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Maize (Zea mays L., hybrid INRA 260) was grown in the greenhouse with mineral nutrition of different sulphate concentrations. Mature seeds from these plants were compared for their free amino acid and protein N forms. For the most S‐deficient sample, the Asx (asparagine + aspartic acid) content increased by 30% as compared with control, while methionine and cysteine decreased (by 25 and 30%, respectively), as well as glycine, lysine, histidine, arginine and tryptophan. In seeds lowest in S the non‐protein N to total N ratio was 77% higher than in the control. Free asparagine dominated in starved seeds (50 mol % of total free amino acids) and was ten‐fold more concentrated than in the control, where proline was the predominant free amino acid. Thus the Asx of non‐protein N reached 28% of the total mol Asx of the whole starved seed. Altered S nutrition had virtually no effect on the amino acid composition of the main protein fractions, but it significantly changed their ratios. Zeins, which are poor in S‐containing amino acids, showed 25% higher level than in seeds supplied with normal S. As a counterbalance, two glutelin subfractions rich in S‐containing amino acids, decreased by 36–71% under limiting S nutrition. It is concluded that the plant reacts against S deficiency by modifying its N metabolism. Significant accumulation occurred of free asparagine, which is the main form of N transportation. The biosynthesis of seed storage protein occurred through the accumulation of the highest possible protein quantity allowed by the available S‐containing amino acids, i.e. proteins low in S‐containing amino acids were preferentially synthesized.

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.