Alanine

Not to be confused with the chemical compound Allantoin, or the phenyl compound Aniline.
Alanine
Alanine in non-ionic form
Skeletal formula of L-alanine (neutral form)
Ball-and-stick model (zwitterionic form)
Space-filling model (zwitterionic form)
Names
IUPAC name
Alanine[1]
Systematic IUPAC name
2-Aminopropanoic acid
Other names
Alanic acid
Alaninic acid
2-Aminopropionic acid
Identifiers
3D model (JSmol)
3DMet
1720248
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.249 Edit this at Wikidata
EC Number
  • L: 206-126-4
49628
KEGG
UNII
  • InChI=1S/C3H7NO2/c1-2(4)3(5)6/h2H,4H2,1H3,(H,5,6)/t2-/m0/s1
    Key: QNAYBMKLOCPYGJ-REOHCLBHSA-N checkY
  • D/L: Key: QNAYBMKLOCPYGJ-UHFFFAOYSA-N
  • D: Key: QNAYBMKLOCPYGJ-UWTATZPHSA-N
  • L: C[C@@H](C(=O)O)N
  • D: C[C@H](C(=O)O)N
  • L Zwitterion: C[C@@H](C(=O)[O-])[NH3+]
  • D Zwitterion: C[C@H](C(=O)[O-])[NH3+]
Properties
C3H7NO2
Molar mass 89.094 g·mol−1
Appearance white powder
Density 1.424 g/cm3
Melting point 258 °C (496 °F; 531 K) (sublimes)
167.2 g/L (25 °C)
log P −0.68[2]
Acidity (pKa)
  • 2.34 (carboxyl; H2O)
  • 9.87 (amino; H2O)[3]
−50.5×10−6 cm3/mol
Supplementary data page
Alanine (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Alanine (symbol Ala or A),[4] or α-alanine, is an α-amino acid that is used in the biosynthesis of proteins. It contains an amine group and a carboxylic acid group, both attached to the central carbon atom which also carries a methyl group side chain. Consequently it is classified as a nonpolar, aliphatic α-amino acid. Under biological conditions, it exists in its zwitterionic form with its amine group protonated (as −NH+3) and its carboxyl group deprotonated (as −CO−2). It is non-essential to humans as it can be synthesized metabolically and does not need to be present in the diet. It is encoded by all codons starting with GC (GCU, GCC, GCA, and GCG).

The L-isomer of alanine (left-handed) is the one that is incorporated into proteins. L-alanine is second only to L-leucine in rate of occurrence, accounting for 7.8% of the primary structure in a sample of 1,150 proteins.[5] The right-handed form, D-alanine, occurs in peptides in some bacterial cell walls[6]: 131  (in peptidoglycan) and in some peptide antibiotics, and occurs in the tissues of many crustaceans and molluscs as an osmolyte.[7]

  1. ^ International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 1392. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
  2. ^ "L-alanine MSDS". ChemSrc.
  3. ^ Haynes WM, ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). CRC Press. pp. 5–88. ISBN 978-1-4987-5428-6.
  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. ^ Doolittle RF (1989). "Redundancies in Protein Sequences". In Fasman GD (ed.). Prediction of Protein Structures and the Principles of Protein Conformation. New York: Plenum. pp. 599–623. ISBN 978-0-306-43131-9.
  6. ^ Mathews CK, Van Holde KE, Ahern KG (2000). Biochemistry (3rd ed.). San Francisco, CA: Benjamin/Cummings Publishing. ISBN 978-0-8053-3066-3. OCLC 42290721.
  7. ^ Yoshikawa N, Sarower MG, Abe H (2016). "Alanine Racemase and D-Amino Acid Oxidase in Aquatic Animals". In Yoshimura T, Nishikawa T, Homma H (eds.). D-Amino Acids: Physiology, Metabolism, and Application. Springer Japan. pp. 269–282. ISBN 978-4-431-56077-7.