BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Abstract
A trisaccharide (Glca1–4Glca1–6Glc) and a tetrasaccharide (Glca1–4Glca1–4Glca1–6Glc) the structures of which are related
to that of repeating unit of pullulan have been obtained, exploiting the transglycolytic activity of Aspergillus niger cyclodextrin
glucanotransferase. Bothproducts were obtained in one-pot reaction using as a donor the a-cyclodextrin and as an acceptor the
disaccharide isomaltose. The regioselectivity of the reaction was 85% for the tetrasaccharide and 80% for the trisaccharide. The
yield of reaction resulted to be 42% for the synthesis of trisaccharide and 25% for that of tetrasaccharide. Purification of
products was performed by size exclusion chromatography and by semipreparative reverse phase HPLC after reversible
derivatization with 2-aminopyridine. Structural characterization was performed by capillary electrophoresis, ion-spray mass
spectrometry, and by
13
C-NMR spectroscopy. A comparison of these results with those obtained by using a-D-glucosidase,
which had been effective for the synthesis of the disaccharide isomaltose, is reported.
