Updated

Updated · BBC.com · Oct 7

Kagan and Soai Win $1.2 Million Chemistry Nobel for Explaining Life’s Molecular Asymmetry

Updated

Updated · BBC.com · Oct 7

Kagan and Soai Win $1.2 Million Chemistry Nobel for Explaining Life’s Molecular Asymmetry

Q: How did a 1995 chemical experiment solve the mystery of why all living things share the exact same molecular handedness?

The 1995 Soai reaction helped solve the mystery by showing, in the lab, how an almost imperceptible excess of one molecular “hand” can be amplified into near-total dominance of that same hand. That offered a plausible chemical route to homochirality — why life uses almost exclusively left-handed amino acids and right-handed sugars. The problem had long been that ordinary chemistry should produce equal amounts of both mirror-image forms, known as enantiomers. Kenso Soai’s experiment changed that picture. In his reaction, the chiral product catalyzes its own formation: once a tiny imbalance appears, even from a minute fluctuation or trace bias, the favored enantiomer helps make more of itself. That positive feedback drives the system away from a 50-50 mix and toward one handedness. Henri Kagan’s earlier work on nonlinear effects explained the broader principle behind this behavior: chirality does not have to be transferred proportionally. Small initial differences can be magnified dramatically during asymmetric synthesis. Soai then provided the most striking experimental proof. Together, the two discoveries showed that homochirality need not require a large external cause. A very small initial asymmetry — from chance, contamination, or a weak physical influence — could be chemically amplified until one mirror form overwhelms the other. That is why the 1995 experiment is seen as a landmark in explaining one of life’s deepest molecular signatures.

3 articles · Updated · BBC.com · Oct 7

Henri B. Kagan of France and Japan’s Kenso Soai were awarded the 2026 Chemistry Nobel for showing why life relies on one mirror-image form of key molecules rather than the other.
The Nobel Committee said their work solved the chirality puzzle by designing reactions that produce far more of the desired molecular version, a central challenge in organic chemistry.
That selectivity matters in drugmaking, where one molecular form can fight disease while its mirror image may be ineffective.
The Royal Swedish Academy previously said the pair’s prize-winning advances included non-linear effects and autocatalysis in asymmetric organic synthesis; the award carries 12 million kronor, about $1.2 million.