Wheat arabinoxylan (water-insoluble fraction) contains ~36% arabinose which may include both singly or doubly substitutions at C2/C3 of the Xylp units. α-L-Arabinofuranosidses (ABFs) of two GH families were analyzed ...Wheat arabinoxylan (water-insoluble fraction) contains ~36% arabinose which may include both singly or doubly substitutions at C2/C3 of the Xylp units. α-L-Arabinofuranosidses (ABFs) of two GH families were analyzed for their respective activities on the hydrolysis of Xylp-Araf. BaABF (GH43) produced twice the yield of arabinose residues from the heteroxylan compared to AnABF (GH51) under the same reaction conditions. Two endo-xylanases (of GH10 and 11) also showed differential hydrolytic activities on the Xylp chain, with the GH10 XYN-ATM double the amount of reducing sugar yield (as xylose equivalent) than using the GH11 XYN-M3. When the ABF and XYN were combined in optimial ratios, a synergistic increase of 73.8% in arabinose yield was observed.展开更多
An α-L-arabinofuranosidase (ARF) gene of 1503 bp was synthesized, subcloned into pET26b vector, and expressed in Escherichia coli. The enzyme was purified in active form, and consisted of 500 amino acid residues, cor...An α-L-arabinofuranosidase (ARF) gene of 1503 bp was synthesized, subcloned into pET26b vector, and expressed in Escherichia coli. The enzyme was purified in active form, and consisted of 500 amino acid residues, corresponding to 55 kD based on SDS-PAGE. The affinity-purified protein was characterized using arabinofuranosyl xylooligosaccharides (AXOS) as substrates. The pH effect was investigated showing an optimum at pH 5.5. XaARF catalyzed the cleavage of arabinose at C3 of the xylopyranosyl unit efficiently if the arabinofuranosyl substitution was at the terminal compared to internal xylose units. The enzyme was able to act on di-substituted xylopyranosyl units with the first cleavage at C3 followed by C2 linkages.展开更多
文摘Wheat arabinoxylan (water-insoluble fraction) contains ~36% arabinose which may include both singly or doubly substitutions at C2/C3 of the Xylp units. α-L-Arabinofuranosidses (ABFs) of two GH families were analyzed for their respective activities on the hydrolysis of Xylp-Araf. BaABF (GH43) produced twice the yield of arabinose residues from the heteroxylan compared to AnABF (GH51) under the same reaction conditions. Two endo-xylanases (of GH10 and 11) also showed differential hydrolytic activities on the Xylp chain, with the GH10 XYN-ATM double the amount of reducing sugar yield (as xylose equivalent) than using the GH11 XYN-M3. When the ABF and XYN were combined in optimial ratios, a synergistic increase of 73.8% in arabinose yield was observed.
文摘An α-L-arabinofuranosidase (ARF) gene of 1503 bp was synthesized, subcloned into pET26b vector, and expressed in Escherichia coli. The enzyme was purified in active form, and consisted of 500 amino acid residues, corresponding to 55 kD based on SDS-PAGE. The affinity-purified protein was characterized using arabinofuranosyl xylooligosaccharides (AXOS) as substrates. The pH effect was investigated showing an optimum at pH 5.5. XaARF catalyzed the cleavage of arabinose at C3 of the xylopyranosyl unit efficiently if the arabinofuranosyl substitution was at the terminal compared to internal xylose units. The enzyme was able to act on di-substituted xylopyranosyl units with the first cleavage at C3 followed by C2 linkages.
文摘从短小芽孢杆菌中克隆阿拉伯呋喃糖苷酶基因xyn43并重组表达,有利于将该酶分离纯化后应用于其他半纤维素多糖的水解。该研究利用E.coli BL21表达系统对实验室克隆到的短小芽孢杆菌的α-L-阿拉伯呋喃糖苷酶基因xyn43进行重组表达并分析其酶学性质,将重组α-L-阿拉伯呋喃糖苷酶Xyn43和来源于棒曲霉突变菌株的商业木聚糖酶联合作用于燕麦木聚糖。结果表明:以燕麦木聚糖为底物,重组α-L-阿拉伯呋喃糖苷酶Xyn43的最适温度为50℃,最适p H为6.0。该酶在p H 5.0~10.0和45~55℃下较稳定。与木聚糖酶单独作用相比,重组Xyn43酶与商业木聚糖酶同时加入以及先用木聚糖酶水解后加入Xyn43酶,水解产物中的还原糖含量分别增加了16%和20%,木糖含量增加了35%和48%。该结果研究结果表明重组Xyn43酶能够和商业木聚糖酶协同降解燕麦木聚糖,提高水解效率,产生更多的木寡糖,阿拉伯糖和木糖。
