What Are Peptides and What Do Peptides Actually Do? (The Science Explained)

"What are peptides?" is the most common search term for new researchers entering the field. But the follow-up question—"What do peptides actually do?"—is where the real science begins. In this technical briefing, we break down the chemistry, the signaling mechanisms, and the crucial terminology you need to understand before you start your research.

The Executive Summary

What Are They? Peptides are short chains of amino acids (the building blocks of proteins) held together by peptide bonds.
What Do They Do? They act as "biological messengers." They do not create new functions; they bind to receptors on cells to trigger specific, pre-existing biological responses.
Why Research Them? Because of their high specificity and low toxicity, they are the primary focus of modern regenerative medicine and biochemical research.

"Peptides are the language cells use to talk to each other. Research is simply the act of decoding that language."

1. What Are Peptides? (The Definition)

To understand peptides, you must first understand the hierarchy of biological molecules. Everything starts with the Amino Acid.

There are 20 canonical amino acids that act as the alphabet of biology. Depending on how you arrange them, you get different structures:

Oligopeptides: Short chains (2 to 20 amino acids).
Polypeptides: Medium chains (20 to 50 amino acids).
Proteins: Long, complex chains (50+ amino acids).

The distinction is important. Because peptides are smaller than proteins, they are more agile. They can penetrate tissues easier and clear the system faster. For a deep dive into terms like "Lyophilization" and "Reconstitution," refer to our Technical Index & Jargon Buster.

2. What Do Peptides Actually Do? (The Function)

This is the core of the "People Also Ask" query. If you put a peptide in a petri dish with a cell, what happens?

The answer is Signaling.

Peptides function via a "Lock and Key" mechanism:

The Lock: The surface of a cell is covered in receptors.
The Key: The peptide travels through the medium until it finds its matching receptor.
The Turn: Once bound, the peptide triggers an intracellular cascade. It might tell the cell to "repair," "secrete hormone," or "divide."

Research Examples:

Different peptides carry different messages:

GHK-Cu: A copper peptide that signals gene expression related to collagen synthesis.
BPC-157: A gastric peptide observed in studies to signal angiogenic (blood vessel formation) pathways.
TB-500: A synthetic fraction of Thymosin Beta-4, researched for its role in actin sequestration (cell mobility).

3. Why Purity Dictates Function

If peptides are "keys," then purity is the shape of that key. If a peptide is damaged by heat (poor storage) or contains impurities from synthesis, the key is bent. It will not fit the receptor lock.

This is why we stress Cold-Chain Storage. A degraded peptide doesn't just work "less well"—it often doesn't work at all.

4. The Legal Context

While understanding what peptides do is vital, understanding what you are allowed to do with them is mandatory.

In the UK, these compounds are legal to possess for research purposes but are not approved for human consumption. There is often confusion regarding the difference between legal reagents and controlled substances.

For a full breakdown of the law, read our updated guide: Are Peptides Legal in the UK? (2026 Guide).

Frequently Asked Questions

Do peptides occur naturally?

Yes. Your body produces peptides (like insulin or oxytocin) every second. Research peptides are synthetic versions created in a lab to mimic these natural signals.

What is the difference between a peptide and a hormone?

Many hormones are peptides (like Insulin). However, not all peptides are hormones. In research terms, we typically study peptides that act as secretagogues—signaling the pituitary gland to release natural hormones.