Thermodynamic and kinetic study of epigallocatechin-3-gallate-bovine lactoferrin complex formation determined by surface plasmon resonance (SPR): A comparative study with fluorescence spectroscopy

The complexation between protein and polyphenol affects their biological functions. A complete understanding of such interactions requires comprehensive thermodynamic and kinetic characterizations. Surface plasmon resonance (SPR) and fluorescence spectroscopy (FS) described similarly the thermodynamic of interaction between bovine lactoferrin (bLF) and epigallocatechin-3-gallate (EGCG). The formation of the bLF-EGCG complex is spontaneous (Delta G(SPR)(0)approximate to -29.00 kJmol(-1), Delta G(FS)(0)approximate to 26.00 kJ mol(-1)) and entropically driven (Delta H-SPR(0) = 14.26, Delta H-FS(0) = 10.20 kJ mol(-1) and T Delta S-SPR(0) approximate to 43.00, T Delta S-FS(0) approximate to 36.00 kJ mol(-1)). The kinetic parameters obtained by SPR showed that the reaction occurs through an activated complex, whose energetic formation parameters from the association of free molecules (E-act (a) = 49.5 kJ mol(-1) Delta H-a(double dagger) = 47.0 kJ mol(-1), and T Delta S-a(double dagger) = -2.10 kJ mol(-1)) were higher than those in the opposite direction (namely the dissociation of the stable complex, E-act (d) = 17.4 kJ mol(-1), Delta H-a(double dagger) = 32.8 kJ mol(-1), and T Delta S-a(double dagger) = -45.10 kJ mol(-1)), except for Delta G(double dagger) (Delta G(a)(double dagger) = 49.1 kJ mol(-1) Delta H-a(double dagger) = 77.9 kJ mol(-1)). This study provides useful information for optimizing the use of bLF-EGCG complex as a bioactive compound in different systems, such as medical, food, cosmetic, and pharmaceutical formulations.