Changes in protease inhibitory activity from pigeon pea (Cajanus cajan (L) Millsp) during seed development and germination

Abstract

The protease inhibitors from seeds of pigeon pea (Cajanus cajan (L) Millsp) have been studied for their physiological role. During seed development the inhibitor was detected even as early as 7 days after flowering (DAF). But the maximum amount accumulated between 14 and 28 DAF. During this period the seed accumulates a major portion of its proteins. During germination the inhibitor activity decreases from 6 days after germination up to 10 days. Accompanying this change there is a marked decrease in the amount of cotyledonary proteins. The inhibitor does not appear to be associated with the protein bodies. The endogenous protease from the seeds was identified as a serine protease and was not inhibited by the inhibitor. The inhibitor was earlier shown to be specific towards mammalian serine protease. Although the inhibitor did not inhibit the protease from Helicoverpa armigera larva as efficiently as soyabean trypsin inhibitor a defence role for the inhibitors cannot be ruled out.