ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Following cereal grain germination the starch and storage proteins accumulated in the starchy endosperm are mobilized by the concerted action of hydrolytic enzymes, such as amylases and proteases, that are produced and secreted by the scutellum and the aleurone layer. We have studied the pattern of endoproteolytic activities following wheat (Triticum aestivum cv. Chinese Spring) grain germination using SDS-PAGE containing a gradient of polyacrylamide copolymerized with gelatin, an artificial substrate for plant proteases. Total proteolytic activity increased as seedling growth proceeded and reached a maximum 5–7 days after imbibition. Up to 20 proteolytic bands could be detected in extracts from these grains. The bands were arbitrarily classified into 3 groups; endoproteases of groups I and II showed higher activity at pH 6.5, while those of group III had maximum activity at pH 4.0. Most of group II and III endoproteases were produced by the aleurone layer and scutellum and secreted to the starchy endosperm. The synthesis of most of the proteases of group III, but not of group II, was activated by exogenous GA3 in de-embryonated wheat grains. Based on activation by thiol-reagents and inhibition by thiol-protease inhibitors, it was determined that GA3-induced proteases were thiol-proteases.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1995.tb00835.x
