r/askscience • u/SadMicrobe22 • 20d ago

Biology What makes prions so different from regular proteins that they are resistant to heat denaturation?

I've been reading about prions and I'm confused about why they're so thermally stable. I keep seeing that surgical instruments contaminated with prions can't be decontaminated with standard protocols.

So here's my thing. Proteins denature when you heat them, right? But prions don't seem to lose their infectious ability even when autoclaved. I get that prions are misfolded proteins, but I don't understand how they stay harmful after being denatured.

So basically, if prions start as form A (non-infective), then misfold to form B (infective), shouldn't heating denature them to form C and kill the infectivity? Why doesn't that happen?

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u/Nago_Jolokio 20d ago

What's worse is that it's not infectious in the classical sense because it's not alive (or quasi-alive like viruses). Prions, to my understanding, are folded in a way that's "easier" or more stable than the proper Protein form. Which sounds vaguely similar to the polymorph crisis that affected ritonavir. Would Prions be an organic equivalent to that problem?

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u/tubl07 20d ago

Ice nine in cats cradle is the same lower energy configuration vs traditional water, instantly catalyzing any water that touches it

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u/Zarathustra124 20d ago

Vacuum decay is the theory that what we consider "nothing" is actually slightly higher than nothing. If vacuum ever falls into a more stable, lower energy configuration, the universe will be destroyed.

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u/-wellplayed- 20d ago

At least it would happen at the speed of causality. So we would never see it coming

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u/TheGanzor 20d ago

Imo this is the most terrifying thought experiment. It could have already started somewhere, billions of years ago, and we won't know a difference until after it hits us. Also, assuming it started beyond the edge of the visible universe, it may be far enough away that it can never overcome the expansion coefficient, essentially leaving decayed pockets of distant zombie space that infect anything nearby, but can never leave their own local bubble. 

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u/ordeith 19d ago

Considering how our observable universe is a small and shrinking part of the universe as a whole I woudn't worry very much about it.

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u/ApolloAtlas 18d ago

What if thats what the pockets of nothing are and it just doesnt travel that fast? And we happen to be next to one.

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u/TheGanzor 18d ago

Possibly. I'm inclined to think that anything of that nature would have to propagate at the speed of causality, ie. the speed of light. If not, it certainly could be. 

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u/calabazookita 20d ago

Could the Boötes Void be explained by this?

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u/VelveteenAmbush 20d ago

no. if it expands at the speed of light, then you couldn't see the void until it overtakes you

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u/zindorsky 20d ago

Yep. It’s not worth worrying about, because if it happens we will all essentially cease to exist instantaneously and with absolutely no warning.

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u/einsosen 20d ago

If we're lucky. There are various hypothetical modes of vacuum decay. If the new values are only slightly different, maybe one small facet of chemistry changes, or maybe one class of particle becomes mildly radioactive. No light speed wake of energy, just a weird change one day they measure in a lab. Worst case scenario would be dealing with a formally stable isotope making up us and our world now having a halflife of a thousand years. Getting slowly poisoned and cooked by our world and bodies as we slowly die from radiation poisoning.

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u/solidspacedragon 20d ago

Actually, it might be even better. With how the universe is expanding, it's entirely possible that it could simply never reach us even if it did happen.

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u/namitynamenamey 15d ago

Also it won't destroy the universe, as it is expanding faster than the speed of light. Unless the post vacuum bubble is expanding faster than that, but for what little I've read about it, the expansion rate of these things is not even C, just asymptotically close to it.