The peptide sequence refers to the order of the amino acid residues in the peptide chain. In our peptide structures the sequence is always defined starting from the N-terminal end on the left (position 1) to the C-terminal end on the right. In the Tocris product information, the peptide sequence is given as two versions - three letter symbols and single letter symbols. In all cases ACS nomenclature is followed when writing symbol codes (for information about symbol codes and their meaning click here).
Tocris preferentially displays the peptide sequence as three letter symbols, with unusual amino acids normally defined using individual three letter codes. In rare cases XXX is used when no standard three letter code exists. Bridges are drawn between the joined amino acids. By default, the N-terminal amino acid exists as the free amine and the C-terminal is the free acid. If they are substituted in any way this is shown. Any other substitution on an amino acid is also shown.
Tocris also displays the peptide sequence in the single letter symbol format, with unusual amino acids normally defined using the letter X. The modification is described underneath and the position of any bridges is explained using the numbers of the amino acids in the chain as reference (the left hand amino acid is position 1). As before, by default the left end amino acid is the free amine and the right end is the free acid. If either of the termini are substituted this is described underneath. Any other substitutions within the peptide sequence are also described underneath.Close Window