[throwup238]

How would we test that the mirror antibiotics actually work without developing mirror organisms and exposing ourselves to the associated risks?

They aren’t going to be mirror copies of terrestrial organisms, there’s no guarantee that mirror copies of our antibiotics will work (AFAIK it’s actually very unlikely). Protein binding sites change when mirrored because it’s not just mirror image but a change in how the proteins twist when folding, which is why most of them are sensitive to chirality. Only very simple molecules are likely to behave the same.

Stuff like bleach will still work by denaturing proteins and disrupting the bilipid layer in cell membranes but anything like tetracycline and penicilin that targets peptidoglycan enzymes or ribosomes or other complex biochemistry almost certainly won’t.

[gus_massa]

Mirror antibiotics must work in mirror bacteria. Mirror proteins should fold exactly like normal proteins, but mirrored. (There may be a problem with the weak force, but I never heard it's used in biology.)

[NoMoreNicksLeft]

Mirror symmetry breaks down in counter-intuitive ways in physics, that probably bubbles up into the chemistry side of things too. Not always, and not often. Probably just often enough to be confusing, and in this case, starkly terrifying and spirit-crushing.

[throwawaymaths]

> probably bubbles up into the chemistry side of things too

it never has so far. many experiments have been done, including an enzyme reaction

[NoMoreNicksLeft]

Ok, sounds completely safe then. Go ahead and work on your mirror life frankenstein experiments, we should be good.

[throwawaymaths]

https://news.ycombinator.com/item?id=42408396#42408731

[selimthegrim]

That is a completely different thing.

[NoMoreNicksLeft]

Prove it. Prove that there's not some corner case where a mirrored molecule stops behaving chemically the same towards other mirrored molecules.

[gus_massa]

The technical term is "parity simetry" https://en.wikipedia.org/wiki/Parity_(physics) that means that a system and the mirrored version behave exactly in the same way.

Chemistry is about electromagnetism, and electromagnetism has parity symmetry. Also gravity is somewhat important, but gravity also has parity symmetry. And even the strong force has parity symmetry. So for all practical purpuses, chemistry has parity symmetry and when you mirror a bunch of molecules, the mirrored versions will behave exacly as the normal ones.

But ... if you were looking carefuly I didn't mention the weak force, because it breaks the parity symmetry. It's very difficult to prove it https://en.wikipedia.org/wiki/Wu_experiment You have to get a bunch of radioactive cobalts, put them in a strong magnetic field, keep them super cold, and you will get 60% of the decays in one direction and 40% in the other, breaking the 50% and 50% expectation if it didn't break the parity symmetry.

Can this experiment be reproduced in a chemistry molecule?????

I need more questions marks ????????

I think no one has done it and it looks very difficult to try. Can I use my imagination and make will guess?

Let's say you get something like the hemo part of hemoglobin https://en.wikipedia.org/wiki/Heme It has four nice nitrogens that probably can bind to cobalt instead, or perhaps you need a variant. Now make some substitutions to break the symmetry so it it's like a recycle symbol that has a clear direction. Add some bridge under the plane, perhaps connect the small part that is bellow the graphic that I'm not sure why iis useful.

And make the mirrored version too.

Now, if the design was super smart, most of the cobalts in a version will have the north pole pointing to the bridge, and the mirrored version will have the south pole. I'm not sure it's possible, but I can handwave some explanation that say it's possible, but perhaps this idea makes no sense.

Now, did I mention you need radioactive cobalt? When it desintegrates it send an electron that will sometimes colide with the bridge and destroy it, or go in the other direction and keep the molecule without changes.

So after some time the you can see that the time to self destruction is different in the original and the mirrored version.

In conclussion, I think it's possible but no one has done it, no sane person would try it, and if someone get it working then they will get a Nobel price.

It will be very expensive, and completely unuseful, so I completely not expect to see something like this is a living cell.

[selimthegrim]

There is another mathematical kind in string theory which I thought they were misappropriating.

[selimthegrim]

I meant that physics uses the term in a different context.

[throw310822]

> Protein binding sites change when mirrored because it’s not just mirror image but a change in how the proteins twist when folding, which is why most of them are sensitive to chirality

Wouldn't this pretty much rule out the synthetic creation of mirror bacteria? We should not just be able to rewrite a simple existing lifeform in mirrored version; we should recode all its proteins from scratch so that they keep their function in a mirror version, assuming that that's even possible.

[danwills]

I think the folding/etc would all be mirrored as well if all the components were on mirror-chirality and the overall molecular-kinetic behavior of the result would in-theory be the same when zoomed-out too (assuming it doesn't encounter too many normal-chirality molecules I guess - would be just as dangerous to them as mirror-chirality is to us).

This should mean that if the DNA is mirror (no need to alter the sequence), and the RNA/proteins/etc are as well (like 100% made of the mirror-chiral molecules), then in isolation it might work just the same as regular-life, just twisting the other way?

Kinda does seem like it might be a bit arbitrary what direction things should curl in, however there are maybe aspects of how quantum-spin might interact with things that might rule out stability with mirror-chirality? I am not a QM scientist but I do find it very fascinating!

[throwup238]

Yeah I think the risk is completely overblown but after the controversy over COVID and Wuhan gain of function research, bioethics discourse seems to have taken a conservative turn.

Long before we’d be able to bootstrap a fully mirrored organism we’d have to develop synthetic biotech that could easily weaponize something already scary like ebola or hendra virus. Synthetic organisms have so far been paired down versions of existing bacteria, not engineered and assembled from the ground up. Once we’re capable of the latter, mirror organisms are just one entry on a very long list of existential threats.

I think the real risk in the foreseeable future is horizontal gene transfer of chiral checkpoint proteins. In order to insert even a single nontrivial D protein into the genome, we’d have to modify the proteins that make sure everything is L-handed. If those managed to escape into the wild, the results would be completely unpredictable and potentially catastrophic. Bacteria mutate and evolve much faster than mammals so if any of them develop surface proteins that are functionally equivalent but D-handed, they could become resistant to antibiotics and our immune systems.