| Revision as of 20:44, 19 January 2009 editAmbix (talk | contribs)489 edits CAS Verify. |
Latest revision as of 21:18, 17 September 2023 edit KoIobok (talk | contribs)Extended confirmed users1,350 edits Added Category:Alpha-Amino acids |
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| ImageFileL1 = L-leucine-skeletal.png |
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| ImageFile = L-Norleucin.svg |
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| ImageSizeL1 = 120px |
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| ImageSize = 180px |
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| PIN = (2''S'')-2-Aminohexanoic acid |
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| ImageFileR1 = L-leucine-3D-sticks.png |
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| ImageSizeR1 = 120px |
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| IUPACName = (''S'')-2-amino-4-methyl-pentanoic acid |
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| OtherNames = |
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| OtherNames = |
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Caprine<br /> |
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| Section1 = {{Chembox Identifiers |
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Glycoleucine |
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| CASNo = 61-90-5 |
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|Section1={{Chembox Identifiers |
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| CASNo_Ref = {{cascite}} |
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| PubChem = 6106 |
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| CASNo = 327-57-1 |
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| CASNo_Comment = (2''S'') |
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| SMILES = CC(C)C(N)C(O)=O}} |
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| PubChem = 9475 |
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| Section2 = {{Chembox Properties |
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| ChemSpiderID = 401917 |
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| C=6 |H=13 |N=1 |O=2 |
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| EINECS = 210-462-7 |
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| DrugBank = DB04419 |
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| KEGG = C01933 |
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| MeSHName = Norleucine |
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| ChEBI = 36405 |
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| RTECS = RC6308000 |
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| UNII = 832C8OV84S |
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| SMILES = CCCCC(N)C(O)=O |
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| InChI = 1S/C6H13NO2/c1-2-3-4-5(7)6(8)9/h5H,2-4,7H2,1H3,(H,8,9) |
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| InChIKey = LRQKBLKVPFOOQJ-UHFFFAOYSA-N |
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| Beilstein = 1721748 |
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| Gmelin = 464584 |
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| 3DMet = B00369}} |
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|Section2={{Chembox Properties |
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| C=6 | H=13 | N=1 | O=2 |
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| Appearance = |
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| Appearance = |
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| Density = |
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| MeltingPtC = 301 |
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| MeltingPt_notes = (decomposes) <ref name="Römpp">Hermann Römpp, Jürgen Falbe und Manfred Regitz: ''Römpp Lexikon Chemie'', 9. Auflage, Georg Thieme Verlag, Stuttgart 1992.</ref> |
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| MeltingPt = |
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| BoilingPt = |
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| BoilingPt = |
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| pKa =2.39 (carboxyl), 9.76 (amino)<ref>Dawson, R.M.C., et al., ''Data for Biochemical Research'', Oxford, Clarendon Press, 1959.</ref> |
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| Solubility = }} |
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| Solubility = 16 g/L at 23 °C <ref>{{dead link|date=February 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> |
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| Section3 = {{Chembox Hazards |
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| MainHazards = |
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| FlashPt = |
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| Autoignition = }} |
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}} |
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|Section7={{Chembox Hazards |
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| GHSPictograms = |
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| HPhrases = {{HPhrases|}} |
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| PPhrases = {{PPhrases|}} |
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| GHS_ref = <ref>GHS: 27-04-2021: "Not a hazardous substance or mixture according to Regulation (EC) No 1272/2008"</ref> |
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}} |
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|Section8={{Chembox Related |
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| OtherFunction_label = ]s |
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| OtherFunction = ] (2-amino-pentanoic)<br />] (6-amino-hexanoic)<br />] (2-amino-4-methyl-pentanoic)<br />] (2-amino-3-methyl-pentanoic)<br />] (2,6-diamino-hexanoic) |
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| OtherCompounds = ] (hexanoic) |
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}} |
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| Watchedfields = changed |
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| verifiedrevid = 265148831}} |
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'''Norleucine''' (abbreviated as '''Nle''') is an ] with the formula CH<sub>3</sub>(CH<sub>2</sub>)<sub>3</sub>CH(NH<sub>2</sub>)CO<sub>2</sub>H. A systematic name for this compound is 2-aminohexanoic acid.<ref>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. {{cite journal | title = Nomenclature and Symbolism For Amino Acids and Peptides | journal = Pure and Applied Chemistry | volume = 56 | issue = 5 | pages = 595–624 | date = 1984 | doi=10.1351/pac198456050595| doi-access = free }}</ref> The compound is an isomer of the more common amino acid ]. Like most other ]s, norleucine is ]. It is a white, water-soluble solid. |
