To determine the physiochemical properties of the 4-α-glucanotransferase from Bifidobacterium sp., the bllj_0114 gene encoding 4-α-glucanotransferase was cloned from Bifidobacterium longum subsp. longum JCM 1217 and expressed in Escherichia coli. The amino acid sequence alignment indicated that the recombinant protein, named BL-αGTase, belongs to the glycoside hydrolase (GH) family 77. BL-αGTase was purified using nickel-nitrilotriacetic acid affinity chromatography and characterized using various substrates. The enzyme catalyzed the disproportionation activity, which transfers a glucosyl unit from oligosaccharides to acceptor molecules, and had the highest activity at 40 °C and pH 6.0. In the presence of 5 mM metal ions, in particular Cu2+, Zn2+, and Fe2+, BL-αGTase activity was reduced. To determine whether BL-αGTase can be used to generate thermoreversible gels, potato starch was treated with BL-αGTase for various reaction times. The BL-αGTase-treated starches showed sol-gel reversibility and melted at 59.6-75.7 °C.

中文翻译：

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长双歧杆菌亚种重组4-α-葡萄糖基转移酶的性质 longum JCM 1217及其应用。

为了确定双歧杆菌属的4-α-葡聚糖转移酶的理化特性，从长双歧杆菌亚种中克隆了编码4-α-葡聚糖转移酶的bllj_0114基因。Longum JCM 1217并在大肠杆菌中表达。氨基酸序列比对表明该重组蛋白BL-αGTase属于糖苷水解酶（GH）家族77。BL-αGTase用镍-亚硝酸三乙酸亲和色谱纯化，并使用多种底物进行表征。该酶催化歧化活性，其将葡糖基单元从寡糖转移至受体分子，并在40°C和pH 6.0下具有最高的活性。在5 mM金属离子（特别是Cu2 +，Zn2 +和Fe2 +）的存在下，BL-αGTase活性降低。为了确定BL-αGTase是否可用于产生热可逆凝胶，将马铃薯淀粉用BL-αGTase处理了各种反应时间。BL-αGTase处理的淀粉显示出溶胶-凝胶可逆性，并在59.6-75.7°C时熔化。