1edt
From Proteopedia
(New page: 200px<br /><applet load="1edt" size="450" color="white" frame="true" align="right" spinBox="true" caption="1edt, resolution 1.90Å" /> '''CRYSTAL STRUCTURE OF...) |
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| - | [[Image:1edt.jpg|left|200px]]<br /><applet load="1edt" size=" | + | [[Image:1edt.jpg|left|200px]]<br /><applet load="1edt" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1edt, resolution 1.90Å" /> | caption="1edt, resolution 1.90Å" /> | ||
'''CRYSTAL STRUCTURE OF ENDO-BETA-N-ACETYLGLUCOSAMINIDASE H AT 1.9 ANGSTROMS RESOLUTION: ACTIVE SITE GEOMETRY AND SUBSTRATE RECOGNITION'''<br /> | '''CRYSTAL STRUCTURE OF ENDO-BETA-N-ACETYLGLUCOSAMINIDASE H AT 1.9 ANGSTROMS RESOLUTION: ACTIVE SITE GEOMETRY AND SUBSTRATE RECOGNITION'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Endo-beta-N-acetylglucosaminidase H (Endo H), an | + | BACKGROUND: Endo-beta-N-acetylglucosaminidase H (Endo H), an endoglycosidase secreted by Streptomyces plicatus, hydrolyzes the glycosidic bond between the core N-acetyglucosamine residues of asparagine-linked high-mannose oligosaccharides. Endo H is a commonly used reagent in glycobiology research, including the characterization of oligosaccharides in glycoproteins. On-going crystallographic studies of Endo H and related endoglycosidases are aimed at identifying the molecular features that determine the different substrate specificities of these enzymes. RESULTS: The three-dimensional structure of Endo H has been determined to 1.9 A resolution. The overall fold of the enzyme is that of an irregular (alpha/beta)8-barrel comprising eight beta-strand/loop/alpha-helix units. Units 5 and 6 have very short loop sections at the top of the molecule and their alpha-helices are replaced by sections of extended geometry. The loop of unit 2 includes a small two-stranded antiparallel beta-sheet. A shallow curved cleft runs across the surface of the molecule from the area of units 5 and 6, over the core of the beta-barrel to the area of the beta-sheet of loop 2. This cleft contains the putative catalytic residues Asp130 and Glu132 above the core of the beta-barrel. These residues are surrounded by several aromatic residues. The loop 2 area of the cleft is formed by neutral polar residues, mostly asparagines. CONCLUSIONS: The structure of Endo H is very similar to that of Endo F1, a closely related endoglycosidase secreted by Flavobacterium meningosepticum. Detailed comparison of the structures of Endo H and Endo F1 supports the model previously proposed for substate binding and recognition, in which the area of loop 2 determines the substrate specificity and the alpha-helices of units 5 and 6 are missing to accommodate the protein moiety of the substrate. |
==About this Structure== | ==About this Structure== | ||
| - | 1EDT is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_plicatus Streptomyces plicatus]. Active as [http://en.wikipedia.org/wiki/Mannosyl-glycoprotein_endo-beta-N-acetylglucosaminidase Mannosyl-glycoprotein endo-beta-N-acetylglucosaminidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.96 3.2.1.96] Full crystallographic information is available from [http:// | + | 1EDT is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_plicatus Streptomyces plicatus]. Active as [http://en.wikipedia.org/wiki/Mannosyl-glycoprotein_endo-beta-N-acetylglucosaminidase Mannosyl-glycoprotein endo-beta-N-acetylglucosaminidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.96 3.2.1.96] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1EDT OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Streptomyces plicatus]] | [[Category: Streptomyces plicatus]] | ||
[[Category: Rao, V.]] | [[Category: Rao, V.]] | ||
| - | [[Category: Roey, P | + | [[Category: Roey, P Van.]] |
[[Category: hydrolase (glucosidase)]] | [[Category: hydrolase (glucosidase)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:26:41 2008'' |
Revision as of 10:26, 21 February 2008
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CRYSTAL STRUCTURE OF ENDO-BETA-N-ACETYLGLUCOSAMINIDASE H AT 1.9 ANGSTROMS RESOLUTION: ACTIVE SITE GEOMETRY AND SUBSTRATE RECOGNITION
Overview
BACKGROUND: Endo-beta-N-acetylglucosaminidase H (Endo H), an endoglycosidase secreted by Streptomyces plicatus, hydrolyzes the glycosidic bond between the core N-acetyglucosamine residues of asparagine-linked high-mannose oligosaccharides. Endo H is a commonly used reagent in glycobiology research, including the characterization of oligosaccharides in glycoproteins. On-going crystallographic studies of Endo H and related endoglycosidases are aimed at identifying the molecular features that determine the different substrate specificities of these enzymes. RESULTS: The three-dimensional structure of Endo H has been determined to 1.9 A resolution. The overall fold of the enzyme is that of an irregular (alpha/beta)8-barrel comprising eight beta-strand/loop/alpha-helix units. Units 5 and 6 have very short loop sections at the top of the molecule and their alpha-helices are replaced by sections of extended geometry. The loop of unit 2 includes a small two-stranded antiparallel beta-sheet. A shallow curved cleft runs across the surface of the molecule from the area of units 5 and 6, over the core of the beta-barrel to the area of the beta-sheet of loop 2. This cleft contains the putative catalytic residues Asp130 and Glu132 above the core of the beta-barrel. These residues are surrounded by several aromatic residues. The loop 2 area of the cleft is formed by neutral polar residues, mostly asparagines. CONCLUSIONS: The structure of Endo H is very similar to that of Endo F1, a closely related endoglycosidase secreted by Flavobacterium meningosepticum. Detailed comparison of the structures of Endo H and Endo F1 supports the model previously proposed for substate binding and recognition, in which the area of loop 2 determines the substrate specificity and the alpha-helices of units 5 and 6 are missing to accommodate the protein moiety of the substrate.
About this Structure
1EDT is a Single protein structure of sequence from Streptomyces plicatus. Active as Mannosyl-glycoprotein endo-beta-N-acetylglucosaminidase, with EC number 3.2.1.96 Full crystallographic information is available from OCA.
Reference
Crystal structure of endo-beta-N-acetylglucosaminidase H at 1.9 A resolution: active-site geometry and substrate recognition., Rao V, Guan C, Van Roey P, Structure. 1995 May 15;3(5):449-57. PMID:7663942
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