Division of Gene Technology, Katholieke Universiteit Leuven, Leuven, Belgium.
Biochem Biophys Res Commun. 2010 Nov 26;402(4):644-50. doi: 10.1016/j.bbrc.2010.10.075. Epub 2010 Oct 29.
Bifidobacterium adolescentis possesses several arabinofuranosidases able to hydrolyze arabinoxylans (AX) and AX oligosaccharides (AXOS), the latter being bifidogenic carbohydrates with potential prebiotic properties. We characterized two new recombinant arabinofuranosidases, AbfA and AbfB, and AXH-d3, a previously studied arabinofuranosidase from B. adolescentis. AbfA belongs to glycoside hydrolase family (GH) 43 and removed arabinose from the C(O)2 and C(O)3 position of monosubstituted xylose residues. Furthermore, hydrolytic activity of AbfA was much larger towards substrates with a low amount of arabinose substitutions. AbfB from GH 51 only cleaved arabinoses on position C(O)3 of disubstituted xyloses, similar to GH 43 AXH-d3, making it to our knowledge, the first reported enzyme with this specificity in GH 51. AbfA acted synergistically with AbfB and AXH-d3. In combination with AXH-d3, it released 60% of arabinose from wheat AX. Together with recent studies on other AXOS degrading enzymes from B. adolescentis, these findings allowed us to postulate a mechanism for the uptake and hydrolysis of bifidogenic AXOS by this organism.
青春双歧杆菌拥有几种能够水解阿拉伯木聚糖（AX）和 AX 低聚糖（AXOS）的阿拉伯呋喃糖苷酶，后者是具有潜在益生元特性的双歧因子碳水化合物。我们对两种新的重组阿拉伯呋喃糖苷酶 AbfA 和 AbfB 以及先前研究过的来自青春双歧杆菌的 AXH-d3 进行了表征。AbfA 属于糖苷水解酶家族（GH）43，能够从单取代木糖残基的 C(O)2 和 C(O)3 位置去除阿拉伯糖。此外，AbfA 对含少量阿拉伯糖取代的底物的水解活性要大得多。GH 51 的 AbfB 仅在二取代木糖的 C(O)3 位置切割阿拉伯糖，与 GH 43 AXH-d3 相似，这使其成为我们所知的 GH 51 中第一个具有这种特异性的报道酶。AbfA 与 AbfB 和 AXH-d3 协同作用。与 AXH-d3 一起，它从小麦 AX 中释放出 60%的阿拉伯糖。结合最近对青春双歧杆菌其他 AXOS 降解酶的研究，这些发现使我们能够推测出该生物体吸收和水解双歧因子 AXOS 的机制。
