An Investigation of Thermodynamic Parameters of Interaction between Bovine Serum Albumin and Methyl Cinnamate

The interaction between bovine serum albumin (BSA) and methyl cinnamate (MC), an strawberry flavor compound, was investigated. We found that BSA and MC form complex with stoichiometry (n) equal 1, driven by system’s entropy increase and enthalpy reduce at pH 7.4, 5.0 and 3.5, with binding constants (Kb) in magnitude of 10 5 L.mol -1 . There was difference in variation of standard enthalpy of complex formation (ΔH°) between pH 7.4 and 5.0 (-8.71 kJ.mol -1 and -12.50 kJ.mol -1 for pH 7.4 and 5.0, respectively), which occurred because conformational changes on protein structure. Differential scanning nanocalorimetry showed that BSA is denatured at pH 3.5 and it is more enthalpically stable at pH 7.4, with variation of denaturation enthalpy (ΔdenH) equal to 803.3 kJ.mol -1 and 943.5 kJ.mol -1 at pH 5.0 and 7.4, respectively. Conformational changes did not affected MC binding site, which was verified to be BSA site III. PALAVRAS-CHAVE: Proteína; aroma alimentício; espectroscopia de fluorescência; nanocalorimetria; interação intermolecular.