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.


1iex

From Proteopedia

(Difference between revisions)
Jump to: navigation, search
Line 1: Line 1:
-
[[Image:1iex.gif|left|200px]]
+
{{Seed}}
 +
[[Image:1iex.png|left|200px]]
<!--
<!--
Line 9: Line 10:
{{STRUCTURE_1iex| PDB=1iex | SCENE= }}
{{STRUCTURE_1iex| PDB=1iex | SCENE= }}
-
'''Crystal structure of barley beta-D-glucan glucohydrolase isoenzyme Exo1 in complex with 4I,4III,4V-S-trithiocellohexaose'''
+
===Crystal structure of barley beta-D-glucan glucohydrolase isoenzyme Exo1 in complex with 4I,4III,4V-S-trithiocellohexaose===
-
==Overview==
+
<!--
-
BACKGROUND: Barley beta-D-glucan glucohydrolases represent family 3 glycoside hydrolases that catalyze the hydrolytic removal of nonreducing glucosyl residues from beta-D-glucans and beta-D-glucooligosaccharides. After hydrolysis is completed, glucose remains bound in the active site. RESULTS: When conduritol B epoxide and 2', 4'-dinitrophenyl 2-deoxy-2-fluoro-beta-D-glucopyranoside are diffused into enzyme crystals, they displace the bound glucose and form covalent glycosyl-enzyme complexes through the Odelta1 of D285, which is thereby identified as the catalytic nucleophile. A nonhydrolyzable S-glycosyl analog, 4(I), 4(III), 4(V)-S-trithiocellohexaose, also diffuses into the active site, and a S-cellobioside moiety positions itself at the -1 and +1 subsites. The glycosidic S atom of the S-cellobioside moiety forms a short contact (2.75 A) with the Oepsilon2 of E491, which is likely to be the catalytic acid/base. The glucopyranosyl residues of the S-cellobioside moiety are not distorted from the low-energy 4C(1) conformation, but the glucopyranosyl ring at the +1 subsite is rotated and translated about the linkage. CONCLUSIONS: X-ray crystallography is used to define the three key intermediates during catalysis by beta-D-glucan glucohydrolase. Before a new hydrolytic event begins, the bound product (glucose) from the previous catalytic reaction is displaced by the incoming substrate, and a new enzyme-substrate complex is formed. The second stage of the hydrolytic pathway involves glycosidic bond cleavage, which proceeds through a double-displacement reaction mechanism. The crystallographic analysis of the S-cellobioside-enzyme complex with quantum mechanical modeling suggests that the complex might mimic the oxonium intermediate rather than the enzyme-substrate complex.
+
The line below this paragraph, {{ABSTRACT_PUBMED_11709165}}, adds the Publication Abstract to the page
 +
(as it appears on PubMed at http://www.pubmed.gov), where 11709165 is the PubMed ID number.
 +
-->
 +
{{ABSTRACT_PUBMED_11709165}}
==About this Structure==
==About this Structure==
Line 30: Line 34:
[[Category: Varghese, J N.]]
[[Category: Varghese, J N.]]
[[Category: 2-domain fold]]
[[Category: 2-domain fold]]
-
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 19:55:45 2008''
+
 
 +
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 10:52:05 2008''

Revision as of 07:52, 1 July 2008

Image:1iex.png

Template:STRUCTURE 1iex

Crystal structure of barley beta-D-glucan glucohydrolase isoenzyme Exo1 in complex with 4I,4III,4V-S-trithiocellohexaose

Template:ABSTRACT PUBMED 11709165

About this Structure

1IEX is a Single protein structure of sequence from Hordeum vulgare. Full crystallographic information is available from OCA.

Reference

Catalytic mechanisms and reaction intermediates along the hydrolytic pathway of a plant beta-D-glucan glucohydrolase., Hrmova M, Varghese JN, De Gori R, Smith BJ, Driguez H, Fincher GB, Structure. 2001 Nov;9(11):1005-16. PMID:11709165

Page seeded by OCA on Tue Jul 1 10:52:05 2008

Proteopedia Page Contributors and Editors (what is this?)

OCA

Retrieved from "http://52.214.119.220/wiki/index.php/1iex"
Personal tools