1v5d
From Proteopedia
(New page: 200px<br /><applet load="1v5d" size="450" color="white" frame="true" align="right" spinBox="true" caption="1v5d, resolution 1.50Å" /> '''The crystal structur...) |
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| - | [[Image:1v5d.jpg|left|200px]]<br /><applet load="1v5d" size=" | + | [[Image:1v5d.jpg|left|200px]]<br /><applet load="1v5d" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1v5d, resolution 1.50Å" /> | caption="1v5d, resolution 1.50Å" /> | ||
'''The crystal structure of the active form chitosanase from Bacillus sp. K17 at pH6.4'''<br /> | '''The crystal structure of the active form chitosanase from Bacillus sp. K17 at pH6.4'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Crystal structures of chitosanase from Bacillus sp. K17 (ChoK) have been | + | Crystal structures of chitosanase from Bacillus sp. K17 (ChoK) have been determined at 1.5 A resolution in the active form and at 2.0 A resolution in the inactive form. This enzyme belongs to the family GH-8, out of 93 glycoside hydrolase families, and exhibits the substrate specificity of subclass II chitosanase. The catalytic site is constructed on the scaffold of a double-alpha(6)/alpha(6)-barrel, which is formed by six repeating helix-loop-helix motifs. This structure is quite different from those of the GH-46 chitosanases and of GH-5. Structural comparison with CelA (a cellulase belonging to the same family GH-8) suggests that the proton donor Glu122 is conserved, but the proton acceptor is the inserted Glu309 residue, and that the corresponding Asp278 residue in CelA is inactivated in ChoK. The four acidic residues, Asp179, Glu309, Asp183 and Glu107, can be involved in substrate recognition through interactions with the amino groups of the glucosamine residues bound in the -3, -2, -1 and +1 sites, respectively. The hydrophobic Trp235, Trp166, Phe413 and Tyr318 residues are highly conserved for binding of the hexose rings at the -3, -2, +1 and +2 sites, respectively. These structural features indicate that enzymes in GH-8 can be further divided into three subfamilies. Different types of chitosanases are discussed in terms of convergent evolution from different structural ancestors. |
==About this Structure== | ==About this Structure== | ||
| - | 1V5D is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Bacillus_sp. Bacillus sp.] with PIN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Chitosanase Chitosanase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.132 3.2.1.132] Full crystallographic information is available from [http:// | + | 1V5D is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Bacillus_sp. Bacillus sp.] with <scene name='pdbligand=PIN:'>PIN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Chitosanase Chitosanase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.132 3.2.1.132] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1V5D 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 15:31:37 2008'' |
Revision as of 13:31, 21 February 2008
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The crystal structure of the active form chitosanase from Bacillus sp. K17 at pH6.4
Overview
Crystal structures of chitosanase from Bacillus sp. K17 (ChoK) have been determined at 1.5 A resolution in the active form and at 2.0 A resolution in the inactive form. This enzyme belongs to the family GH-8, out of 93 glycoside hydrolase families, and exhibits the substrate specificity of subclass II chitosanase. The catalytic site is constructed on the scaffold of a double-alpha(6)/alpha(6)-barrel, which is formed by six repeating helix-loop-helix motifs. This structure is quite different from those of the GH-46 chitosanases and of GH-5. Structural comparison with CelA (a cellulase belonging to the same family GH-8) suggests that the proton donor Glu122 is conserved, but the proton acceptor is the inserted Glu309 residue, and that the corresponding Asp278 residue in CelA is inactivated in ChoK. The four acidic residues, Asp179, Glu309, Asp183 and Glu107, can be involved in substrate recognition through interactions with the amino groups of the glucosamine residues bound in the -3, -2, -1 and +1 sites, respectively. The hydrophobic Trp235, Trp166, Phe413 and Tyr318 residues are highly conserved for binding of the hexose rings at the -3, -2, +1 and +2 sites, respectively. These structural features indicate that enzymes in GH-8 can be further divided into three subfamilies. Different types of chitosanases are discussed in terms of convergent evolution from different structural ancestors.
About this Structure
1V5D is a Protein complex structure of sequences from Bacillus sp. with as ligand. Active as Chitosanase, with EC number 3.2.1.132 Full crystallographic information is available from OCA.
Reference
Crystal structure of family GH-8 chitosanase with subclass II specificity from Bacillus sp. K17., Adachi W, Sakihama Y, Shimizu S, Sunami T, Fukazawa T, Suzuki M, Yatsunami R, Nakamura S, Takenaka A, J Mol Biol. 2004 Oct 22;343(3):785-95. PMID:15465062
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