Glycogen Synthesis and Breakdown Enzymes

Glycogen Syntheis

Glyconeogenesis: 2 ATP used

Phosphoglucomutase

Converts glucose 6-phosphate into glucose 1-phosphate (uses 1 ATP)

UDP glucose-phosphorylase

Converts UTP glucose to UDP glucose (uses 1 UTP)

Pyrophosphatase

Hydrolyses pyrophosphate into 2Pi so that the UDP glucose formation reaction can be irreversible

Glycogenin

Provides the necessary 4 glucose primer for glycogen synthase

Glycogen synthase

Joins the glucose from UDP glucose to the non-reducing end of the pre-existing glycogen chain in an alpha 1-4 linkage resulting in longer glycogen chain + UDP

Glycogen branching enzyme

Moves the 7 glucose residues left of the non-reducing end of a glycogen chain (min. 11) away to be branched and bonded through alpha 1-6 linkage to make a lot of non-reducing ends + increased solubility

Glycogen Breakdown

Glycogenlysis: 3 ATP produced

Glycogen phosphorylase

Removes a glucose molecule from the glycogen chain using inorganic phosphate resulting in shorter glycogen chain and glucose 1-phosphate BUT stops 4 residues from branching point

Glycogen debranching enzyme

Transferase: Shifts three residues from C1 linked side to C6 linked side

Alpha 1-6 glusidase: Uses H20 to cleave the alpha 1-6 linkages to yield a free glucose

Phosphoglucomutase (OG)

Converts glucose 1-phosphate back to glucose 6-phosphate (save one ATP)