gluconeogeneesiä

Gluconeogenesis is a metabolic pathway that produces glucose from non-carbohydrate precursors, primarily amino acids, lactate, and glycerol. This process is crucial for maintaining blood glucose levels, especially during fasting or periods of low carbohydrate intake. Gluconeogenesis occurs primarily in the liver and, to a lesser extent, in the kidneys.

The pathway begins with the conversion of pyruvate, derived from amino acids or lactate, into oxaloacetate. This step is facilitated by the enzyme pyruvate carboxylase, which requires biotin as a cofactor. Oxaloacetate is then converted into phosphoenolpyruvate (PEP) by the enzyme phosphoenolpyruvate carboxykinase (PEPCK). PEP is subsequently converted into fructose 1,6-bisphosphate, which can enter the glycolytic pathway to produce glucose.

Glycerol, derived from triglycerides, can also be converted into glucose through gluconeogenesis. Glycerol is first phosphorylated to glycerol 3-phosphate, which is then converted into dihydroxyacetone phosphate (DHAP). DHAP can enter the glycolytic pathway to produce glucose.

Gluconeogenesis is regulated by various hormones and metabolic signals. For example, glucagon, a hormone released by the pancreas in response to low blood glucose levels, stimulates gluconeogenesis by activating the enzyme PEPCK. Conversely, insulin, which is released in response to high blood glucose levels, inhibits gluconeogenesis by suppressing the activity of PEPCK.

In summary, gluconeogenesis is a vital metabolic pathway that ensures the continuous supply of glucose to the body, particularly during periods of low carbohydrate intake. It is regulated by various hormones and metabolic signals to maintain blood glucose levels within a narrow range.