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Polymeric Assembly of Gluten Proteins in an Aqueous Ethanol Solvent
journal contribution
posted on 2014-09-25, 00:00 authored by Mohsen Dahesh, Amélie Banc, Agnès Duri, Marie-Hélène Morel, Laurence RamosThe
supramolecular organization of wheat gluten proteins is largely
unknown due to the intrinsic complexity of this family of proteins
and their insolubility in water. We fractionate gluten in a water/ethanol
mixture (50/50 v/v) and obtain a protein extract which is depleted
in gliadin, the monomeric part of wheat gluten proteins, and enriched
in glutenin, the polymeric part of wheat gluten proteins. We investigate
the structure of the proteins in the solvent used for extraction over
a wide range of concentration, by combining X-ray scattering and multiangle
static and dynamic light scattering. Our data show that, in the ethanol/water
mixture, the proteins display features characteristic of flexible
polymer chains in a good solvent. In the dilute regime, the proteins
form very loose structures of characteristic size 150 nm, with an
internal dynamics which is quantitatively similar to that of branched
polymer coils. In more concentrated regimes, data highlight a hierarchical
structure with one characteristic length scale of the order of a few
nm, which displays the scaling with concentration expected for a semidilute
polymer in good solvent, and a fractal arrangement at a much larger
length scale. This structure is strikingly similar to that of polymeric
gels, thus providing some factual knowledge to rationalize the viscoelastic
properties of wheat gluten proteins and their assemblies.