Purification of α-amylase from Bacillus lentus cultures

Acetone fractionation of Bacillus lentus culture filtrate yielded the highest alpha -amylase activity and the 66.6% fraction reached 13-fold that of the crude enzyme preparation. Gel filtration and ion exchange chromatography afforded a pure alpha -amylase (relative molecular mass, 42 000). The pure enzyme was highly active on starch and dextrin. It produced a mixture of oligosaccharides as major products of starch hydrolysis. Maximal activity was reached at 70 degree C and pH 6.1. Ca super(2+), Na super(+), K super(+) and Sr super(2+) ions stabilized or slightly stimulated the enzyme whereas Ag super(+), Co super(2+), Hg super(2+), Zn super(2+), Cd super(2+) and Fe super(3+) ions strongly inhibited the activity. The enzyme contained 16 amino acids, of which aspartic and glutamic acids were present in the highest proportions.