  We study the efficiency of several Asymmetrical Flow Field-Flow Fractionation
(AF4) techniques to investigate the self-associating wheat gluten proteins. We
compare the use of a denaturing buffer including sodium dodecyl sulfate (SDS)
and a mild chaotropic solvent, water/ethanol, as eluent, on a model gluten
sample. Through a thorough analysis of the data obtained from coupled light
scattering detectors, and with the identification of molecular composition of
the eluted protein, we evidence co-elution events in several conditions. We
show that the focus step used in conventional AF4 with the SDS buffer leads to
the formation of aggregates that co-elute with monomeric proteins. By contrast,
a frit-inlet device enables the fractionation of individual wheat proteins in
the SDS buffer. Interestingly conventional AF4, using water/ethanol as eluent,
is an effective method for fractionating gluten proteins and their complex
dynamic assemblies which involve weak forces and are composed of both monomeric
and polymeric proteins.
