Isolation and characterization of cyclic alpha-(1-->4)-glucans having degrees of polymerization 9-31 and their...

Cyclic alpha-(1-->4)-glucans with degrees of polymerization (DPs) 9-31 were isolated from a mixture of cyclization products formed in the early stage of the action of cyclodextrin glucanotransferase (CGTase) on synthetic amylose, and characterized by matrix-assisted laser desorption ionization time-of-flight MS, 13C-NMR and HPLC of their partial acid hydrolyzates. High-performance anion-exchange chromatography (HPAEC) with pulsed amperometric detection for an accurate estimation of cyclic alpha-(1-->4)-glucans was developed using those isolate glucans as quantification standards, and by HPAEC, the time course of the cyclization reaction of CGTase from an alkalophilic Bacillus sp. A2-5a on synthetic amylose was determined.