RESUMO
An extraction procedure using Tris-HCl buffer solution was employed in order to extract water-soluble proteins from seed samples of oat, wheat and soybean. Initially, the total protein concentration was determined by the Bradford method in each solution, after the extraction procedure. The soybean sample showed a higher concentration of total protein compared to the others. The protein extracts obtained were separated by reverse-phase chromatography (RP-HPLC-UV). The protein fractions were collected and analyzed by graphite furnace atomic absorption spectrometry (GFAAS) and matrix-assisted laser desorption/ionization (MALDI-TOF-MS) for determination of Cu, Fe, Mn and Zn and identification of proteins, respectively. The combination of techniques such as RP-HPLC-UV, GFAAS and MALDI-TOF-MS allowed the identification of several proteins bound to metals present in the seed samples.