Purification and Properties of an Amylase from Bacillus cereus NY-14

An extracellular amylase was obtained from a culture medium of Bacillus cereus NY-14. This enzyme was purified to show a single band on disc gel electrophoresis by ammonium sulfate fractionation and Sephadex G-100 gel filtration to 1101-fold of the activity of the original culture liquor. The purified enzyme had a molecular weight of 55,000, an isoelectric point of 6.13, an optimum pH of 6.0, and an optimum temperature of 55°C. The pH-stability range was wide; the enzyme retained more than 80% of its initial activity in the range of pH 5.5 to 12. It was stable below 35°C and required calcium ions for the stabilization. The action pattern of this enzyme on amylaceous polysaccharides was unique in that the predominant product was maltopentaose. The purified amylase could also digest starch granules of such plants as rice, barley, corn, and kuzu to produce maltopentaose as the main product.