[A thermostable alpha-amylase from Thermoactinomyces vulgaris: purification and characterization]

Alpha-amylase from Thermoactinomyces vulgaris (strain 94-2A) was purified by cellulose chromatography and gel-chromatography on Sephadex G-75 and subsequently characterised. The enzyme shows a single band in the polyacrylamide gel electrophoresis (PAGE). The isoelectric point was determined to be pH 5.4, and the molecular mass was estimated as 53,000 Dalton by PAGE. The amino acid composition was determined; it shows characteristics of other microbial alpha-amylases. A comparison of the N-terminal sequence with that of other alpha-amylases shows a homology of 66.6% to Taka-amylase. The pH-optimum for the alpha-amylase activity is 4.8 to 6.0 and the temperature optimum 62.5 degrees C. The heat inactivation was investigated under different conditions (temperature, time, Ca2+, EDTA).