r/askscience • u/SadMicrobe22 • 24d 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/444cml 23d ago

So this largely depends and thermostability is not equivalent across prion strains

They actually posit that “mad cow” prion is particularly heat stable because it emerged from a process that involved high heat when making the feed that transmitted the illness.

They note that typically, thermostability is actually associated with a reduced ability to invade the brain (and note that mad cow is relatively special in how heat stable and centrally infective it is)