Branched-chain amino acids

leucine

isoleucine

valine

The phrase branched-chain amino acids or BCAA is sometimes used to refer to the amino acids having aliphatic side-chains that are non-linear. These are leucine, isoleucine and valine. The combination of these three essential amino acids makes up approximately 1/3 of skeletal muscle in the human body, and plays an important role in protein synthesis. BCAA’s are currently used clinically to aid in the recovery of burn victims, as well as for supplementation for strength athletes.

Degradation

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The body uses branched chain aminotransferase and 3-methyl-2-oxobutanoate dehydrogenase to degrade branched-chain amino acids.

Insulin stimulation

The BCAAs stimulate the effect of insulin in three different manners. The first manner through which the metabolic pathway is affected is the increased production of insulin. It has been demonstrated that BCAA supplementation in accordance with carbohydrate intake following resistance exercise increases insulin output by 221%, which is much greater than the 66% supplementation without leucine. Leucine is the most readily oxidized BCAA and therefore the most effective at causing insulin secretion from the pancreas, and stimulating the metabolic pathway. This is important because insulin is the initiating factor that begins the signalling cascade. The second effect is outlined with the red arrows clearly indicating a phosphorylation cascade beginning with the activation of the Ras Rhed and ending with rpS6. The importance of rpS6 is that it induces mRNA translation. This translation leads to the production of proteins. The other side of the pathway indicated by the blue arrow induces the action of eIF4G. This initiation factor causes the binding of mRNA within the ribosome thus providing the initial products needed for translation. This leads down to the final product via protein binding and phosphorylation, resulting in eIF4E which induces mRNA translation which in turn leads to chain elongation, and termination, resulting in net protein growth.^{[citation needed]}

References

See also

• Branched-chain alpha-keto acid dehydrogenase complex
• Branched chain aminotransferase

External links

• MeSH Branched-chain+amino+acids

v • d • e Metabolism map Glucuronate metabolism Pentose interconversion Inositol metabolism Cellulose and sucrose metabolism Starch and glycogen metabolism Other sugar metabolism Pentose phosphate pathway Glycolysis and Gluconeogenesis Amino sugars metabolism Small amino acid synthesis Branched amino acid synthesis Purine biosynthesis Histidine metabolism Aromatic amino acid synthesis Pyruvate decarboxylation Fermentation Fatty acid metabolism Urea cycle Aspartate amino acid group synthesis Porphyrins and corrinoids metabolism Citric acid cycle Glutamate amino acid group synthesis Pyrimidine biosynthesis  v • d • e  All pathway labels on this image are links, simply click to access the article. A high resolution labeled version of this image is available here.