Most of the peptides (in this field) are far too small to be physically capable of forming prions. The peptides(well, mostly proteins) have to be certain size to achieve 'structural flexibility' to switch like that, must have the hydrophobic areas that could subsequently be exposed and be unstable enough that interaction with 'turned brethren' would overcome the barrier to enter a different state. But not too unstable otherwise it wouldn't pass to start with.
At least that's my amateur take on it.
I just enjoy learning about these.
It's insanely interesting field of study.
I hope my insatiable curiosity never comes off as disregarding the infinitely greater knowledge you have in this area.
As I understand it, only a subset of proteins can become infectious brain damaging prions. It requires several elements,
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1. Must be able to cross the blood brain barrier.
2. They must be able to take on an amyloid configuration.
3. Have the ability to self replicate by acting as a "template" to modify existing natural cellular proteins.
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I'll use my favorite peptide, Semaglutide to illustrate.
GLP-1 has more research behind it. so I'll use it for reference. but the same charachteristics apply to close analogs like Sema.
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1. GLP-1 easily crosses the blood brain barrier.
2. GLP-1 forms amyloid fibrils as the result of simply being reconstituted in a solution with the wrong PH, unless Polysorbate 80(or similar) is included as an excipient!
"Protein or peptide aggregation into amyloid fibrils is a widespread phenomenon that plays a critical role not only in many neurodegenerative diseases but also in the stability of protein- and peptide-based biopharmaceuticals."
3. Whether GLP-1 fibrils can replicate, and what would make it happen, is unknown.
So we have 2 of the 3 factors constituting a potential prion disease present in UGL Sema, and the 3rd is an unknown.
It's been demonstrated that aggregates, including fibrils, can be significantly reduced, and their future development slowed, by filtering at .10um or larger. Unexpectedly, smaller pore sizes cause more fibrils to form.
No good can come from injecting amyloids into our bodies regardless whether they can replicate or not, especially if they can cross the blood brain barrier. So in my opinion, filtering the larger aggregates out of peptides will reduce the amount of that harmful gunk, and reduce the chances of some mutated form turning out to be something much worse years later.