Novel maltose-producing amylase from Bacillus megaterium G-2.

Abstract

A novel maltose-producing amylase, which strictly hydrolyzes the α-1,4-glucosidic linkages in starch with maltose units and releases α-maltose, was found in the culture filtrate of a strain of Bacillus megaterium newly isolated from soil. The enzyme was purified to almost homogeneity by means of ammonium sulfate fractionation, DEAE-Sepharose column chromatography and Bio-gel A 0.5 m column chromatography. Its optimum pH and temperature were around 7.0 and around 60°C, respectively. The enzyme was inhibited by sulfhydryl reagents such as mercuric chloride and p- chloromercuribenzoate, and the inhibition was recovered by cysteine. Its molecular weight was estimated to be about 60,000 by the gel filtration method. Its enzymatic properties, including its action pattern, were very similar to those of β-amylase, except for the configuration of the maltose produced.