This guide summarizes, for research reference only, what peptides are, how they are made and characterized, and how they are typically handled in a laboratory setting. Nothing on this page is medical advice or a recommendation for use in humans or animals.
What is a peptide?
A peptide is a short polymer of amino acids joined by amide bonds between the carboxyl group of one residue and the amino group of the next. Chains up to roughly 50 residues are called peptides; longer chains that fold into defined three-dimensional structures are called proteins. A peptide is fully described by its primary sequence (written N-terminus to C-terminus), any terminal modifications such as N-acetylation or C-amidation, and any non-natural residues or side-chain modifications.
How research peptides are synthesized
Most research peptides are produced by solid-phase peptide synthesis (SPPS). The C-terminal residue is anchored to a resin and each subsequent protected amino acid is coupled in turn; after the final coupling the peptide is cleaved from the resin and side-chain protecting groups are removed. The crude product is then purified by reverse-phase HPLC and the pure fractions are lyophilized (freeze-dried) to a stable powder, usually as a trifluoroacetate or acetate salt.
How purity and identity are verified
Analytical HPLC separates the target peptide from deletion sequences, truncated chains and oxidized species; purity is reported as the area percentage of the main peak. Mass spectrometry (ESI or MALDI-TOF) confirms that the observed molecular mass matches the theoretical mass of the intended sequence. Both results appear on the lot Certificate of Analysis.
Purity versus net peptide content
Purity describes the fraction of peptide material that is the correct sequence. Net peptide content describes the fraction of the vial’s gross weight that is peptide at all, as opposed to bound water and counter-ions. A vial can be 99% pure and 80% net peptide content; both numbers matter when preparing solutions of known concentration.
Handling and storage in the laboratory
Lyophilized peptides are generally stable for extended periods when stored sealed, dry, protected from light and refrigerated or frozen. Vials should be allowed to reach room temperature before opening to avoid condensation. Peptides containing cysteine, methionine or tryptophan are more sensitive to oxidation and benefit from minimal exposure to air.
Research categories in our catalog
- Growth hormone secretagogues, such as Ipamorelin, are studied for their interaction with the ghrelin receptor (GHS-R1a).
- Incretin-class peptides, such as Tirzepatide and Retatrutide, are engineered analogs studied at GIP, GLP-1 and glucagon receptors.
- Tissue-signaling peptides, such as Thymosin Beta-4 (TB-500), GHK-Cu and KPV, are studied in cell migration, extracellular-matrix and inflammation models.
- Neuro- and immuno-active peptides, such as Pinealon, VIP, Thymosin Alpha-1 and Kisspeptin-10, are studied in neuronal, immune and endocrine cell systems.
- Antioxidant peptides, such as Glutathione, are studied for their role in cellular redox chemistry.
Detailed chemistry, mechanism summaries and literature references appear on each product page.
