Differential Proteolysis of Glycinin and β-Conglycinin Polypeptides during Soybean Germination and Seedling Growth

Abstract

The degradation of the major seed storage globulins of the soybean (Glycine max [L.] Merrill) was examined during the first 12 days of germination and seedling growth. The appearance of glycinin and fl-conglycinin degradation products was detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of cotyledon extracts followed by electroblotting to nitrocellulose and immunostaining using glycinin and B-conglycinin specific antibodies. The three subunits of fl-conglycinin were preferentially metabolized. Of the three subunits of j-conglycinin, the larger a and a' subunits are rapidly degraded, generating new #-conglycinin cross-reactive polypeptides of 51,200 molecular weight soon after imbibition of the seed. After 6 days of growth the a-subunit is also hydrolyzed. At least six polypeptides, ranging from 33,100 to 24,000 molecular weight, appear as apparent degradation products of