Springer Online Journal Archives 1860-2000
Process Engineering, Biotechnology, Nutrition Technology
Summary A purification procedure for an extracellular α-amylase from Streptomyces rimosus, oxytetracycline-producing strain, is described. The enzyme obtained was shown to be an acidic (pI 4.75) monomer with a relative molecular mass (Mr) of 43 000, containing three cysteines involved in the catalytic activity of the enzyme. Its amino-terminal part has 57–67% homology with amylases from other Streptomyces species. S. rimosus α-amylase is sensitive to higher temperatures, and partially stabilized by Ca2+ ions. It hydrolyses starch (optimum at pH 5.0–6.0) in an endohydrolase manner giving rise to maltotriose, maltotetraose and higher oligosaccharides. Starch granules, except those from rice, were not significantly affected by the isolated α-amylase.
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