1qbb
From Proteopedia
(New page: 200px<br /><applet load="1qbb" size="450" color="white" frame="true" align="right" spinBox="true" caption="1qbb, resolution 2.00Å" /> '''BACTERIAL CHITOBIASE...) |
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| - | [[Image:1qbb.jpg|left|200px]]<br /><applet load="1qbb" size=" | + | [[Image:1qbb.jpg|left|200px]]<br /><applet load="1qbb" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1qbb, resolution 2.00Å" /> | caption="1qbb, resolution 2.00Å" /> | ||
'''BACTERIAL CHITOBIASE COMPLEXED WITH CHITOBIOSE (DINAG)'''<br /> | '''BACTERIAL CHITOBIASE COMPLEXED WITH CHITOBIOSE (DINAG)'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Chitin, the second most abundant polysaccharide on earth, is degraded by | + | Chitin, the second most abundant polysaccharide on earth, is degraded by chitinases and chitobiases. The structure of Serratia marcescens chitobiase has been refined at 1.9 A resolution. The mature protein is folded into four domains and its active site is situated at the C-terminal end of the central (beta alpha)8-barrel. Based on the structure of the complex with the substrate disaccharide chitobiose, we propose an acid-base reaction mechanism, in which only one protein carboxylate acts as catalytic acid, while the nucleophile is the polar acetamido group of the sugar in a substrate-assisted reaction. The structural data lead to the hypothesis that the reaction proceeds with retention of anomeric configuration. The structure allows us to model the catalytic domain of the homologous hexosaminidases to give a structural rationale to pathogenic mutations that underlie Tay-Sachs and Sandhoff disease. |
==About this Structure== | ==About this Structure== | ||
| - | 1QBB is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Serratia_marcescens Serratia marcescens] with CBS and SO4 as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Beta-N-acetylhexosaminidase Beta-N-acetylhexosaminidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.52 3.2.1.52] Full crystallographic information is available from [http:// | + | 1QBB is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Serratia_marcescens Serratia marcescens] with <scene name='pdbligand=CBS:'>CBS</scene> and <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Beta-N-acetylhexosaminidase Beta-N-acetylhexosaminidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.52 3.2.1.52] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QBB OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Perrakis, A.]] | [[Category: Perrakis, A.]] | ||
[[Category: Tews, I.]] | [[Category: Tews, I.]] | ||
| - | [[Category: Vorgias, C | + | [[Category: Vorgias, C E.]] |
| - | [[Category: Wilson, K | + | [[Category: Wilson, K S.]] |
[[Category: CBS]] | [[Category: CBS]] | ||
[[Category: SO4]] | [[Category: SO4]] | ||
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[[Category: glycosyl hydrolase]] | [[Category: glycosyl hydrolase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:37:52 2008'' |
Revision as of 12:38, 21 February 2008
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BACTERIAL CHITOBIASE COMPLEXED WITH CHITOBIOSE (DINAG)
Overview
Chitin, the second most abundant polysaccharide on earth, is degraded by chitinases and chitobiases. The structure of Serratia marcescens chitobiase has been refined at 1.9 A resolution. The mature protein is folded into four domains and its active site is situated at the C-terminal end of the central (beta alpha)8-barrel. Based on the structure of the complex with the substrate disaccharide chitobiose, we propose an acid-base reaction mechanism, in which only one protein carboxylate acts as catalytic acid, while the nucleophile is the polar acetamido group of the sugar in a substrate-assisted reaction. The structural data lead to the hypothesis that the reaction proceeds with retention of anomeric configuration. The structure allows us to model the catalytic domain of the homologous hexosaminidases to give a structural rationale to pathogenic mutations that underlie Tay-Sachs and Sandhoff disease.
About this Structure
1QBB is a Single protein structure of sequence from Serratia marcescens with and as ligands. Active as Beta-N-acetylhexosaminidase, with EC number 3.2.1.52 Full crystallographic information is available from OCA.
Reference
Bacterial chitobiase structure provides insight into catalytic mechanism and the basis of Tay-Sachs disease., Tews I, Perrakis A, Oppenheim A, Dauter Z, Wilson KS, Vorgias CE, Nat Struct Biol. 1996 Jul;3(7):638-48. PMID:8673609
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