Computer modelling of kappa carrageenan-mannan interactions.

Molecular modelling has been used as a theoretical approach to investigate the kappa carrageenan structure and its interactions with mannan chains. Calculations revealed the existence of six minima for the kappa carrageenan structure in solution. Two of them were very close to the structure found in the solid state. The methodology allowed the calculation of a theoretical counterpart of the structures based on x-ray fibre diffraction studies. In the second step of this study, we have shown that there is the possibility of interactions between kappa carrageenan double helices and mannan chains. This interacting process is allowed by the flexibility of the mannan chains and structural changes of the kappa carrageenan double helices. The calculations suggest that a disaccharide mannan fragment might be required for recognition. The results of our investigation are in good agreement with a model of gel structure based on experimental data. This approach could be applied to simulate and predict other associations in molecular assemblies.