1994 Volume 40 Issue 4 Pages 319-329
The enzyme alpha amylase was purified from cells of Nocardia asteroides by gel filtration on Sephadex G-150 and by DEAE-Sepharose column chromatography. The purified enzyme revealed a single band on a polyacrylamide gel electrophoresis under native conditions, indicating its homogeneity. The native molecular weight of the purified enzyme on a Sephadex G-200 column was estimated to be 150, 000. The enzyme showed two protein bands of molecular weights 65, 000 and 56, 000 on a 10% SDS-PAGE under denatured conditions, indicating that the native enzyme has two or more subunits of different molecular weights. The purified enzyme had an optimal pH of 6.9 and an optimal temperature of 50°C. The enzyme activity was enhanced by MgCl2 and inhibited by EDTA. Starch or maltose in the culture medium significantly enhanced the enzyme production compared with the culture medium containing glucose.