Untitled research work

Two amylases produced by Streptomyces were purified, and some properties were studied. The one, named NA-468 amylase, was produced by a strain of Streptomyces griseus and formed about 55% of maltotriose from starch. NA-468 amylase was purified to almost 100-fold of the culture broth, and showed its maximal activity at 45°C and pH 5.6-6.0. Amylose was hydrolyzed to almost 100%, but waxy starch Q-limit dextrin was not acted. It was found that NA-468 amylase cleaved the third glucosidic bond from the end of the maltooligosaccharide. The other one, named NA-273 amylase, was produced by a strain of Streptomyces praecox, and formed more than 80% of maltose from starch. NA-273 amylase was purified to about 170-fold, and showed its maximal activity at 47°C and pH 6.0. Acting on amylose, soluble starch and waxy starch β-limit dextrin, the amylase produced a large amount of α-maltose. The amylase also hydrolyzed maltotriose to form maltose without the formation of glucose. The action mechanism of it was considered that glucose formed by hydrolysis was transferred to the non-reducing end of other maltotriose, and that maltotetraose formed was again hydrolyzed to maltose.