User guide

V Val Valine
W Trp Tryptophan
Y Tyr Tyrosine
The tables below list the three letter codes for non-specific and non-proteinogenic amino acids.
IUPAC amino
acid code
Three
letter
code
Non-specific Amino Acid
B Asx asparagine or aspartic acid
Z Glx glutamic acid or glutamine
J Xle leucine or isoleucine
X Xaa Any amino acid (no nickname)
IUPAC amino
acid code
Three
letter
code
Non-proteinogenic Amino
Acid
O Pyl Pyrrolysine
U Sec Selenocysteine
Aib
α-Aminoisobutyric acid
Abz 2-Aminobenzoic acid
Nle Norleucine
Cyclic, crosslinked, and branched peptides
You can create cyclic peptides by bonding together the terminal residues in a peptide sequence. A looped bond indi-
cates the peptide is cyclic. An example of cyclic peptide is shown below:
ChemBioDraw 13.0
Chapter 5: Drawing biopolymers 72 of 401