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Crystalline structure in oriented fibers of KBr–amylose
Author(s) -
Jackobs John J.,
Bumb Robert R.,
Zaslow Bert
Publication year - 1968
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1968.360061110
Subject(s) - chemistry , amylose , crystallography , helix (gastropod) , residue (chemistry) , starch , organic chemistry , ecology , snail , biology
The study of the structure of KBr–amylose begun by Senti and Witnauer has been extended by a three‐dimensional crystallographic analysis and by stereochemical considerations. Location of Br − at (0.200, 0.200, 0.000) and K + at (0.540, 0.540, 0.000) was obtained from the three‐dimensional map of vector interactions. By using known parameters for the D ‐glucose residue and accurate space‐filling models, an amylose helix was constructed to meet the fiber repeat spacing of 16.1 Å. The helix was determined to be left‐handed, and the correct space group for KBr–amylose is P 4 3 2 1 2. Placement of the helix in the unit cell resulted from structure factor calculations; minima in the grid of R values were checked with space‐filling models to establish the final structure. Both ions are located in a waterlike environment. The oxygen atoms O(2), O(3), and O(4) from glucose residues on adjacent chains coordinate around K + .