Thermus thermophilus木糖异构酶与木糖醇的分子对接及模型分析

Xylose isomerase from Thermus thermophilus is widely used in the production of high-fructose corn syrup and the construction of xylose via recombinant strains. In this paper, the positions of Mg ions and xylitol in 1BXB were established by structure analysis, molecular docking and computing. The Complex of 1BXB with xylitol was modeled and analyzed. Comparing the structure of 1BXB complex with 1S5N, it was found that the overall structure of them showed a high similarity. The residues around xylitol were highly conserved in xylose isomerase, and the orientation and positions of xylitol were very similar in both structures. The coordination bonds formed between Mg1 and O2 or O4 of xylitol stabilized the conformation of xylitol at the active site of 1BXB.

Thermus thermophilus木糖异构酶复合物模型的建立与分析(英文)

Thermus thermophilus木糖异构酶在高果糖浆的工业生产及木糖发酵重组菌的构建方面具有极其广阔的应用前景．本文主要运用结构分析和分子对接及计算软件,确定了Mg^2及木糖异构酶天然底物D-木糖在1BXB晶体结构中的定位,构建出1BXB复合物模型并进行评价与分析．通过对1BXB复合物模型1与1XIC的结构进行比较,发现所构建模型中D-木糖周围的残基在木糖异构酶中高度保守,并且D-木糖的定位与取向与1XIC中底物分子基本一致．

嗜热木糖异构酶在大肠杆菌中的表达、纯化及性质研究

为获得具有高热稳定性的木糖异构酶,运用基因工程技术,从嗜热栖热菌Thermus thermophilus HB8中克隆到嗜热木糖异构酶基因xylA。测序结果表明,该基因与GenBank数据库中相比271位的碱基A突变为G,导致氨基酸序列中N91D突变。将该基因克隆到载体pET22b(+),并在E.coli BL21(DE3)中进行高效表达。通过热变性和强阴离子交换两步对该酶进行纯化,并对酶学性质进行了研究。结果表明,该酶最适温度为80℃,最适pH为8.0,80℃下半衰期为225 min。在60℃,pH7.5该酶的Km为15.20 mmol/L,Vmax为69.54μmol/min,kcat为50.62/s,kcat/Km为3.33L/s·mmol。研究结果为嗜热木糖异构酶的进一步工业应用奠定了基础。