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tl;dr: Living organisms polymerize amino acids using ribosomes which are complex machines made up of proteins and ribosomal RNA (i.e. see 16S in prokaryotes[1])

tl;dr: Living organisms polymerize amino acids using ribosomes which are complex machines made up of proteins and ribosomal RNA (i.e. see 16S in prokaryotes[1]). This creates a chicken and egg problem in early evolution because only simple polypeptides - a chain of amino acids before they've been folded into a functional protein - form spontaneously and they do so in basic solutions that make RNA unstable. This study found that boric acid acts as a catalyst to successfully polymerize several amino acids (alanine and glycine up to 39 peptides long) in environments with acidic and near-neutral pH levels at 130C, which resembles that of the primordial earth. This would be just a tiny piece of the puzzle but it shows that polypeptides could start forming alongside RNA to bootstrap cellular machinery. This leaves many questions unanswered like how did the polypeptides fold along with RNA into the first ribosomes. [1] https://en.wikipedia.org/wiki/16S_ribosomal_RNA https://en.wikipedia.org/wiki/16S_ribosomal_RNA

DoreenMichele 3y ago
In human cells currently, proteins fail to fold in the presence of chemical derangement. In some cases, if you correct the pH balance or other chemical derangement, some denatured proteins will refold. Others will not.
- akiselev 3y ago
  Protein folding in modern organisms depends on hydrophobic/hydrophilic zones [1], disulfide bonds formed by cystine [2], chaperone proteins [3], and who knows what else that evolved over billions of years. On top of that, all cells from prokaryotes to archaea to human cells maintain a complex homeostasis that allows their proteins to fold the right way. Bootstrapping that cellular machinery is a completely different story because there was no stable state - this research was carried out at 130C which is well beyond any archaea. This was probably on the order of tens or hundreds of millions of years before the first cell walls. [1] https://en.wikipedia.org/wiki/Hydrophobic_collapse https://en.wikipedia.org/wiki/Hydrophobic_collapse [2] https://en.wikipedia.org/wiki/Disulfide https://en.wikipedia.org/wiki/Disulfide [3] https://en.wikipedia.org/wiki/Chaperone_(protein) https://en.wikipedia.org/wiki/Chaperone_(protein)
  - DoreenMichele 3y ago
    Protein folding must be thermodynamically favorable within a cell in order for it to be a spontaneous reaction. Since it is known that protein folding is a spontaneous reaction, (etc) And: Under some conditions proteins will not fold into their biochemically functional forms. Temperatures above or below the range that cells tend to live in will cause thermally unstable proteins to unfold or denature (this is why boiling makes an egg white turn opaque). Protein thermal stability is far from constant, however; for example, hyperthermophilic bacteria have been found that grow at temperatures as high as 122 °C,[38] which of course requires that their full complement of vital proteins and protein assemblies be stable at that temperature or above. https://en.m.wikipedia.org/wiki/Protein_folding https://en.m.wikipedia.org/wiki/Protein_folding
    - akiselev 3y ago
      Yes that's what hydrophobic/hydrophilic zones are for! Your quote is literally from the "Hydrophobic effect" section of that wikipedia article under "Driving forces of protein folding" that explains exactly what I was talking about. The first proteins with those features evolved tens or hundreds of millions of years after the polypeptides that are the subject of this research. > Conformations differ based on environmental factors as well; similar proteins fold differently based on where they are found. https://en.wikipedia.org/wiki/Protein_folding#Primary_structure https://en.wikipedia.org/wiki/Protein_folding#Primary_struct...

DoreenMichele 3y ago

In human cells currently, proteins fail to fold in the presence of chemical derangement. In some cases, if you correct the pH balance or other chemical derangement, some denatured proteins will refold. Others will not.

akiselev 3y ago
Protein folding in modern organisms depends on hydrophobic/hydrophilic zones [1], disulfide bonds formed by cystine [2], chaperone proteins [3], and who knows what else that evolved over billions of years. On top of that, all cells from prokaryotes to archaea to human cells maintain a complex homeostasis that allows their proteins to fold the right way. Bootstrapping that cellular machinery is a completely different story because there was no stable state - this research was carried out at 130C which is well beyond any archaea. This was probably on the order of tens or hundreds of millions of years before the first cell walls. [1] https://en.wikipedia.org/wiki/Hydrophobic_collapse https://en.wikipedia.org/wiki/Hydrophobic_collapse [2] https://en.wikipedia.org/wiki/Disulfide https://en.wikipedia.org/wiki/Disulfide [3] https://en.wikipedia.org/wiki/Chaperone_(protein) https://en.wikipedia.org/wiki/Chaperone_(protein)
- DoreenMichele 3y ago
  Protein folding must be thermodynamically favorable within a cell in order for it to be a spontaneous reaction. Since it is known that protein folding is a spontaneous reaction, (etc) And: Under some conditions proteins will not fold into their biochemically functional forms. Temperatures above or below the range that cells tend to live in will cause thermally unstable proteins to unfold or denature (this is why boiling makes an egg white turn opaque). Protein thermal stability is far from constant, however; for example, hyperthermophilic bacteria have been found that grow at temperatures as high as 122 °C,[38] which of course requires that their full complement of vital proteins and protein assemblies be stable at that temperature or above. https://en.m.wikipedia.org/wiki/Protein_folding https://en.m.wikipedia.org/wiki/Protein_folding
  - akiselev 3y ago
    Yes that's what hydrophobic/hydrophilic zones are for! Your quote is literally from the "Hydrophobic effect" section of that wikipedia article under "Driving forces of protein folding" that explains exactly what I was talking about. The first proteins with those features evolved tens or hundreds of millions of years after the polypeptides that are the subject of this research. > Conformations differ based on environmental factors as well; similar proteins fold differently based on where they are found. https://en.wikipedia.org/wiki/Protein_folding#Primary_structure https://en.wikipedia.org/wiki/Protein_folding#Primary_struct...