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Updated: Jun 25, 2026

Denaturing Urea Polyacrylamide Gel Electrophoresis (Urea PAGE)
Published on: October 29, 2009
Detection of low-molecular weight allergens resolved on two-dimensional electrophoresis with acid-urea polyacrylamide
Kazumi Kitta1, Mayumi Ohnishi-Kameyama, Tatsuya Moriyama
1National Food Research Institute, Research Planning and Coordination Division, Tsukuba, Ibaraki 305-8642, Japan. kaz@nfri.affrc.go.jp
Abstract:
Two-dimensional electrophoresis with immobilized pH gradient (IPG) followed by acetic acid/urea-polyacrylamide gel electrophoresis (AU-PAGE) was developed for the detection of low-molecular weight food allergens. Wheat proteins were used to test the applicability of AU-PAGE for the analysis of food allergens. Isoelectric focusing (IEF) for first dimension was performed with IPG pH 3-10. AU-PAGE was performed as a second-dimensional electrophoresis and high resolution was obtained, especially for proteins below 15 kDa. For immunodetection, the proteins resolved on AU gel were transferred to a polyvinylidene difluoride membrane. The assembly of semidry electroblotting for AU gel was set reversed as for sodium dodecyl sulfate (SDS)-PAGE gel. The electroblotted membrane was immunolabeled with serum from a radio-allergosorbent test-positive individual for wheat to identify allergenic proteins. Protein spots strongly recognized by the patient's serum were chosen for further analysis. Mass spectrometry analysis revealed that these proteins were alpha-amylase/trypsin inhibitors and lipid transfer protein. The system developed in this study was shown to be useful as a standard protocol for the separation of low-molecular weight proteins. Moreover, the IPG strips on which IEF was performed could be used either for SDS-PAGE or AU-PAGE by only changing equilibrating conditions, allowing for a wide range of allergen analysis.
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