Proline

For other uses, see Proline (disambiguation).
Not to be confused with Prolene.
Proline
Structural formula of proline
Structural formula of proline
Names
IUPAC name
Proline
Systematic IUPAC name
Pyrrolidine-2-carboxylic acid[1]
Identifiers
3D model (JSmol)
80812
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.009.264 Edit this at Wikidata
EC Number
  • L: 210-189-3
26927
KEGG
MeSH Proline
RTECS number
  • L: TW3584000
UNII
  • InChI=1S/C5H9NO2/c7-5(8)4-2-1-3-6-4/h4,6H,1-3H2,(H,7,8)/t4-/m0/s1 checkY
    Key: ONIBWKKTOPOVIA-BYPYZUCNSA-N checkY
  • D/L: Key: ONIBWKKTOPOVIA-UHFFFAOYSA-N
  • D: Key: ONIBWKKTOPOVIA-SCSAIBSYSA-N
  • L: C1C[C@H](NC1)C(=O)O
  • L Zwitterion: [O-]C(=O)[C@H](CCC2)[NH2+]2
Properties
C5H9NO2
Molar mass 115.132 g·mol−1
Appearance Transparent crystals
Melting point 205 to 228 °C (401 to 442 °F; 478 to 501 K) (decomposes)
Solubility 1.5g/100g ethanol 19 degC[2]
log P -0.06
Acidity (pKa) 1.99 (carboxyl), 10.96 (amino)[3]
Supplementary data page
Proline (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Proline (symbol Pro or P)[4] is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group -NH
2 but is rather a secondary amine. The secondary amine nitrogen is in the protonated form (NH2+) under biological conditions, while the carboxyl group is in the deprotonated −COO− form. The "side chain" from the α carbon connects to the nitrogen forming a pyrrolidine loop, classifying it as a aliphatic amino acid. It is non-essential in humans, meaning the body can synthesize it from the non-essential amino acid L-glutamate. It is encoded by all the codons starting with CC (CCU, CCC, CCA, and CCG).

Proline is the only proteinogenic amino acid which is a secondary amine, as the nitrogen atom is attached both to the α-carbon and to a chain of three carbons that together form a five-membered ring.

  1. ^ "Proline". PubChem. U.S. National Library of Medicine. Archived from the original on 16 January 2014. Retrieved 8 May 2018.
  2. ^ Belitz HD, Grosch W, Schieberle P (2009-01-15). Food Chemistry. Springer. p. 15. ISBN 978-3-540-69933-0. Archived from the original on 2016-05-15.
  3. ^ Nelson DL, Cox MM. Principles of Biochemistry. New York: W.H. Freeman and Company.
  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.