Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
Int J Biol Macromol. 2020 Jun 1;152:473-482. doi: 10.1016/j.ijbiomac.2020.02.247. Epub 2020 Feb 22.
Glucansucrases catalyse the formation of glucans from sucrose. The glucansucrase-encoding gene from Leuconostoc citreum ABK-1, dex-N, was successfully cloned and expressed in E. coli BL21 Star (DE3). DEX-N produces 2 types of glucans: soluble (S-dextran) and insoluble (I-glucan) glucans. The S-dextran was determined to be ca. 10 kDa in size and contained >90% α-1,6 linkages; along with its water solubility, this is similar to commercial dextran. On the other hand, I-glucan was water-insoluble, harbouring a block-wise pattern of α-1,3 and α-1,6 linkages in its structure. Notably, the FTIR and powder X-ray diffraction pattern of I-glucan exhibited a combination of features found in α-1,6-linked dextran and α-1,3-linked mutan. Although both I-glucan and mutan are insoluble glucans, their physical characteristics are notably dissimilar.
葡聚糖蔗糖酶能够催化蔗糖合成葡聚糖。已成功地将来源于肠膜明串珠菌 ABK-1 的葡聚糖蔗糖酶基因 dex-N 在大肠杆菌 BL21 Star (DE3) 中进行克隆和表达。DEX-N 可产生 2 种葡聚糖：可溶性（S-葡聚糖）和不溶性（I-葡聚糖）葡聚糖。S-葡聚糖的分子量约为 10 kDa，且含有>90%的α-1,6 键；因其水溶性，其与商业葡聚糖相似。另一方面，I-葡聚糖不溶于水，其结构中具有α-1,3 和α-1,6 键的块状模式。值得注意的是，I-葡聚糖的傅里叶变换红外光谱和粉末 X 射线衍射图谱表现出与α-1,6 键连接的葡聚糖和α-1,3 键连接的变聚糖共有的特征。尽管 I-葡聚糖和变聚糖都是不溶性葡聚糖，但它们的物理特性明显不同。
