Fig. 1: Purification, characterization, and SOD-like activity of ferritins from different organisms.

a Multiple sequence alignment of amino acid sequences of different ferritins; the colors referred to the amino acid similarity, blue: 80%, gray: 60%. b Phylogenetic tree of the ferritin amino acid sequences; the numbers on the branch represented the bootstrap value. c Scheme of biosynthesis process of different ferritin iron cores. d Representative negative stained and unstained TEM images of biomineralized ferritins of three independent experiments with similar results; inset figures represented partially enlarged images; the scale bar referred to 50 nm and inset scale bar referred to 20 nm. e The SOD-like activity of biomineralized ferritins with the final protein concentration at 50 μg/mL; data are presented as mean ± SD (n = 3 independent experiments). f The SOD-like activity of apo-pfFn (iron-removed ferritin), pfFn, and biomineralized pfFn (pfFn-Fe); data are presented as mean ± SD (n = 3 independent experiments); the significant difference was evaluated by the Two-way ANOVA with post-hoc Tukey HSD test. g The SOD-like activity of archaeal ferritins after the protease K (ProK) digestion; data are presented as mean ± SD (n = 3 independent experiments). Source data are provided as a Source Data file.