Identification of proteins contained in aqueous extracts of wheat bran through a proteomic approach

Proteins of aqueous extracts of wheat bran are usually considered as the albumin fraction, and have been characterized in terms of molecular weight, amino acid content and functional properties. However, there are no reports on the variety of the extracted proteins and their amino acid sequence, despite this information would be useful if the extracts were used in distinct applications. In the present work, the proteins contained in the aqueous extracts of wheat bran were separated by SDS-PAGE. Nineteen bands with molecular weights in the range 8─93 kDa were revealed in the SDS-PAGE gels. After tryptic digestion of proteins, the resulting peptides were analyzed by tandem mass spectrometry. Database search against the Viridiplantae subset of the NCBInr protein database resulted in 39 unique proteins, 11 from which had not been previously identified in different sections of the wheat grain through proteomic analysis. Most of the proteins were metabolic and stress defense enzymes, with the storage proteins representing just a minor fraction.