Graduate School of Biotechnology and Institute of Life Science and Resources, Kyung Hee University, Yongin 17104, Republic of Korea.
Department of Food Science and Technology, College of Agriculture and Life Sciences, Jeonbuk National University, Jeonju 54896, Republic of Korea.
Int J Biol Macromol. 2020 Jul 15;155:535-542. doi: 10.1016/j.ijbiomac.2020.03.176. Epub 2020 Mar 24.
Amylosucrase (ASase) is α-glucan-producing enzyme. Four putative ASase genes (bdas, blas, bpas, and btas) were cloned from Bifidobacterium sp. and expressed in Escherichia coli. All ASases from Bifidobacterium sp. (BAS) displayed typical ASase properties with slightly different characteristics. Among the BASs studied, BdAS and BpAS showed maximal enzyme activities at 35 and 30 °C, respectively, whereas BlAS and BtAS were maximally active at higher temperatures, i.e., 45 and 50 °C, respectively. BpAS exhibited optimum pH under slightly basic conditions (pH 8.0), while BdAS, BlAS, and BtAS preferred weakly acidic conditions (pH 5.0-6.0). All BASs showed higher isomerization activities. Particularly, BlAS produced more trehalulose than turanose. Although polymerization was the highest for BtAS, BtAS synthesized α-1, 4-glucans with a lower degree of polymerization than that of the other BASs. The versatile properties of the BASs described could contribute to the efficient production of highly valuable biomaterials for the agriculture, food, and pharmaceutical industries.
淀粉蔗糖酶（ASase）是一种产生α-葡聚糖的酶。从双歧杆菌属中克隆了 4 个假定的 ASase 基因（bdas、blas、bpas 和 btas），并在大肠杆菌中表达。双歧杆菌属的所有 ASase（BAS）均表现出典型的 ASase 特性，但略有不同。在研究的 BAS 中，BdAS 和 BpAS 的最大酶活分别在 35°C 和 30°C 下达到，而 BlAS 和 BtAS 的最大活性在较高温度下达到，即 45°C 和 50°C。BpAS 在略碱性条件（pH 8.0）下表现出最佳 pH 值，而 BdAS、BlAS 和 BtAS 则更喜欢弱酸性条件（pH 5.0-6.0）。所有 BAS 均表现出较高的异构化活性。特别是，BlAS 产生的棉子糖多于海藻糖。尽管 BtAS 的聚合度最高，但 BtAS 合成的α-1,4-葡聚糖的聚合度低于其他 BAS。BAS 具有多种特性，这可能有助于高效生产农业、食品和制药行业所需的高价值生物材料。
