1v5c
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(New page: 200px<br /><applet load="1v5c" size="450" color="white" frame="true" align="right" spinBox="true" caption="1v5c, resolution 2.00Å" /> '''The crystal structur...)
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Revision as of 02:29, 25 November 2007
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The crystal structure of the inactive form chitosanase from Bacillus sp. K17 at pH3.7
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
1V5C is a Protein complex structure of sequences from Bacillus sp. with SO4 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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