The influence of α-1,4-glucan substrates on 4,6-α-d-glucanotransferase reaction dynamics during isomalto/malto-polysaccharide synthesis.

C E Klostermann, P H van der Zaal, H A Schols, P L Buwalda, J H Bitter

International journal of biological macromolecules 2021 Jun 30

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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 1H 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. Copyright © 2021. Published by Elsevier B.V.

Citation

C E Klostermann, P H van der Zaal, H A Schols, P L Buwalda, J H Bitter. The influence of α-1,4-glucan substrates on 4,6-α-d-glucanotransferase reaction dynamics during isomalto/malto-polysaccharide synthesis. International journal of biological macromolecules. 2021 Jun 30;181:762-768