The interactions between konjac glucomannan and carrageenan were studied with the method of molecular dynamics simulation. Part representative structure segments of KGM and two unit structures of κ-carrageenan (Fig. 2) were used as mode, and the force-field was AMBER2. The stability and sites of konjac glucomannan/carrageenan interactions in water were researched at 373 K with the following results: the potential energy (EPOT) of the mixed gel was dropped, while those of single-konjac glucomannan gel and single carrageenan were increased. The surface area (SA) of KGM in the mixed system was decreased to 1002.2 2, and that of carrageenan to 800.9 2. The variations of two parameters showed that the stability of compound gel konjac glucomannan/carrageenan was improved, which is consistent with the previous studies. The sites of interactions in the mixed gel were the -OH groups on C(2), C(4) and C(6), the acetyl group in KGM mannose, and the -OH group on C(6) in carrageenan. The hydrogen bond was formed directly or indirectly by the bridge of waters.
In order to prove up the interaction between konjac glucomannan (KGM) and other amyloses, by using KGM, guaran gum and carrageenan as materials, their blending in different external conditions was modeled by means of molecular dynamics (MD) method. The result showed that 323 K was a significant turning point for the formation of hydrogen bond, and KGM and guaran gum were just juxtaposed together via intermolecular hydrogen bond; but with the addition of carrageenan, KGM, guaran gum and carrageenan were spirally twisted together, and when their blending proportion is 3:2:9 the combination was the most compact. Moreover, the research result has provided the sequent studies afterwards on amyloses with some references.
PANG JieYE Bing-HongHUANG Yong-MeiLIN QiongZENG CuiSUN Yuan-Ming
In this paper, the hydrogen bonding network models of konjac gluco- mannan (KGM) are predicted in the approach of molecular dynamics (MD). These models have been proved by experiments whose results are consistent with those from simulation. The results show that the hydrogen bonding network structures of KGM are stable and the key linking points of hydrogen bonding network are at the O(6) and O(2) positions on KGM ring. Moreover, acetyl has significant influence on hydrogen bonding network and hydrogen bonding network structures are more stable after deacetylation.
