Department of Microbial & Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Spanish National Research Council (CSIC), C/Ramiro de Maeztu 9, 28040 Madrid, Spain.
The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
Int J Mol Sci. 2023 Jul 26;24(15):11997. doi: 10.3390/ijms241511997.
α-l-arabinofuranosidases are glycosyl hydrolases that catalyze the break between α-l-arabinofuranosyl substituents or between α-l-arabinofuranosides and xylose from xylan or xylooligosaccharide backbones. While they belong to several glycosyl hydrolase (GH) families, there are only 24 characterized GH62 arabinofuranosidases, making them a small and underrepresented group, with many of their features remaining unknown. Aside from their applications in the food industry, arabinofuranosidases can also aid in the processing of complex lignocellulosic materials, where cellulose, hemicelluloses, and lignin are closely linked. These materials can be fully converted into sugar monomers to produce secondary products like second-generation bioethanol. Alternatively, they can be partially hydrolyzed to release xylooligosaccharides, which have prebiotic properties. While endoxylanases and β-xylosidases are also necessary to fully break down the xylose backbone from xylan, these enzymes are limited when it comes to branched polysaccharides. In this article, two new GH62 α-l-arabinofuranosidases from (named ARA1 and ARA-2) have been heterologously expressed and characterized. ARA-1 is more sensitive to changes in pH and temperature, whereas ARA-2 is a robust enzyme with wide pH and temperature tolerance. Both enzymes preferentially act on arabinoxylan over arabinan, although ARA-1 has twice the catalytic efficiency of ARA-2 on this substrate. The production of xylooligosaccharides from arabinoxylan catalyzed by a endoxylanase was significantly increased upon pretreatment of the polysaccharide with ARA-1 or ARA-2, with the highest synergism values reported to date. Finally, both enzymes (ARA-1 or ARA-2 and endoxylanase) were successfully applied to enhance saccharification by combining them with a β-xylosidase already characterized from the same fungus.
α-L-阿拉伯呋喃糖苷酶属于糖苷水解酶，能够催化α-L-阿拉伯呋喃糖取代基之间或木聚糖或木二糖骨架上的α-L-阿拉伯呋喃糖苷与木糖之间的键断裂。虽然它们属于几个糖苷水解酶（GH）家族，但只有 24 种特征明确的 GH62 阿拉伯呋喃糖苷酶，这使它们成为一个小而代表性不足的群体，其许多特性仍然未知。除了在食品工业中的应用外，阿拉伯呋喃糖苷酶还可以帮助处理复杂的木质纤维素材料，其中纤维素、半纤维素和木质素紧密结合。这些材料可以完全转化为糖单体，以生产第二代生物乙醇等二次产品。或者，它们可以部分水解以释放具有益生元特性的木二糖寡糖。虽然内切木聚糖酶和β-木糖苷酶对于完全从木聚糖中分解木糖骨架也是必需的，但这些酶在支链多糖方面受到限制。在本文中，从（命名为 ARA1 和 ARA-2）中异源表达和表征了两种新的 GH62 α-L-阿拉伯呋喃糖苷酶。ARA-1 对 pH 和温度的变化更敏感，而 ARA-2 是一种具有宽 pH 和温度耐受性的强酶。两种酶都优先作用于阿拉伯木聚糖而不是阿拉伯聚糖，尽管 ARA-1 在该底物上的催化效率是 ARA-2 的两倍。用 ARA-1 或 ARA-2 预处理多糖后，用 内切木聚糖酶催化阿拉伯木聚糖生产木二糖寡糖的产量显著增加，报道的协同作用值达到了迄今为止的最高水平。最后，将两种酶（ARA-1 或 ARA-2 和内切木聚糖酶）与从同一真菌中已经表征的β-木糖苷酶结合使用，成功地应用于增强糖化。
