CRYSTALLINE FEATURES OF STREPTOCOCCAL (1-]3)-ALPHA-D-GLUCANS OF HUMANSALIVA

Crystalline polymorphs of the backbone (1-->3)-alpha-D-glucans of two streptococcal alpha-glucans were studied by X-ray diffraction measurem ents in comparison with that of a fungal (1-->3)-alpha-D-glucan. The g lucan produced by S. salivarius changed its polymorph from the hydrate d form at 100% relative humidity to the dehydrated form under vacuum, that produced by cariogenic S. mutans took the dehydrated form only, a nd the fungal glucan always showed the hydrated form. The difference o f polymorphic behavior was ascribed to the molecular weight of the glu can since the fungal glucan showed the highest viscosity, the saliveri us glucan, middle, and the mutans glucan, the lowest.