Abstract
B. subtilis 65 α-amylase (MW 68, 000) showed raw potato starch-digestibility and hydrolyzing ability toward low molecular weight substrates such as maltotriose (G3) γ-cyclodextrin (γCD) and p-nitrophenylmaltoside (PNP-G2). Kleistase α-amylase (MW 48, 200), α-amylase purified from B. subtilis, showed strong raw corn starch-digestibility, but it was deficient in raw potato starch-digestibility and low molecular weight substrate-hydrolyzing ability. Liquefying α-amylase (MW 45, 000; purified from B. subtilis), which hardly digested raw starches, could not hydrolyze low molecular weight substrates. Raw starch-digesting α-amylase of B. subtilis 65 was converted to a raw starch-nondigesting form through the action of pronase. But, the pronase-digested α-amylase retained the hydrolyzing ability toward low molecular weight substrates. It is suggested that the characteristic region liberated by pronase is essential for digestion of raw starch by the amylase.
