Peptide
Also known as: Polypeptide, Oligopeptide
Peptide is a short chain of amino acids (typically 2-50) linked by peptide bonds. Peptides are smaller than proteins and serve as signaling molecules, hormones, and building blocks in biological systems. In research and therapeutics, peptides are studied for their ability to interact with specific receptors and cellular processes.
Last updated: January 20, 2026
What Makes a Peptide?
Peptides are formed when amino acids link together through peptide bonds (a type of covalent bond). The distinction between peptides and proteins is based on size:
| Type | Amino Acids | Example |
|---|---|---|
| Dipeptide | 2 | Carnosine |
| Oligopeptide | 2-20 | BPC-157 (15 amino acids) |
| Polypeptide | 20-50 | Semaglutide (31 amino acids) |
| Protein | 50+ | Insulin (51 amino acids) |
How Peptides Work in the Body
Peptides serve many biological functions:
Signaling
Many hormones are peptides that carry messages between cells and organs. Examples include insulin, glucagon, and growth hormone-releasing hormone (GHRH).
Structural
Collagen peptides contribute to skin, bone, and connective tissue structure.
Enzymatic
Some peptides act as enzyme inhibitors or cofactors in metabolic processes.
Antimicrobial
Certain peptides (like LL-37) have natural antibiotic properties and are part of the innate immune system.
Peptides in Research
Peptides are of significant research interest because they:
- Have high specificity - Can target specific receptors with precision
- Are generally well-tolerated - Break down into natural amino acids
- Can be synthesized - Modern chemistry allows precise peptide manufacturing
- Cross biological barriers - Some can reach targets that small molecules cannot
Natural vs Synthetic Peptides
Natural Peptides
Produced by the body, including hormones like insulin, oxytocin, and endorphins.
Synthetic Peptides
Created in laboratories to mimic or enhance natural peptide functions. Examples include:
- BPC-157 - Derived from a protein found in gastric juice
- Semaglutide - Modified version of natural GLP-1
- Ipamorelin - Synthetic growth hormone secretagogue
Frequently Asked Questions
Are peptides the same as proteins?
No. Peptides are shorter chains of amino acids (typically 2-50), while proteins are longer (50+). The distinction matters because size affects how molecules behave, their stability, and how they’re processed by the body.
Are peptides safe?
This depends entirely on the specific peptide, dose, and context. Some peptides are FDA-approved medications (like semaglutide), while others are still being researched. Always consult healthcare providers before using any peptide therapeutically.
How are peptides administered?
Most peptides cannot survive digestion and must be injected (subcutaneous or intramuscular). Some newer formulations allow oral delivery through protective mechanisms.
Related Peptides
Related Terms
Disclaimer: This glossary entry is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider for medical questions.