Acid Catalysis - removing the UDP

A group in the active that is in the acid state, acts to protonate the oxygen on C1 of of the UPD-Glucose. The effect is that a protonated UPG then leaves C1

Transition State

The results of the previous step is shown. UDP is protonated and released - free to leave the active site. C1 of the incoming glucose molecule is in a C⁺ (carbocation state) - this is very reactive ans shortlived. The oxygen of C4 of the existing glycogen polymer is deprtonated by a base which then attackes the carbocation.

The final results are shown - glycogen has grown by one glucose unit and UDP leaves the active site.

Anaerobic Glucose Metabolism

Glycogen Synthase Information

Reaction

Rationale

Thermodynamics

Mechanism

Pictures

JMOL

Enzyme Name	Glycogen Synthase

Reaction Catalyzed	Group Transfer of glucose onto C4 (always) of the terminal glucose of the glycogen polymer
Reaction Type	Group Transfer Reaction
Pathway Involvement	Glycogen Synthesis
Cofactors/Cosubstrates	None.

Rationale	Now that we have spent the last two reactions in the pathway preparing we are finally ready to add one glucose to the c4 of the terminal glucose on the polymer. Recall that glycogen is a branched polymer, but glycogen synthase only makes the 1→4 bonds in the growing polymer. Adding branch points is the responsibility of another enzyme = Branching Enzyme.

Mechanism for Chemistry
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Picture of Enzyme with substrate