PURIFICATION AND CHARACTERIZATION OF A THERMOSTABLE ALPHA-AMYLASE FROM BACILLUS SP-JF STRAIN

A thermostable alpha-amylase (EC 3.2.1.1, alpha-1, 4-glucan-glucanhydrolase) from a new Bacillus sp-JF2 strain was purified and characterized. The molecular weight of the alpha-amylase was about 110,000 by the method of polyacrylamide gel gradient electrophoresis and that of the subunit was about 50,000 by the method of SDS polyacrylamid gel gradient electrophoresis. The alpha-helix content of the enzyme protein was 41% by the method of the circular dichroism. The enzyme protein molecule contained calcium ion, but the calcium ion did not closely relate with the activity site of alpha-amylase. The temperature for the high enzyme activity was 85 to 90-degrees-C. Calcium and magnesium ions did not highly affect enzyme activity, but Fe2+, Cu2+, Zn2+ and Ag+ ions inhibited the activity.