Unique Steps of Gluconeogenesis

Reactions that are bypassed or you can say which are unique are :

 These are the four steps.
Note: These steps are irreversible steps of glycolysis and as gluneogenesis is reverse of glycolysis these irreversible steps are bypassed by using following enzymes.

Step 1 is conversion of pyruvate --> oxaloacetate and is catalyzed by : Pyruvate Carboxylase


Step 2 is the conversion of  by oxaloacetate --> PEP
Thus PEP  is an intermediate of glycolysis so the reaction move in opposite direction as far as Fructose 1,6-Bisphosphate step is reached.


*Step 3 is the conversion of
  Fructose 1,6-Bisphosphate -->  Fructose 6-phosphate


Step 4 is the conversion of Glucose 6-phosphate --> Glucose 

Global Regulation in liver cells includes reciprocal effects of a cyclic AMP, triggered by the hormone glucagon when blood glucose is low. Phosphorylation of enzymes and regulatory proteins in liver by Protein Kinase A (cAMP-Dependent Protein Kinaseresults in inhibition of glycolysis and stimulation of gluconeogenesis, making glucose available for release to the blood. 

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Posted in: Biochemistry