| Leucine | |
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Leucine |
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Other names
2-Amino-4-methylpentanoic acid |
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| Identifiers | |
| CAS number | 61-90-5 |
| PubChem | 6106 |
| ChemSpider | 5880 |
| UNII | GMW67QNF9C |
| DrugBank | DB01746 |
| KEGG | D00030 |
| ChEBI | CHEBI:57427 |
| ChEMBL | CHEMBL291962 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C6H13NO2 |
| Molar mass | 131.17 g mol−1 |
| Acidity (pKa) | 2.36 (carboxyl), 9.60 (amino)[1] |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Leucine (abbreviated as Leu or L)[2] is a branched-chain α-amino acid with the chemical formula HO2CCH(NH2)CH2CH(CH3)2. Leucine is classified as a hydrophobic amino acid due to its aliphatic isobutyl side chain. It is encoded by six codons (UUA, UUG, CUU, CUC, CUA, and CUG) and is a major component of the subunits in ferritin, astacin and other 'buffer' proteins. Leucine is an essential amino acid.
Contents |
As an essential amino acid, leucine is unable to be synthesised by animals. Consequently, it must be ingested, usually as a component of proteins. In plants and microorganisms, leucine is synthesised from pyruvic acid by a series of enzymes:[3]
Synthesis of the small, hydrophobic amino acid Valine also includes the initial part of this pathway.
Leucine is utilized in the liver, adipose tissue, and muscle tissue. In adipose and muscle tissue, leucine is used in the formation of sterols, and the combined usage of leucine in these two tissues is seven times greater than its use in the liver.[4]
Leucine is the only dietary amino acid that has the capacity to stimulate muscle protein synthesis.[5] As a dietary supplement, leucine has been found to slow the degradation of muscle tissue by increasing the synthesis of muscle proteins in aged rats.[6] While once seen as an important part of the three branch chained amino acids in sports supplements, leucine has since earned more attention on its own as a catalyst for muscle growth and muscular insurance. Supplement companies once marketed the "ideal" 2:1:1 ratio of leucine, iso-leucine and valine; but with furthered evidence that leucine is the most important amino acid for muscle building, it has become much more popular as the primary ingredient in dietary supplements.[7]
Leucine potently activates the mammalian target of rapamycin kinase that regulates cell growth. Infusion of leucine into the rat brain has been shown to decrease food intake and body weight via activation of the mTOR pathway.[8]
Leucine toxicity, as seen in decompensated Maple Syrup Urine Disease (MSUD), causes delirium and neurologic compromise, and can be life-threatening.
In yeast genetics, mutants with a defective gene for leucine synthesis (leu2) are transformed with a plasmid that contains a working leucine synthesis gene (LEU2) and grown on minimal media. Leucine synthesis then becomes a useful selectable marker.
| Food | g/100g |
|---|---|
| Soy protein concentrate | 4.917 |
| Soybeans, mature seeds, raw | 2.97 |
| Beef, round, top round, separable lean and fat, trimmed to 1/8" fat, select, raw | 1.76 |
| Peanuts | 1.672 |
| Salami, Italian, pork | 1.63 |
| Fish, salmon, pink, raw | 1.62 |
| Wheat germ | 1.571 |
| Almonds | 1.488 |
| Chicken, broilers or fryers, thigh, meat only, raw | 1.48 |
| Chicken egg, yolk, raw, fresh | 1.40 |
| Oat | 1.284 |
| Beans, pinto, cooked | 0.765 |
| Lentils, cooked | 0.654 |
| Chickpea, cooked | 0.631 |
| Corn, yellow | 0.348 |
| Cow milk, whole, 3.25% milk fat | 0.27 |
| Rice, brown, medium-grain, cooked | 0.191 |
| Milk, human, mature, fluid | 0.10 |
Leucine is a branched-chain amino acid (BCAA) since it possesses an aliphatic side-chain that is non-linear.
Racemic leucine had been subjected to circularly polarized synchrotron radiation in order to better understand the origin of biomolecular asymmetry. An enantiomeric enhancement of 2.6 % had been induced, indicating a possible photochemical origin of biomolecules' homochirality.[10]
As a food additive, L-Leucine has E number E641 and is classified as a flavor enhancer.
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