A look inside the cavity of hydrated α-cyclodextrin: A computer simulation study

Monte Carlo simulations of hydrated α-cyclodextrin are made to analyze the properties of the water molecules inside the hydrophobic cavity. An average of five water molecules is found in the cavity, where only 2.4 are hydrogen bonded to the α-CD. The hydrogen-bond interactions between the α-CD and the inner water molecules are reduced when compared with those outside the cavity. The free energy of binding one water molecule inside the hydrated α-CD is obtained using the thermodynamic perturbation theory. From these the entropy contribution is obtained to ascertain the hydrophobic strength of the cavity.