The development of proteolytic activity and protein degradation during the germination of Pisum sativum L.

The change in protein content and composition of the cotyledons of Pisum sativum L. cv. Burpeeana during germination was studied. Protein depletion from the cotyledons was slow during the first 4 days of germination but became rapid on the 5th day and by the 16th day the majority of the protein had disappeared. During the first 4 days the depletion of the globulins exceeded that of the albumins; legumin appeared to be degraded slightly more rapidly than vicilin during the early phase of germination. Sodium-dodecylsulfate (SDS) electrophoresis of SDS- and dithiothreitol-dissociated globulins indicated that before rapid protein depletion there were marked changes in the component composition of the major globulins legumin and vicilin. The onset of rapid protein depletion was associated with an increase in the level of an acid-sulfhydryl protease in the cotyledons. These findings indicate that the reserve globulins undergo modifications prior to their eventual hydrolysis.