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Wheat cultivar discrimination by capillary electrophoresis of gliadins in isoelectric buffers
Author(s) -
Capelli Laura,
Forlani Fabio,
Perini Fabio,
Guerrieri Nicoletta,
Cerletti Paolo,
Righetti Pier Giorgio
Publication year - 1998
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.1150190228
Subject(s) - isoelectric focusing , capillary electrophoresis , chromatography , electrophoresis , cultivar , isoelectric point , chemistry , capillary action , biochemistry , botany , biology , materials science , enzyme , composite material
Abstract A modified method is reported for screening of wheat cultivars: capillary zone electrophoresis of gliadins in isoelectric buffers. Previously published procedures recommended a 100 m M phosphate buffer, supplemented with 0.05% hydroxypropylmethylcellulose and 20% acetonitrile, in uncoated capillaries. Due to the very high conductivity of such a buffer (4.7 mmhos at 25°C) high speed separations (10—12 min analysis time at 800 V/cm) could only be elicited in 20 μm internal diameter (ID) capillaries, at the expense of sensitivity. In the present report, we optimized the background electrolyte as follows: 40 m M aspartic acid (pH = p I = 2.77) in the presence of 7 M urea and 0.5% short‐chain hydroxyethylcellulose ( M n 27000 Da; apparent pH 3.9 in 7 M urea). As an alternative recipe, the same isoelectric buffer can be supplemented with a mixed organic solvent composed of 4 M urea and 20% acetonitrile (apparent pH 3.66). Due to the much lower conductivity (0.7 mmhos), separations can be carried out at 1000 V/cm in only 10 min, but in larger bore capillaries (50 μm ID), ensuring a five‐times higher sensitivity. The gliadin patterns thus obtained are species‐specific and allow easy identification of all cultivars tested of both durum and bread wheat. No adsorption of proteins to the silica wall seems to occur and high reproducibility in peak areas and transit times is obtained.