SUPRAMOLECULAR LIQUID CRYSTALLINITY - SPHERICAL COILS OF LEVAN SURROUNDING CYLINDRICAL RODS OF DNA

Levan, which adopts a compact spherical conformation in aqueous soluti on, can form a liquid crystalline phase if DNA is also present. We pro pose that supramolecular rodlike structures, assembled by the noncoval ent aggregation of levan around DNA, stabilize the lyotropic phase. We describe a geometric model for the aggregates. The model is quantitat ively consistent with the relative amounts of DNA and levan needed for liquid crystallinity, and it agrees qualitatively with the shape of t he boundary between the isotropic and heterogeneous fields on an exper imentally determined phase diagram.