1ieq

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[[Image:1ieq.gif|left|200px]]<br /><applet load="1ieq" size="350" color="white" frame="true" align="right" spinBox="true"
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[[Image:1ieq.gif|left|200px]]
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caption="1ieq, resolution 2.70&Aring;" />
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'''CRYSTAL STRUCTURE OF BARLEY BETA-D-GLUCAN GLUCOHYDROLASE ISOENZYME EXO1'''<br />
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{{Structure
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|PDB= 1ieq |SIZE=350|CAPTION= <scene name='initialview01'>1ieq</scene>, resolution 2.70&Aring;
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|SITE=
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|LIGAND= <scene name='pdbligand=GLC:GLUCOSE'>GLC</scene>
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|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]
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|GENE=
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}}
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'''CRYSTAL STRUCTURE OF BARLEY BETA-D-GLUCAN GLUCOHYDROLASE ISOENZYME EXO1'''
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==Overview==
==Overview==
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==About this Structure==
==About this Structure==
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1IEQ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Hordeum_vulgare Hordeum vulgare] with <scene name='pdbligand=GLC:'>GLC</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [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] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IEQ OCA].
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1IEQ 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=1IEQ OCA].
==Reference==
==Reference==
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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://ispc.weizmann.ac.il//pmbin/getpm?pmid=11709165 11709165]
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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]]
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[[Category: 2-domain fold]]
[[Category: 2-domain fold]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:11:09 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 11:49:26 2008''

Revision as of 09:49, 20 March 2008


PDB ID 1ieq

Drag the structure with the mouse to rotate
, resolution 2.70Å
Ligands:
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


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

1IEQ 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

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