The double-helical molecular structure of crystalline b-amylose |
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Authors: | Anatole Sarko |
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Institution: | Department of Chemistry, SUNY College of Environmental Science & Forestry, Syracuse, New York 13210 U.S.A. |
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Abstract: | The crystal structure of the B-polymorph of amylose appears to be based on double-stranded helices. The individual strands are in a right-handed six-fold helical conformation repeating in 20.8 Å and are wound parallel around each other. The steric disposition of O-6 is gt. The double helices pack in a hexagonal unit-cell (a b 18.50 Å, c (fiber repeat) 10.40 Å, γ 120°), with two helices (12 d-glucose residues) per cell. The helices are packed antiparallel and leave an open channel within a hexagonal array that is filled with water molecules. The reliability of the structure analysis is indicated by R 0.22. The structure of B-amylose is consistent with the diffraction diagrams of B-starches and accounts for the physical properties of such starches. |
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Keywords: | To whom correspondence should be addressed |
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