Separation and characterization of wheat protein fractions by high-performance capillary electrophoresis

Abstract

Wheat protein fractions, separated by the Osborne Solvent Fractionation Procedure, were characterized by high-performance capillary electrophoresis (HPCE). Each fraction was separated on a 27-cm fused-glass capillary (20 μm, i.d.) using 0.1M phosphate buffer (pH 2.5) containing hydroxypropylmethylcellulose, a polymer additive, at 45°C and 22 kV constant voltage. Albumins and globulins migrated in the first 4 min, whereas gliadins and glutenins migrated after 4 min. Individual α, β, γ, and ω gliadin proteins, which were collected from reversed-phase high-performance liquid chromatography (RP-HPLC) separations, were also separated by HPCE. Combined results of this study and our previous studies provide a catalog of individual gliadin information from HPCE, HPLC, acid-polyacrylamide gel electrophoresis (A-PAGE) and sodium dodecyl sulfate (SDS)-PAGE, relating class, relative molecular size, hydrophobicity, relative charge, and separation times of each gliadin subclass by HPLC and HPCE. The main advantages of HPCE are : 1) the complementing of other electrophoretic and chromatographic protein separation methods, and 2) safety because no toxic acrylamides and only minute amounts of organic solvents and buffers are used.