4xia
From Proteopedia
(New page: 200px<br /> <applet load="4xia" size="450" color="white" frame="true" align="right" spinBox="true" caption="4xia, resolution 2.3Å" /> '''STRUCTURES OF D-XYLO...) |
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caption="4xia, resolution 2.3Å" /> | caption="4xia, resolution 2.3Å" /> | ||
'''STRUCTURES OF D-XYLOSE ISOMERASE FROM ARTHROBACTER STRAIN B3728 CONTAINING THE INHIBITORS XYLITOL AND D-SORBITOL AT 2.5 ANGSTROMS AND 2.3 ANGSTROMS RESOLUTION, RESPECTIVELY'''<br /> | '''STRUCTURES OF D-XYLOSE ISOMERASE FROM ARTHROBACTER STRAIN B3728 CONTAINING THE INHIBITORS XYLITOL AND D-SORBITOL AT 2.5 ANGSTROMS AND 2.3 ANGSTROMS RESOLUTION, RESPECTIVELY'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
| - | 4XIA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Arthrobacter_sp. Arthrobacter sp.] with SOR and MG as [http://en.wikipedia.org/wiki/ligands ligands]. The following page contains interesting information on the relation of 4XIA with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb74_1.html Alpha-amylase]]. Active as [http://en.wikipedia.org/wiki/Xylose_isomerase Xylose isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.1.5 5.3.1.5] Full crystallographic information is available from [http:// | + | 4XIA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Arthrobacter_sp. Arthrobacter sp.] with <scene name='pdbligand=SOR:'>SOR</scene> and <scene name='pdbligand=MG:'>MG</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. The following page contains interesting information on the relation of 4XIA with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb74_1.html Alpha-amylase]]. Active as [http://en.wikipedia.org/wiki/Xylose_isomerase Xylose isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.1.5 5.3.1.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4XIA OCA]. |
==Reference== | ==Reference== | ||
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[[Category: isomerase(intramolecular oxidoreductse)]] | [[Category: isomerase(intramolecular oxidoreductse)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri Feb 15 17:45:44 2008'' |
Revision as of 15:45, 15 February 2008
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STRUCTURES OF D-XYLOSE ISOMERASE FROM ARTHROBACTER STRAIN B3728 CONTAINING THE INHIBITORS XYLITOL AND D-SORBITOL AT 2.5 ANGSTROMS AND 2.3 ANGSTROMS RESOLUTION, RESPECTIVELY
Overview
The structures of D-xylose isomerase from Arthrobacter strain B3728, containing the polyol inhibitors xylitol and D-sorbitol have been solved, at 2.5 A and 2.3 A, respectively. The structures have been refined using, restrained least-squares refinement methods. The final crystallographic, R-factors for the D-sorbitol (xylitol) bound molecules, for 43,615, (32,989) reflections are 15.6 (14.7). The molecule is a tetramer and the, asymmetric unit of the crystal contains a dimer, the final model of which, incorporates a total of 6086 unique protein, inhibitor and magnesium atoms, together with 535 bound solvent molecules. Each subunit of the enzyme, contains two domains: the main domain is a parallel-stranded alpha-beta, barrel, which has been reported in 14 other enzymes. The C-terminal domain, is a loop structure consisting of five helical segments and is involved in, intermolecular contacts between subunits that make up the tetramer. The, structures have been analysed with respect to molecular symmetry, intersubunit contacts, inhibitor binding and active site geometry. The, refined model shows the two independent subunits to be similar apart from, local deviations due to solvent contacts in the solvent-exposed helices., The enzyme is dependent on a divalent cation for catalytic activity. Two, metal ions are required per monomer, and the high-affinity magnesium(II), site has been identified from the structural results presented here. The, metal ion is complexed, at the high-affinity site, by four carboxylate, side-chains of the conserved residues, Glu180, Glu216, Asp244 and Asp292., The inhibitor polyols are bound in the active site in an extended open, chain conformation and complete an octahedral co-ordination shell for the, magnesium cation via their oxygen atoms O-2 and O-4. The active site lies, in a deep pocket near the C-terminal ends of the beta-strands of the, barrel domain and includes residues from a second subunit. The tetrameric, molecule can be considered to be a dimer of "active" dimers, the active, sites being composed of residues from both subunits. The analysis has, revealed the presence of several internal salt-bridges stabilizing the, tertiary and quaternary structure. One of these, between Asp23 and Arg139, appears to play a key role in stabilizing the active dimer and is, conserved in the known sequences of this enzyme.(ABSTRACT TRUNCATED AT 400, WORDS)
About this Structure
4XIA is a Single protein structure of sequence from Arthrobacter sp. with and as ligands. The following page contains interesting information on the relation of 4XIA with [Alpha-amylase]. Active as Xylose isomerase, with EC number 5.3.1.5 Full crystallographic information is available from OCA.
Reference
Structures of D-xylose isomerase from Arthrobacter strain B3728 containing the inhibitors xylitol and D-sorbitol at 2.5 A and 2.3 A resolution, respectively., Henrick K, Collyer CA, Blow DM, J Mol Biol. 1989 Jul 5;208(1):129-57. PMID:2769749
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