This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.

Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.


2exk

From Proteopedia

(Difference between revisions)
Jump to: navigation, search
Line 1: Line 1:
-
[[Image:2exk.gif|left|200px]]
+
{{Seed}}
 +
[[Image:2exk.png|left|200px]]
<!--
<!--
Line 9: Line 10:
{{STRUCTURE_2exk| PDB=2exk | SCENE= }}
{{STRUCTURE_2exk| PDB=2exk | SCENE= }}
-
'''Structure of the family43 beta-Xylosidase E187G from geobacillus stearothermophilus in complex with xylobiose'''
+
===Structure of the family43 beta-Xylosidase E187G from geobacillus stearothermophilus in complex with xylobiose===
-
==Overview==
+
<!--
-
beta-D-Xylosidases are glycoside hydrolases that catalyze the release of xylose units from short xylooligosaccharides and are engaged in the final breakdown of plant cell-wall hemicellulose. Here we describe the enzyme-substrate crystal structure of an inverting family 43 beta-xylosidase, from Geobacillus stearothermophilus T-6 (XynB3). Each XynB3 monomeric subunit is organized in two domains: an N-terminal five-bladed beta-propeller catalytic domain, and a beta-sandwich domain. The active site possesses a pocket topology, which is mainly constructed from the beta-propeller domain residues, and is closed on one side by a loop that originates from the beta-sandwich domain. This loop restricts the length of xylose units that can enter the active site, consistent with the exo mode of action of the enzyme. Structures of the enzyme-substrate (xylobiose) complex provide insights into the role of the three catalytic residues. The xylose moiety at the -1 subsite is held by a large number of hydrogen bonds, whereas only one hydroxyl of the xylose unit at the +1 subsite can create hydrogen bonds with the enzyme. The general base, Asp15, is located on the alpha-side of the -1 xylose sugar ring, 5.2 Angstroms from the anomeric carbon. This location enables it to activate a water molecule for a single-displacement attack on the anomeric carbon, resulting in inversion of the anomeric configuration. Glu187, the general acid, is 2.4 Angstroms from the glycosidic oxygen atom and can protonate the leaving aglycon. The third catalytic carboxylic acid, Asp128, is 4 Angstroms from the general acid; modulating its pK(a) and keeping it in the correct orientation relative to the substrate. In addition, Asp128 plays an important role in substrate binding via the 2-O of the glycon, which is important for the transition-state stabilization. Taken together, these key roles explain why Asp128 is an invariant among all five-bladed beta-propeller glycoside hydrolases.
+
The line below this paragraph, {{ABSTRACT_PUBMED_16631196}}, adds the Publication Abstract to the page
 +
(as it appears on PubMed at http://www.pubmed.gov), where 16631196 is the PubMed ID number.
 +
-->
 +
{{ABSTRACT_PUBMED_16631196}}
==About this Structure==
==About this Structure==
Line 33: Line 37:
[[Category: Xylose]]
[[Category: Xylose]]
[[Category: Xylosidase]]
[[Category: Xylosidase]]
-
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 03:13:51 2008''
+
 
 +
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 10:38:03 2008''

Revision as of 07:38, 28 July 2008

Image:2exk.png

Template:STRUCTURE 2exk

Structure of the family43 beta-Xylosidase E187G from geobacillus stearothermophilus in complex with xylobiose

Template:ABSTRACT PUBMED 16631196

About this Structure

2EXK is a Single protein structure of sequence from Geobacillus stearothermophilus. Full crystallographic information is available from OCA.

Reference

The structure of an inverting GH43 beta-xylosidase from Geobacillus stearothermophilus with its substrate reveals the role of the three catalytic residues., Brux C, Ben-David A, Shallom-Shezifi D, Leon M, Niefind K, Shoham G, Shoham Y, Schomburg D, J Mol Biol. 2006 May 26;359(1):97-109. Epub 2006 Mar 20. PMID:16631196

Page seeded by OCA on Mon Jul 28 10:38:03 2008

Proteopedia Page Contributors and Editors (what is this?)

OCA

Retrieved from "http://52.214.119.220/wiki/index.php/2exk"
Personal tools