Analysis of the interaction of gallic acid and myoglobin by UV-vis absorption spectroscopy

UV-vis absorption spectroscopy has been used to analyze the interaction of myoglobin (Мb) and gallic acid (GA). The binding constants (4.38 × 10 4 M –1 at 298.15 K and 0.42 × 10 4 М –1 at 308.15K), the number of binding sites ( h = 1.0), and the thermodynamic parameters of binding (Δ H , Δ S , and Δ G ) have been determined. Hydrogen bonds have been shown to play a major role in the stabilization of the GA–Мb complexes. GA binding led to slight changes in the electronic state of the heme ring of the protein.