|Jmol interactive 3D||Image|
|Molar mass||131.18 g·mol−1|
|Acidity (pKa)||2.36 (carboxyl), 9.60 (amino)|
|Supplementary data page|
|Refractive index (n),
Dielectric constant (εr), etc.
|UV, IR, NMR, MS|
|what is ?)(|
Leucine (abbreviated as Leu or L) is an essential, branched-chain α-amino acid, classified hydrophobic due to the isobutyl side chain. Its chemical formula is HO2CCH(NH2)CH2CH(CH3)2. L-Leucine 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.
As an essential amino acid, leucine cannot be synthesized 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:
- Acetolactate synthase
- Acetohydroxy acid isomeroreductase
- Dihydroxyacid dehydratase
- α-Isopropylmalate synthase
- α-Isopropylmalate isomerase
- Leucine aminotransferase
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.
Leucine is an activator of mTOR; it is the only dietary amino acid that has the capacity to directly stimulate muscle protein synthesis. 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. However, results of comparative studies are conflicted. Long-term leucine supplementation does not increase muscle mass or strength in healthy elderly men. More studies are needed, preferably those which utilize an objective, random sample of society. Factors such as lifestyle choices, age, gender, diet, exercise, etc. must be factored into the analyses in order to isolate the effects of supplemental leucine as a standalone, or if taken with other branched chain amino acids (BCAAs). Until then, dietary supplemental leucine cannot be associated as the prime reason for muscular growth or optimal maintenance for the entire population.
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.
Leucine toxicity, as seen in decompensated maple syrup urine disease (MSUD), causes delirium and neurologic compromise, and can be life-threatening. More studies need to be done on liver overactivity due to taking supplemental leucine.
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.
|Soybeans, mature seeds, raw||2.97|
|Beef, round, top round, separable lean and fat, trimmed to 1/8" fat, select, raw||1.76|
|Fish, salmon, pink, raw||1.62|
|Chicken, broilers or fryers, thigh, meat only, raw||1.48|
|Chicken egg, yolk, raw, fresh||1.40|
|Beans, pinto, cooked||0.765|
|Cow milk, whole, 3.25% milk fat||0.27|
|Rice, brown, medium-grain, cooked||0.191|
|Milk, human, mature, fluid||0.10|
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.
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- Leucine biosynthesis
- Leucine prevents muscle loss in rats
- Leucine helps regulate appetite in rats
- Combined ingestion of protein and free leucine with carbohydrate increases postexercise muscle protein synthesis in vivo in male subjects
- A leucine-supplemented diet restores the defective postprandial inhibition of proteasome-dependent proteolysis in aged rat skeletal muscle