Interaction between Cucurbit[7]uril and Bile Salts: An Isothermal Titration Calorimetry Study

The interaction of three very well-known bile salts namely sodium deoxycholate (NaDC), sodium cholate (NaC) and sodium taurocholate (NaTC) with cucurbit[7]uril (CB7) have been investigated using isothermal titration calorimetry (ITC). The change in heat during the titration was recorded using microcal ITC200, from which several important thermodynamic parameters of the complexation process like enthalpy, Gibbs free energy, and entropy were obtained with very good precision. The ITC measurement showed that CB7 formed the complex with all the three bile salts at 1 : 1 stoichiometry but with a different binding affinity. The binding affinity of CB7 with the studied bile salts was found to be in the following order NaDC>NaC>NaTC. The overall investigation recommended that the complexation of bile salts with CB7 was highly influenced by both the degree of hydroxylation of bile salt and conjugation in bile salt.

Automated summary

In this study, the interaction between three well-known bile salts and CB7 was investigated using ITC, and significant thermodynamic parameters of the complexation process were obtained. The results showed that the degree of hydroxylation and conjugation of bile salts greatly influenced the binding affinity with CB7.