What is a peptide? A plain-English guide

Peptides are short chains of amino acids

Amino acids are the building blocks your body uses to make proteins. When a small number of them are linked together in a chain, the result is called a peptide. Most definitions put the cutoff at around 50 amino acids: shorter chains are peptides, longer ones are proteins.

Your body makes thousands of peptides on its own. Many act as signals that carry messages between cells, and several well-known hormones are peptides.

Peptide vs. protein

• Peptide: a short chain, usually 2 to 50 amino acids
• Protein: a long chain, often hundreds of amino acids, folded into a 3D shape
• Both use the same building blocks; size and structure are the main difference

Natural, synthetic, analogs and fragments

Research peptides are almost always made in a lab (synthetic). Some copy a sequence found in the body exactly. Analogs change a few amino acids or add a chemical group so the peptide lasts longer or behaves differently. Fragments are short pieces of a larger natural peptide or protein.

Why they come as powder in a vial

Most research peptides ship freeze-dried (lyophilized) as a small cake or powder in a sealed vial, because they are more stable that way. Before use in research they are mixed with a liquid, which is called reconstitution. Once mixed, they usually need to be kept cold and used within a set time.

Words you will see on labels

• mg per vial: how much peptide powder is in the vial
• Lyophilized: freeze-dried
• Reconstitute: mix the powder with a liquid
• Bacteriostatic water: sterile water with a small amount of preservative, commonly used for mixing
• Purity: how much of the contents is the intended peptide, usually tested by HPLC
• COA: certificate of analysis, the lab report for a batch
• Lot or batch number: links a vial to its COA

How The Pep Planner fits in

The Pep Planner does not tell you what to use. It keeps your records: what you have in stock, what is mixed and when, your protocol schedule and your notes. Each compound gets its own entry with strength, vendor and lot, so your history stays tied to the right vial.

Common questions

Are peptides the same as steroids?

No. Steroids are a different class of molecule built on a ring structure, not chains of amino acids.

Are research peptides approved for human use?

Most peptides sold for research are not approved medicines. A few peptides are active ingredients in approved prescription drugs, which are separate, regulated products. Check the rules in your country.