Cyclodextrin glucosyl transferase

Enzymatic process is the main method to produce cyclodextrins (CDs), and so far, chemical methods have been reported. CD is industrially produced from starch, glucogen, malto-oligosaccharides, and other dextrins through catalysis by cyclodextrin glucosyl transferase (CGTase). More and more researchers focus on the essential CGTase to prepare CD due to its wide applications in food, medicine, cosmetics, environmental protection, and analytical chemistry. 

Jamuna, R., Saswathi, N., Sheela, R., Ramakrishna, S. V. Synthesis of cyclodextrin glucosyl transferase by Bacillus cereus for the production of cyclodextrins. Appl Biochem Bio-fec/ o/1993,43,163-176. 

They are prepared by the action of cyclodextrin-glucosyl-transferase from different Bacillus sp. (- cyclodextrins) on mixtures of soluble starch and sucrose. During reaction, short-chain ->starch hydrolysis products are transferred with their reducing end group to the C4 of the sucrose-AGU. 

Closely related to the helical amyloses are the cycloamyloses which are produced by enzymatic degradation of amylose by glucosyl transferase enzymes. Cycloamyloses, better known as cyclodex-trins (Table 10.5), have been characterised with 6,7,8 and 9 glucose units (a,p,Y,8, varieties). The p form (10.28a) is the most studied and most used to date. Like the helical amyloses, the toroidalshaped cyclodextrins can form inclusion complexes with various molecules. These are usually formed by adding guest molecules to saturated solutions of the latter. 

Reactions carried out on disaccharide derivatives included the conversion of peracetates to l-phenylthio- 3-derivatives by use of phase-transfer methods and the epimerization at C-2 by calcium -amine systems (CaCl2.2H20, EtjN, for example). By this means maltose, lactose, isomaltose and melibiose were converted into the corresponding glucosyl-D-mannoses. An extensive range of variously substituted maltosyl fluorides have been made from maltose derivatives as substrates for cyclodextrin transferase. Only the 6 -methyl ether and 6 -acetate were transformed into cyclic products. In the course of the work the thio-derivatives (83) and (84) were made. ... 

The transglycosylation reactions catalysed by cyclodextrin D-glucano-transferases from B. megaterium and B. macerans have been shown to differ towards such acceptors as D-glucose, maltose, maltotriose, and sucrose. It was suggested that cyclodextrin D-glucanotransferase may transfer D-glucosyl residues from starch, as well as from cyclodextrins, to an acceptor. 

---