J Agric Food Chem. 2019 Sep 4;67(35):9868-9876. doi: 10.1021/acs.jafc.9b04023. Epub 2019 Aug 20.
Amylosucrase (EC 2.4.1.4, ASase), a typical carbohydrate-active enzyme, can catalyze 5 types of reactions and recognize more than 50 types of glycosyl acceptors. However, most ASases are unstable even at 50 °C, which limits their practical industrial applications. In this study, an extremely thermostable ASase was discovered from DSM 17022 (CT-ASase) with an optimal activity temperature of 55 °C, half-life of 1.09 h at 70 °C, and melting temperature of 74.47 °C. The recombinant CT-ASase was characterized as the first tetrameric ASase, and a structure-based truncation mutation was conducted to confirm the effect of tetrameric conformation on its thermostability. In addition, α-1,4-glucan was found to be the predominant product of CT-ASase at pH 6.0-8.0 and 30-60 °C.
淀粉蔗糖酶（EC 2.4.1.4，ASase）是一种典型的碳水化合物活性酶，可催化 5 种反应，识别超过 50 种糖基供体。然而，大多数 ASase 即使在 50°C 下也不稳定，这限制了它们在实际工业应用中的应用。在这项研究中，从 DSM 17022（CT-ASase）中发现了一种极其耐热的 ASase，其最佳活性温度为 55°C，70°C 时半衰期为 1.09 小时，熔点为 74.47°C。重组 CT-ASase 被表征为第一个四聚体 ASase，并进行了基于结构的截断突变，以确认四聚体构象对其热稳定性的影响。此外，在 pH 值为 6.0-8.0 和 30-60°C 时，发现α-1,4-葡聚糖是 CT-ASase 的主要产物。
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