Properties of thermosensitive extracellular alpha-amylases of Bacillus subtilis.

Enzymological properties of four thermosensitive alpha-amylases (M3, M9, M18, and M20) brought by different mutation sites in alpha-amylase structural gene of Bacillus subtilis were compared with those of the parental alpha-amylase NA64. Two thermosensitive alpha-amylases (M9 and M20) were altered not only in their thermosensitivity but also in their immunological properties, catalytic properties, molecular weights determined by the gel filtration on a Bio-Gel P-100 column, and others. The other two thermosensitive alpha-amylases (M3 and M18) were altered only in their thermosensitivity.