Determination of Metal Associated with Proteins of Wheat Seed Samples After Sequential Extraction Procedure

This work was initially conducted to study the distribution of Cu, Fe, Mn and Zn in the protein fractions of wheat sample subjected to sequential extraction procedure. The highest metal concentrations were determined in the fraction extracted with Tris-HCl buffer containing 1% sodium dodecyl sulfate (SDS). The fractions of wheat sample obtained after the extraction procedure were analyzed by one-dimensional polyacrylamide gel electrophoresis (1D SDS-PAGE) and protein bands were treated to quantify Cu, Fe, Mn, and Zn by graphite furnace atomic absorption spectrometry (GF AAS). Metals were associated to protein bands of specific molecular weight, determined using a standard protein. The protein fractions were also analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) after a typical protein digestion protocol, identifying lipid transfer protein and grain softness, the latter being possibly associated to Mn.