An a-amylase[ƒ¿-1,4-glucan 4-glucanohydrolase, EC 3.2.1.1.], found in the culture filtrate of a strain of Thermoactinomyces vulgaris, was purified by ammonium sulfate fractionation , and DEAF-cellulose and CM-cellulose chromatographies. The purified enzyme showed a single band on disc gel electrophoresis. The optimum reaction pH and temperature were determined to be around pH 5.0 and 70°C. The isoelectric point was determined to be pH 5.2. The a-amylase was stabilized by Cal+. The a-amylase was found to hydrolyze pullulan to panose. Therefore, the hydrolytic pattern of this enzyme is different from those of pullulanase and isopullulanase. The authors have screened thermophilic acti nomycetes strains for a-amylase production and found that one actinomycetes strain iso lated from a soil sample at 50°C produced a new type of ƒ¿-amylase. The a-amylase had the ability to hydrolyze pullulan and showed different properties from the Thermoactino myces a-amylase reported by M. J. Kuo and P. A. Hartman.1,2) Since no ƒ¿-amylases have been reported to hydrolyze the part of pullulan consisting of maltotriose unit, this enzyme seems to be a new type of a-amylase. The present report describes the procedure of puri fication, some properties, and the pattern of pullulan hydrolysis of this ƒ¿-amylase. MATERIALS AND METHODS Microorganism and culture. A thermophilic acti nomycetes strain showing both ƒ¿-amylase and pullulan hydrolyzing activities was isolated from soil at 50°C.

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