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I remember first learning about chirality in my biochemistry course in college, and it was definitely a mind-blower. I had already started to understand that molecules had 3d structures, but the idea (and attempting to visualize it mentally) of mirror image molecules stretched my brain significantly.
It's also still amazing to me how people first recognized this: poking around looking at the crystals that form in the bottom of a wine under a microscope, noticing that some of them were mirror images of the other, and then seperating them manually with tweezer, dissolving them into two different solutions, and demonstrating that they rotated light in opposite directions.
"To his surprise, he noticed that each crystal has a tiny facet on one of its edges oriented sometimes to the right and sometimes to the left. He could separate them by hand with a tweezer."
It's moments like that, and Kekule's story of the snake dream for benzene that make me feel unworthy of being a scientist. I sometimes wonder: in my career of looking at things, did I miss something fundamental and significant simply because my powers of observation and general intelligence were insufficient?
For me as early as high school it was easy to understand the concept of molecules having 3D structure (the standard textbook explanation of left glove versus right glove is easy), but it was really difficult for me to visualize it. I was not and am still not a visual thinker. This caused me a lot of problems when I needed to distinguish between enantiomers. For example I had a great deal of trouble when given two molecules that only differ in chirality, which one is levo and which is dextro, despite studying very hard.
At least for me (because I have aphantasia) I found that using molecular visualization apps (ideally with 3D stereo glasses) makes a huge difference. I can sort of rotate the molecules around and build up a working mental picture that way.
I don't think it's funny, I think it's a decent way to learn it. The game does oversell the stakes, though. Mirror-image food mostly wouldn't poison you, it'd just pass through undigested. L-glucose tastes sweet and your body ignores it.
Enantiomers and Diastereomers are one of the more interesting and challenging things in Organic Chemistry. It also makes carbohydrate chemistry challenging in Biochem.
As I understand it, the chirality problem is one of the big ones in abiogenesis - the beginning of life. How does some initial series of inorganic "accidents" lead to life? The necessary chemistry has to give the right chirality.
But maybe someone better informed can explain... I've only heard James Tour ranting about it
Isn't that what Soai's reaction speaks to, amplifying a tiny excess into one handed product? But it runs with diisopropylzinc in dry organic solvent. Has anyone shown something similar working in water, with actual prebiotic compounds? Otherwise it's a neat model, not really an explanation.
Chemist here.
I read this and thought it was either lies or propaganda. But after a while of pondering , it would say that the word "homochiralic" (creation-from-nothing) does a lot of heavy lifting here to make their claim technically true, if at all:
Asymmetric synthesis was already well established before 1995. Chemists like Knowles, Noyori, Sharpless, and Evans could routinely produce highly enantioenriched molecules using chiral catalysts or auxiliaries.
What made Soai's reaction different was that it did not require an external chiral source. The chiral product catalyzes its own formation, so a tiny random imbalance can be amplified into a very large enantiomeric excess.
Other examples of abiotic asymmetry, such as Pasteur's crystallization experiments and circularly polarized light, were also known earlier.
So the Nobel press release is best understood as shorthand: Soai did not discover asymmetric synthesis, but demonstrated a remarkable form of self-amplifying, spontaneous chiral symmetry breaking in an abiotic chemical system.
That helps a lot! I'm a novice learning about enzymatic synthesis. I'm not there yet, but my assumption is the target molecules (And reactants/intermediate-products) will all have specific chiralities, unlike the chemical-synthesis ones which may produce 50/50. Everything in my data structures (And the pubchem CID / ChEBI ids they reference) are chiral.
Is it explained why, in this drawing, the right catalyst forms at a higher rate than the left? Or put another way why left/right catalyst gets formed at a higher rate than right? I’m trying to understand the why behind the amplification effect.
That's very interesting. But am I right that means when you start out, you don't whether you are going to end up with a big excess of left or right, just that it will be one of them?
The chirality of biomolecules is also the source of the differentiation of left and right in a developing embryo.
Cilia form that are tilted toward the tail of the embryo. The chirality of the protein motors driving them causes them to turn clockwise, which creates a leftward flow of water.
Congratulations to Professor Soai on winning the Nobel Prize. The discovery of asymmetric autocatalysis is truly groundbreaking, and as a fellow Japanese, I am incredibly proud of this achievement.
