Crystal and molecular structure of V-amylose complexed with butan-1-ol

10 March 2022
By combining a systematic approach of energy relaxation and molecular modeling with structural refinement from diffraction data, we have determined the molecular and crystal structure of the complex of amylose with butan-1-ol, validating the geometrical model proposed by William Helbert and Henri Chanzy in 1994. Click on the title for more information.

These results were obtained during the thesis work of Cong Anh Khanh Le in the “Structure and Properties of Glycomaterials” team in collaboration with the “Nova” team of the Department of Molecular Pharmacology. Chain-folded lamellar V-amylose single crystals were prepared by adding butan-1-ol to hot dilute aqueous solutions of native amylose. The base‑plane electron and X-ray diffraction patterns recorded from hydrated specimens agreed with a P212121 space group and an orthorhombic unit cell. A molecular model resulting from an exhaustive search of helix position and restrained structure refinement against diffraction data was proposed. The unit cell contains 4 antiparallel left-handed 6‑fold amylose single helices with 1 butan‑1-ol molecule located inside each of the helical cavities. In addition, 4 butan‑1-ol and 20 water molecules are distributed in the 4 interstitial spaces. The amylose helices form rows along the b-axis that are alternatively shifted by ±b/8 with respect to one another, which validates the geometrical model proposed by William Helbert and Henri Chanzy in 1994.

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