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      Characterization of Bacillus stearothermophilus cyclodextrin glucanotransferase in ascorbic acid 2-O-alpha-glucoside formation.

      1 , ,
      Biochimica et biophysica acta

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          Abstract

          In this study, we characterized cyclodextrin glucanotransferase (CGTase) from Bacillus stearothermophilus in L-ascorbic acid-2-O-alpha-D-glucoside (AA-2G) formation and compared its enzymological properties with those of rat intestinal and rice seed alpha-glucosidases which had the ability to form AA-2G. CGTase formed AA-2G efficiently using alpha-cyclodextrin (alpha-CD) as a substrate and ascorbic acid (AA) as an acceptor. Several AA-2-oligoglucosides were also formed in this reaction mixture, and they could be converted to AA-2G by the additional treatment of glucoamylase. The optimum temperature for AA-2G formation was 70 degrees C and its optimum pH was around 5.0. CGTase also utilized beta- and gamma-CDs, maltooligosaccharides, dextrin, amylose, glycogen and starch as substrates, but not any disaccharides except maltose. CGTase showed the same acceptor specificity as two alpha-glucosidases, whereas its hydrolyzing activity towards AA-2G was very low compared with those of alpha-glucosidases. Cleavage profiles of AA-2-oligoglucosides by CGTase present a possible mechanism for AA-2G formation that CGTase transfers a glucose-hexamer to an acceptor at the first step and then a glucose is stepwisely removed from the non-reducing end of the product through glucoamylase-like action of this enzyme. These results indicate that CGTase is able to synthesize AA-2G more efficiently than rat and rice alpha-glucosidases and utilization of this enzyme makes the mass production of AA-2G possible.

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          Author and article information

          Journal
          Biochim. Biophys. Acta
          Biochimica et biophysica acta
          0006-3002
          0006-3002
          Jun 24 1991
          : 1078
          : 2
          Affiliations
          [1 ] Department of Immunochemistry, Faculty of Pharmaceutical Sciences, Okayama University, Japan.
          Article
          0167-4838(91)99000-1
          1829640
          e396b7fb-08a1-49b0-9fed-d485fabbc5b0
          History

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