Institute of Chemistry, Slovak Academy of Sciences, Dúbravska cesta 9, 845 38 Bratislava, Slovakia.
Department of Biotechnology and Food Technology, Faculty of Applied Sciences, Durban University of Technology, Durban, South Africa.
Biotechnol Adv. 2016 Nov 15;34(7):1260-1274. doi: 10.1016/j.biotechadv.2016.09.001. Epub 2016 Sep 9.
Significant progress over the past few years has been achieved in the enzymology of microbial degradation and saccharification of plant xylan, after cellulose being the most abundant natural renewable polysaccharide. Several new types of xylan depolymerizing and debranching enzymes have been described in microorganisms. Despite the increasing variety of known glycoside hydrolases and carbohydrate esterases, some xylan structures still appear quite recalcitrant. This review focuses on the mode of action of different types of depolymerizing endoxylanases and their cooperation with β-xylosidase and accessory enzymes in breakdown of complex highly branched xylan structures. Emphasis is placed on the enzymatic hydrolysis of alkali-extracted deesterified polysaccharide as well as acetylated xylan isolated from plant cell walls under non-alkaline conditions. It is also shown how the combination of selected endoxylanases and debranching enzymes can determine the nature of prebiotic xylooligosaccharides or lead to complete hydrolysis of the polysaccharide. The article also highlights the possibility for discovery of novel xylanolytic enzymes, construction of multifunctional chimeric enzymes and xylanosomes in parallel with increasing knowledge on the fine structure of the polysaccharide.
在纤维素作为最丰富的天然可再生多糖之后，过去几年中，在微生物降解和糖化植物木聚糖的酶学方面取得了重大进展。已经在微生物中描述了几种新型的木聚糖解聚和去支链酶。尽管已知糖苷水解酶和碳水化合物酯酶的种类不断增加，但一些木聚糖结构仍然显得相当顽固。这篇综述重点介绍了不同类型的内切木聚糖酶的作用模式及其与β-木糖苷酶和辅助酶在分解复杂的高度支化木聚糖结构中的协同作用。强调了在非碱性条件下从植物细胞壁中提取的碱提取去酯化多糖以及乙酰化木聚糖的酶水解。还展示了如何组合选择的内切木聚糖酶和去支链酶可以决定益生元木二糖的性质，或者导致多糖的完全水解。本文还强调了在不断增加的多糖精细结构知识的基础上，发现新型木聚糖酶、构建多功能嵌合酶和木聚糖体的可能性。
