长双歧杆菌中一种冷活性的 1,4-α-葡聚糖分支酶可降低小麦淀粉的回生程度并提高其缓慢消化性。
A cold-active 1,4-α-glucan branching enzyme from Bifidobacterium longum reduces the retrogradation and enhances the slow digestibility of wheat starch.
机构信息
Key Laboratory of Agro-products Processing Technology, Jilin Provincial Department of Education, Changchun University, 6543 Weixing Road, Changchun 130022, People's Republic of China; Key Laboratory of Human Health Status Identification and Function Enhancement, Jilin Provincial Department of Science and Technology, Changchun University, 6543 Weixing Road, Changchun 130022, People's Republic of China.
Key Laboratory of Agro-products Processing Technology, Jilin Provincial Department of Education, Changchun University, 6543 Weixing Road, Changchun 130022, People's Republic of China.
出版信息
Food Chem. 2020 Sep 15;324:126855. doi: 10.1016/j.foodchem.2020.126855. Epub 2020 Apr 20.
To develop a 1,4-α-glucan branching enzyme (BE) without homology to known allergens, the glgB gene from Bifidobacterium longum was overexpressed under the control of BLMA promoter in Escherichia coli. B. longum BE (BlBE) had a molecular weight of 86.1 kDa and a specific activity of more than 18.5U/mg protein at 25-35 °C and pH 5.5-7.0, and exhibited 30% of the maximum activity at 10 °C. The cold-active BlBE preferred to transfer maltohexaose and introduced DP 4-36 branches into amylose. BlBE also increased the proportion of DP 2-10 branches in amylopectin and decreased its Mw from 1.39 × 10 to 1.16 × 10 g/mol. As the BlBE concentration increased from 0.0 to 0.5U/mg substrate, the retrogradation enthalpy of BlBE-modified wheat starch decreased from 4.50 to 1.83 J/g (p < 0.05) at day 14 and the slowly digestible starch content increased from 2.10% to 17.39% (p < 0.05).
为了开发一种与已知过敏原无同源性的 1,4-α-葡聚糖分支酶 (BE)，我们在大肠杆菌中，受 BLMA 启动子的控制，过表达长双歧杆菌的 glgB 基因。长双歧杆菌 BE（BlBE）的分子量为 86.1 kDa，在 25-35°C 和 pH 5.5-7.0 下的比活度超过 18.5U/mg 蛋白，在 10°C 下具有 30%的最大活性。冷活性 BlBE 更喜欢转移麦芽六糖，并在直链淀粉中引入 DP 4-36 分支。BlBE 还增加了支链淀粉中 DP 2-10 分支的比例，并将其 Mw 从 1.39×10 降低到 1.16×10 g/mol。随着 BlBE 浓度从 0.0 增加到 0.5U/mg 底物，BlBE 修饰的小麦淀粉的回生焓从第 14 天的 4.50 降低到 1.83 J/g（p<0.05），慢消化淀粉含量从 2.10%增加到 17.39%（p<0.05）。
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