Peptide products in the Tocris catalogue consist of sequences of common amino acids, uncommon amino acids and derivatives of amino acids (where they have attached substituents). Common (“proteinogenic” or “coded”) amino acids have a three-letter symbol and are also represented by a one-letter symbol. Uncommon amino acids also have three-letter symbols and can be represented by the one-letter symbol “X”. The tables below list symbols / abbreviations used in this catalogue.

• Table 1. Common Amino Acids
• Table 2. Uncommon Amino Acids
• Table 3. Substituents

Table 1. Common Amino Acids

Key -   Acidic   Basic   Non-polar (hydrophobic)   Polar (uncharged)

Amino acid	Three-letter symbol	One-letter symbol	Chemical structure
Alanine	Ala	A
Arginine	Arg	R
Asparagine	Asn	N
Aspartic acid	Asp	D
Cysteine	Cys	C
Glutamine	Gln	Q
Glutamic acid	Glu	E
Glycine	Gly	G
Histidine	His	H
Isoleucine	Ile	I
Leucine	Leu	L
Lysine	Lys	K
Methionine	Met	M
Phenylalanine	Phe	F
Proline	Pro	P
Serine	Ser	S
Threonine	Thr	T
Tryptophan	Trp	W
Tyrosine	Tyr	Y
Valine	Val	V

Solubility
Most peptides are soluble in distilled water. The addition of 1.0 M acetic acid may aid solubilization of peptides containing mainly basic amino acids, and 1.0 M ammonium hydroxide may be added to peptides containing mainly acidic amino acids.

Table 2. Uncommon Amino Acids

Table 3. Substituents