Mössbauer effect studies of transferrin

Mössbauer effect experiments with 57Fe in transferrin at p H 7.5 exhibit paramagnetic hyperfine structure and show no difference between the two iron sites. The spectra have been analyzed in terms of a spin Hamiltonian with zero field splitting of the electronic states D = 0.15 cm−1, E/D = 0.31; the magnetic hyperfine coupling Ax :Ay :Az = 221:215:223 kOe/unit spin, respectively. The quadrupole splitting Δ E = 0.75 mm/sec. The effect of ligand nuclear moments is observed in the zero field Mössbauer spectrum. Mössbauer data were also taken with 151Eu but no hyperfine splitting was observed.