Pullulan chain conformation

Figure 17. Projection into the xz plane of a pullulan chain conformation based on the chain model described in the text...

Figure 18. Projection into the yz plane of the same pullulan chain conformation...

Figure 19. Projection of a pullulan chain conformation based on a chain model different from that used to generate Figures 17 and 18. See text for details.

Comparison of projection drawings and calculated chain dimensions for amylose, linear "dextran", and pullulan chains shows that the a-1,6-linkage is a source of considerable conformation freedon in D-glucan chains v ich incorporate this linkage. Experimental studies of the coil dimensions of pullulan and other polysaccharides containing a-1,6-linkages will be required to refine the parameters of the theoretical model for this linkage. 

The SEC partition coefficient [6] (.K sec) was measured on a Superose 6 column for three sets of well-characterized symmetrical solutes the compact, densely branched nonionic polysaccharide, Ficoll the flexible chain nonionic polysaccharide, pullulan and compact, anionic synthetic polymers, carboxylated starburst dendrimers. All three solutes display a congruent dependence of K ec on solute radius, R. In accord with a simple geometric model for SEC, all of these data conform to the same linear plot of i sEc versus R. This plot reveals the behavior of noninteracting spheres on this column. The mobile phase for the first two solutes was 0.2M NaH2P04-Na2HP04, pH 7.0. In order to ensure the suppression of electrostatic repulsive interactions between the dendrimer and the packing, the ionic strength was increased to 0.30M for that solute. 

---