Turanose is a natural isomer of sucrose. It is an emerging functional sweetener of the next generation. Turanose is catalytically synthesized from the sucrose biomass by employing amylosucrase enzyme. In this study, a novel gene encoding amylosucrase (Asmet) has been identified from the metagenome of a thermal aquatic habitat. Asmet exhibits 37-55% identity at the protein level with the known amylosucrases characterized till date. Asmet was cloned and expressed in Escherichia coli, followed by protein purification, and characterization. Asmet protein exhibited the maximum total activity at 9.0 pH and 60 °C temperature, whereas, 8.0 pH and 50 °C temperature were found optimum for transglycosylation activity. Asmet showed fairly high thermal tolerance at 50 °C. The conjugation of Asmet protein with functionalized iron nanoparticles significantly improved its thermal tolerance, showing hardly any loss in the enzyme's activity even after 72 h of heat (50 °C) exposure. The turanose yield of about 47% was achieved from 1.5 M sucrose, containing 0.5 M fructose in the reaction. Turanose was purified (˜95%) via a bio-physical process, and characterized by TLC, HPLC, and NMR. The novel amylosucrase gene was demonstrated to be a potential candidate for turanose production, utilizing various sucrose containing feedstocks.

中文翻译：

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来自热水生栖息地宏基因组的新型淀粉蔗糖酶基因的表征，及其在蔗糖生物质生产中的应用

图拉糖是蔗糖的天然异构体。它是下一代新兴的功能性甜味剂。通过使用淀粉蔗糖酶从蔗糖生物质催化合成Turanose。在这项研究中，已从热水生栖息地的宏基因组中鉴定出编码淀粉蔗糖酶 (Asmet) 的新基因。Asmet 与迄今为止表征的已知淀粉蔗糖酶在蛋白质水平上表现出 37-55% 的同一性。Asmet 在大肠杆菌中进行克隆和表达，然后进行蛋白质纯化和表征。Asmet 蛋白在 9.0 pH 和 60 °C 温度下表现出最大的总活性，而发现 8.0 pH 和 50 °C 温度最适合转糖基化活性。Asmet 在 50 °C 下表现出相当高的耐热性。Asmet 蛋白与功能化铁纳米颗粒的结合显着提高了其耐热性，即使在加热 (50 °C) 72 小时后，酶的活性也几乎没有任何损失。从反应中含有 0.5 M 果糖的 1.5 M 蔗糖获得约 47% 的松果糖产率。通过生物物理过程纯化（～95%）Turanose，并通过TLC、HPLC和NMR表征。新的淀粉蔗糖酶基因被证明是利用各种含蔗糖原料生产核糖的潜在候选者。并通过TLC、HPLC和NMR表征。新的淀粉蔗糖酶基因被证明是利用各种含蔗糖原料生产核糖的潜在候选者。并通过TLC、HPLC和NMR表征。新的淀粉蔗糖酶基因被证明是利用各种含蔗糖原料生产核糖的潜在候选者。