Single crystals of V Amylose complexed with glycerol

Lamellar single crystals of amylose V glycerol were grown at 100°C by evaporating water from solutions of amylose in aqueous glycerol. The crystals which were square, with lateral dimensions of several micrometers, gave sharp electron diffraction patterns presenting an orthorhombic symmetry with a probable space group P212121 and unit cell parameters: a = 1.93 ± 0.01 nm, b = 1.86 ± 0.01 nm and c (fiber axis) = 0.83 ± 0.03 nm. The amylose V(glycerol) crystal structure which is isomorphous to that of V(DMSO) consists of an antiparallel pair of left-handed six-fold amylose helices centered on the two-fold screw axes of the cell and probably separated by glycerol molecules. This packing mode is confirmed by de-solvation experiments where the V(glycerol) amylose crystals, annealed in ethanol, could be converted into V(H) amylose without losing their external appearance. The V(glycerol) amylose crystals could be seeded by cellulose microfibrils to yield a shish-kebab structure where the amylose crystalline lamellae grew perpendicular to the microfibril directions.