Glycogenolysis

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Glycogenolysis is the breakdown of glycogen (n) to glucose-1-phosphate and glycogen (n-1). Glycogen branches are catabolized by the sequential removal of glucose monomers via phosphorolysis, by the enzyme glycogen phosphorylase.

glycogen(n residues) + Pi ⇌ glycogen(n-1 residues) + glucose-1-phosphate

Here, glycogen phosphorylase cleaves the bond linking a terminal glucose residue to a glycogen branch by substitution of a phosphoryl group for the α[1→4] linkage. Glucose-1-phosphate is converted to glucose-1,6-bisphosphate (which often ends up in glycolysis) by the enzyme phosphoglucomutase.

Yeast glycogen phosphorylase dimer with pyridoxal-5-phosphate and phosphate (PDB entry 1ygp)

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References

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Alexander Berchansky

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