STOCKHOLM (AP) — Scientists Henri B. Kagan and Kenso Soai won the Nobel Prize in chemistry Wednesday for untangling mysterious mirror images in molecules, a discovery that has been used to develop countless drugs and transformed modern medicine.

Many molecules come in versions that look alike but are not exactly identical, like right and left hands. One mirror image of the chemical carvone smells like mint, for example, while the other has a whiff of caraway, a spice often used in rye bread.

Even life itself prefers one mirror image over the other. DNA twists to the right, and the proteins in human bodies are made of mostly left-handed building blocks.

Versions of the same molecule can behave differently when interacting with other chemicals. When designing drugs to treat diseases, scientists want to be choosy about which mirror image they get. They want the version of a molecule to treat a cold, not one that will make the sniffles worse.

Kagan, who is from France, and Soai, from Japan, found ways to make chemistry pick a side, designing and manipulating reactions to produce the desired mirror image.

“The medicines we have today would not be possible without this chemistry,” said Rigoberto Hernandez, president of the American Chemical Society.

The discovery enabled most modern medicines

Scientists paid tribute to Kagan and Soai's work, which the Nobel committee described as a feat never previously achieved by anyone “other than life itself.”

“It might be difficult to say that this drug, or that drug, was developed using this,” said Peter Somfai, a member of the Nobel Committee for Chemistry. “I would say all of them, because we use this as a tool, we use this as an understanding, how to develop catalysts, how they function.”

In the 1980s, Kagan’s work showed there might be a way to design reactions to produce one form of a molecule over the other. Years later, Soai perfected the process. He created the first-ever chemical reaction to efficiently produce only one of a molecule’s mirror images, in what’s now known as the Soai reaction.

“This is probably the coolest experiment in organic chemistry,” Somfai said.

In addition to developing better medicines or fragrances, deciphering the mirror images of molecules can help scientists understand the chemical architecture of life, said chemist Holden Thorp, editor-in-chief of the journal Science.

Kagan, 95, is affiliated with the Université Paris-Sud in Orsay, France. Soai, 76, is affiliated with the Tokyo University of Science.

The French Academy of Sciences, of which Kagan is a member, congratulated the two scientists and expressed its pride in the prize.

Neither the Université Paris-Sud nor the Tokyo University of Science immediately responded to requests for comment from The Associated Press.

“I’m very excited to receive the very nice news,” Soai told the committee and journalists by phone. “Of course this is one of the most exciting days in my life.”

He said he was shopping near his home when he was reached by the Nobel committee.

More Nobel prizes will be awarded over the next week

The Royal Swedish Academy of Sciences announced the winner in Stockholm.

Last year, three scientists won the chemistry Nobel for their development of new molecular structures that can trap vast quantities of gas inside, laying the groundwork to potentially suck greenhouse gases out of the atmosphere or harvest moisture from desert environments.

This year's prizes began with the Nobel for medicine, awarded Monday to three scientists whose work led to a tool that uses light to help unravel how the brain works. The physics award Tuesday recognized a scientist's efforts to demystify a rare group of neutrinos.

The literature prize is set to be awarded Thursday. After Friday’s peace prize is awarded, the Nobel Memorial Prize in Economic Sciences will be announced Monday.

The prize money this year is 12 million Swedish kronor (about $1.2 million), whether for an individual, a small group of laureates or an organization.

___

This story has been corrected to correct that Kagan, not Soai, is 95.

___

Ramakrishnan reported from New York. Dazio reported from Berlin. Associated Press journalists Alexa St. John in Detroit, Catherine Gaschka in Paris and Mari Yamaguchi in Tokyo contributed to this report.

___

AP Nobel Prizes: https://apnews.com/hub/nobel-prizes