Synthesis of malto-oligosaccharides via the acceptor reaction catalyzed bycyclodextrin glycosyltransferases

The disproportionation activity (intermolecular transglycosylation) of cycl omaltodextrin glycosyltransferases (CGTases) from Thermoanaerobacter sp. an d Bacillus circulans strain 251 was studied. Using soluble starch as donor, the CGTase from Thermoanaerobacter sp. showed the highest transglycosylati on activity with all the malto-oligosaccharides tested as accepters. At rat ios of starch:D-glucose from 2:1 to 1:2 (w/w), the formation of cyclodextri ns was completely inhibited, and a homologous series of malto-oligosacchari des (G(n)) was produced. The conversion of starch into acceptor products wa s in the range of 63-79% in 48 h. The degree of polymerisation of malto-oli gosaccharides formed could be modulated by the ratio of starch:D-glucose pr ovided; at a ratio of 1:2 (w/w), the reaction was quite selective for the f ormation of G2-G3.