Peptide Terminology Glossary

Essential Peptide Terms

Understanding peptide terminology is crucial for researchers working with these complex molecules. This glossary covers the fundamental terms you’ll encounter in peptide research and laboratory work.

Amino Acids

The building blocks of peptides. Each amino acid contains an amino group, a carboxyl group, and a unique side chain that determines its properties and function within the peptide sequence.

Peptide Bond

A covalent bond formed between the carboxyl group of one amino acid and the amino group of another during condensation, releasing a water molecule. This bond creates the peptide backbone.

Primary Structure

The linear sequence of amino acids in a peptide chain, reading from the N-terminus to the C-terminus. This sequence determines all higher-order structures and biological activity.

Secondary Structure

Local folding patterns within the peptide chain, primarily alpha-helices and beta-sheets, stabilized by hydrogen bonds between backbone atoms.

Lyophilization

Also known as freeze-drying, this process removes water from peptide solutions to create a stable powder. Most research peptides are supplied in lyophilized form to maximize shelf life and stability.

Reconstitution

The process of dissolving lyophilized peptides in an appropriate solvent, typically bacteriostatic water or acetic acid solution, to create a working solution for research applications.

Purity

The percentage of the desired peptide in the final product, typically measured by HPLC. Research grade peptides typically have 99%+ purity to ensure reliable and reproducible results.

HPLC

High-Performance Liquid Chromatography – an analytical technique used to separate, identify, and quantify peptide components. HPLC testing provides a certificate of analysis confirming peptide purity and identity.

Mass Spectrometry

An analytical technique that measures the mass-to-charge ratio of molecules, used to confirm peptide identity and detect impurities. Often used alongside HPLC for comprehensive characterization.

N-Terminus and C-Terminus

The N-terminus is the end of a peptide chain with a free amino group, while the C-terminus has a free carboxyl group. Peptide sequences are conventionally written from N-terminus to C-terminus.

Disulfide Bonds

Covalent bonds formed between cysteine residues that help stabilize peptide structure. These bonds are critical for maintaining the tertiary structure of many bioactive peptides.

Acetylation and Amidation

Common modifications: acetylation adds an acetyl group to the N-terminus, while amidation replaces the C-terminal carboxyl with an amide group. Both modifications often improve peptide stability.

Bacteriostatic Water

Sterile water containing 0.9% benzyl alcohol as a preservative, commonly used for reconstituting research peptides. The bacteriostatic agent inhibits bacterial growth in multi-use vials.

Peptide Analog

A modified version of a naturally occurring peptide where one or more amino acids have been substituted, deleted, or added to alter properties such as stability, selectivity, or activity.

In Vitro

Latin for “in glass” – refers to research conducted in a controlled laboratory environment outside living organisms. All peptides from Group Peptides are intended solely for in-vitro research use.

Certificate of Analysis (COA)

A document verifying peptide identity, purity, and composition. COAs typically include HPLC chromatograms and mass spectrometry data, provided with every batch.

For questions about peptide terminology or guidance on selecting the right peptides for your research, please contact our team.