The influence of α-1,4-glucan substrates on 4,6-α-d-glucanotransferase reaction dynamics during isomalto/malto-polysaccharide synthesis.
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.
['Klostermann|C E|CE|', 'van der Zaal|P H|PH|', 'Schols|H A|HA|', 'Buwalda|P L|PL|', 'Bitter|J H|JH|']
D005936:Glucans D006004:Glycogen Debranching Enzyme System D006868:Hydrolysis D007534:Isomaltose D011134:Polysaccharides D013379:Substrate Specificity
Starch Fingerprinting Structural analysis α-Glucan modification