Probing the binding of (+)-catechin to bovine serum albumin by isothermal titration calorimetry and spectroscopic techniques

• (+)-Catechin-BSA system is driven by enthalpy and entropy.
• (+)-Catechin can quench the fluorescence of BSA through a static quenching.
• (+)-Catechin can be stored and carried by serum albumin to reach its target organ.
• Binding site I is the primary binding site for (+)-catechin.
• (+)-Catechin may induce conformational and microenvironmental changes of BSA.

In this study, the interaction between (+)-catechin and bovine serum albumin (BSA) was investigated using isothermal titration calorimetry (ITC), in combination with fluorescence spectroscopy, UV–vis absorption spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy. Thermodynamic investigations reveal that the electrostatic interaction and hydrophobic interaction are the major binding forces in the binding of (+)-catechin to BSA. The binding of (+)-catechin to BSA is synergistically driven by enthalpy and entropy. Fluorescence experiments suggest that (+)-catechin can quench the fluorescence of BSA through a static quenching mechanism. The obtained binding constants and the equilibrium fraction of unbound (+)-catechin show that (+)-catechin can be stored and transported from the circulatory system to reach its target organ. Binding site I is found to be the primary binding site for (+)-catechin. Additionally, as shown by the UV–vis absorption, synchronous fluorescence spectroscopy and FT-IR, (+)-catechin may induce conformational and microenvironmental changes of BSA.

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