Fig. 6: Characterization of the reaction process of the SOD-like activity of ferritins.

a Ferrous-ferrozine production curve in the reaction of ferritins with XOD-Xan. b Content of the ferrous-ferrozine production in the reaction of ferritin with XOD and gradient xanthine. c The ferrous-ferrozine production in the reaction of ferritin and XOD-Xan when the ferrozine was added 30 min later than xanthine oxidase. d The proportion of intermediate ferrous ions to the whole iron content in different ferritins after their reaction with XOD-Xan. e SOD-like activity of the archaeal ferritins and relative ferric ion, which was generated in the reaction of archaeal ferritins with XOD-Xan in the 30 min course. f The ferrous production of archaeal ferritin and ferric salt after the reaction with the XOD-Xan in the iron concentration at 44.8 μg/mL. g ESR spectra of the DMPO/HOO• in the presence of XOD/Xan and gradient pyFn; the marked concentration referred to iron content. h The ESR intensity of DMPO/HOO• of HFn, pfFn and pyFn groups. The line at 3488.125 G of DMPO/ HOO• spectra was used to represent the intensity. i SOD-like activity of the pyFn and phosphate-doped ferrihydrite after their reaction with gradient xanthine. All data in (a−f, i) are mean ± SD (n = 3 independent experiments). The significant difference was evaluated by Two-tailed unpaired Student’s t-test for (e), and by One-way ANOVA with post-hoc Tukey HSD test for (i). The p value in (i) compared with Ctrl for pyFn group from left to right were 0.7532, 0.0742, 0.1398; and for phosphate-doped ferrihydrite were 0.9967, 0.7771, 0.5676; ns: not significant, p > 0.05. Source data are provided as a Source Data file.