Enzymatic preparation of radiolabeled linear maltodextrins and cyclodextrins of high specific activity from [14C] maltose using amylomaltase, cyclodextrin glucosyltransferase and cyclodextrinase

Radiolabeled linear and cyclic maltodextrins of high specific radioactivity were prepared using enzymes involved in maltodextrin metabolism. C-14-Labeled maltose was the starting material yielding products of identical specific radioactivity with respect to glucosyl residues. The enzymatic steps involved: i) Formation of linear C-14-labeled maltodexrins (<maltooctaose) using amylomaltase from Escherischia coli; ii) Cyclisation to alpha-cyclodextrin using cyclodextrin-glucosyl-transferase of Klebsiella oxytoca M5a1; iii) Removal of the remaining linear dextrins by amyloglucosidase. The products were purified by paper chromatography, or malto(1).exaose was specifically obtained from purified alpha-cyclodextrin by the action of cyclodextrinase of K. oxytoca M5a1. (C) 1998 Elsevier Science Ltd. All rights reserved.