Electrophoretic studies of α‐amylase in wheat. II

Abstract

The lack of correlation between the degree of sprouting and the α‐amylase activity in wheat and rye, as well as the apparent variation in the falling number during ripening, can be explained as the result of two amylase systems acting during different stages of the development of the grain. During the early stages of the development of the grain, α‐amylase is continuously inactivated. This process is reversible, however, and when the evaporation of moisture is retarded the α‐amylase activity increases as a consequence of the higher amount of dissolved enzyme. This results in an occasional decrease in the falling number, which might amount to more than 50 sec. During germination, a new kind of α‐amylase develops. The synthesis of the new form of α‐amylase is irreversible and causes a much greater and permanent reduction in the falling number. During the initial stages of germination, the amylase activity thus increases owing to the combined action of both the original amylase and the new form. The two kinds of amylases show different electrophoretic patterns. Drying the grain after harvesting reduces the activity of ‘green’ amylase (amylase in unripened grain), which might explain the frequent observations of increasing falling number during storage.