler AP, Pettigrew CA (1994). "Biodegradation of thermally synthesized polyaspartate". J Environ Polym Degr. 2 (4): 225–236. Bibcode:1994JEPD....2..225A. doi:10.1007/BF02071970.
25. Kelling K (2001). Crop Responses to Amisorb in the North Central Region. University of Wisconsin-Madison.
26. Kozlowski LP (January 2017). "Proteome-pI: proteome isoelectric point database". Nucleic Acids Research. 45 (D1): D1112 – D1116. doi:10.1093/nar/gkw978. PMC 5210655. PMID 27789699.

External links

• GMD MS Spectrum
• American Chemical Society (21 April 2010). "Ancestral Eve' Crystal May Explain Origin of Life's Left-Handedness". ScienceDaily. Archived from the original on 23 April 2010. Retrieved 2010-04-21.