Abstract
An amylase which produces maltotriose from starch as the main product was found in the culture filtrate of a strain of Bacillus subtilis newly isolated from soil. The enzyme was purified to almost complete homogeneity, as judged by disc electrophoresis in polyacrylamide gel, by means of ammonium sulfate fractionation, DEAE-Sepharose column chromatography and Sephadex gel filtration.
The optimum pH and temperature of the enzyme were around 6-7 and 50°C, respectively. Metal ions such as Hg2+, Cu2+, Zn2+, Ni2+ and Fe2+ strongly inhibitied the enzyme activity. The molecular weight was found to be about 25, 000 by gel filtration. The yields of maltotriose from short-chain amylose (DP 17), amylopectin, soluble starch and glycogen were about 69, 56, 56 and 40%, respectively.
