Studies of specific cyclodextrin production starting from pure maltooligosaccharides using Thermoanaerobacter sp. Cyclodextrin GlycosylTransferase

The behaviour of the highly thermostable Cyclodextrin GlycosylTransferase (CGTase) of Thermoanaerobacter sp., with substrates like pure cyclodextrins and/or I;hort maltooligosaccharides was investigated. This enzyme has been found to be able to disproportionate all the saccharides tested (from maltose to malloheptaose) to produce suitable intermediate substrates for cyclization. The disproportionation of maltose leads to a sequential series of higher degree polymers and cyclodextrins, mainly composed of alpha-cyclodextrin. However, Thermoanaerobacter sp. CGTase produces mainly beta-cyclodextrin starting from the maltooligosaccharides that we tested, while gamma-cyclodextrin production can be improved by using longer polymers of glucose (maltopentaose) and cyclodextrin as substrates. An alpha/beta/gamma molar ratio of 4/5/1 was obtained with 10 mM of maltopentaose which changed to 9/12/8 with initial addition of 100 mu M of beta-cyclodextrin.