Last updated:2014.11.21.

Modified and Unusual Amino Acids

Codes Used in Sequence Description

Amino Acid

For other amino acids, those that are not included in Amino Acid Codes, abbreviation listed below is used.

All of these amino acids are described with one letter abbreviation "X" in amino-acid sequence for the coding region.

Abbreviation Amino acid name
Aad 2-Aminoadipic acid
bAad 3-Aminoadipic acid
bAla beta-Alanine, beta-Aminoproprionic acid
Abu 2-Aminobutyric acid
4Abu 4-Aminobutyric acid, piperidinic acid
Acp 6-Aminocaproic acid
Ahe 2-Aminoheptanoic acid
Aib 2-Aminoisobutyric acid
bAib 3-Aminoisobutyric acid
Apm 2-Aminopimelic acid
Dbu 2,4-Diaminobutyric acid
Des Desmosine
Dpm 2,2'-Diaminopimelic acid
Dpr 2,3-Diaminoproprionic acid
EtGly N-Ethylglycine
EtAsn N-Ethylasparagine
Hyl Hydroxylysine
aHyl allo-Hydroxylysine
3Hyp 3-Hydroxyproline
4Hyp 4-Hydroxyproline
Ide Isodesmosine
aIle allo-Isoleucine
MeGly N-Methylglycine, sarcosine
MeIle N-Methylisoleucine
MeLys 6-N-Methyllysine
MeVal N-Methylvaline
Nva Norvaline
Nle Norleucine
Orn Ornithine
OTHER Other (Amino acid not found in this list can be annotated by using /note qualifier)