Note that the paper gives a hint about why 3 of the 20 amino acids were selected, it is not clear that the same rule can be applied to the other 17 amino acids and why the number is 20 (or approximately 20).
From a comment in a previous post:
In the research paper they analyzed a few amino acids like Lysine. Lysine is an amino acid that has the usual amino group and the usual acid group in one side, and it has an additional amino group in the other side. In the study they compared Lysine with Lysine-like amino acids that are shorter and the additional amino group are closer to the usual amino group and the usual acid group. For example https://en.wikipedia.org/wiki/Ornithine
They found that the usual amino acids like Lysine are better to form spontaneously protein-like chains than the shorter versions when they are in a solution that gets dried. I'm not sure if this is enough to explain why Lysine is used in proteins but it's an interesting result anyway.
In the more optimistic case, the research article "explain" why the 3 usual amino acids that they used are better than the 3 shorter variants that they used. It doesn't "explain" why the other 17 amino acids where selected.
In particular they used amino acids with an additional amino group, so the polymerization can get "confused" and instead of using the usual amino group use the other group, so instead of a nice chain, you get some other structure. There are 17 of the other usual amino acids that don't have an additional amino group, so the polymerization process can't get confused.
From a comment in a previous post:
In the research paper they analyzed a few amino acids like Lysine. Lysine is an amino acid that has the usual amino group and the usual acid group in one side, and it has an additional amino group in the other side. In the study they compared Lysine with Lysine-like amino acids that are shorter and the additional amino group are closer to the usual amino group and the usual acid group. For example https://en.wikipedia.org/wiki/Ornithine
They found that the usual amino acids like Lysine are better to form spontaneously protein-like chains than the shorter versions when they are in a solution that gets dried. I'm not sure if this is enough to explain why Lysine is used in proteins but it's an interesting result anyway.
In the more optimistic case, the research article "explain" why the 3 usual amino acids that they used are better than the 3 shorter variants that they used. It doesn't "explain" why the other 17 amino acids where selected.
In particular they used amino acids with an additional amino group, so the polymerization can get "confused" and instead of using the usual amino group use the other group, so instead of a nice chain, you get some other structure. There are 17 of the other usual amino acids that don't have an additional amino group, so the polymerization process can't get confused.