Inhibition of Gibberellic Acid-induced alpha-Amylase Formation by Polyethylene Glycol and Mannitol.

Both polyethylene glycol (PEG) and mannitol inhibit gibberellic acid-induced alpha-amylase production in barley aleurone layers. The effect of the osmotic solution is on enzyme synthesis rather than alpha-amylase secretion. The inhibition of alpha-amylase synthesis does not appear to be mediated via an indirect effect on respiration or protein synthesis. Rather it seems that the osmotic solutions reduce the extent of proteolysis of the stored aleurone grain protein thus making available less substrate for new protein synthesis.