Disease Motifs
Investigating the Biomechanics of Disease
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Basic Information

Amino Acids

Proteins are made up of amino acids, and here is a list of the twenty amino acids found in biological systems. Strictly speaking there are nineteen amino acids and one imino acid as proline is an imino acid although usually proline is labelled as an amino acid along with the others.

The 20 'amino' acids can be placed in to four groups depending on their chemical properties: acidic; basic; polar neutral; and non-polar neutral. Each amino acid can be represented by a three letter code or by a one letter code. The three letter code is much easier to identify with the amino acid but for bioinformatics it is always best to use the one letter code. Here is a list of amino acids in their chemical property group with both the three and one letter code.

Amino Acid
Amino Acid Three Letter
Single Letter
Acidic Aspartic Acid Asp D
Glutamic Acid Glu E
Basic Lysine Lys K
Arginine Arg R
Histidine His H
Polar Neutral Tyrosine Tyr Y
Serine Ser S
Threonine Thr T
Asparagine Asn N
Glutamine Gln Q
Cysteine Cys C
Non-Polar Neutral Tryptophan Trp W
Phenylalanine Phe F
Glycine Gly G
Alanine Ala A
Valine Val V
Isoleucine Ile I
Leucine Leu L
Methionine Met M
Proline Pro P