Administrative Instructions under the Patent Cooperation Treaty 

Annex C, Appendix 2

Nucleotide and Amino Acid Symbols and Feature Table

Table 4:  List of Modified and Unusual Amino Acids

Symbol Meaning
Aad 2-Aminoadipic acid
bAad 3-Aminoadipic acid
bAla beta-Alanine, beta-Aminopropionic 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-Diaminopropionic 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