Aggregation and weak gel formation by pectic polysaccharide homogalacturonan

This study presents a novel model of homogalacturonan (HG) based on the dissipative particle dynamics (DPD). The model was applied to investigate the mechanism of self-aggregation of low-methoxylated homogalacturonan in aqueous solutions in the absence of cations. The coarse-grained model provided new insights into the structural features of HG aggregates and networks in aqueous solutions. Depending on the properties and concentration of polysaccharides, two major patterns of self-assembly were observed for HG - ellipsoidal aggregates and a continuous three-dimensional network. Simulations showed that a decrease in the degree of dissociation of HG results in a higher rate of self-aggregation, as well as facilitating the formation of larger assemblies or thicker nanofilaments depending on the type of final self-assembly. Simulations of polysaccharides of different chain lengths suggested the existence of a structural threshold for the formation of a spatial network for HG consisting of less than 35 GalA units.

Automated summary

This study introduces a new model of homogalacturonan based on dissipative particle dynamics and investigates the self-aggregation mechanism of low-methoxylated homogalacturonan in aqueous solutions without cations. The simulations reveal two major patterns of self-assembly for homogalacturonan, ellipsoidal aggregates and a continuous three-dimensional network, depending on polysaccharide properties and concentration. The decrease in the degree of dissociation of homogalacturonan is found to lead to a higher rate of self-aggregation and the formation of larger assemblies or thicker nanofilaments in different types of self-assembly.