Nobel chemistry prize for solving the mystery of life's left-handed molecules

The 2026 Nobel Prize in Chemistry has been awarded to Henri Kagan of France and Kenso Soai of Japan, for discoveries that help explain why the molecules of life come in only one of two mirror-image forms.

The Royal Swedish Academy of Sciences gave the prize "for the discovery of non-linear effects and autocatalysis in asymmetric organic synthesis".

Professor Kagan, 95, is associated with the Université Paris-Sud in Orsay. Professor Soai, 76, is at the Tokyo University of Science.

"A chemical mystery that is over a century old"

Heiner Linke, chair of the Nobel Committee for Chemistry, said: "Henri Kagan and Kenso Soai have provided a solution to a chemical mystery that is over a century old: how homochirality can emerge spontaneously. The chemical reactions they have developed are spectacular."

Left hand, right hand

Many molecules exist in two forms that are mirror images of each other, like a left and a right hand. They contain the same atoms, but cannot be laid exactly on top of each other. Chemists call this chirality.

The two forms can behave very differently. One version of the molecule carvone smells of mint, while its mirror image smells of caraway. In medicines, one form of a drug can heal while the other does nothing, or causes harm.

Living things are strikingly one-sided. The amino acids that make up proteins are almost all the left-handed form, and the sugars in DNA are all right-handed. This preference is called homochirality, and how it arose has puzzled scientists since the 19th century.

What they discovered

In the 1980s, Professor Kagan showed that a catalyst that is not perfectly pure in one mirror form can still produce a product much purer than expected. He called this a non-linear effect, and it showed that a small imbalance can be magnified.

Professor Soai went further. In the reaction that now bears his name, the Soai reaction, the product of the reaction acts as a catalyst for its own formation, a process known as autocatalysis. Starting from a tiny excess of one mirror form, the reaction amplifies it until almost all of the product is the same hand. The Nobel Committee described this as something "never previously achieved by anyone other than life itself".

Why it matters

The committee said their discoveries "have been decisive for chemists who design reactions for the manufacture of pharmaceuticals". The president of the American Chemical Society said: "The medicines we have today would not be possible without this chemistry."

Earlier work on asymmetric catalysis was recognised with Nobel Prizes in 2001 and 2021.

A life story

During the Second World War, Professor Kagan's family hid in a French village under assumed names. He went on to become a leading organic chemist in France, and at 95 is among the oldest people ever to receive a Nobel Prize.

The prize

The two laureates share 12 million Swedish kronor and will receive their medals in Stockholm on 10 December. The Nobel Prize in Literature will be announced on Thursday.