Hydrolyzes alpha-, beta- and gamma-cyclodextrins with the highest activity with alpha-cyclodextrin (cyclomaltohexaose). Pullulan is the preferred substrate from linear substrates. Maltose is a major product of these reactions. Is also able to hydrolyze maltotriose and acarbose, and transglycosylate their hydrolytic products. Major reaction products of maltotriose and of acarbose are maltose and glucose, and glucose and pseudotrisaccharide, respectively. No activity with glucose or maltose as substrate. cyclomaltodextrin + H2O = linear maltodextrin No metal dependence, but Mn(2+) increases the activity with alpha-cyclodextrin as substrate. No effect on the activity with presence or absence of Ca(2+), Zn(2+), Tween-20 or EDTA. kcat is 2739 sec(-1) with alpha-cyclodextrin as substrate. kcat is 1678 sec(-1) with beta-cyclodextrin as substrate. kcat is 821 sec(-1) with gamma-cyclodextrin as substrate. kcat value calculations are based on the dimeric enzyme. Optimum pH is 6.0 for hydrolysis of alpha-cyclodextrin. Optimum temperature is 55 degrees Celsius for hydrolysis of alpha-cyclodextrin. Thermostable. No significant loss of catalytic activity even after overnight incubation at 65 degrees. EDTA enhances the thermostability, the half-life being 90 min at 70 degrees Celsius in the absence of EDTA, increasing to 360 min in the presence of 10 mM EDTA. However, overnight incubation at 4 degrees Celsius is first required for enhancement of thermostability. Activity decreases drastically at 75 degrees Celsius. Exists as a monomer or a homodimer in solution. Homodimer is more active and stable than the monomer. Belongs to the glycosyl hydrolase 13 family.