1qw9
From Proteopedia
(New page: 200px<br /><applet load="1qw9" size="450" color="white" frame="true" align="right" spinBox="true" caption="1qw9, resolution 1.20Å" /> '''Crystal structure of...) |
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| - | [[Image:1qw9.jpg|left|200px]]<br /><applet load="1qw9" size=" | + | [[Image:1qw9.jpg|left|200px]]<br /><applet load="1qw9" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1qw9, resolution 1.20Å" /> | caption="1qw9, resolution 1.20Å" /> | ||
'''Crystal structure of a family 51 alpha-L-arabinofuranosidase in complex with 4-nitrophenyl-Ara'''<br /> | '''Crystal structure of a family 51 alpha-L-arabinofuranosidase in complex with 4-nitrophenyl-Ara'''<br /> | ||
==Overview== | ==Overview== | ||
| - | High-resolution crystal structures of alpha-L-arabinofuranosidase from | + | High-resolution crystal structures of alpha-L-arabinofuranosidase from Geobacillus stearothermophilus T-6, a family 51 glycosidase, are described. The enzyme is a hexamer, and each monomer is organized into two domains: a (beta/alpha)8-barrel and a 12-stranded beta sandwich with jelly-roll topology. The structures of the Michaelis complexes with natural and synthetic substrates, and of the transient covalent arabinofuranosyl-enzyme intermediate represent two stable states in the double displacement mechanism, and allow thorough examination of the catalytic mechanism. The arabinofuranose sugar is tightly bound and distorted by an extensive network of hydrogen bonds. The two catalytic residues are 4.7 A apart, and together with other conserved residues contribute to the stabilization of the oxocarbenium ion-like transition state via charge delocalization and specific protein-substrate interactions. The enzyme is an anti-protonator, and a 1.7 A electrophilic migration of the anomeric carbon takes place during the hydrolysis. |
==About this Structure== | ==About this Structure== | ||
| - | 1QW9 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Geobacillus_stearothermophilus Geobacillus stearothermophilus] with KHP as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Alpha-N-arabinofuranosidase Alpha-N-arabinofuranosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.55 3.2.1.55] Full crystallographic information is available from [http:// | + | 1QW9 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Geobacillus_stearothermophilus Geobacillus stearothermophilus] with <scene name='pdbligand=KHP:'>KHP</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Alpha-N-arabinofuranosidase Alpha-N-arabinofuranosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.55 3.2.1.55] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QW9 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: hydrolase]] | [[Category: hydrolase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:44:19 2008'' |
Revision as of 12:44, 21 February 2008
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Crystal structure of a family 51 alpha-L-arabinofuranosidase in complex with 4-nitrophenyl-Ara
Overview
High-resolution crystal structures of alpha-L-arabinofuranosidase from Geobacillus stearothermophilus T-6, a family 51 glycosidase, are described. The enzyme is a hexamer, and each monomer is organized into two domains: a (beta/alpha)8-barrel and a 12-stranded beta sandwich with jelly-roll topology. The structures of the Michaelis complexes with natural and synthetic substrates, and of the transient covalent arabinofuranosyl-enzyme intermediate represent two stable states in the double displacement mechanism, and allow thorough examination of the catalytic mechanism. The arabinofuranose sugar is tightly bound and distorted by an extensive network of hydrogen bonds. The two catalytic residues are 4.7 A apart, and together with other conserved residues contribute to the stabilization of the oxocarbenium ion-like transition state via charge delocalization and specific protein-substrate interactions. The enzyme is an anti-protonator, and a 1.7 A electrophilic migration of the anomeric carbon takes place during the hydrolysis.
About this Structure
1QW9 is a Single protein structure of sequence from Geobacillus stearothermophilus with as ligand. Active as Alpha-N-arabinofuranosidase, with EC number 3.2.1.55 Full crystallographic information is available from OCA.
Reference
Crystal structure and snapshots along the reaction pathway of a family 51 alpha-L-arabinofuranosidase., Hovel K, Shallom D, Niefind K, Belakhov V, Shoham G, Baasov T, Shoham Y, Schomburg D, EMBO J. 2003 Oct 1;22(19):4922-32. PMID:14517232
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