Kenso Soai
Kenso Soai (born 1950, Hiroshima, Japan) is a Japanese chemist who, along with the French chemist Henri Kagan, was awarded the 2026 Nobel Prize for Chemistry for his contributions to answering fundamental questions regarding the origin of homochirality. At the time of receiving the award, Soai was associated with the applied chemistry department of Tokyo University of Science as an emeritus professor.
- Education: University of Tokyo (Ph.D., 1979)
- Affiliation: Tokyo University of Science
Soai received a Ph.D. in 1979 from the University of Tokyo. After completing his postdoctoral work at the University of North Carolina at Chapel Hill, he joined Tokyo University of Science in 1981, where he served successively as a lecturer, associate professor, full professor, and emeritus professor. His research focuses on synthetic chemistry and the origin of homochirality.
Many biomolecules and other organic molecules can be either left- or right-handed, forming nonidentical mirror images of each other. Living systems, however, predominantly use only one of the two forms of these molecules, with the other occurring much less frequently. This phenomenon is called homochirality, from Greek homos, meaning “one and the same,” and cheir, meaning “hand.” The homochirality of biomolecules such as sugars and amino acids—the building blocks of living systems—is essential to many fundamental biological processes and the effectiveness of pharmaceutical drugs. However, its origin has long puzzled researchers.
In 1953 English physicist Charles Frank proposed the following criteria for a chemical reaction to give rise to homochirality: (1) a chiral catalyst must drive an asymmetric reaction; (2) the reaction must favor the formation of one mirror-image form over the other; and (3) the reaction must also produce more of the catalyst itself, creating a self-reinforcing process called autocatalysis that increasingly favors one form. The first of the three criteria had already been fulfilled in the first decade of the 20th century. The research of Soai, along with that of Kagan, contributed to fulfilling the remaining two criteria, for which the duo received the 2026 Nobel Prize for Chemistry.
Experimenting with the chiral compound 5-pyrimidyl alkanol, Soai demonstrated that a very small or spontaneous chiral imbalance could grow into near homochirality through asymmetric autocatalysis. This reaction, which was named the Soai reaction, provided the first proof of concept that chirality could be generated and amplified in a closed, nonliving system. The Royal Swedish Academy of Sciences called Soai’s work one of “the most elegant chemical experiments ever conducted.”
Soai has been recognized with the 2002 Molecular Chirality Award, the 2003 Synthetic Organic Chemistry Award, and the 2005 Chirality Medal, among others.