Affinity capillary electrophoresis and isothermal titration calorimetry for the determination of fatty acid binding with beta-cyclodextrin

Affinity capillary electrophoresis (ACE) and isothermal titration calorimetry (ITC) were used to investigate the binding interaction between several fatty acids (FAs) and beta-cyclodextrin (β-CD). Within each method, steps taken to obtain accurate binding constants are discussed. The stoichiometry of interaction was revealed to be 1:1 regardless of FA chain length. The binding constants obtained using ACE were: octanoate, 6.4 × 102; 2-octenoate, 4.7 × 102; decanoate, 3.7 × 103; 9-decenoate, 1.8 × 103 and dodecanote, 1.4 × 104. The binding constants obtained from ITC were of the same order of magnitude, but were consistently greater than those from ACE. Thermodynamic data obtained using ITC are used to explain the observed trends in binding strength.