Two genes encoding the probable α-L-arabinofuranosidase (EC 3.2.1.55) isozymes with 92.3% amino acid sequence identity, ABF51A and ABF51B, were found from the chromosomes 3 and 5 of Saccharomycopsis fibuligera KJJ81, the amylolytic yeast isolated from Korean wheat-based Nuruk, respectively. Each open reading frame consists of 1,551 nucleotides which encodes a protein of 517 amino acids with the molecular mass of approximately 59 kDa. These isozymes share approximately 49% of amino acid sequence identities with eukaryotic ABFs from the filamentous fungi. The corresponding genes were cloned, functionally expressed, and purified from Escherichia coli. SfABF51_A and SfABF51_B showed the highest activities on p-nitrophenyl arabinofuranoside at 40~45°C and pH 7.0 in sodium phosphate buffer and at 50°C and pH 6.0 in sodium acetate buffer, respectively. These exo-acting enzymes belonging to the Glycoside Hydrolase (GH) family 51 could hydrolyze arabinoxylo-oligosaccharides (AXOS) and arabino-oligosaccharides (AOS) to produce only L-arabinose, whereas they could hardly degrade any polymeric substrates including arabinans and arabinoxylans. The detailed product analyses revealed that both SfABF51 isozymes can catalyze the versatile hydrolysis of α-(1,2)- and α-(1,3)-L-arabino furanosidic linkages of AXOS, and α-(1,2)-, α-(1,3)-, and α-(1,5)-linkages of linear and branched AOS. On the contrary, they have much lower activity against the α-(1,2)- and α-(1,3)-double substituted substrates than the single substituted ones. These hydrolases are supposed to play the important roles in the degradation and utilization of hemicellulosic biomass by S. fibuligera.

中文翻译：

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来自淀粉分解酵母 Saccharomycopsis fibuligera 的阿拉伯木糖和阿拉伯寡糖特异性 α-L-阿拉伯呋喃糖苷酶 GH51 同工酶。

从Saccharomycopsis fibuligera KJJ81的染色体 3 和 5 中发现了两个编码可能具有 92.3% 氨基酸序列同一性的 α-L-阿拉伯呋喃糖苷酶 (EC 3.2.1.55) 同工酶的基因ABF51A和ABF51B ，这是从韩国小麦中分离的淀粉分解酵母基于努鲁克，分别。每个开放阅读框由 1,551 个核苷酸组成，编码 517 个氨基酸的蛋白质，分子量约为 59 kDa。这些同工酶与来自丝状真菌的真核 ABF 共享大约 49% 的氨基酸序列同一性。从大肠杆菌中克隆、功能表达和纯化相应的基因。SfABF51 _A和 SfABF51 _B在 40~45°C 和 pH 7.0 的磷酸钠缓冲液中以及在 50°C 和 pH 6.0 的乙酸钠缓冲液中分别显示出对硝基苯阿拉伯呋喃糖苷的最高活性。这些exo属于糖苷水解酶 (GH) 家族 51 的作用酶可以水解阿拉伯木寡糖 (AXOS) 和阿拉伯寡糖 (AOS) 以仅产生 L-阿拉伯糖，而它们几乎不能降解任何聚合物底物，包括阿拉伯聚糖和阿拉伯木聚糖。详细的产物分析表明，两种 SfABF51 同工酶都可以催化 AXOS 的 α-(1,2)- 和 α-(1,3)-L-阿拉伯呋喃糖苷键以及 α-(1,2)-，线性和支化 AOS 的 α-(1,3)- 和 α-(1,5)- 连接。相反，它们对 α-(1,2)- 和 α-(1,3)- 双取代底物的活性远低于单取代底物。这些水解酶被认为在S. fibuligera降解和利用半纤维素生物质中发挥重要作用。