Peptide
A peptide is a short chain of 2 to 50 amino acids linked by peptide bonds. Peptides act as biological signaling molecules, triggering specific cellular responses when they bind to receptors.
Overview
Peptides are short chains of amino acids — the same building blocks used in proteins — but generally contain fewer than 50 residues. Their relatively small size allows them to diffuse across tissue barriers and interact with specific cell-surface receptors. In research contexts, synthetic peptides are designed to mimic or modulate the activity of endogenous signaling peptides found in the body. Many research peptides are sold in lyophilized (freeze-dried) form, requiring reconstitution with sterile diluent before use. The small molecular size of peptides also means oral bioavailability is typically poor; subcutaneous injection is the most common research administration route.
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Frequently asked questions
What is the difference between a peptide and a protein?+
Peptides contain fewer than 50 amino acids while proteins contain 50 or more. Proteins are also typically folded into complex three-dimensional structures, whereas many peptides remain relatively linear.
Are peptides naturally occurring?+
Yes. The body produces hundreds of endogenous peptides — including hormones, neurotransmitters, and growth factors. Synthetic research peptides are often designed to mimic or amplify these natural signals.
Why are most research peptides injected rather than taken orally?+
Digestive enzymes in the stomach and small intestine break down most peptides before they can reach systemic circulation, resulting in very low oral bioavailability. Subcutaneous injection bypasses this degradation.