Changes in glycinin-digesting protease activity during soybean germination have been investigated.
The glycinin-digesting protease activities of imbibed or germinated soybean seed were assayed by
RP‒HPLC using a tryptic peptide from CM‒glycinin or by SDS‒PAGE using CM‒glycinin as the endogenous
substrate. Proteolytic activities of the germinated soybean seeds were found through the whole
period of germination, the activities were maintained significantly unchanged during germination for 4
days, and then those specific activities declined slowly. AE‒HPLC analysis of the glycinin-digesting
protease in the imbibed or germinated soybean seeds showed unchanged peaks corresponding to glycinin-
digesting activity, suggesting that the glycinin-digesting protease was not induced during germination
but had already been synthesized during seed maturation.