Predict the effect on Gluconeogenesis in the following scenarios Increase |Decre

Question

Predict the effect on Gluconeogenesis in the following scenarios Increase |Decre 2 pts each Inhibition of phosphoenolpyruvate carboxykinase (PEPKC more acetyl-CoA available Phosphorylation of phosphofructokinase-2 Increase in ATPIAMP ratio High concentration of Fructose- 2,6- bisphosphate High citrate levels Mutation leading to loss of pyruvate carboxylase activit decrease of cAMP Mutation leading to loss of Protein Kinase A activi Mutation leading to increase of Phosphoprotein phosphatase activit

Explanation / Answer

Gluconeonenesis is process of formation of glucose from fats , proteins etc . That is from non carbohydrate substrate .

Inhibition of PEPKC = PEPKC is rate limiting enzyme of gluconeogenesis.

Ihibition of this enzyme leads to stop formation of phosphoenolpyruvate ,so decrease in gluconeogenesis.

More acetyl coenzyme A available = it activates the enzymes of gluconeogenesis

So enzyme activity increase leads to increase in gluconeogenesis .

Phosphorylation of phosphofructokinase -2 = this enzyme inhibits fructose 1,6-biphosphase enzyme

So it will decrease gluconeogenesis

Increase in ATP/AMP ratio= more energy available so increade in gluconeogenesis .

and phosphofructokinase is not affected by ATP

High concentration of fructose 2,6- biphosphate= it will block production of fructose 6 phosphate from fructose 1,6 biphosphate

So decrease in gluconeogenesis.

High citrate concentration = as it activate enzymes of this pathway ( pyruvate carboxylase , fructose 1,6- biphosphatase)

So it will increase gluconeogenesis

Mutation leading to loss pf pyruvate carboxylase activity = as it replenish oxaloacetic acid  

It catalyses first step , so loss of this cause decrease in gluconeogenesis .

Decrease cyclic AMP = less cAMP less protein kinase activity so less gluconeogenesis

Mutation leading to increase of phosphoprotein phosphatase activity = stimulation of this is by insulin , and insulin inhibit gluconeogenesis of

Decrease by this enzyme

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