Single crystals of inulin.
Lamellar crystals of inulin were grown by crystallizing sharp fractions of low molecular weight inulin from dilute aqueous ethanol solutions. The crystals were analyzed using three-dimensional electron diffraction and X-ray powder diagrams. Two crystalline polymorphs were observed, depending on the hydration conditions: a hydrated form which indexed on an orthorhombic unit cell, with space group P2(1)2(1)2(1) and with cell dimensions of a = 1.670 nm, b = 0.980 nm and c (chain axis) = 1.47 nm, together with a pseudo-hexagonal semi-hydrated form with unit cell parameters a = 1.670 nm, b = 0.965 nm and c (chain axis) = 1.44 nm. These parameters, together with the density data, indicate that inulin crystallizes along a pseudo-hexagonal six-fold symmetry with an advance per monomer of 0.24 nm. The difference between the hydrated and the semi-hydrated unit cells does not seem to correspond to any change in the conformation of inulin, but rather to a variation in water content.
André
I
I
Centre de Recherches sur les Macromolécules Végétales (CNRS), Grenoble, France.
Putaux
J L
JL
Chanzy
H
H
Taravel
F R
FR
Timmermans
J W
JW
de Wit
D
D
D002236:Carbohydrate Conformation; D003460:Crystallization; D018360:Crystallography, X-Ray; D000431:Ethanol; D007444:Inulin / Q000737:chemistry*; D008970:Molecular Weight; D012996:Solutions; D014867:Water
D012996:Solutions; D014867:Water; D000431:Ethanol; D007444:Inulin