The behaviour of the highly thermostable Cyclodextrin GlycosylTransferase (CGTase) of Thermounuerobacter sp., with substrates like pure cyclodextrins and/or short maltooligosaccharides was investigated. This enzyme has been found to be able to disproportionate all the saccharides tested (from maltose to maltoheptaose) 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 a-cyclodextrin. However, Thermoanuerobacter sp. CGTase produces mainly P-cyclodextrin starting from the maltooligosaccharides that we tested, while y-cyclodextrin production can be improved by using longer polymers of glucose (maltopentaose) and cyclodextrin as substrates. An ol/P/y molar ratio of 4/5/1 was obtained with lOmM of maltopentaose which changed to 9/12/8 with initial addition of 100pM of p-cyclodextrin.

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