Fun fact: his family name in kanji 硤合 is so rare that most people don't even know how to read it thus most japanese news sites using a hiragana translation そあい
Is it common for family names in Japan to be this rare? Like, collectively, is the percentage of Japanese people with rare family names greater than 1%? I ask because I know that many Italian people (myself included) have rare last names that are almost exclusively found in the city their family is from.
In 2004, left-handed sugar was hyped as a way to eat junk food without absorbing the sugar. It turned out to be too expensive, but I think it's an interesting story (oddly involving Mars!). More here:
Cool, brings back some memories from grad school. Always found these types of reactions with self-reenforcing quite interesting.
Reminds me of another paper where just stirring a solution or not would determine the chirality of crystals formed and gives an idea how highly chiral environments can arise from "nothing":
I remember an offhand comment from a professor in grad school about the origin of chirality in life, he said some people had speculated it had to do with parity of the electroweak force (https://ui.adsabs.harvard.edu/abs/1985Natur.318..172T/abstra...) or something like that, but it always seemed unlikely because the energy difference due to that is so tiny that it would be hard for a single or small number of events to be biased significantly in one direction.
Yeah, I believe the estimates from parity breaking where on the order of 10^-10 J/mol or something, so almost completely irrelevant for anything near room temperature energy scales.
So some random self-enriching chiral process seems much more likely to be the origin. But who knows! :)
Yes, this sounds like a situation where progress in that field may have led them to go back and give more credit to the original experiments going in that direction
This is a plot point in one of my most favourite science fiction novels by Roger Zelazny... bit of a spoiler, so ROT13:
_Qbbejnlf va gur Fnaq_
which still has my favourite life situation for a protagonist (room, board, tuition and generous stipend so long as he attends his uncle's alma mater until such time as he graduates....)
I watched the announcement video [0] and found it strange that they cut off Prof Soai during the last question — he was trying to understand whether he was being asked for his favorite molecule in the context of autocatalysis or in general.
As a right-handed person, I find this deeply offensive and request all left-handed life be destroyed at once!!
That said, would it be possible to make "right-handed" food that is safe to eat, satisfies the psychological urge to consume food in every sensory measure, but still contributes 0 calories?
We have matter-antimatter asymmetry in physics... and now I just learned there's a similar concept in chemistry (one variant frequently occurs in life while the other mirrored variant is rarely found in nature)
No, in this case neither isomer is inherently preferred, i.e. if you repeat the reaction you could end up with the opposite isomer, but in each run the symmetry is broken leading to an excess of just one.
(Though what you're saying is not impossible per se, I think I read an experimental proposal a while ago which suggested achieving just that, iirc by using parity violation to generate chiral photons which then initiate some kind of reaction!)
No. Even in the absence of parity violations you can imagine a reaction that has a 50% chance of producing only left handed products and a 50% chance of producing only right handed products. This discovery is more like that.
Soai's reaction is basically an amplifier. Tiny random imbalance in, big imbalance out. In practice the seed can be a dust speck, a chiral crystal, or noise in the flask. We'd call that contamination in any other lab. Parity violation would be a way smaller push than any of those.
Reading Wikipedia it seems he also didn't win another Nobel because the max number of recipients is 3. It's not that unusual that people get the prize a loooong time after their actual work though.
Throughout my life as a student from elementary school to university, I’ve had so many teachers with an extremely diverse ability to actually teach that I no longer think of any subject as inherently hard or easy. I always think it’s a bad teacher or a bad textbook. When I self-studied chemistry I switched textbooks three times before I found one that really matched the way I think.
I have to admit that when I read the intro header of the piece on the page, “They made chemistry choose a mirror image,” it struck me as LLM-speak and I immediately lost interest. I have no idea whether the authors used one to draft that phrase, which seems like an innocent summary of their contributions, but somehow I feel like if it were three years ago we would have never seen that in the title.
Nobel's popular-science blurbs have always had that punchy tone, honestly. And it's accurate for Soai: his reaction takes an absurdly tiny excess of one enantiomer and amplifies it to nearly pure product. The system really does pick a hand. I covered it in a grad seminar and it still seems wrong.
What strikes me about Soai's reaction is that it's an autocatalytic loop where the product amplifies its own tiny enantiomeric excess. As far as I know, it's still the only well-characterized organic example, and nobody has shown it was actually how biological homochirality began. Plausible, not demonstrated.
It's also still amazing to me how people first recognized this: poking around looking at the crystals that form in the bottom of a wine under a microscope, noticing that some of them were mirror images of the other, and then seperating them manually with tweezer, dissolving them into two different solutions, and demonstrating that they rotated light in opposite directions.