Enzymatic synthesis and analysis of large-ring cyclodextrins

Large-ring cyclodextrins (LR-CD) are cyclic alpha-1,4-glucans composed of nine to more than several hundred glucopyranose units. Cyclodextrins are able to form highly specific inclusion complexes with a wide range of guest molecules thereby modifying their physicochemical properties. Only in the past 10 years, LR-CD with a degree of polymerization between 9 and 32 have been isolated and characterized. The structures of these LR-CD show novel features distinct from those of the extensively studied alpha-, beta-, and gamma-CD composed of six, seven, and eight glucopyranose units, respectively. Recent work on the enzymatic synthesis of LR-CD has confirmed the ability of different 4-alpha-glucanotransferases to form large cyclic alpha-1,4-glucans from amylose and amylopectin, depending on the specificity of the enzyme used and on the substrate and reaction conditions chosen. The potential of LR-CD for specific host-guest interactions and corresponding applications has been demonstrated.