Insights into the molecular interaction of cyclodextran with a guest molecule: A computational study

Cyclodextran (CI) is a cyclic oligosaccharide in which d-glucose forms a ring structure by α-1,6 glycoside linkage and forms an inclusion complex with various guest molecules. In this study, we conducted quantum chemical calculations and molecular dynamics (MD) simulations to analyze the molecular interaction mechanism of CI with a guest molecule. Calculations of cyclodextrin (CD), in which d-glucose forms a ring structure by α-1,4 glycoside linkage, were also performed for comparison. Here, coenzyme Q10 (CoQ10), a promising molecule for industrial application with CI, was chosen as a guest molecule. Our MD simulation demonstrated that the molecular fluctuation was similarly large for both CI and CD when CoQ10 was absent. In the case that CoQ10 exists, the CD was found to form a rigid one-by-one inclusion structure, while CI does not. Additional simulations including multiple CI-8s indicated the possibility that an inclusion structure is maintained by the existence of other CI-8s.