Crystal Structure of Amylose Triacetate I

Amylose triacetate was synthesized by using enzymatically synthesized amylose. The enzymatically synthesized amylose is a linear 1,4-linked poly-α- d -glucose, which does not contain a 1,6-linkage. X-ray crystal structure analysis was carried out for amylose triacetate I. Two left-handed (14/3) helices pass through a unit cell with parameters a = 10.92 Å, b = 18.91 Å, and c (fiber axis) = 53.91 Å and space group P 2 1 2 1 2 1 . The molecule does not have 14 11 symmetry but only has 2 1 symmetry in the crystal. The up- and down-pointing molecules statistically coexist at a crystal site with the ratio 0.87:0.13. The conformation of the O6 atom is almost tg, but one gg and one gt conformations are included.