Studies on Biosynthesis of 7S and 11S Proteins, the Main Components of Soybean Protein

Part IV. Effect of protease in unmatured seeds on the major soybean globulins

Abstract

The crude major globulins (7S and 11S) of unmatured soybean seeds were simultaneously isolated by the simple method that was effective in separating the globulins of matured seeds. The protease activity in the crude 7S fraction from unmatured seeds was detected to an extremely higher degree as compared with the crude 11S fraction. The 7S globulin, isolated by gel-filtration on Sepharose 4B from the crude 7S fraction of the seeds harvested at 30 days after flowering, was identical with that of the matured seeds on ultracentrifugal and gel electrophoretical patterns. The protease peak on the Sepharose 6B column chromatogram of the crude 7S fraction was different from the 7S globulin peak. The activity of the protease fraction of which maximum value was observed in the seeds harvested at 25 days after flowering, decreased remarkably during seeds development. The effect of the protease fraction from the unmatured seeds harvested at 25 days after flowering on the major globulins isolated from the matured seeds was examined by gel electrophoresis. The results indicated that the products produced by the protease came from only the 7S globulin.