Biobased Chemistry & Technology, Wageningen University & Research, PO Box 17, 6700 AA Wageningen, the Netherlands; Laboratory of Food Chemistry, Wageningen University & Research, P.O. Box 17, 6700 AA Wageningen, the Netherlands.
Biobased Chemistry & Technology, Wageningen University & Research, PO Box 17, 6700 AA Wageningen, the Netherlands.
Int J Biol Macromol. 2021 Jun 30;181:762-768. doi: 10.1016/j.ijbiomac.2021.02.220. Epub 2021 Mar 30.
Starch-based isomalto/malto-polysaccharides (IMMPs) are soluble dietary fibres produced by the incubation of α-(1 → 4) linked glucans with the 4,6-α-glucanotransferase (GTFB) enzyme. In this study, we investigated the reaction dynamics of the GTFB enzyme by using isoamylase debranched starches as simplified linear substrates. Modification of α-glucans by GTFB was investigated over time and analysed with H NMR, HPSEC, HPAEC combined with glucose release measurements. We demonstrate that GTFB modification of linear substrates followed a substrate/acceptor model, in which α-(1 → 4) linked glucans DP ≥ 6 functioned as donor substrate, and α-(1 → 4) linked malto-oligomers DP < 6 functioned as acceptor. The presence of α-(1 → 4) linked malto-oligomers DP < 6 resulted in higher GTFB transferase activity, while their absence resulted in higher GTFB hydrolytic activity. The information obtained in this study provides a better insight into GTFB reaction dynamics and will be useful for α-glucan selection for the targeted synthesis of IMMPs in the future.
基于淀粉的异麦芽糖/麦芽寡糖多聚糖（IMMPs）是通过用 4,6-α-葡聚糖转移酶（GTFB）酶孵育α-（1→4）连接的葡聚糖而产生的可溶性膳食纤维。在这项研究中，我们使用异淀粉酶支化的淀粉作为简化的线性底物来研究 GTFB 酶的反应动力学。通过 H NMR、HPSEC、HPAEC 结合葡萄糖释放测量，研究了 GTFB 对α-葡聚糖的修饰随时间的变化。我们证明，GTFB 对线性底物的修饰遵循底物/受体模型，其中 DP≥6 的α-（1→4）连接的葡聚糖作为供体底物，DP<6 的α-（1→4）连接的麦芽低聚糖作为受体。存在 DP<6 的α-（1→4）连接的麦芽低聚糖会导致更高的 GTFB 转移酶活性，而不存在 DP<6 的α-（1→4）连接的麦芽低聚糖则会导致更高的 GTFB 水解酶活性。本研究获得的信息提供了对 GTFB 反应动力学的更深入了解，将有助于未来针对 IMMPs 的靶向合成选择α-葡聚糖。
