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Fe-transferrins or their homologues in ex-vivo mushrooms as identified by ESR spectroscopy and quantum chemical calculations: A full spin-Hamiltonian approach for the ferric sextet state with intermediate zero-field splitting parameters
- Nakazawa, Shigeaki, Kanno, Tomomi, Sugisaki, Kenji, Kameya, Hiromi, Matsui, Miki, Ukai, Mitsuko, Sato, Kazunobu, Takui, Takeji
- Food chemistry 2018 v.266 pp. 24-30
- Grifola frondosa, electron paramagnetic resonance spectroscopy, enzymes, helium, humans, iron, liquids, mushrooms, oxalates, temperature
- Fe-transferrins/their homologues in ex-vivo mushrooms were identified by ESR spectroscopy at liquid helium temperature, 4 K. The ESR fine-structure signals from Grifola frondosa were analyzed by spectral simulation with a full spin-Hamiltonian approach, determining the spin Hamiltonian parameters of the ferric iron species bound in the biological environment: S = 5/2, g = (2.045, 2.01, 2.235), |D| = 0.28 cm−1, |E/D| = 0.05. The zero-field splitting (ZFS) parameters, D- and E-values, are very close to the reported values, |D| = 0.25 cm−1 and |E/D| = 0.06, for an Fe-transferrin with oxalate anion, and to |D| = 0.25 cm−1 and |E/D| = 0.04 for one with malonate anion in human sera, suggesting that the Fe3+ species are from Fe-transferrins or their homologues. Quantum chemical calculations of the ZFS tensors for Fe-transferrins were carried out. Fe-transferrins/homologues have been identified for all the mushrooms under study, suggesting that such Fe3+ enzymes are widely distributed in mushrooms.