Abstract
A gene encoding an exoinulinase (inu) from Bacillus polymyxa MGL21 was cloned and sequenced. It is composed of 1455 nucleotides, encoding a protein (485 amino acids) with a molecular mass of 55,522 Da. Inu was expressed in Escherichia coli and the His-tagged exoinulinase was purified. The purified enzyme hydrolyzed sucrose, levan and raffinose, in addition to inulin, with a sucrose/inulin ratio of 2. Inulinase activity was optimal at 35 degrees C and pH 7, was completely inactivated by 1 mM Ag+ or Hg2+. The Km and Vmax values for inulin hydrolysis were 0.7 mM and 2500 microM min(-1) mg(-1) protein. The enzyme acted on inulin via an exo-attack to produce fructose mainly.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Bacillus / classification
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Bacillus / enzymology*
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Bacillus / genetics
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Bacillus / isolation & purification*
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Cloning, Molecular
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Enzyme Activation
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Escherichia coli / enzymology*
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Escherichia coli / genetics
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Fructose / biosynthesis
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Glycoside Hydrolases / biosynthesis*
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Glycoside Hydrolases / chemistry*
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Glycoside Hydrolases / genetics
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Glycoside Hydrolases / isolation & purification
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Inulin / metabolism
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Molecular Sequence Data
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Molecular Weight
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Recombinant Proteins / biosynthesis
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Sequence Alignment
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Soil Microbiology
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Species Specificity
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Substrate Specificity
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beta-Fructofuranosidase
Substances
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Recombinant Proteins
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Fructose
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Inulin
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Glycoside Hydrolases
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beta-Fructofuranosidase