Mechanisms of the release of bound beta-amylase

The aim was to identify the mechanism(s) responsible for the release of bou nd beta-amylase in soluble forms in vitro and during the germination of bar ley. Preparations of bound beta-amylase, from barley, were treated with dif ferent agents including papain, thiols, starchy endosperm extract and reage nts with amphipathic characteristics. The time courses of the release of th e bound enzyme were compared using the different releasing agents. All the reagents tested caused some release of bound beta-amylase. Probably a very complex combination of mechanisms is involves in the releas e of bound beta-amylase as barley germinates. Initial release may be by cle avage of disulphine bonds which bind beta-amylase to insoluble protein. Mat erial having amphipathic characteristics may break hydrophobic associations between beta-amylase and insoluble protein(s). The larger molecular weight isoforms are proteolysed to form the lower molecular weight materials pres ent in malt. Limited proteolysis may also occur before the release of bound enzyme. Whether or not proteolysis is directly responsible for the release of bound enzyme remains uncertain.