1r87
From Proteopedia
(New page: 200px<br /><applet load="1r87" size="450" color="white" frame="true" align="right" spinBox="true" caption="1r87, resolution 1.67Å" /> '''Crystal structure of...) |
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| - | [[Image:1r87.jpg|left|200px]]<br /><applet load="1r87" size=" | + | [[Image:1r87.jpg|left|200px]]<br /><applet load="1r87" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1r87, resolution 1.67Å" /> | caption="1r87, resolution 1.67Å" /> | ||
'''Crystal structure of the extracellular xylanase from Geobacillus stearothermophilus T-6 (XT6, monoclinic form): The complex of the WT enzyme with xylopentaose at 1.67A resolution'''<br /> | '''Crystal structure of the extracellular xylanase from Geobacillus stearothermophilus T-6 (XT6, monoclinic form): The complex of the WT enzyme with xylopentaose at 1.67A resolution'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Relating thermodynamic parameters to structural and biochemical data | + | Relating thermodynamic parameters to structural and biochemical data allows a better understanding of substrate binding and its contribution to catalysis. The analysis of the binding of carbohydrates to proteins or enzymes is a special challenge because of the multiple interactions and forces involved. Isothermal titration calorimetry (ITC) provides a direct measure of binding enthalpy (DeltaHa) and allows the determination of the binding constant (free energy), entropy, and stoichiometry. In this study, we used ITC to elucidate the binding thermodynamics of xylosaccharides for two xylanases of family 10 isolated from Geobacillus stearothermophilus T-6. The change in the heat capacity of binding (DeltaCp = DeltaH/DeltaT) for xylosaccharides differing in one sugar unit was determined by using ITC measurements at different temperatures. Because hydrophobic stacking interactions are associated with negative DeltaCp, the data allow us to predict the substrate binding preference in the binding subsites based on the crystal structure of the enzyme. The proposed positional binding preference was consistent with mutants lacking aromatic binding residues at different subsites and was also supported by tryptophan fluorescence analysis. |
==About this Structure== | ==About this Structure== | ||
| - | 1R87 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 ZN, CL and SO4 as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Endo-1,4-beta-xylanase Endo-1,4-beta-xylanase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.8 3.2.1.8] Full crystallographic information is available from [http:// | + | 1R87 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=ZN:'>ZN</scene>, <scene name='pdbligand=CL:'>CL</scene> and <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Endo-1,4-beta-xylanase Endo-1,4-beta-xylanase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.8 3.2.1.8] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1R87 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 14:48:09 2008'' |
Revision as of 12:48, 21 February 2008
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Crystal structure of the extracellular xylanase from Geobacillus stearothermophilus T-6 (XT6, monoclinic form): The complex of the WT enzyme with xylopentaose at 1.67A resolution
Overview
Relating thermodynamic parameters to structural and biochemical data allows a better understanding of substrate binding and its contribution to catalysis. The analysis of the binding of carbohydrates to proteins or enzymes is a special challenge because of the multiple interactions and forces involved. Isothermal titration calorimetry (ITC) provides a direct measure of binding enthalpy (DeltaHa) and allows the determination of the binding constant (free energy), entropy, and stoichiometry. In this study, we used ITC to elucidate the binding thermodynamics of xylosaccharides for two xylanases of family 10 isolated from Geobacillus stearothermophilus T-6. The change in the heat capacity of binding (DeltaCp = DeltaH/DeltaT) for xylosaccharides differing in one sugar unit was determined by using ITC measurements at different temperatures. Because hydrophobic stacking interactions are associated with negative DeltaCp, the data allow us to predict the substrate binding preference in the binding subsites based on the crystal structure of the enzyme. The proposed positional binding preference was consistent with mutants lacking aromatic binding residues at different subsites and was also supported by tryptophan fluorescence analysis.
About this Structure
1R87 is a Single protein structure of sequence from Geobacillus stearothermophilus with , and as ligands. Active as Endo-1,4-beta-xylanase, with EC number 3.2.1.8 Full crystallographic information is available from OCA.
Reference
Mapping glycoside hydrolase substrate subsites by isothermal titration calorimetry., Zolotnitsky G, Cogan U, Adir N, Solomon V, Shoham G, Shoham Y, Proc Natl Acad Sci U S A. 2004 Aug 3;101(31):11275-80. Epub 2004 Jul 26. PMID:15277671
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