The method of molecular dynamics simulation is carried out to simulate the KGM segment in solution, investigate the stable conformation and compute its energy, and discuss the effect of the change of hydrogen bond on its structure and energy. The results show that the structure of KGM segment can be optimized by molecular simulation method and the most stable conformation can be found, indicating the hydrogen bond is the main factor influencing the conformation and property of KGM.
Molecular dynamics (MD) method is adopted to simulate the conformation variations of konjac glucomannan (KGM) saline solution at different temperatures, and structurally analyze the trends and reasons of viscosity change in KGM saline solution with temperature. The experimental results have been analyzed to find out that the sum of formative hydrogen bonds decreases with the rise of temperature and the amount of intramolecular hydrogen bonds suddenly increases at 323 K. Besides, in terms of molecular orbital data obtained from simulation, we can know that hydrogen bonding energy also decreases with the rise of temperature. Therefore, we can predict the viscosity of KGM saline solution decreases gradually when rising the temperature.
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.
