1R85

Crystal structure of the extracellular xylanase from Geobacillus stearothermophilus T-6 (XT6): The WT enzyme (monoclinic form) at 1.45A resolution

1R85 の概要

• エントリーDOI: 10.2210/pdb1r85/pdb
• 関連するPDBエントリー: 1r86 1r87
• 分子名称: Endo-1,4-beta-xylanase, ZINC ION, CHLORIDE ION, ... (6 entities in total)
• 機能のキーワード: hydrolase
• 由来する生物種: Geobacillus stearothermophilus
• 細胞内の位置: Secreted: P40943
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 46439.39

構造登録者

Bar, M.,Golan, G.,Nechama, M.,Zolotnitsky, G.,Shoham, Y.,Shoham, G. (登録日: 2003-10-23, 公開日: 2004-07-20, 最終更新日: 2024-04-03)

主引用文献

Zolotnitsky, G.,Cogan, U.,Adir, N.,Solomon, V.,Shoham, G.,Shoham, Y.
Mapping glycoside hydrolase substrate subsites by isothermal titration calorimetry.
Proc.Natl.Acad.Sci.Usa, 101:11275-11280, 2004

PubMed Abstract: 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.

PubMed: 15277671
DOI: 10.1073/pnas.0404311101

実験手法

X-RAY DIFFRACTION (1.45 Å)