Extracellular alpha-amylase from Streptomyces rimosus.
A purification procedure for an extracellular alpha-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 (M(r)) 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 alpha-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 alpha-amylase.
Department of Organic Chemistry and Biochemistry, Ruder Bosković Institute, Zagreb, Croatia.
B
B
Vukelić
A
A
Ritonja
M
M
Renko
M
M
Pokorny
L
L
Vitale
D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013302:Streptomyces / Q000201:enzymology*; D013696:Temperature; D000516:alpha-Amylases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism
D000516:alpha-Amylases; D003545:Cysteine; D002118:Calcium