Comparative studies of the relative mobility of gliadin at low pH by capillary electrophoresis and conventional electrophoretic techniques

Abstract

Gliadins are one of the major wheat grain storage proteins. They are a group of more than 50 proteins that share structural homology and similar physicochemical properties. Electrophoresis at pH 3.1 using acidic-polyacrylamide gel electrophoresis (A-PAGE) has traditionally been a way to characterize them. Gliadins were classified in α, β, γ, and ω-gliadins, according to their decreasing mobility in the A-PAGE system. CE has been successfully applied to the analysis of gliadins demonstrating high efficiency and resolution for wheat cultivar identification. We compared purified gliadin fractions using CE and A-PAGE through their relative mobility. The conditions selected for the fastest CE separation employed a 25-pm-i.d. fused-silica capillary column using 0.1 M phosphate, pH 2.5; 20% acetonitrile; and 0.03% hydroxypropylmethylcellulose (HPMC) as the running buffer. The analysis of the purified gliadin fractions showed the same relative mobility pattern in both systems, allowing the characterization of cultivars commonly grown in Argentina. Because it provides efficiency, reproducibility, and short analysis times, CE is a more suitable technique for routine cultivar differentiation. In addition, the CE separation in which all gliadin fractions, even the slow-moving ones, are presented, will be useful for future applications such as control of gliadin fraction isolation or gliadin quantification.