HOW DO PEPTIDES WORK?
MECHANISM EXPLAINER · 5 PEPTIDE FAMILIES ON GIGARESEARCH
WHAT IS A PEPTIDE?
A peptide is a short chain of amino acids linked together by peptide bonds. By convention, chains of about 2 to 50 amino acids are called peptides. Longer chains are called proteins. Insulin (51 amino acids) sits at the boundary. Every protein in the body is built from the same 20 amino-acid building blocks. The sequence determines the molecule.
HOW PEPTIDES SIGNAL CELLS
Bioactive peptides bind specific cell-surface receptors. The metaphor used in textbooks is key-and-lock. The peptide is the key. The receptor is the lock. When the key fits, the receptor changes shape and triggers a cascade of intracellular events. Some peptides activate G-protein-coupled receptors (most incretins, melanocortin receptors). Some bind receptor tyrosine kinases (IGF-1 LR3 binds IGF-1 receptor). Some bind nuclear receptors. Some, like BPC-157, appear to act through indirect pathways that are still under active research. The mechanism family determines the downstream effect.
THE 5 MECHANISM FAMILIES ON GIGARESEARCH
GigaResearch organizes its 27 compounds into five mechanism families. Each compound page links to its mechanism category at /mechanisms.
1 · Incretin axis
GLP-1, GIP and glucagon receptor agonists. Drive glucose-dependent insulin secretion, glucagon suppression, delayed gastric emptying, and central appetite suppression. The largest weight-loss effects in published trials. Compounds: the triple-receptor incretin agonist, the GLP-1 / GIP dual agonist, the long-acting GLP-1 agonist, the daily GLP-1 agonist, the amylin receptor agonist, the GLP-1 / glucagon dual agonist, the oral GLP-1 receptor mimetic, the GLP-1 / glucagon dual agonist (β).
2 · Growth-hormone secretagogue
Raise endogenous growth hormone and IGF-1 pulses via the GHRH receptor (CJC-1295, tesamorelin) or the ghrelin receptor (ipamorelin, hexarelin). Drive downstream IGF-1-mediated effects on lean mass and recovery. Compounds: CJC-1295 + Ipamorelin (ipa-cjc1295), tesamorelin, hexarelin family.
3 · Tissue repair
Drive angiogenesis, growth-factor signaling, cell migration. Animal-model evidence for accelerated tendon, ligament, gut-mucosal and dermal healing. Compounds: BPC-157, TB-500, the Wolverine stack.
4 · Copper-binding
GHK-Cu is the canonical example. The glycyl-L-histidyl-L-lysine tripeptide binds copper(II) and modulates growth-factor signaling, extracellular matrix remodeling, dermal-papilla cell proliferation, and follicle activity. Small clinical and follicle-biology studies report hair-growth signal. Compounds: GHK-Cu.
5 · Mitochondrial
Mitochondrial-derived peptides like MOTS-c (encoded in the mtDNA 12S rRNA region) act on AMPK pathways, insulin sensitivity, and exercise capacity in rodent models. Distinct from incretin and GH-axis families. Compounds: MOTS-c, humanin, SS-31.
RESEARCH VS CLINICAL USE
Some peptides on GigaResearch are FDA-approved as prescription drugs (the GLP-1 / GIP dual agonist as separate FDA-approved class members, the long-acting GLP-1 agonist as separate FDA-approved class members, the daily GLP-1 agonist as an FDA-approved class member, tesamorelin as Egrifta). Most are investigational or research-only. Compounds sold as research-grade reference material are for in-vitro laboratory use only, distinct from any branded prescription product. GigaResearch documents mechanism and published evidence. GigaResearch does not recommend any human dose.
FAQ
▶ What's the difference between peptides and proteins?
Both are chains of amino acids linked by peptide bonds. The line is convention rather than chemistry: chains of roughly 2 to 50 amino acids are called peptides; longer chains are called proteins. Insulin (51 amino acids) sits at the boundary. Function tracks length only loosely. Many peptides are biologically active cell-signaling molecules. Many proteins are structural or catalytic.
▶ Do peptides work like steroids?
No. Anabolic-androgenic steroids are testosterone derivatives that bind androgen receptors and drive direct protein synthesis. Research peptides act on different receptors. Incretin agonists (GLP-1, GIP, glucagon receptors) modulate insulin, gastric emptying and appetite. Growth-hormone secretagogues raise endogenous GH and IGF-1. Tissue-repair peptides act on angiogenesis and cell migration. Different mechanism class, different side-effect profile, different regulatory status.
▶ How are research peptides administered?
Most research peptides are studied as subcutaneous injection because they are large, polar, and rapidly degraded by gastric protease, which makes oral bioavailability low. A few have alternative routes in studies: GHK-Cu has topical evidence. Some compounds are also studied intranasally (selank, semax). the oral GLP-1 receptor mimetic is unusual as an orally bioavailable small-molecule GLP-1 agonist (not a true peptide). GigaResearch documents the published route per compound.
▶ How long until peptides take effect?
Depends on the compound and the endpoint. Incretin agonists show measurable appetite reduction within days; meaningful weight change accrues over weeks. Tissue-repair peptides (BPC-157, TB-500) show animal-model healing acceleration over 2 to 4 weeks. Growth-hormone secretagogues raise GH and IGF-1 within hours; downstream effects accrue over weeks. Half-life and steady-state math are documented per compound on the /tools/half-life-chart page.