Studies on amylase inhibitor (S-AI) from Streptomyces diastaticus subsp. amylostaticus No. 2476. II. Purification and some properties of amylase inhibitor (S-AI).

Abstract

Amylase inhibitor (S-AI) was purified by about 25 times from culture filtrate of Streptomyces diastaticus subsp. amylostaticus No. 2476 through the methods of adsorption on active carbon, column chromatographies on Dowex 50 W×2 (H-form) and Dowex 50 W×2 (NH4-form), gel filtration on Sephadex G-25, EI-complex formation with BLA, isolation of complex by gel filtration on Sephadex G-75, dissociation from complex by the method of acid denaturation, rechromatographies on Dowex 50 W×2 (NH4-form) and Sephadex G-25. Homogeneity of this S-AI was examined by means of TLC, where S-AI gave a single spot in various solvent systems. S-AI specially inhibited α-amylases and glucoamylase, but not β-amylases and other glucoside hydrolases. S-AI was a very stable substance, as it retained 100% of its original activity after being kept for 30min at 100°C in a pH range between 3.0 and 10.0. The molecular weight of S-AI was estimated to be about 1500 by gel filtration on Sephadex G-15. S-AI was regarded to be an oligosaccharide which was mainly composed of glucose in an amount of about 85%. S-AI was hydrolyzed by β-amylase from non-reducing terminal and released two moles of maltose succesively.