The solution was applied to a Hiprep DEAE FF column
(1 ml) pre-equilibrated with 20 mM Tris–HCl buffer (pH 7.5),
The unbound proteins from the column were removed by washing
with the same buffer at a flow rate of 1 ml/min. Proteins bound
to the column were eluted with 20 ml 20 mM Tris–HCl buffer (pH
7.5) containing 0–1 M NaCl at the same flow rate, and fractions
of 2.0 ml were collected with online monitoring of protein elution
at 280 nm. Each fraction was assayed for -amylase activity and
fractions with enzyme activity were pooled. The pooled solution
was condensed by freeze-drying, then dissolved in 20 mM Tris–HCl
buffer (pH 7.5). A 0.5 ml aliquot of the solution was loaded onto a
superdex 75 10/300 GL (GE Healthcare) gel filtration column equilibrated
with 20 mM Tris–HCl buffer (pH 7.5) and eluted with the
same buffer at a flow rate of 0.5 ml/min.