Single crystals of V amylose complexed with glycerol

Lamellar single crystals of amylose V glycerol were grown at 100 degrees 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 P2(1)2(1)2(1) 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-DIMSO 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.