2gft
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(New page: 200px<br /><applet load="2gft" size="350" color="white" frame="true" align="right" spinBox="true" caption="2gft, resolution 2.30Å" /> '''Crystal structure of...)
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Revision as of 17:58, 29 January 2008
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Crystal structure of the E263A nucleophile mutant of Bacillus licheniformis endo-beta-1,4-galactanase in complex with galactotriose
Overview
The beta-1,4-galactanase from Bacillus licheniformis (BLGAL) is a plant, cell-wall-degrading enzyme involved in the hydrolysis of beta-1,4-galactan, in the hairy regions of pectin. The crystal structure of BLGAL was, determined by molecular replacement both alone and in complex with the, products galactobiose and galactotriose, catching a first crystallographic, glimpse of fragments of beta-1,4-galactan. As expected for an enzyme, belonging to GH-53, the BLGAL structure reveals a (betaalpha)(8)-barrel, architecture. However, BLGAL betaalpha-loops 2, 7 and 8 are long in, contrast to the corresponding loops in structures of fungal galactanases, determined previously. The structure of BLGAL additionally shows a calcium, ion linking the long betaalpha-loops 7 and 8, which replaces a disulphide, bridge in the fungal galactanases. Compared to the substrate-binding, subsites predicted for Aspergillus aculeatus galactanase (AAGAL), two, additional subsites for substrate binding are found in BLGAL, -3 and -4. A, comparison of the pattern of galactan and galactooligosaccharides, degradation by AAGAL and BLGAL shows that, although both are most active, on substrates with a high degree of polymerization, AAGAL can degrade, galactotriose and galactotetraose efficiently, whereas BLGAL prefers, longer oligosaccharides and cannot hydrolyze galactotriose to any, appreciable extent. This difference in substrate preference can be, explained structurally by the presence of the extra subsites -3 and -4 in, BLGAL.
About this Structure
2GFT is a Single protein structure of sequence from Bacillus licheniformis with as ligand. Active as Arabinogalactan endo-1,4-beta-galactosidase, with EC number 3.2.1.89 Full crystallographic information is available from OCA.
Reference
The structure of endo-beta-1,4-galactanase from Bacillus licheniformis in complex with two oligosaccharide products., Ryttersgaard C, Le Nours J, Lo Leggio L, Jorgensen CT, Christensen LL, Bjornvad M, Larsen S, J Mol Biol. 2004 Jul 30;341(1):107-17. PMID:15312766
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