A proteinogenic amino acid is incorporated into proteins during translation. The conventional twenty include glycine, alanine, methionine and proline; they are a subset of amino acids, not a definition of the whole family. [ref]
Nomenclature and Symbolism for Amino Acids and Peptides (Recommendations 1983) by IUPAC-IUB Joint Commission on Biochemical Nomenclature. 3AA-1, Table 1: alpha-amino acids incorporated into protein under mRNA direction
Tyrosine has a phenolic side chain. Its hydroxyl can participate in hydrogen bonding and, when the environment is suitable, acid/base chemistry.
Glutamine has a neutral side-chain amide. Its N–H groups can donate hydrogen bonds and its carbonyl oxygen can accept them; its amide nitrogen is not an ordinary amine base.
Proline is a cyclic alpha-amino acid whose amine nitrogen is joined to two carbon positions within a five-membered ring. This explains the exception to in amino acid. [ref]
A proteinogenic amino acid represented by K or Lys in protein primary structure. Its amino acid side chain carries predominantly positive electric charge near neutral pH.[ref]
26.1 Structures of Amino Acids. Organic Chemistry by John McMurry; Table 26.1, lysine and arginine rows; side-chain protonation at pH 7.3
Trypsin preferentially cleaves after its amino acid residues.
A proteinogenic amino acid represented by R or Arg in protein primary structure. Its amino acid side chain carries predominantly positive electric charge near neutral pH.[ref]
26.1 Structures of Amino Acids. Organic Chemistry by John McMurry; Table 26.1, lysine and arginine rows; side-chain protonation at pH 7.3
Trypsin preferentially cleaves after its amino acid residues.
