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Title
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New type of pullulanase from Bacillus stearothermophilus and molecular cloning and expression of the gene in Bacillus subtilis.
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Authors
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T.Kuriki,
S.Okada,
T.Imanaka.
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Ref.
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J Bacteriol, 1988,
170,
1554-1559.
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PubMed id
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Abstract
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A new type of pullulanase which mainly produced panose from pullulan was found
in Bacillus stearothermophilus and purified. The enzyme can hydrolyze pullulan
efficiently and only hydrolyzes a small amount of starch. When pullulan was used
as a substrate, the main product was panose and small amounts of glucose and
maltose were simultaneously produced. By using pTB522 as a vector plasmid, the
enzyme gene was cloned and expressed in Bacillus subtilis. Since the enzyme from
the recombinant plasmid carrier could convert pullulan into not only panose but
also glucose and maltose, we concluded that these reactions were due to the
single enzyme. The new pullulanase, with a molecular weight of 62,000, was
fairly thermostable. The optimum temperature was 60 to 65 degrees C, and about
90% of the enzyme activity was retained even after treatment at 60 degrees C for
60 min. The optimum pH for the enzyme was 6.0.
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