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.

中文翻译：

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双歧杆菌中四种淀粉酶的比较研究。

淀粉蔗糖酶（ASase）是产生α-葡聚糖的酶。从双歧杆菌中克隆了四个假定的ASase基因（bdas，blas，bpas和btas）。并在大肠杆菌中表达。来自双歧杆菌属的所有酶。（BAS）显示典型的ASase属性，但特性略有不同。在所研究的BAS中，BdAS和BpAS分别在35和30°C下显示出最大的酶活性，而BlAS和BtAS在较高的温度下（分别在45和50°C下）具有最大的活性。BpAS在弱碱性条件下（pH 8.0）表现出最佳pH，而BdAS，BlAS和BtAS优选弱酸性条件（pH 5.0-6.0）。所有BAS均显示出更高的异构化活性。特别地，BlaS比海藻糖产生更多的海藻糖。尽管BtAS的聚合反应最高，但BtAS合成了α-1，4-葡聚糖的聚合度比其他BAS低。所描述的BAS的多用途特性可有助于有效生产用于农业，食品和制药行业的极有价值的生物材料。