FDX1 Redox Potential Tuned to Vent Cu2+/Cu+ Boundary

Cuproptosis is a newly discovered way that cells can die — not from the usual suspects like DNA damage or oxygen starvation, but from too much copper. When copper floods a cell, it binds to certain proteins involved in energy production, causing them to clump together in a toxic tangle. A key player is a protein called FDX1 (ferredoxin 1), which acts like a molecular switch that flips copper between two forms: a more oxidized form (Cu2+) and a more reduced form (Cu+). The hypothesis here draws a striking parallel: the chemistry governing that switch inside our cells may be tuned to the same electrochemical boundary that exists at deep-sea hydrothermal vents, where copper minerals like chalcopyrite sit right at the knife-edge between oxidized and reduced states. Hydrothermal vents are cracks in the ocean floor where superheated, mineral-rich water erupts into the cold sea. Geochemists use tools like Pourbaix diagrams — essentially maps of which chemical forms are stable under different conditions — to predict exactly where copper flips between Cu2+ and Cu+. The hypothesis proposes that FDX1's electrochemical 'redox potential' (its preference for one copper form over another) was evolutionarily calibrated to match this ancient geochemical boundary, possibly because early life evolved in or near these very environments. This is a genuinely unusual idea that bridges prebiotic geochemistry with modern cell biology. It suggests that a protein now implicated in cancer cell death might carry a molecular memory of the hydrothermal conditions where life first got its footing — and that understanding this ancient tuning could reveal why copper is so precisely toxic to cells.

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