ABSTRACT
Cyclodextrin glycosyltransferase (CGTase; EC 2.4.1.19) is an extracellular enzyme which converts starch into nonreducing, cyclic malto-oligosaccharides called cyclodextrins (CDs). It is a hydrolytic enzyme that carries out reversible intermolecular as well as intramolecular transglycosylation reaction toward cyclization, coupling, and disproportionation of malto-oligosaccharides. CD is a nonreducing closed-ring malto-oligosaccharide with glucose monomers linked with each other by α1 →4 glycosidic bonds. The most common form of CDs are consist with Six, seven, and eight glucose residues, i.e., α-, β-, γ-cyclodextrin, respectively. CGTase exhibits an axis of cyclization either with phenylalanine (Phe) or tyrosine (Tyr), essentially for the formation of CDs. The CGTase enzyme is efficient of transglycosylation and is specifically dependent on the centrally located Tyr residue for cyclization. Similarly, Phe and Arginine (Arg) are known for CD binding residues, whereas, lysine (Lys), and asparagine (Asp) are known for linear substrate binding residues of CGTase enzyme. The kinetics of coupling reaction exhibit the binding of both the donor (CD) and acceptor (monosaccharide) to the active binding cleft of the CGTase enzyme module before processing of CDs. Environmental 126conditions are regulatory aspects for growth of the microbial population and metabolic production. Enhanced CD production could be achieved through providing appropriate conditions. Induction of more thermostable CGTase enzymes are required to increase the CD production by ignoring the traditional problem of increase in temperature with inactivating the enzyme. Fermentation conditions such as the concentration of nutrients, temperature, and compositions of the carbon and nitrogen sources determine the optimum production of CGTase. Similarly, the CD-drug inclusion complex can be utilized for management of drug toxicity and regulated drug delivery.
