Is Oxaloacetate, a TCA cycle intermediate also a metabolite in gluconeogenesis? If not, which ones of these TCA cycle intermediates are also a metabolite in gluconeogenesis? Succinate Oxaloacetate Pyruvate Citrate
Is Oxaloacetate, a TCA cycle intermediate also a metabolite in gluconeogenesis?
If not, which ones of these TCA cycle intermediates are also a metabolite in gluconeogenesis?
Gluconeogenesis is the synthesis of glucose from non-carbohydrate precursors. Gluconeogenesis is a universal pathway, found in all animals, plants, fungi and microorganisms.
Site of gluconeogenesis: In higher animals, gluconeogenesis occurs in the liver and, to a smaller extent, in the kidney cortex. Under normal circumstances, the liver is responsible for 85% to 95% of the glucose that is made.. During starvation or during metabolic acidosis, the kidney is capable of making glucose and then may contribute up to 50% of the glucose formed, since, in these conditions, the amount contributed by the liver decreases considerably.
Precursors of gluconeogenesis: Gluconeogenetic precursors include:
- Gycolytic products like lactate, pyruvate, glycerol
- Citric acid cycle intermediates and
- Some amino acids (termed glucogenic amino acids). Lysine and leucine are the only amino acids that are not substrate for gluconeogenesis. These amino acids produce only acetyl-CoA upon degradation.
Animal cells can carry out gluconeogenesis from three- and four-carbon precursors, but not from the two acetyl actors of acetyl-CoA. Animal cells have no way to convert acetyl-CoA to pyruvate or oxaloacetate. Thus, fatty acids are not substrates for gluconeogenesis in animals, because most fatty acids yield only acetyl-CoA upon degradation. Unlike animals, plants and some microorganisms can convert acetyl-CoA derived from fatty acid oxidation to glucose.
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