What are the enzymatic regulations in breakdown of glycogen?

Expert Solution

Regulation of glycogen breakdown and synthesis: is controlled by two key enzyme (glycogen phosphorylase and glycogen synthase) activities which are activated/inactivated by allosteric regulation and phosphorylation / dephosphorylation.

Glycogen breakdown

Glycogen structure

- Glucose molecules in the main chains are connected by α(1→4) glycosidic bonds.

- The branches are attached by α(1→6) glycosidic linkages.

- A glucose unit on the non-reducing ends is cleaved or attached one by one.

Different pathways of glycogen breakdown

In muscle: Glycogen → glucose-6-phosphate (G6P) → glycolysis –

In liver: Glycogen → G6P → glucose → bloodstream → various cells → glycolysis –

Because the muscle cells mainly consume glucose molecules whereas the liver cells mainly store the glucose molecules.

Glycogen breakdown requires three enzymes

Glycogen phosphorylase (simply call it phosphorylase)

Glycogen debranching enzyme

Phosphoglucomutase

queen_honey_blossom answered 2 years ago

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