THE DEVELOPMENT OF β‐GLUCAN SOLUBILASE DURING BARLEY GERMINATION

β‐Glucan solubilase in either germinating barley or in endosperm slices treated with gibberellic acid is synthesized before endo‐β‐glucanase, α‐amylase and protease. In common with these enzymes, β‐glucan solubilase is synthesized much sooner in endosperm slices than in whole grain. Gibberellic acid stimulates β‐glucan solubilase synthesis in endosperm slices and most of the activity is rapidly released into the surounding medium, irrespective of whether the hormone is present. Inhibitors of RNA and protein synthesis block the formation of β‐glucan solubilase. Unlike β‐glucanase, α‐amylase and protease, β‐glucan solubilase is present in significant quantity in untreated barley where it is concentrated in the embryo‐containing half of the grain. The only β‐glucan solubilase activity in barley is due to an acidic carboxypeptidase. Malt contains a small amount of a second solubilizing enzyme which appears to be an endo‐β1, 3‐glucanase.