glycogen debranching enzyme (GDE)

Question 1

GDE structure

Answer 1

monomeric with two different active sites. These are known as the transferase (GT) and Glucosidase (GC)

Four domains.

Question 2

Transferase GT

Answer 2

working on an alpha 1-4, and will be breaking them.

Moves a 3C sugar unit from a GP-limited branch.

When GP is moving down a glycogen chain, it gets stuck at a branch due to its crevice only fitting the linear portion of the chain. So, can yank off the limit branch and transfer it over to another branch by lengthening it.

** Not only are we breaking alpha 1-4, also reforming an alpha 1-4 as well. THIS IS ENERGY NEUTRAL**

Question 3

glucosidase GC

Answer 3

removes last alpha 1-6 sugar by hydrolysis and no phospho sugar is made.

Breaking the 1-6 bond is the driving force, because we are releasing energy.