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Purification and Characterization of α‐Amylases of an Alkalopsychrotrophic Micrococcus sp
Author(s) -
Kimura Takuhei,
Horikoshi Koki
Publication year - 1990
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.19900421008
Subject(s) - amylase , pullulan , thermostability , pullulanase , enzyme , chemistry , isoelectric point , chromatography , micrococcus , biochemistry , bacteria , biology , polysaccharide , genetics
Two amylases of an alkalopsychrotrophic Micrococcus were purified by chromatographies of DEAE‐Toyopearl, Butyl‐Toyopearl and Shodex WS‐2003. Molecular weights and pI values of the purified enzymes, I and II, were 185000 and 125000 by SDS‐PAGE and 4.8 and 4.3 by isoelectric focusing, respectively. Enzyme I had not only amylase but also pullulanase activity. In the presence of Ca 2+ ions, other properties of both enzymes were very similar: optimum temperature 55–60°C, optimum pH 7.5–8.0 k m value for maltopentaose 0.09 mM. Both amylases were completely inactivated after incubation with EDTA at 30°C and thereafter, could be reactivated by an addition of CaCl 2 . In the absence of Ca 2+ ions, amylase I became thermoresistant, while the thermostability of amylase II decreased. Neither amylase activity of enzyme I nor enzyme II was inhibited by pullulan.