Chemistry:Ketogenic amino acid

From HandWiki
Summary of amino acid catabolism

A ketogenic amino acid is an amino acid that can be degraded directly into acetyl-CoA, which is the precursor of ketone bodies and myelin, particularly during early childhood, when the developing brain requires high rates of myelin synthesis.[1] This is in contrast to the glucogenic amino acids, which are converted into glucose. Ketogenic amino acids are unable to be converted to glucose as both carbon atoms in the ketone body are ultimately degraded to carbon dioxide in the citric acid cycle.

In humans, two amino acids – leucine and lysine – are exclusively ketogenic. Five more are both ketogenic and glucogenic: phenylalanine, isoleucine, threonine, tryptophan and tyrosine. The remaining thirteen are exclusively glucogenic.[2]

Studies

Ketogenic amino acids serve important roles in the human body, leading to the study of ketogenic amino acid rich (KAAR) diets as possible treatment for non-alcoholic fatty liver disease (NAFLD) and diabetes.[3] Dietary studies of fatty liver disease in mice show that decreasing the intake of ketogenic amino acids lysine and threonine may induce hepatic steatosis, a major cause of non-alcoholic fatty liver disease.[4] Leucine in particular has been shown to serve an important role in the metabolic pathway for insulin via activation of the rapamycin complex 1 (mTORC1) and protein S6 kinase 1 (S6K1) for which over-activation leads to insulin resistance.[5] Further studies illustrate that ketogenic amino acid rich diets may aid in decreasing obesity and insulin resistance, but their usage remains disputed.[3]

See also

References

  1. Yudkoff, Marc; Daikhin, Yevgeny; Melø, Torun Margareta; Nissim, Ilana; Sonnewald, Ursula; Nissim, Itzhak (2007). "The Ketogenic Diet and Brain Metabolism of Amino Acids: Relationship to the Anticonvulsant Effect". Annual Review of Nutrition 27: 415–430. doi:10.1146/annurev.nutr.27.061406.093722. ISSN 0199-9885. PMID 17444813. 
  2. Berg, Jeremy; Tymoczko, John; Stryer, Lubert (2015-04-08). "Protein Turnover and Amino Acid Catabolism". Biochemistry (8th ed.). ISBN 978-1-4641-2610-9. http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=stryer.chapter.3193. 
  3. 3.0 3.1 "Ketogenic essential amino acids modulate lipid synthetic pathways and prevent hepatic steatosis in mice". PLOS ONE 5 (8): e12057. August 2010. doi:10.1371/journal.pone.0012057. PMID 20706589. Bibcode2010PLoSO...512057N. 
  4. "The production of fatty livers in rats on threonine-and lysine-deficient diets". The Journal of Biological Chemistry 200 (2): 867–74. February 1953. doi:10.1016/S0021-9258(18)71436-1. PMID 13034849. http://www.jbc.org/content/200/2/867. 
  5. "Amino acids and leucine allow insulin activation of the PKB/mTOR pathway in normal adipocytes treated with wortmannin and in adipocytes from db/db mice". FASEB Journal 18 (15): 1894–6. December 2004. doi:10.1096/fj.03-1409fje. PMID 15479767. 

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