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Simplified gluconeogenesis processed (in humans). Acetyl-CoA derived from fatty acids (dotted lines) may be changed to pyruvate a bit under fasting.

Gluconeogenesis (GNG) is a chemical process in living bodies. In gluconeogenesis, the body turns fats and proteins (glucogenic amino acids) into sugars called glucose.[1] In most animals with spines, gluconeogenesis happens in the liver, but some animals have gluconeogenesis in the kidneys.[2] gluconeogenesis usually happens when the organism has not eaten many starches or sugars or eaten nothing at all for a long time. Not eating and not eating starch can cause ketosis, which is when some cells cannot use ketones for fuel.[3]

Process[change | change source]

Simplification of proteinogenic amino acids. Some amino acids can be used in gluconeogenesis and some cannot:[4]

In humans, the main gluconeogenic compounds are lactate, glycerol (a part of the triglyceride molecule), alanine and glutamine. They are involved in over 90% of the overall process.[5]

Lactate comes back to the liver where it is converted into pyruvate by the Cori cycle using the enzyme lactate dehydrogenase. Pyruvate, the first designated substrate of the gluconeogenic pathway, can then be used to make glucose.[6]

Fat is mostly broken down, but if there is no fat to break down, or the body cannot access the fat stores, then proteins found in the muscle can break down, resulting in muscle loss.[7]

References[change | change source]

  1. Lehninger, Albert L.; Nelson, David L. (David Lee); Cox, Michael M. (2000). Lehninger principles of biochemistry. Duke University Libraries. New York : Worth Publishers. ISBN 978-1-57259-153-0.
  2. "Key protein causing excess liver production of glucose in diabetes identified". ScienceDaily. Retrieved 2021-06-03.
  3. Rui, Liangyou (January 2014). "Energy Metabolism in the Liver". Comprehensive Physiology. 4 (1): 177–197. doi:10.1002/cphy.c130024. ISBN 9780470650714. ISSN 2040-4603. PMC 4050641. PMID 24692138.
  4. Ferrier DR, Champe PC, Harvey RA (1 August 2004). "20. Amino Acid Degradation and Synthesis". Biochemistry (Lippincott's Illustrated Reviews). Hagerstwon, MD: Lippincott Williams & Wilkins. ISBN 978-0-7817-2265-0.
  5. Gerich JE, Meyer C, Woerle HJ, Stumvoll M (February 2001). "Renal gluconeogenesis: its importance in human glucose homeostasis". Diabetes Care. 24 (2): 382–91. doi:10.2337/diacare.24.2.382. PMID 11213896.
  6. Garrett RH, Grisham CM (2002). Principles of Biochemistry with a Human Focus. USA: Brooks/Cole, Thomson Learning. pp. 578, 585. ISBN 978-0-03-097369-7.
  7. Manninen, Anssi H (2006-01-31). "Very-low-carbohydrate diets and preservation of muscle mass". Nutrition & Metabolism. 3: 9. doi:10.1186/1743-7075-3-9. ISSN 1743-7075. PMC 1373635. PMID 16448570.