Understanding peptide nomenclature and sequences
How peptide names, one-letter codes and modifications are written.
Peptide names can look like a jumble of letters, numbers and hyphens. Once you know the conventions, they become a compact and precise way to describe a molecule. This article explains the basics of how peptides are named and how their sequences are written.
Amino acids as building blocks
A peptide is a short chain of amino acids joined by peptide bonds. Twenty standard amino acids are commonly used, and each has a three-letter code and a one-letter code. For example, glycine is Gly or G, lysine is Lys or K, and proline is Pro or P. A sequence written as Lys-Pro-Val uses three-letter codes, while KPV writes the same tripeptide with one-letter codes.
Direction matters
Sequences are written from the N-terminus, the end with a free amino group, to the C-terminus, the end with a free carboxyl group. Reversing the order describes a different molecule. When a sequence is listed on a product page or certificate, read it left to right as N to C.
Modifications and non-standard residues
Many research peptides include changes to the standard chain. A C-terminal amide is often written as -NH2. Acetylation at the N-terminus may be written Ac-. Non-standard amino acids, such as Aib (aminoisobutyric acid), are usually written in full or in brackets. Metal complexes, such as the copper complex in GHK-Cu, are indicated in the name itself.
Common names and codes
Some peptides are known by a common or trade-style name, a code made of letters and numbers, or both. These names are convenient but not always precise. The sequence, molecular formula and molecular weight are what define the molecule, which is why our product pages list them where available. A CAS registry number adds another unambiguous identifier.
Isomers and stereochemistry
Most amino acids exist in two mirror-image forms, labeled L and D. Standard peptide sequences assume the L form unless stated otherwise. When a D-amino acid is used, it is usually marked with a lowercase letter or a D- prefix, for example D-Ala. This small notation changes the molecule, so it should always be read carefully.
Blends
A blend contains two or more separate peptides in one vial. Each component keeps its own name, sequence and identifiers, and the label should state the amount of each. A blend name is a product name, not a new molecule.
Reading a specification table
On a Bio Elevate product page, the specification table may list sequence, formula, molecular weight, CAS number and purity information. Use these fields together: the sequence describes the chain, the formula and weight follow from it, and the CAS number links the compound to public chemistry records. If anything looks inconsistent, contact us with the product and lot number.
Educational content for laboratory research. Bio Elevate products are for research use only and are not for human or veterinary use.