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* 4-α-D-glucanotransferase ({{EC number|2.4.1.25}}), or [[glucosyltransferase]], transfers three glucose [[residue (chemistry)|residues]] from the four-residue glycogen branch to a nearby branch. This exposes a single glucose residue joined to the glucose chain through an α -1,6 glycosidic linkage<ref name="Berg"/>
* Amylo-α-1,6-glucosidase ({{EC number|3.2.1.33}}), or [[glucosidase]], cleaves the remaining alpha-1,6 linkage, producing glucose and a linear chain of glycogen.<ref name=Berg/> The mechanism by which the glucosidase cleaves the α -1,6-linkage is not fully known because the [[amino acids]] in the [[active site]] have not yet been identified. It is thought to proceed through a two step acid base assistance type mechanism, with an [[oxocarbenium]] ion intermediate, and retention of configuration in glucose.<ref name=Molecule/> This is a common method through which to cleave bonds, with an acid below the site of [[hydrolysis]] to lend a proton and a base above to deprotinate a water which can then act as a [[nucleophile]]. These acids and bases are amino acid side chains in the active site of the enzyme. A scheme for the mechanism is shown in the figure below.<ref name=MCCarter/>
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[[File:Hypothesized substraight binding ___location.png]]
It was seen that when glucose ‘a’, ‘b’, ‘c’ and ‘0’ in the [[active site]] was hydrolyzed the most rapidly.<ref name=Yamamoto/> This indicated that this region of the glycogen chain bond strongest to the active site because a stronger interaction between enzyme and substrate leads to a more rapid hydrolysis.
Despite these advances, the complete structure of GDE in eukaryotes has yet to be determined.<ref name="Woo"/> The glycogen-degrading enzyme of the [[archaea]] ''[[Sulfolobus solfataricus]]'' is better characterized than those of [[eukaryotes]]. The GDE of ''S. solfataricus'' is known as treX. Although, like mammalian GDE, treX has both amylosidase and glucanotransferase functions, TreX is structurally similar to glgX, and hass a mass of 80kD and one active site.<ref name=Woo/><ref name ="UniProt A8QX06"/> Unlike either glgX or AGL, however, treX exists as a dimer and tetramer in solution. TreX's oligomeric form seems to play a significant role in altering both enzyme shape and function. Dimerization is thought to stabilize a "flexible loop" located close to the active site. This may be key to explaining why treX (and not glgX) shows glucosyltransferase activity. As a tetramer, the catalytic efficiency of treX is increased fourfold over its dimeric form.<ref name=Song/><ref name="Park"/>
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