Amino acids are modeled as simple sequences using Bio.BaseSequence.

Examples

iex>aa = AminoAcid.new("ymabagta")
...>"mabag" in aa
true

iex>alias Bio.Enum, as: Bnum
...>AminoAcid.new("ymabagta")
...>|>Bnum.map(&(&1))
%AminoAcid{sequence: "ymabagta", length: 8}

iex>alias Bio.Enum, as: Bnum
...>AminoAcid.new("ymabagta")
...>|>Bnum.slice(2, 2)
%AminoAcid{sequence: "ab", length: 2}

If you are interested in defining conversions of amino acids then look into the Bio.Polymer module for how to deal with creating a Conversion module.

The simple Bio.Sequence.AminoAcid does define the Bio.Polymeric protocol, which will allow you to define conversions from this to any type you may desire.