The Amino Acids
Index to Course Material
Index to Section 2
Single and 3-Letter Codes for Amino Acids
All proteins are polymers of the 20 naturally occuring amino acids. They are listed here along with their
abbreviations :-
Alanine Ala A
Cysteine Cys C
Aspartic AciD Asp D
Glutamic Acid Glu E
Phenylalanine Phe F
Glycine Gly G
Histidine His H
Isoleucine Ile I
Lysine Lys K
Leucine Leu L
Methionine Met M
AsparagiNe Asn N
Proline Pro P
Glutamine Gln Q
ARginine Arg R
Serine Ser S
Threonine Thr T
Valine Val V
Tryptophan Trp W
TYrosine Tyr Y
It is important to take the time to commit the single letter code to memory, as it is
invariably used when comparing and aligning sequences of proteins.
Most are easily remembered
by their initial letters. Try and invent for yourself memorable mnemonic aids to remember the others.
Note that Cysteine and Methionine are the only two sulphur-containing amino acids.
Index to Course Material
Index to Section 2
Last updated 28th Jan '96