Packing analysis of carbohydrates and polysaccharides. II. B‐amylose

A procedure is described for the simultaneous optimization of the bond lenglths and angles of the glucose residue and the chain conformation of the B‐amylose helix, while performing a packing analysis of the chains into a crystalline array. The results show that care must be exercised in selecting monomer residue coordinates for the packing analyis and optimum coordinates are given for the α‐D‐glucopyranose residue suitable for B‐amylose. The packing analysis shows that of the four proposed unit cells for B‐amylose the Rundle‐Daasch‐French, the Schieltz and the hexagonal unit cell of Blackwell et al. are not suitable, while the larger cell of Blackwell et al. is suitable. The most probable packing of B‐amylose chains in that cells is antiparallel, which the chains in a lefthanded sixfold helical conformation and with the O(6) atoms in the gt rotational position.