Immunology & Host Response (New Arrivals)

Peptides are short sequences of amino acids found naturally in the body, where they contribute to a range of biological functions. All products we offer are intended exclusively for laboratory research use.

All products sold by Function Dose are intended for laboratory research use only and are considered final sale.

Due to the sensitive and perishable nature of these materials, we do not accept returns, exchanges, or refunds once an order has been shipped.

If your order arrives damaged, incorrect, or incomplete, you may be eligible for a replacement shipment or store credit under our 48-Hour Delivery Guarantee. To qualify, you must contact us within 48 hours of delivery and provide your order number along with clear photos of the issue.

Whenever you wish to cancel an order, please contact us at (645) 253-8087 as soon as possible. Once your order has been shipped, we cannot accept cancellations. Once your order has been shipped, you can begin the refund process by logging into your account. Most unopened products are eligible for a 30 day refund or exchange. Our refund policy lasts 30 days after the delivery date has passed. For more information on our refund policy, click here. 

The following credit cards are currently accepted on our website: Visa, Mastercard, and Discover.

Peptides sit at a useful intersection between chemistry and biology. They are large enough to carry highly specific biological information, yet small enough to be synthesized precisely in a laboratory. That combination makes them powerful tools across a wide range of research areas — including receptor binding studies, mapping of signaling pathways, development of analytical reference standards, and investigation of cellular processes such as metabolism, immune regulation, tissue maintenance, and cell communication. Their specificity and structural tunability are exactly what make peptides a central subject of modern biochemistry, pharmacology, and molecular biology research.

A polypeptide is a single, unbranched chain of amino acids joined together by peptide bonds. It is essentially a longer peptide. Shorter chains — typically between 2 and 50 amino acids — are usually called peptides, while longer chains are called polypeptides. When one or more polypeptide chains fold into a stable, functional three-dimensional structure, the result is what we call a protein. So the progression goes: amino acid → peptide → polypeptide → protein. The exact length cutoffs between these terms are not strictly defined and can vary between sources.

No. Peptides and steroids are two entirely different classes of molecules with different chemistry, structure, and mechanism of action. Peptides are short chains of amino acids linked by peptide bonds — they are typically water-soluble and interact with receptors on the surface of the cell. Steroids, by contrast, are lipid-based compounds built around a four-ring carbon skeleton derived from cholesterol; they usually cross the cell membrane and bind to receptors inside the cell. Their regulatory classification also differs significantly. In short, a peptide is not a steroid, and calling one a version of the other is scientifically inaccurate.

Standard shipping (3–5 days) is free within the United States for orders over $99 (excluding Hawaii and Alaska). Orders under $99 incur a $9.99 shipping fee.

Open the COA library, search by peptide name, and open the certificate for the matching product and strength. Review the lot code and batch-specific results shown on the COA.

All products offered by Function Dose are sold strictly for laboratory research use only. They are not intended for human or animal consumption, injection, ingestion, inhalation, or topical application, and they are not drugs, dietary supplements, cosmetics, or medical devices. See our Research Use Only Policy.