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The V amylose–H 2 O system: Structural changes resulting from hydration
Author(s) -
Zaslow Bert,
Murphy Vincent Gerard,
French Alfred Dexter
Publication year - 1974
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.1974.360130413
Subject(s) - chemistry , crystallography , amylose , hydrate , electron diffraction , molecule , diffraction , residue (chemistry) , helix (gastropod) , starch , organic chemistry , ecology , physics , snail , optics , biology
Abstract X‐ray diffraction and stereochemical analyses were used to study the hydrated structure of the helical amylose polymorph having a fiber repeat spacing of 8 Å. Intensity calculations using computer models confirmed six as the number of residues per turn and supported the space group P2 1 2 1 2 1 . Both diffraction intensity and stereochemical methods indicate the suitability of residue G3 from the potassium acetate complex of cyclohexaamylose as opposed to residues with longer O (4)– O (1) vectors. Comparison of the present results with those obtained for V amylose dehydrate indicated no major conformational differences between the two helix skeletons. A net helical rotation of approximately 30° accompanied the hydrate–dehydrate transition and the rotational position in the hydrate allowed packing that was less close. Hydration water molecules were not located; noncarbohydrate peaks on the electron density maps were primarily due to Fourier series termination errors.