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

• Published in: Food chemistry Vol. 266; pp. 24 - 30
• Main Authors: Nakazawa, Shigeaki, Kanno, Tomomi, Sugisaki, Kenji, Kameya, Hiromi, Matsui, Miki, Ukai, Mitsuko, Sato, Kazunobu, Takui, Takeji
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.11.2018
• Subjects: Agaricales - chemistry; Electron Spin Resonance Spectroscopy; Enzyme identification; Fe-transferrin; Humans; Iron - chemistry; Mushroom; Oxidation-Reduction; Quantum chemical calculations; Quantum Theory; Sequence Homology, Amino Acid; Transferrins - chemistry; Transferrins - metabolism; Zero-field splitting; Electron spin resonance spectroscopy; Fe-transferrin; Enzyme identification; Quantum chemical calculations; Zero-field splitting; Mushroom
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2018.05.092

•Fe-transferrins/homologues in edible mushrooms identified by ESR spectroscopy at 4 K.•The g-values and ZFS parameters close to those of Fe-transferrins in human serums.•The theoretical calculations of the ZFS parameters made for known Fe-transferrins.•The quantum chemical calculations support the identifications of the Fe-transferrins.•Wide distribution of Fe-transferrins in mushrooms suggested for the first time. 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.