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Amino Acid Chart and Reference Table

Amino acids are the backbone of peptides and proteins. All amino acids contain both amino and carboxylic acids, and in certain cases, side chains.

The properties of amino acids are determined by the functional substituents linked on the side chains, which are most commonly referred to as R groups. In the amino acid chart listed here, we describe the 20 standard residues found in nature, along with the universal genetic codes.


  1. Aliphatic Amino Acids with Hydrophobic Side Chain
  2. Aromatic Amino Acids with Hydrophobic Side Chain
  3. Amino Acids with Neutral Side Chain
  4. Amino Acids with Positive Charged Side Chain
  5. Amino Acids with Negative Charged Side Chain
  6. Unique Amino Acids

Aliphatic Amino Acids with Hydrophobic Side Chain

Name
3-Letter Symbol
1-Letter Symbol
Formula
Molecular Weight
Isoelectric Point
Structure
Alanine ALA A C3H7N1O2 89.09 6.00 Alanine
Isoleucine ILE I C6H13N1O2 131.17 5.94 Isoleucine
Leucine LEU L C6H13N1O2 131.17 5.98 Leucine
Valine VAL V C5H11N1O2 117.15 5.96 Valine

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Aromatic Amino Acids with Hydrophobic Side Chain

Name
3-Letter Symbol
1-Letter Symbol
Formula
Molecular Weight
Isoelectric Point
Structure
Phenylalanine PHE F C9H11N1O2 165.19 5.48 Phenylalanine
Tryptophan TRP W C11H12N2O2 204.23 5.89 Tryptophan
Tyrosine TYR Y C9H11N1O3 181.19 5.66 Tyrosine

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Amino Acids with Neutral Side Chain

Name
3-Letter Symbol
1-Letter Symbol
Formula
Molecular Weight
Isoelectric Point
Structure
Asparagine ASN N C4H8N2O3 132.12 5.41 Asparagine
Cysteine CYS C C3H7N1O2S1 121.16 5.02 Cysteine
Glutamine GLN Q C5H10N2O3 146.15 5.65 Glutamine
Methionine MET M C5H11N1O2S1 149.21 5.74 Methionine
Serine SER S C3H7N1O3 105.09 5.68 Serine
Threonine THR T C4H9N1O3 119.12 5.64 Threonine

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Amino Acids with Positive Charged Side Chain

Name
3-Letter Symbol
1-Letter Symbol
Formula
Molecular Weight
Isoelectric Point
Structure
Arginine ARG R C6H14N4O2 174.2 11.15 Arginine
Histidine HIS H C6H9N3O2 155.16 7.47 Histidine
Lysine LYS K C6H14N2O2 146.19 9.59 Lysine

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Amino Acids with Negative Charged Side Chain

Name
3-Letter Symbol
1-Letter Symbol
Formula
Molecular Weight
Isoelectric Point
Structure
Aspartic Acid ASP D C4H7N1O4 133.1 2.77 Aspartic Acid
Glutamic Acid GLU E C5H9N1O4 147.13 3.22 Glutamic Acid

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Unique Amino Acids

Name
3-Letter Symbol
1-Letter Symbol
Formula
Molecular Weight
Isoelectric Point
Structure
Glycine GLY G C2H5N1O2 75.07 5.97 Glycine
Proline PRO P C5H9N1O2 115.13 6.30 Proline
 
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