The interactions of polyethylene glycol-coated (PEG) iron oxide magnetic nanoparticles (MNPs) and myoglobin (Mb) from equine skeletal muscle were explored using various spectroscopic techniques. UV-Vis spectrophotometry indicated strong binding between myoglobin and the iron oxide MNPs. Fluorescence quenching experiments were used to determine the binding constants (Ka), enthalpy changes (ΔHθ), entropy changes (ΔSθ), and free energy changes (ΔGθ). Results indicated that the iron oxide MNPs quenched myoglobin’s fluorescence. The binding constants (Ka) were determined as 8.32 ± 0.26 x 106 M-1, 7.42 ± 0.67 x 106 M-1, 4.83 ± 0.18 x 106 M-1 at 298, 303, and 308K, respectively. The enthalpy changes (ΔHθ), entropy changes (ΔSθ), and free energy changes (ΔGθ) were determined to be -17.19 kJ/mol, 74.76 J/mol*K, and -39.47 kJ/mol, respectively. Circular Dichroism (CD) showed moderate changes in tertiary structure of myoglobin in the presence of the iron oxide MNPs. Furthermore, the stability of myoglobin and myoglobin-MNPs were studied by denaturation with urea and guanidinium chloride.

Binding and thermodynamic studies of myoglobin with polyethylene glycol coated iron oxide nanoparticles

253rd National Meeting (2017)

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