1iew
From Proteopedia
| Line 1: | Line 1: | ||
| - | [[Image:1iew.gif|left|200px]] | + | [[Image:1iew.gif|left|200px]] |
| - | + | ||
| - | '''Crystal structure of barley beta-D-glucan glucohydrolase isoenzyme Exo1 in complex with 2-deoxy-2-fluoro-alpha-D-glucoside''' | + | {{Structure |
| + | |PDB= 1iew |SIZE=350|CAPTION= <scene name='initialview01'>1iew</scene>, resolution 2.55Å | ||
| + | |SITE= | ||
| + | |LIGAND= <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene> and <scene name='pdbligand=G2F:2-DEOXY-2FLUORO-GLUCOSE'>G2F</scene> | ||
| + | |ACTIVITY= [http://en.wikipedia.org/wiki/Glucan_1,3-beta-glucosidase Glucan 1,3-beta-glucosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.58 3.2.1.58] | ||
| + | |GENE= | ||
| + | }} | ||
| + | |||
| + | '''Crystal structure of barley beta-D-glucan glucohydrolase isoenzyme Exo1 in complex with 2-deoxy-2-fluoro-alpha-D-glucoside''' | ||
| + | |||
==Overview== | ==Overview== | ||
| Line 7: | Line 16: | ||
==About this Structure== | ==About this Structure== | ||
| - | 1IEW is a [ | + | 1IEW is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Hordeum_vulgare Hordeum vulgare]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IEW OCA]. |
==Reference== | ==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:[http:// | + | 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:[http://www.ncbi.nlm.nih.gov/pubmed/11709165 11709165] |
[[Category: Glucan 1,3-beta-glucosidase]] | [[Category: Glucan 1,3-beta-glucosidase]] | ||
[[Category: Hordeum vulgare]] | [[Category: Hordeum vulgare]] | ||
| Line 23: | Line 32: | ||
[[Category: 2-domain fold]] | [[Category: 2-domain fold]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 11:49:28 2008'' |
Revision as of 09:49, 20 March 2008
| |||||||
| , resolution 2.55Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | and | ||||||
| Activity: | Glucan 1,3-beta-glucosidase, with EC number 3.2.1.58 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Crystal structure of barley beta-D-glucan glucohydrolase isoenzyme Exo1 in complex with 2-deoxy-2-fluoro-alpha-D-glucoside
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.
About this Structure
1IEW 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 Thu Mar 20 11:49:28 2008
