Purification Method of Proteins by Preparative Gel Electrophoresis. Crystallisation of α-amylases.

Taka-amylase A from Aspergillus orizae and huma α-amylase were crystallized in a three-step procedure: (1) Crude extract o fTaka-diastase (Sankyo) or saliva supernatant was applied to a gel slab type apparatus of preparative electrophoresis. The active fractions were extracted by crushing the gel slices with a buffer solution.(2) The soluble gel components, which were extracted from the gel slices together with protein fractions, were removed by electrophoresis with a discontinuous buffer system containing sucrose gradient (purification electrophoresis).(3) After acetone fractionation, crystalline amylases were obtained. The overall recovery rates of Taka-amylase A and human salivary amylase were 51% and 53%, respectively. Further usage of preparative gel electrophoresis and purification electrophoresis to obtaining pure proteins was examined.