1990 Volume 37 Issue 3 Pages 129-136
The α-amylase usually contained in commercial Rhizopus glucoamylase preparations was isolated and purified to an electrophoretically pure state. The optimum pH of the enzyme was around 5.0-5.2 The enzyme was stable over a pH range from 3.0 to 8.0 where the stability was not affected by the presence of EDTA. On the other hand, the enzyme was sensitive at temperatures higher than 50°C, and highly sensitive to mercuric ions. The action pattern on and specificity for starch of Rhiz, α-amylase considerably differed from those of Taka amylase. In the specificity, Rhiz. α-amylase seemed to be rather similar to bacterial α-amylase of saccharifying type. On the other hand, Rhiz. α-amylase showed negligible activity in degrading raw corn starch, but accelerated the hydrolysis of starch by Rhiz. glucoamylase. This acceleration mechanism of Rhiz. α-amylase remains unsolved. However, the a-amylase was observed to make wider the holes being bored by glucoamylase on starch granules and the implication of the results was discussed.
