Characterization of sunflower seed and kernel proteins

Total sunflower proteins, storage proteins, and helianthinin (11S) and 2S albumin fractions and their respective subunits in seeds and kernels of three sunflower hybrids were analyzed. Protein contents were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and coupled with densitometry. The SDS-PAGE profiles of the seed and kernel proteins in the crude extracts for all genotypes showed a very similar number of protein bands (thirty two) in the electrophoretograms. Three polypeptide groups of helianthinin fraction were detected. Two of these were acidic (α, Mw = 36,800 - 42,900 Da and α', Mw = 31,000 - 35,300 Da), while one was basic (β, Mw=21,000 - 29,600 Da). The molecular weight of the 2S albumin proteins ranged from 11,500 to 20,100 Da. According to our results, there were significant differences among the seed and kernel protein contents. The 2S albumin content was significantly higher in kernels than in whole seeds of sunflower hybrids (P lt 0.05). By contrast, the 11S helianthinin content was significantly higher in seeds (where it ranged from 61.75 to 67.70% of totally extracted proteins) than in kernels (varied from 57.36 to 61.51% of totally extracted proteins) of sunflower hybrids (P lt 0.05)