Abstract Glucansucrases, which can be produced by different Lactic Acid Bacteria (LAB), catalyze the synthesis of α-glucans with different structures and properties using sucrose as substrate. In this study, a novel glucansucrase (GTFA) from Lactobacillus reuteri E81 was identified and heterologously expressed. Alignments of GTFA with other glucansucrases revealed its novelty and a putative 3D model structure was obtained. The biochemical properties of the truncated enzyme without the N-terminal variable region, GTFA-ΔN, was characterized. The Km and Vmax were found to be 7.5 mM and 1.49 IU/mg, respectively, and it showed optimum activities at pH 7 and at 50 °C. The GTFA-ΔN produced in vitro an α-glucan with (α1 → 3) and (α1 → 6) glycosidic linkages using sucrose as the substrate. Importantly, GTFA-ΔN synthesized DP = 9 oligosaccharides using sucrose and maltose as the donor and acceptor sugars, respectively, as detected by TLC, HPLC, LC-MS and NMR analysis.

中文翻译：

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罗伊氏乳杆菌 E81 葡聚糖蔗糖酶的表征和麦芽低聚糖的生产

摘要 葡聚糖蔗糖酶可以由不同的乳酸菌（LAB）产生，以蔗糖为底物催化合成不同结构和性质的α-葡聚糖。在这项研究中，鉴定并异源表达了一种来自罗伊氏乳杆菌 E81 的新型葡聚糖蔗糖酶 (GTFA)。GTFA 与其他葡聚糖蔗糖酶的比对揭示了其新颖性，并获得了推定的 3D 模型结构。表征了不含 N 端可变区的截短酶 GTFA-ΔN 的生化特性。发现 Km 和 Vmax 分别为 7.5 mM 和 1.49 IU/mg，并且在 pH 7 和 50 °C 下显示出最佳活性。GTFA-ΔN 使用蔗糖作为底物在体外产生具有 (α1 → 3) 和 (α1 → 6) 糖苷键的 α-葡聚糖。重要的，