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Topic summary

Aspartic acid

Related topics
Names IUPAC name
Aspartic acid
Systematic IUPAC name
2-Aminobutanedioic acid
Other names
  • Aminosuccinic acid
  • Asparagic acid
  • Asparaginic acid
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard100.000.265EC Number
  • L: 200-291-6
KEGG
UNII
  • InChI=1S/C4H7NO4/c5-2(4(8)9)1-3(6)7/h2H,1,5H2,(H,6,7)(H,8,9)/t2-/m0/s1
    Key: CKLJMWTZIZZHCS-REOHCLBHSA-N
  • D/L: Key: CKLJMWTZIZZHCS-UHFFFAOYSA-N
  • D: Key: CKLJMWTZIZZHCS-UWTATZPHSA-N
  • 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 C4H7NO4Molar mass133.103 g·mol Appearance colourless crystals Density1.7 g/cm Melting point270 °C (518 °F; 543 K) Boiling point324 °C (615 °F; 597 K) (decomposes) 4.5 g/L Acidity (pKa)
  • 1.99 (α-carboxyl; H2O)
  • 3.90 (side chain; H2O)
  • 9.90 (amino; H2O)
Conjugate baseAspartate −64.2·10 cm/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).

Aspartic acid (symbol Asp or D; known as aspartate in its anionic form), is an α-amino acid that is used in the biosynthesis of proteins. 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. 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.

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. Under physiological conditions (pH 7.4) in proteins the side chain usually occurs as the negatively charged aspartate form, −COO. 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 pKa 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, with the proposed mnemonic asparDic acid.

Wikipedia source