Barley Seed α-Glucosidases: Their Characteristics and Roles in Starch Degradation

摘要

The identities of enzymes involved in degradation of seed starch are well established, as are the characteristics of several of the individual enzymes. However, the interactions between the different enzymes as they function together to hydrolyze starch are not well understood. The development of a reconstituted starch hydrolyzing system using components isolated from seeds allowed the identification of an interaction between a-amylases and a-glucosidases that resulted in synergistic hydrolysis of native starch granules. The relative importance of this interaction, as well as interactions with P-amylase and starch debranching enzyme, was influenced by whether or not the crystalline structure of starch was disrupted. Examination of these four enzymes as they function in a multistep biochemical process revealed that the importance of their independent actions, in addition to their interactions, varied depending upon the structure of the starch being hydrolyzed.