Nobel Prize in Chemistry 2026 Explained: Mirror Molecules (EP 63)

Lester Nare (0:03)

A chemist in Paris and a chemist in Tokyo who cracked one of life's oddest habits. Look at your hands. Mirror images. But a left glove won't fit your right hand. Many molecules come in left and right versions, too. One smells like spearmint, its mirror twin smells like rye bread.

But chemistry in a flask always makes both. 50-50.

In 1986, Henri Kagan found something odd. A catalyst that was only a little right-handed made products that were mostly right-handed. Picture six right-handers and four lefties on a dance floor. Each lefty pairs off with a right-hander and sits down. Who's still dancing? Only right-handers. Then, Kenso Soai built a molecule that copies itself hand in all, like a rumor that spreads. A head start of one molecule in two million became more than 99% in just three rounds.

Life builds itself from just one hand. This is a clue to how that happened and a sharper way to make medicines.

And this is the 2026 Nobel Prize in Chemistry.

Hello, internet. This is your captain speaking Lester Nare, joined as always by my co-host and our resident PhD, Krishna Choudhary. We are on day three and our final day of Nobel Prize week. We are going to go from the search for ghostly particles in Antarktica to the winner of the Chemistry Nobel Prize. And this one is interesting and it reminds me of one of my favorite episodes that we did at the end of last year. We have left and right hands. And similarly, there are left and right molecules, but life overwhelmingly prefers one specific type. Today's prize is about how chemistry can make that asymmetry happen. It connects the way we make medicines to a much older question. Why did life settle on particular molecular building blocks in the first place? This is going to be interesting. As always, we are going to talk about the science from the ground up today, starting with who won.

Krishna Choudhary (2:49)

The 2026 Nobel Prize in Chemistry has been awarded to Henri B. Kagan of the former University of Paris-Sud in France and Kenso Soai of Tokyo University of Science in Japan.

And the official citation is for the discovery of nonlinear effects and autocatalysis in asymmetric organic synthesis.

Lester Nare (3:14)

Talk about a mouthful.

Krishna Choudhary (3:15)

Yeah, but by the end of the episode, we will have unpacked that statement. And there's a hint in the words nonlinear and asymmetric autocatalysis. For anyone familiar with biochemistry, this should immediately ring a bell because that's kind of what life is, okay? It's a nonlinear phenomenon because reproduction happens. And if you've ever seen the bacterium sort of expand in a petri dish from one, you get two to four to eight, and there's this doubling factor. So obviously that's nonlinear. And it's a kind of autocatalysis because it's a bunch of chemical reactions that make themselves, right? The DNA makes more DNA, makes more DNA. Obviously there are multiple steps in the process. But at the end of the day, life is nonlinear and it is autocatalysis. It's also asymmetric because of the kinds of molecules that life prefers.

Even though the molecules in life can exist in symmetric parts, life is remarkably consistent with which one it uses. DNA is a great example of this.

DNA is right-handed, meaning if I were to put my thumb on the axis of a DNA molecule, the curve is always the way that my fingers wrap around. It's always going to go right-handed sort of clockwise if I were looking up the axis of DNA. But you can make DNA that is left-handed, right? It's just that life never does it. So the two Lorentz contributions fit together here because Kagan showed that a small imbalance in a catalyst can produce a substantially greater imbalance in the product. If you start out with a little bit more right-handed than left-handed, then you can make that nonlinear effect. And Soai found a reaction in which the product becomes the catalyst for making more product, that's that autocatalysis part.

Lester Nare (5:08)

Okay, so before we unpack the chemistry, what is the surprising part here? Why wouldn't a small advantage naturally just become a big advantage?

Krishna Choudhary (5:18)

Right, and that's actually what I was asking when I was researching this kind of stuff. It turns out that making more material and increasing its purity are two different achievements. Okay, so if you repeatedly double, let's say you've got a mixture of 51-49, okay? But the 51% of molecules start making their own version and the 49% make their own version, the ratio is going to remain exactly the same, right? So there's something in the chemistry that has to favor the majority disproportionately for the imbalance to grow.