@Buttonwood just pointing to neversaint's reply.

@neversaint I'm only saying that I am not aware of a Python script which would «digest» a SMILES string of a sequence of amino acids /amino acid by amino acid/ to report the three-letter code or the Fasta one-letter code.

One potential hurdle in writing such a script would be that there are multiple dialects of SMILES (universal, inchified, canonical, etc), which may represent the same structure with a different string. (cf. open-babel.readthedocs.io/en/latest/FileFormats/…).

An other, joining the amino acids, that engaging bonds between the amino acids, that these (sub)strings are no longer visible /as such/. It is not that one could just search for a recurrent separator one may use e.g., in Python's split() string function.

@Tyberius Thank you for the moderation, i.e., moving what developed into a chat into the chat room.