Studies on the interaction of α-cyclodextrin with phospholipid by a flexible docking algorithm

The single-molecule complexation model was provided to study the interactions of α-cyclodextrin with phospholipid components of the erythrocyte membrane using the flexible docking algorithm FDOCK. The energies and structures of the complexes between α-cyclodextrin and phospholipid at each different inclusion depth were calculated. In which, some important complexation states during the inclusion procedure were also investigated by molecular dynamics simulations. The results show that the phospholipid molecule cannot pass through the α-cyclodextrin cavity due to the prominent energy barrier when the two acyl chains are included into the α-cyclodextrin cavity simultaneously. The driving force responsible for the complexation of α-cyclodextrin with phospholipid is the van der Waals force. The complex structure of α-cyclodextrin with phospholipid acyl chain, comparing with that of headgroup, is of the lower energy. Furthermore, comparing with sn1 chain, the complex of sn2 chain with α-cyclodextrin is probably more stable due to the bendability of the unsaturated sn2 chain, which restricts α-cyclodextrin slipping on the acyl chain.