Crystal Structure of B-Amylose

A fiber specimen of B-amylose was prepared from enzymatically synthesized amylose, which is a purely linear 1,4-linked poly-α-d-glucose. X-ray crystal structure analysis was carried out by using the newly collected intensity data, which was estimated by using imaging plate according to the new procedure. The molecule of B-amylose assumes a left-handed parallel strand double helix, and two double helices pass through a hexagonal unit cell with parameters a = b = 18.52 Å, c (fiber axis) = 10.57 Å, γ = 120°, and the space group P61C62. A total of 36 water molecules were contained in a unit cell. The conformation of the primary hydroxyl group is gg, and the conformation of the bonds linking two glucose residues, Φ and Ψ, are +84.3 and −135.2°, respectively.