Fractionation of sunflower seed proteins

Abstract

Abstract Fractionation of sunflower seed salt‐soluble proteins, which amount to nearly 80% of the total seed nitrogen, has been performed by a method we proposed in 1970 and which was confirmed by several others. Three varieties of seeds have been investigated: ‘Armavirec,’ ‘Peredovik’, and a pure strain. The occurrence of three groups of proteic fractions was confirmed. Their proportions, which fluctuate with varieties, are roughly: 20% for “light” (low molecular weight) albumins, 5–10% for “heavy albumins,” and 70–80% for globulins. The first group was isolated by Sephadex G‐50 chromatography from the other two, which were separated by dialysis. A second chromatography of these three groups on Sephadex G‐200 has been realized (with preliminarily calibrated columns for molecular weight evaluations). “Light” albumins appear as a rather homogeneous constituent with a molecular weight of 14,000 and an aminoacid composition showing high amounts of methionine, cystine, arginine and glutamine. “Heavy” albumins, which are still mixed with globulin fractions after dialysis, have a molecular weight of 48,000 and a very different aminoacid composition with a high level of lysine. Globulins are composed of at least four different fractions, two of which (M=12,000 and M=25,000) are presumably subunits of the other two and have significantly different aminoacid compositions.