Harris G W, Pickersgill R W, Connerton I, Debeire P, Touzel J P, Breton C, Pérez S
Food Macromolecular Science Department, Reading Laboratory, United Kingdom.
Proteins. 1997 Sep;29(1):77-86.
A thermophilic xylanase from Bacillus strain D3 suitable for use as a bleach booster in the paper pulping industry has been identified and characterized. The enzyme is suited to the high temperature and alkaline conditions needed for using xylanases in the pulp industry. The xylanase is stable at 60 degrees C and relatively stable at high temperatures, with a temperature optimum of 75 degrees C. The pH optimum is 6, but the enzyme is active over a broad pH range. The xylanase has been cloned and sequenced, and the crystal structure has been determined. The structure of Bacillus D3 xylanase reveals an unusual feature of surface aromatic residues, which form clusters or "sticky patches" between pairs of molecules. These "sticky patches" on the surface of the enzyme are responsible for the tendency of the protein to aggregate at high concentrations in the absence of reagents such as ethylene glycol. The formation of dimers and higher order polymers via these hydrophobic contacts may also contribute to the thermostability of this xylanase.
已鉴定并表征了一种来自芽孢杆菌菌株D3的嗜热木聚糖酶，该酶适用于造纸制浆工业中作为漂白助剂。该酶适合制浆工业中使用木聚糖酶所需的高温和碱性条件。该木聚糖酶在60℃稳定，在高温下相对稳定，最适温度为75℃。最适pH为6，但该酶在较宽的pH范围内都有活性。该木聚糖酶已被克隆和测序，并且其晶体结构已被确定。芽孢杆菌D3木聚糖酶的结构揭示了表面芳香族残基的一个不寻常特征，这些残基在分子对之间形成簇或“粘性斑块”。在没有诸如乙二醇等试剂的情况下，酶表面的这些“粘性斑块”导致蛋白质在高浓度时倾向于聚集。通过这些疏水接触形成二聚体和高阶聚合物也可能有助于这种木聚糖酶的热稳定性。
