Three-Letter One-Letter Symbols
NONPOLAR (hydrophobic) RESIDUES: Alanine Ala A Isoleucine Ile I Leucine Leu L Methionine Met M Phenylalanine Phe F Proline Pro P Tryptophan Trp W Valine Val V UNCHARGED POLAR RESIDUES: Asparagine* Asn N Cysteine Cys C Glutamine* Gln Q Glycine Gly G Serine Ser S Threonine Thr T Tyrosine Tyr Y NEGATIVELY-CHARGED (acidic) RESIDUES: Aspartic Acid* Asp D Glutamic Acid* Glu E POSITIVELY-CHARGED (basic) RESIDUES: Arginine Arg R Histidine His H Lysine Lys K
*Asparagine and glutamine are the amides of aspartic and glutamic acids. When the amide content is unspecified, asparagine + aspartic acid and glutamine + glutamic acid are represented as Asx/B and Glx/Z, respectively.