How do you denote peptides? (by amino acid sequence)

Mar 16, 2021

By three-letter code and one-letter code.

Three-letter code: N- and C-terminus are specified, H- signifies a free amino terminus, -OH an unmodified C-terminus, -NH2 a peptide amide, e.g. H-Ala-Ala-Ala-OH, H-Ala-D-Ala-Ala-OH, H-Ala-Ala-Ala-NH2.

One-Letter code: Only modified termini are specified, e.g. AAA, Ac-AAA, AAA-NH2.

In case of peptides containing unusual amino acids, the three-letter code abbreviation can be inserted and marked as such by hyphens: Ac-SYS-Nle-EHfRWGKPV-NH2.