The present invention relates to the field of proteomics and more specifically to a method for analyzing a sample possible containing peptides or modified peptides; in particular useful for biomarker discovery or validation of biomarkers. The method uses isoelectric focusing and mass spectrometry (MS) and enables identification of modified peptides with high resolution and predictability.

The present invention provides novel antigens of an allergy to wheat, methods and kits for diagnosing an allergy to wheat, compositions comprising such an antigen, wheat or processed products of wheat in which such an antigen is eliminated, and a tester composition for determining the presence or absence of a wheat antigen in an object of interest. The present invention also relates to polypeptides comprising an epitope of an antigen, kits, compositions and methods for diagnosing an allergy, comprising such a polypeptide, compositions comprising such a polypeptide, and raw materials or processed products in which an antigen comprising such a polypeptide is eliminated or reduced. The present invention further relates to a tester composition for determining the presence or absence of an antigen in an object of interest.

A method for analyzing a protein and a peptide, includes: providing a capillary for isoelectric focusing; providing a capillary device for separation and analysis having the capillary and a solid-phase extraction column being unified as a single tube-like structure; providing an electrophoresis instrument having the capillary device and the mechanism regulating the pressure difference at both ends of the capillary device; introducing a sample containing a target protein or peptide into the solid-phase extraction column to let the target protein or peptide be adsorbed on the column, and filling the capillary device with a carrier ampholyte solution; starting separation by isoelectric focusing after eluting the target protein or peptide by filling the solid-phase extraction column with electrode solution or acid or base solution, or after firstly eluting the target protein or peptide with an eluting solution containing carrier ampholyte and secondly filling the solid-phase extraction column with electrode solution or acid or base solution; and focusing the eluted target protein or peptide in the capillary for isoelectric focusing.

A method for analyzing a protein and a peptide, includes: providing a capillary for isoelectric focusing; providing a capillary device for separation and analysis having the capillary and a solid-phase extraction column being unified as a single tube-like structure; providing an electrophoresis instrument having the capillary device and the mechanism regulating the pressure difference at both ends of the capillary device; introducing a sample containing a target protein or peptide into the solid-phase extraction column to let the target protein or peptide be adsorbed on the column, and filling the capillary device with a carrier ampholyte solution; starting separation by isoelectric focusing after eluting the target protein or peptide by filling the solid-phase extraction column with electrode solution or acid or base solution, or after firstly eluting the target protein or peptide with an eluting solution containing carrier ampholyte and secondly filling the solid-phase extraction column with electrode solution or acid or base solution; and focusing the eluted target protein or peptide in the capillary for isoelectric focusing.

Embodiments of the present disclosure are directed to charge variants of a protein such as vascular endothelial growth factor VEGF-Trap, and methods, systems, devices and kits corresponding to methods for analyzing the same.

Embodiments of the present disclosure are directed to charge variants of a protein such as vascular endothelial growth factor VEGF-Trap, and methods, systems, devices and kits corresponding to methods for analyzing the same.