Characterization of Fe-S Clusters in Proteins by Mӧssbauer Spectroscopy

The Mössbauer effect using 57Fe-ferrabisdicarbollide ([o-57FESAN]−): a glance into the potential of a low-dose approach for glioblastoma radiotherapy

“…In fact, in biological systems, iron is by far one of the most structurally and relevant metal ions and 57 Fe Mössbauer spectroscopy has been very useful in the elucidation of the electronic structures of iron-containing biomolecules, the role of iron in living processes and pathological changes in living systems, organs and tissues. 3–6…”

“…In fact, in biological systems, iron is by far one of the most structurally and relevant metal ions and 57 Fe Mössbauer spectroscopy has been very useful in the elucidation of the electronic structures of iron-containing biomolecules, the role of iron in living processes and pathological changes in living systems, organs and tissues. [3][4][5][6] Radiation therapy (RT) is the most frequently used therapeutic option for the treatment of cancer but high doses of ionizing radiation are delivered to tumours since only a small fraction of the absorbed dose can damage cancer cells. Moreover, the efficacy of RT is limited by the resistance of tumours as well as by the toxicity to normal cells and tissues.…”

The HBx protein from hepatitis B virus coordinates a redox-active Fe-S cluster

“…The 4.2 K Mössbauer spectrum of the aerobically isolated DsbC-HBx was collected in a small magnetic field (78 mT) applied parallel to the direction of the γ irradiation ( Fig. 1 B ) and shows a quadrupole doublet with parameters characteristic of antiferromagnetically coupled all-ferric [2Fe-2S] 2+ clusters (δ = 0.28 mm/s, ΔE Q = 0.51 mm/s, ∼84% of the total Fe absorption) ( Table S2 ) ( 31 , 32 ). A broad baseline spectrum makes up the rest of the signal intensity (16%) and is attributed to adventitiously bound high-spin ( S = 5/2) Fe 3+ .…”

“…In a first experiment we mimicked the conditions employed previously for the bacterial IscU, in which reductive transformation of [2Fe-2S] clusters was afforded by stoichiometric addition of reducing equiv ( 24 ). Because the [4Fe-4S] cluster in DsbC-HBx can be reduced to the 1+ state, in contrast to that of IscU that reductively degrades, Mössbauer spectra were recorded at 4.2 and 80 K because spin relaxation for paramagnetic species is temperature dependent ( 31 , 32 ) ( Figs. 4 A and S7 ).…”

Metal Dependence and Functional Diversity of Type I Cas3 Nucleases

“…The mixed-valence Fe II –Fe III form consists of two AF-coupled Fe ions, resulting in an S = 1/2 paramagnetic ground state. , At low temperatures and in the presence of an external magnetic field, the spectral components are magnetically split and exhibit broad resonances, in contrast to those of the Fe III –Fe III and Fe II –Fe II forms that appear as quadrupole doublets (Figure E, middle). At high temperatures, the Fe II –Fe III spectrum collapses into two quadrupole doublets (Figure S4), as a result of the electronic relaxation rate being fast compared to the nuclear Larmor precession frequency. , Identification and quantification of the Fe II –Fe III was afforded by parallel analysis of high-temperature Mössbauer spectra (Figure S4) and EPR spectra (vide infra). Reaction with the stronger reducing agent sodium dithionite affords a sample homogeneously enriched in the Fe II –Fe II form (Figure E, bottom).…”