Abiotic vs Enzymatic PLOOH Regioselectivity as Chemical Fossil of Antioxidant Evolution

Two seemingly unrelated fields turn out to share a fascinating chemical thread. Ferroptosis is a form of cell death — recently discovered to play roles in cancer, neurodegeneration, and aging — where iron triggers a runaway destruction of fat molecules in cell membranes. Serpentinization is a geological process where iron-rich rocks react with water deep in the Earth's crust, producing reactive iron chemistry that's been happening since before life existed. The connection? Both involve iron attacking the same type of fat molecules, called polyunsaturated fatty acids. Here's the key insight: when ancient iron chemistry attacks these fats randomly, like a wrecking ball, it hits multiple spots on the molecule almost equally. But when the enzyme that drives ferroptosis does it — a protein called 15-lipoxygenase — it hits one very specific spot over 90% of the time. This hypothesis proposes that the jarring contrast between random abiotic destruction and precise enzymatic targeting is essentially a chemical fossil: evidence that early life evolved these selective enzymes *because* they needed to control and counteract the dangerous random iron chemistry that was everywhere in the primordial environment. The experiment to test this is elegantly simple — run both reactions side by side and count where the damage lands. What makes this clever is that it's not just philosophical speculation about evolution. It generates a concrete, falsifiable prediction with actual numbers: abiotic chemistry should produce roughly 15-25% damage at the specific position, while the enzyme should produce over 90%. If the numbers don't land there, the hypothesis is dead. That kind of testability is exactly what separates good science from storytelling.

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