Bacillus macerans cyclomaltodextrin glucanotransferase transglycosylation reactions with different molar ratios of d-glucose and cyclomaltohexaose Original Research Article

It was found that Bacillus macerans cyclomaltodextrin glucanotransferase (CGTase) reacts with cyclomaltohexaose (α-cyclodextrin, α-CD) to give a series of cyclomaltooligosaccharides (cyclomaltodextrins, CDs), having seven to more than 20 d-glucose residues and maltooligosaccharides (maltodextrins, MDs) from G5 to G12+. When d-glucose (Glc) was added to the α-CD at very low molar ratios (1:100) of Glc to α-CD, the predominant products (95%) were CDs, some of which were macrocyclic MDs with 20–60 d-glucose residues, along with MDs that also had high molecular weights, containing 10–75 d-glucose residues and gave a blue iodine–iodide color. As the molar ratio of Glc to α-CD was increased, the amount of CDs progressively decreased and MDs proportionately increased in the range of G2–G12. At 25 mM α-CD and Glc to α-CD molar ratio of 1:1, a 75% yield of MDs, G1–G12, each in approximately equal amounts, was obtained; and at 20 mM and a 5:1 ratio, a 97% yield of MDs, G2–G9, was obtained but in unequal amounts. At higher ratios (10:1), the CDs completely disappeared, and at very high ratios (50:1 to 100:1) only low-molecular-weight MDs, G2–G4, were formed.