Ferritins for Chemistry and for Life.

Ferritins, highly symmetrical protein nanocages, are reactors for Fe and dioxygen or hydrogen peroxide that are found in all kingdoms of life and in many different cells of multicellular organisms. They synthesize iron concentrates required for cells to make cofactors of iron proteins (heme, FeS, mono and diiron). The caged ferritin biominerals, FeO•HO are also antioxidants, acting as sinks for iron and oxidants scavenged from damaged proteins; genetic regulation of ferritin biosynthesis is sensitive to both iron and oxidants. Here, the emphasis here is ferritin oxidoreductase chemistry, ferritin ion channels for Fe transit into and out of the protein cage and Fe O mineral nucleation, and uses of ferritin cages in nanocatalysis and nanomaterial synthesis. The Fe and O ferritin protein reactors, likely critical in the transition from anaerobic to aerobic life on earth, play central, contemporary roles that balance iron and oxygen chemistry in biology and have emerging roles in nanotechnology.