Indole group
Tryptophan
Thiol
Cysteine, ?
Carboxyl
Glutamate
Aspartate
Amide
Asparagine
Glutamine
Amine
Lysine
Arginine
Imidazole
Histidine
Guanidinium
Arganine
Disulfide bond
A covalent bond between sulfurs from two cysteine molecules by oxidation
Primary structure of a protein
Peptide bonds