Sandbox Reserved 338
From Proteopedia
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==Mechanism== | ==Mechanism== | ||
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Revision as of 19:18, 30 March 2011
| This Sandbox is Reserved from January 10, 2010, through April 10, 2011 for use in BCMB 307-Proteins course taught by Andrea Gorrell at the University of Northern British Columbia, Prince George, BC, Canada. |
To get started:
More help: Help:Editing |
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| 2vnc, resolution 3.00Å () | |||||||||
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| Related: | 2vuy, 2vr5, 2vnb | ||||||||
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| Resources: | FirstGlance, OCA, RCSB, PDBsum | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
Contents |
Introduction
A debranching enzyme is responsible for the breakdown of glycogen [1]. There are two main groups of debranching enzymes, and they are separated according to their activity [1]. The first group, consists of pullulanases and isoamylases which only exhibit α-1,6-glycosidase activity [1]. Whereas the second group consists of glycogen debranching enzymes which possess two functions; both α-1,6-glycosidase and α-1,4-transferase activity [1].
TreX is an archaeal glycogen debranching enzyme from the species, Sulfolobus solfataricus [1]. Even though TreX exhibits 74% sequence similarity to the isoamylase from Sulfolobus acidocaldarium, TreX itself exhibits both α-1,6-glycosidase and α-1,4-transferase activity [1]. It functions to debranch the side chains of glycogen into maltodextrin, and subsequently TreY and TreZ convert the maltodextrin into trehalose [1] [2]. TreX can be found in two oligomeric states, either as a dimer or as a tetramer. As TreX is an oligomer, each conformational state exhibits a different catalytic activity [1].
there is a glutamate residue, that I am interested in showing.
Structure and Function
TreX is an oligomer, as it exists in a dimeric state and a tetrameric state, both of which are active in solution [1]. All subunits are identical, where the monomer contains 612 amino acids in total [1]. The polypeptide folds into two secondary structures, a β-sandwhich in the N terminal region, comprised of six β-strands and a (β/α)8 – barrel motif in the central domain, comprised of eight parallel α-strands which encircle eight parallel β-strands [1]. The sequence composition of the TreX monomer exhibits a high degree of homology to the isoamylase debranching enzyme of Pseudomona, however the TreX monomer mainly deviates from this similarity in its substrate binding groove and the absence of a calcium ion ligand [1].
In the dimeric form, the individual subunits are adjacent to each other, where both of the active sites face the same side [1]. In the tetrameric form, two of the associated dimers face each other so as to position the active sites on the inside of the tetramer [1].
More to come…
Mechanism
This is my new image.References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 Woo EJ, Lee S, Cha H, Park JT, Yoon SM, Song HN, Park KH. Structural insight into the bifunctional mechanism of the glycogen-debranching enzyme TreX from the archaeon Sulfolobus solfataricus. J Biol Chem. 2008 Oct 17;283(42):28641-8. Epub 2008 Aug 14. PMID:18703518 doi:10.1074/jbc.M802560200
- ↑ doi: https://dx.doi.org/10.1080/10242420701806652
