Norleucine

Norleucine^[a] (abbreviated as Nle) is an amino acid with the formula CH₃(CH₂)₃CH(NH₂)CO₂H. A systematic name for this compound is 2-aminohexanoic acid. The compound is an isomer of the more common amino acid leucine. Like most other α-amino acids, norleucine is chiral. It is a white, water-soluble solid.

Norleucine

Names
Preferred IUPAC name (2S)-2-Aminohexanoic acid
Other names Caprine Glycoleucine
Identifiers
CAS Number	327-57-1 (2S)
3D model (JSmol)	Interactive image
Beilstein Reference	1721748
ChEBI	CHEBI:36405
ChemSpider	401917
DrugBank	DB04419
ECHA InfoCard	100.009.512
EC Number	210-462-7
Gmelin Reference	464584
KEGG	C01933
MeSH	Norleucine
PubChem CID	9475
RTECS number	RC6308000
UNII	832C8OV84S
CompTox Dashboard (EPA)	DTXSID40861874
InChI InChI=1S/C6H13NO2/c1-2-3-4-5(7)6(8)9/h5H,2-4,7H2,1H3,(H,8,9) Key: LRQKBLKVPFOOQJ-UHFFFAOYSA-N
SMILES CCCCC(N)C(O)=O
Properties
Chemical formula	C6H13NO2
Molar mass	131.175 g·mol−1
Melting point	301 °C (574 °F; 574 K) (decomposes) [1]
Solubility in water	16 g/L at 23 °C [2]
Acidity (pKa)	2.39 (carboxyl), 9.76 (amino)[3]
Related compounds
Related Aminoacids	Norvaline (2-amino-pentanoic) Aminocaproic acid (6-amino-hexanoic) Leucine (2-amino-4-methyl-pentanoic) Isoleucine (2-amino-3-methyl-pentanoic) Lysine (2,6-diamino-hexanoic)
Related compounds	Caproic acid (hexanoic)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Occurrence

Together with norvaline, norleucine is found in small amounts in some bacterial strains where its concentration can approach millimolar. Its biosynthesis has been examined. It arises via the action of 2-isopropylmalate synthase on α-ketobutyrate. The incorporation of Nle into peptides reflects the imperfect selectivity of the associated aminoacyl-tRNA synthetase. In Miller–Urey experiments probing prebiotic synthesis of amino acids, norleucine and especially norvaline are formed.^[6]

Uses

It is nearly isosteric with methionine, even though it does not contain sulfur.^[7] For this reason, norleucine has been used to probe the role of methionine in Amyloid-β peptide (AβP) the central constituent of senile plaques in Alzheimer's disease. A study showed that with the substitution of the methionine at the 35 position with norleucine the neurotoxic effects of the Aβ peptides were completely negated.^[8]

See also

• Leucines, description of the isomers of leucine
• norvaline, isomer of valine that has similar biochemistry to that of norleucine.

Notes

1. The use of the name norleucine is discouraged as it is a misnomer, given than nor- is defined for an amino acid with one less methylene group than found in the proteinogenic form.^[4][5]