An investigation on acarbose inhibition and the number of active sites in an amylopullulanase (L14-APU) from an Iranian Bacillus sp. |
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Authors: | Marzieh Ghollasi Khosro Khajeh Nasrin Mollania Shekufeh Zareian Hossein Naderi-Manesh |
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Institution: | (1) Department of Biochemistry and Biophysics, Tarbiat Modares University, P.O Box 14115-175, Tehran, Iran |
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Abstract: | An amylopullulanase (L14-APU) from an Iranian thermophilic bacterium was purified and the effect of acarbose, as a general inhibitor of α-amylases, on pullulan and starch hydrolysis catalyzed by L14-APU was investigated. The inhibition is a competitive type whereas inhibition constants for pullulan and starch are 99 μM
and 72 μM, respectively. Investigation of the reaction rate in a system contains competitive substrates and the inhibition
type of acarbose in presence of different substrates suggests that L14-APU possesses only one active site for two activities. The analysis of metal ions and other reagents effects has shown that
Ca2+, Mg2+, Mn2+ and Co2+ enhanced both activities of the enzyme while N-bromosuccinimide treatment leads to the complete inactivation of the enzyme.
The enzyme activity increased in the presence of low concentration of SDS as a surfactant. |
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Keywords: | amylopullulanase acarbose single active site metal ions inhibitors |
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