What Do Peptides Actually Do?

Your body already uses thousands of peptides every day. They're short chains of amino acids — the same building blocks that make up proteins — and they act as biological messengers, telling your cells what to do, when to do it, and how urgently.

Insulin is a peptide. Growth hormone releasing hormone is a peptide. The signals that tell your gut you're full, that trigger your immune system to respond to an injury, that regulate your sleep cycle — all driven by peptides.

The Lock and Key Mechanism

Peptides work by binding to specific receptors on the surface of cells — like a key fitting into a lock. When the peptide binds, it triggers a cascade of intracellular signals that produce a biological response. The specificity of this binding is what makes peptides so valuable in research: a well-designed peptide can target a single receptor pathway with minimal off-target effects.

How Synthetic Peptides Differ

Synthetic research peptides are lab-manufactured versions of these natural messengers. They're designed to either replicate a natural peptide's action (like semaglutide mimicking GLP-1) or enhance it (like retatrutide targeting three receptors instead of one). Some are modified to last longer in the body, some to be more potent, and some to be more selective.

Why Are Peptides Delivered as Injections?

Most research peptides are supplied as lyophilised (freeze-dried) powder because the dry form is significantly more stable than liquid. Before use, they're reconstituted with bacteriostatic water. Injectable delivery bypasses the digestive system, which would break down the peptide bonds before they could reach their target receptors.