Department of Food Science and Technology, College of Agriculture and Life Sciences, Jeonbuk National University, Jeonju 54896, Republic of Korea.
Department of Food Science & Biotechnology and Carbohydrate Bioproduct Research Center, Sejong University, Seoul 05006, Republic of Korea.
Int J Biol Macromol. 2024 Jun;269(Pt 2):131834. doi: 10.1016/j.ijbiomac.2024.131834. Epub 2024 Apr 29.
The amylosucrase (ASase, EC 2.4.1.4) utilizes sucrose as the sole substrate to catalyze multifunctional reactions. It can naturally synthesize α-1,4-linked glucans such as amylose as well as sucrose isomers with more favorable properties than sucrose with a lower intestinal digestibility and non-cariogenic properties. The amino acid sequence of the asase gene from Deinococcus cellulosilyticus (DceAS) exhibits low homology with those of other ASases from other Deinococcus species. In this study, we cloned and expressed DceAS and demonstrated its high activity at pH 6 and pH 8 and maintained stability. It showed higher polymerization activity at pH 6 than at pH 8, but similar isomerization activity and produced more turanose and trehalulose at pH 6 than at pH 8 and produced more isomaltulose at pH 8. Furthermore, the molecular weight of DceAS was 226.6 kDa at pH 6 and 145.5 kDa at pH 8, indicating that it existed as a trimer and dimer, respectively under those conditions. Additionally, circular dichroism spectra showed that the DceAS secondary structure was different at pH 6 and pH 8. These differences in reaction products at different pHs can be harnessed to naturally produce sucrose alternatives that are more beneficial to human health.
淀粉蔗糖酶（ASase，EC 2.4.1.4）利用蔗糖作为唯一底物，催化多功能反应。它可以天然合成α-1,4 连接的葡聚糖，如直链淀粉，以及具有比蔗糖更低的肠道消化率和非致龋性的蔗糖异构体。来自纤维素分解球菌（DceAS）的 asase 基因的氨基酸序列与其他 Deinococcus 物种的其他 ASases 的序列同源性较低。在本研究中，我们克隆并表达了 DceAS，并证明其在 pH 6 和 pH 8 时具有高活性和稳定性。它在 pH 6 时的聚合活性高于 pH 8，但异构化活性相似，在 pH 6 时产生更多的棉子糖和海藻糖，在 pH 8 时产生更多的异麦芽酮糖。此外，DceAS 在 pH 6 时的分子量为 226.6 kDa，在 pH 8 时的分子量为 145.5 kDa，表明其在这两种条件下分别以三聚体和二聚体的形式存在。此外，圆二色光谱显示，DceAS 的二级结构在 pH 6 和 pH 8 时不同。这些在不同 pH 值下产生的反应产物的差异可以被利用来天然生产更有益于人类健康的蔗糖替代品。