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'''Leucine''' (abbreviated as '''Leu''' or '''L''')<ref>{{cite web | author=IUPAC-IUBMB Joint Commission on Biochemical Nomenclature | title=Nomenclature and Symbolism for Amino Acids and Peptides | work=Recommendations on Organic & Biochemical Nomenclature, Symbols & Terminology etc | url=http://www.chem.qmul.ac.uk/iupac/AminoAcid/ | accessdate=2007-05-17}}</ref> is an α-] with the ] HO<sub>2</sub>CCH(NH<sub>2</sub>)CH<sub>2</sub>CH(CH<sub>3</sub>)<sub>2</sub>. It is an ], which means that humans cannot synthesise it. Its codons are UUA, UUG, CUU, CUC, CUA, and CUG. With a hydrocarbon side chain, leucine is classified as a ] amino acid. It has an isobutyl R group. Leucine is a major component of the sub units in ], ] and other 'buffer' ]s. |
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== Biosynthesis == |
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==Occurrence== |
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Together with ], norleucine is found in small amounts in some bacterial strains where its concentration can approach millimolar. Its ] has been examined. It arises via the action of ] on ]. The incorporation of Nle into peptides reflects the imperfect selectivity of the associated ]. In ]s probing prebiotic synthesis of amino acids, norleucine and especially norvaline are formed.<ref>Alvarez-Carreno, Claudia; Becerra, Arturo; Lazcano, Antonio "Norvaline and Norleucine May Have Been More Abundant Protein Components during Early Stages of Cell Evolution" Origins of Life and Evolution of Biospheres 2014, volume 43, 363-375. {{doi|10.1007/s11084-013-9344-3}}</ref> |
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As an essential amino acid, leucine is not synthesized in animals, hence it must be ingested, usually as a component of proteins. It is synthesized in plants and microorganisms via several steps starting from ]. The initial part of the pathway also leads to ]. The intermediate ] is converted to ] and then ], which is dehydrogenated to ], which in the final step undergoes ]. Enzymes involved in a typical leucine biosynthesis include<ref>Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. ISBN 1-57259-153-6.</ref> |
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* ], |
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* Acetohydroxy acid isomero], |
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* Dihydroxyacid ], |
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* α-Isopropylmalate ], |
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* α-Isopropylmalate ], |
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* Leucine ]. |
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==Biological Uses== |
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==Uses== |
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It is nearly isosteric with ], even though it does not contain ].<ref>Moroder, Luis "Isosteric replacement of sulfur with other chalcogens in peptides and proteins" Journal of Peptide Science 2005, volume 11, 187-214. {{doi|10.1002/psc.654}}</ref> For this reason, norleucine has been used to probe the role of methionine in ] (AβP) the central constituent of senile plaques in ]. A study showed that with the substitution of the ] at the 35 position with norleucine the neurotoxic effects of the Aβ peptides were completely negated.<ref>{{cite journal |author1=Clementi, ME |author2=Misiti, F |name-list-style=amp | title = Substitution of methionine 35 inhibits apoptotic effects of Abeta(31-35) and Abeta(25-35) fragments of amyloid-beta protein in PC12 cells | journal = Med. Sci. Monit. | date = Nov 2005 | volume = 11 | issue = 11 | pages = BR381-5 | pmid= 16258386}}</ref> |
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As a dietary supplement, leucine has been found to slow the degradation of muscle tissue by increasing the synthesis of muscle proteins.<ref>{{cite web | author=L. Combaret, et al Human Nutrition Research Centre of Clermont-Ferrand | title=A leucine-supplemented diet restores the defective postprandial inhibition of proteasome-dependent proteolysis in aged rat skeletal muscle | work=Journal of Physiology Volume 569, issue 2, p. 489-499 | url=http://jp.physoc.org/cgi/reprint/569/2/489 | accessdate=2008-03-25}}</ref> Leucine is utilized in the liver, adipose tissue, and muscle tissue. In adipose and muscle tissue, leucine is used in the formation of ]s, and the combined usage of leucine in these two tissues is seven times greater than its use in the liver.<ref>{{cite web | author=J. Rosenthal, et al Department of Medicine, University of Toronto, Toronto, Canada | title=Metabolic fate of leucine: A significant sterol precursor in adipose tissue and muscle | work= American Journal of Physiology Vol. 226, No. 2, p. 411-418 | url=http://ajplegacy.physiology.org/cgi/reprint/226/2/411 | accessdate=2008-03-25}}</ref> |
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== Chemical properties == |
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] leucine had been subjected to circularly polarized ] in order to better understand the origin of biomolecular asymmetry. An enantiomeric enhancement of 2.6 % had been induced, indicating a photochemical origin of biomolecules' ].<ref name=>]: ''Amino acids and the asymmetry of life'', Springer-Verlag, 2008, ISBN 978-3-540-76885-2</ref> |
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== Food additive == |
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As a ] L-Leucine has ] '''E641''' and is classified as a ]. |
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== See also == |
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== See also == |
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* ], description of the isomers of leucine |
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* ], description of the isomers of leucine |
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* ], isomer of ] that has similar biochemistry to that of norleucine. |
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* ] |
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==References== |
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==References== |
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