The fractionation and purification of gliadins by hydrophobic interaction chromatography

Abstract The apolar nature of wheat gliadins has been studied. Apolar properties have been exploited to fractionate components by hydrophobic interaction chromatography and fractions have been analysed further by polyacrylamide gel electrophoresis. Experiments were carried out in pH 5.0 buffer in absence of additives such as urea or dimethylformamide. Gliadin was not retarded by ethyl or butyl agarose but showed a strong affinity for both the phenyl and octyl derivatives. The strength of the hydrophobic interactions was such that aqueous alcohol was required to achieve appreciable desorption. Even so, only two‐thirds of the bound gliadin could be eluted with aqueous ethanol alone; complete desorption required the presence of small concentrations of tetramethylammonium chloride. The elution of protein from columns followed the general order ω‐,β‐, α‐, and γ‐gliadin, respectively. This procedure provides a simple system for the fractionation of wheat prolamines under mild conditions. Results suggest that a higher degree of resolution may be attainable by further modification of experimental conditions. Interaction of gliadin with nonpolar groups covalently bound to agarose apparently reflects the presence of hydrophobic patches on the surface of the gliadin molecule.