Chimeras and CGTases mutants with a focus on the specificity of γ-cyclodextrin production

Abstract

Much has been achieved in the 135-year history of cyclodextrin research and all that goes with it. Cyclodextrins are ring-shaped molecules composed of glucose residues produced by the enzymatic transformation of starch and have toroidal structures with a hydrophobic cavity and a hydrophilic surface that allow them to form inclusion complexes with a broad range of compounds. As the bacterial enzymes that produce cyclodextrins, specifically cyclodextrin glucanotransferases (CGTases), are inextricably linked to cyclodextrins, the new molecular biological period of their research began 40 years ago, when the first genes of these enzymes were cloned and sequenced. This allowed the differences between α , β , and γ CGTases at the amino acid level, to be identified, since these enzymes normally produce a mixture of different cyclodextrins composed of 6, 7 and 8 glucosylpyranose residues. Most CGTases produce γ cyclodextrin in less quantity than their counterparts. However, γ cyclodextrin has a larger internal cavity and may therefore contain larger "guest" molecules. Various chimeras and mutants of CGTases have been developed to increase the yield of γ cyclodextrin. The article also focuses at the worldwide production of cyclodextrins. Cyclodextrins with more than 8 glucose residues are also listed.