The Nobel prize in chemistry 2026 has been awarded to two scientists for discoveries that showed how chemical reactions can produce an overwhelming excess of one of two mirror image forms of a molecule.
Henri B Kagan at Paris-Sud University in France and Kensō Soai at Tokyo University of Science in Japan have been awarded the prize “for the discovery of nonlinear effects and autocatalysis in asymmetric organic synthesis”.
The Royal Swedish Academy of Sciences announced the winners in Stockholm, Sweden, on Wednesday. They will each receive an equal share of a prize of 12m Swedish kronor (about £900,000).
Many molecules, including amino acids that form the building blocks of proteins, can exist in two forms that contain the same atoms, but are mirror images of one another, much like a person’s left and right hands. This property is known as chirality.
However, the chemistry underpinning life is surprisingly “homochiral”, or same-handed. Proteins are built almost exclusively from L-amino acids, while the sugars that form the backbone of DNA and RNA have the opposite D- configuration.
How this homochirality could have emerged when chemical reactions in the laboratory typically produce equal quantities of both forms had long puzzled scientists. The question also had practical consequences: “Although these molecules look very similar, they can behave very differently when they interact with other molecules,” said Prof Andre Cobb, an organic chemist at King’s College London.
“This matters enormously for medicines because many of the molecules in our bodies, including proteins that drugs target, are themselves chiral. So the ‘left-handed’ and ‘right-handed’ versions of a drug can interact with the body in different ways which can lead to different or weakened drug effects.”
The drug thalidomide provides a potent example. During the early 1960s, thousands of children were affected by birth defects after their mothers were prescribed it to combat morning sickness during pregnancy. Researchers subsequently found differences in the biological effects of the drug’s two mirror image forms.
Manufacturers wanted a way of steering reactions towards particular forms of the molecules that they produced, and Kagan and Soai eventually provided a solution.
It began in 1986, when Kagan discovered that a relatively small imbalance between left- and right-handed forms of a catalyst could create a greater excess of one of the mirror image products than the other.
Soai took the idea further, developing a reaction in which the molecules produced themselves acted as catalysts for making more of themselves, a process known as autocatalysis. “You have to be aware, this is probably the coolest experiment in organic chemistry ever,” said Prof Peter Somfai, an organic chemist at Lund University and a member of the Nobel committee for chemistry.
In 2003, Soai demonstrated a reaction that produced almost exclusively one mirror-image form, reproducing the kind of molecular one-handedness found in living organisms for the first time.
Speaking by telephone at Wednesday’s announcement, Soai, 76, said he was “very proud” of the experiment as it offered a potential explanation for how the molecular one-handedness of life could have arisen. He described hearing the news about the prize as “one of the most exciting days of my life”.
Taken together, Kagan and Soai’s discoveries had “reshaped our understanding of molecular chirality, how it is created, amplified and transmitted”, Somfai said.
These insights have since become embedded in the development of catalysts that steer chemical reactions towards producing a particular mirror image form across different industries. “It is in the backsides of our heads all the time,” said Somfai.
“It might be difficult to say that this drug or that drug was developed using this. I would say all of them because we use this as a tool. We use this as an understanding of how to develop catalysts and how they function.”
