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Branched-chain amino acid

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Branched-chain amino acids (BCAA) are amino acids having aliphatic side-chains with a branch (a carbon atom bound to more than two other carbon atoms). There are three branched-chain amino acids leucine, isoleucine and valine of twelve common ones.[1]

leucine
valine

The BCAAs are among the nine essential amino acids for humans, accounting for 35% of the essential amino acids in muscle proteins and 40% of the preformed amino acids required by mammals[2]. BCAA’s have been used clinically to aid in the recovery of burn victims[3].

Degradation

Degradation of branched-chain amino acids involves the branched-chain alpha-keto acid dehydrogenase complex (BCKDH). A deficiency of this complex leads to a buildup of the branched-chain amino acid (leucine, isoleucine, and valine) and their toxic by-products in the blood and urine, giving the condition the name maple syrup urine disease.

Enzymes involved are branched chain aminotransferase and 3-methyl-2-oxobutanoate dehydrogenase.

The BCKDH complex converts branched-chain amino acids into Acyl-CoA derivatives, which after subsequent reactions are converted either into acetyl-CoA or succinyl-CoA that enter the citric acid cycle.[4]

References and notes

  1. ^ "Branched chain amino acids". LifeHugger. Retrieved 2009-09-23.
  2. ^ "Exercise Promotes BCAA Catabolism: Effects of BCAA Supplementation on Skeletal Muscle during Exercise". The Journal of Nutrition published by The American Society for Nutrition.
  3. ^ "Therapeutic Use of Branched-Chain Amino Acids in Burn, Trauma, and Sepsis". The Journal of Nutrition published by The American Society for Nutrition.
  4. ^ β-oxidation, TCA cycle and branched-chain amino acid degradation PNAS, published by the National Academy of Sciences
  • Karlsson HK, Nilsson PA, Nilsson J, Chibalin AV, Zierath JR, Blomstrand E (2004). "Branched-chain amino acids increase p70S6k phosphorylation in human skeletal muscle after resistance exercise". Am. J. Physiol. Endocrinol. Metab. 287 (1): E1–7. doi:10.1152/ajpendo.00430.2003. PMID 14998784.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  • Blomstrand E, Eliasson J, Karlsson HK, Köhnke R (2006). "Branched-chain amino acids activate key enzymes in protein synthesis after physical exercise". J. Nutr. 136 (1 Suppl): 269S–73S. PMID 16365096.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  • Norton LE, Layman DK (2006). "Leucine regulates translation initiation of protein synthesis in skeletal muscle after exercise". J. Nutr. 136 (2): 533S–537S. PMID 16424142.

See also

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