Norleucine (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.[4] 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.
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Preferred IUPAC name
(2S)-2-Aminohexanoic acid | |
Other names
Caprine
Glycoleucine | |
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3D model (JSmol)
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1721748 | |
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ECHA InfoCard | 100.009.512 |
EC Number |
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464584 | |
KEGG |
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MeSH | Norleucine |
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Properties | |
C6H13NO2 | |
Molar mass | 131.175 g·mol−1 |
Melting point | 301 °C (574 °F; 574 K) (decomposes) [3] |
16 g/L at 23 °C [1] | |
Acidity (pKa) | 2.39 (carboxyl), 9.76 (amino)[2] |
Related compounds | |
Related Aminoacids
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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
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Caproic acid (hexanoic) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
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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.[5]
It is nearly isosteric with methionine, even though it does not contain sulfur.[6] 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.[7]