What are peptides? A comprehensive explanation for researchers

What are Peptides? A Comprehensive Explanation for Researchers

In recent years, peptides have become an increasingly prominent topic in scientific circles. They are being studied in laboratories worldwide as model systems for receptor binding, cellular communication, and metabolic regulation. But what exactly are they, and why are they so interesting as research tools?

To understand peptides, you start with amino acids. The human body uses twenty standard amino acids as building blocks for almost all proteins and biological compounds. Amino acids link together via peptide bonds to form chains. A chain of two amino acids is called a dipeptide. Three amino acids form a tripeptide. From twenty amino acids upwards, scientists generally speak of a polypeptide or protein.

Peptides fall in between: they consist of two to approximately fifty amino acids. This relatively compact structure gives them several properties that make them particularly suitable for laboratory research. They are smaller and more controllable than complete proteins, they can be produced synthetically with high precision, and their behavior in a cellular environment is more predictable.

The exact sequence of amino acids in a peptide determines everything. Two peptides with the same amino acids in a different order can have completely different properties. This makes sequence precision in production and purity control so important — a point we will return to later.

Peptides are not a laboratory invention. They play a central role in almost every biological system. Hormones such as insulin and glucagon are peptides. Neurotransmitters such as oxytocin and vasopressin are peptides. Even many antibiotics that bacteria produce themselves to kill competitors are peptides.

The human body continuously produces peptides as signaling molecules, transmitting information between cells, organs, and systems. It is precisely this signaling role that makes synthetic peptides so interesting for scientists: by synthesizing and adding specific peptides to a cell system, you can study how that system responds to a particular signal.

Well-known examples of peptides extensively studied in scientific literature include BPC-157 for gastrointestinal cell research, GHK-Cu for dermal cell biology, and Semax for neuropeptidological research.

Most research peptides are produced synthetically via a method called Solid Phase Peptide Synthesis (SPPS) — a technique developed in the 1960s by biochemist Robert Bruce Merrifield, for which he received the Nobel Prize in Chemistry in 1984.

In SPPS, amino acids are linked step by step to a solid support in the desired sequence. Upon completion, the peptide is cleaved from the support and purified. The quality of this process — and of the subsequent purification step — directly determines the reliability of the final product.

A synthetic peptide that is 95% pure contains 5% other compounds. In a cell biology experiment, these impurities can have measurable effects on the outcome. That is why serious researchers work with peptides whose purity has been independently tested and documented — preferably above 98 or 99%.

At Peptidera, all products are externally tested for purity via HPLC analysis and for molecular identity via mass spectrometry. The corresponding Certificate of Analysis is publicly available per lot number.

When you order a research peptide, you almost always receive a small vial containing a white powder. This is no coincidence — peptides are typically supplied in lyophilized (freeze-dried) form.

Lyophilization is a process where the peptide is first frozen and then dried under vacuum, with the ice directly sublimating without passing through the liquid phase. The result is a stable, lightweight powder that retains its structure for months to years with proper storage.

The alternative liquid form is significantly less stable: peptides in solution degrade faster, are more sensitive to temperature fluctuations, and offer less flexibility in transport and storage. Lyophilization is the industry standard and the only format suitable for serious laboratory research.

For use, the powder is reconstituted — dissolved in a solvent such as sterile water or a buffer solution, depending on the specific research protocol.

The scientific literature on peptides covers dozens of research domains. Some of the most studied areas include:

• Tissue and Cell Biology — Peptides such as BPC-157 and TB-500 are studied in the context of cellular migration, angiogenesis, and extracellular matrix biology. See also our recovery & tissue research collection.
• Metabolic Signaling Pathways — Compounds such as Retatrutide (a tri-agonist with affinity for the GLP-1, GIP, and glucagon receptors) are being investigated as model systems for energy homeostasis and receptor interaction. More in our metabolism & GLP-1 collection.
• Dermal and Cellular Biology — GHK-Cu, Snap-8, and Epithalon are studied in in-vitro research on fibroblast activity, collagen synthesis, and telomere biology. See our skin & cell biology collection.
• Neuropeptidology — Semax, Selank, and Pinealon are subjects of published research on neurotrophic factor expression and GABAergic neurotransmission. More in our neurological & cognitive collection.

As a researcher or professional, you depend on the quality of your starting material. A peptide that is not what it claims to be — incorrect sequence, too low purity, impurities — makes your research results unreliable.

Criteria to consider when choosing a supplier:

• Each lot must be tested externally, not internally. A supplier who tests their own products has a conflict of interest. Independent laboratory analysis is the only reliable standard.

• The COA must be available per lot number, not as a generic document that applies to all products. Each production batch has its own test results.

• Purity percentage must be substantiated with HPLC data, not just stated as a claim on the packaging.

• Molecular identity confirmation via mass spectrometry is necessary to verify that the delivered compound is indeed the specified peptide.

At Peptidera, all products meet these criteria. The COA library is public and no account is required.

Research peptides in the Netherlands fall under a specific legal framework. The compounds sold by Peptidera are not registered as medicines with the CBG or EMA, are not on the Opium Act lists, and are offered exclusively as research chemicals. Sales are legally permitted provided the compounds are explicitly not offered for human consumption.

For more information about the legal background, please refer to our FAQ page.

Scientific References:

• Merrifield, R.B. (1963). Solid phase peptide synthesis. Journal of the American Chemical Society, 85(14), 2149–2154. → PubMed
• Fosgerau, K. & Hoffmann, T. (2015). Peptide therapeutics: current status and future directions. Drug Discovery Today, 20(1), 122–128. → PubMed