Semaglutide is a synthetic 31-residue analog of human glucagon-like peptide-1 (GLP-1), engineered so that it resists enzymatic breakdown and binds reversibly to albumin, giving it a circulating persistence measured in days rather than minutes. It is one of the most heavily characterised GLP-1 receptor agonists in the published literature, and it is the reference molecule most laboratories reach for when they need a long-acting, single-target incretin agonist. We supply it as lyophilized research-grade semaglutide in sealed vials for in vitro and preclinical work only.
Everything below describes what has been reported in the scientific literature about the molecule and its approved pharmaceutical counterparts. Research-grade material is not a medicine, is not for human or veterinary use, and no part of this page is a protocol for people.
What is semaglutide, in one paragraph
Semaglutide belongs to the incretin mimetic class: peptides that copy the signalling of gut hormones released after nutrient intake. Native GLP-1 has a plasma half-life of roughly one to two minutes because dipeptidyl peptidase-4 (DPP-4) clips it at position 8 almost immediately. Semaglutide was designed to defeat that clearance route while keeping potent agonism at the GLP-1 receptor, a class B G-protein-coupled receptor expressed in pancreatic islets, the stomach, the vagal afferents and several hypothalamic and hindbrain nuclei. Functionally it is a GLP-1 receptor agonist and nothing else — it does not engage the GIP or glucagon receptors, which is precisely why it is useful as a clean single-receptor comparator.
Origin and structure
The scaffold is GLP-1(7-37). Three engineering decisions define the molecule:
- Alpha-aminoisobutyric acid (Aib) at position 8. Substituting this non-proteinogenic residue for alanine removes the DPP-4 cleavage site, which is the single largest contributor to native GLP-1 instability.
- Arginine for lysine at position 34. This directs the acylation chemistry to a single defined site rather than producing a mixture of regioisomers.
- A C18 fatty diacid on Lys26 through a gamma-glutamyl and short PEG-like spacer. The diacid binds reversibly to serum albumin. Albumin-bound peptide is shielded from renal filtration and proteolysis and is released slowly, which is the mechanistic basis for the extended half-life reported in pharmacokinetic studies of the approved product.
Our catalog entry lists CAS 910463-68-2, molecular formula C187H291N45O59 and a monoisotopic-adjacent average molecular weight of 4113.58 Da. That mass is worth internalising: it is what you use to convert milligrams into nanomoles when preparing an assay stock. A 4,113 Da peptide is large enough that trace water and counter-ion content meaningfully shift the true peptide mass in a vial, which is one reason net peptide content on the certificate matters more than nominal fill weight.
How semaglutide is thought to work
The reported mechanism is straightforward receptor pharmacology with an unusually long exposure window. On binding the GLP-1 receptor, semaglutide stabilises the active receptor conformation, Gs coupling raises intracellular cAMP, and protein kinase A and Epac2 signalling follow. In isolated islet preparations this has been reported to amplify glucose-dependent insulin secretion — the response scales with ambient glucose rather than overriding it, which is the defining feature of incretin signalling and the reason the class behaves differently from insulin secretagogues that act regardless of glucose.
Beyond the islet, published work using receptor-mapping and neuronal-activation techniques has reported GLP-1 receptor engagement in the area postrema, nucleus tractus solitarius and arcuate nucleus. Rodent studies have described reduced food intake and slowed gastric emptying following administration, effects that are generally attributed to central and vagal receptor populations rather than a direct action on adipose tissue. Beta-arrestin recruitment is comparatively low relative to G-protein signalling for this molecule, a bias that several in vitro papers have linked to sustained cAMP output and reduced receptor internalisation. If your research question concerns biased agonism at class B GPCRs, semaglutide is one of the standard tool comparators.
What research has examined
The evidence base separates cleanly into three tiers, and keeping them separate is essential to reading this literature honestly.
- Cell and receptor work. cAMP accumulation assays, radioligand and fluorescent binding studies, beta-arrestin recruitment assays and receptor internalisation imaging in cell lines expressing the human GLP-1 receptor. This is where potency and selectivity numbers come from.
- Rodent and non-human preclinical work. Feeding behaviour, gastric transit, islet morphology, hepatic lipid content, and neuronal c-Fos mapping in mice and rats. Diet-induced obesity models are the most common setting; several groups have also reported effects in models of hepatic steatosis and atherosclerosis.
- Human clinical trials of the approved pharmaceutical. Large randomised programmes in type 2 diabetes and in weight management, plus cardiovascular outcome trials, have been published. These trials studied a regulated medicine manufactured, formulated and administered under prescription. They are informative about the molecule; they say nothing about research-grade powder and confer no human-use permission on it.
Active areas of published investigation as of 2026 include hepatic outcomes, renal endpoints, neuroinflammation and central GLP-1 receptor biology, and mechanistic comparisons against multi-receptor agonists. For a wider map of the field see our GLP-1 and incretin pathway hub.
Forms and sizes we supply
| Attribute | Specification |
|---|---|
| Form | Lyophilized powder, sealed glass vial with flip-off seal |
| Sizes | 5 mg, 10 mg, 20 mg, 30 mg, 50 mg |
| Purity | Greater than or equal to 99% by HPLC, lot-matched COA |
| CAS | 910463-68-2 |
| Molecular weight | 4113.58 Da |
| Formula | C187H291N45O59 |
| Class | Acylated GLP-1 receptor agonist (mono-agonist) |
| Intended use | Laboratory research only |
Larger vials cost less per milligram but commit you to a single reconstitution event, so the size decision is really a decision about how many working aliquots your study design needs. Sizes and current pricing are listed on the semaglutide product page, and the full range sits in the GLP-1 and incretin peptides collection.
Reconstitution and storage in a lab context
Semaglutide arrives as a dry cake and is reconstituted with bacteriostatic water for most bench applications. The arithmetic is a straightforward concentration calculation, not a human instruction: a 10 mg vial brought up in 2 mL of diluent yields 5 mg/mL, which is 5,000 mcg/mL; withdrawing 0.1 mL from that solution transfers 500 mcg of peptide. Add diluent slowly down the vial wall rather than directly onto the cake, and swirl instead of shaking — mechanical agitation drives aggregation and surface denaturation in acylated peptides.
Lyophilized material is stable at minus 20 degrees Celsius, sealed and protected from light and moisture. Reconstituted solution is normally held at 2 to 8 degrees Celsius and used within the study window. Repeated freezing and thawing is the most common avoidable cause of purity loss, which is why aliquoting into single-use volumes at the point of reconstitution is standard practice. Our reconstitution guide covers the mechanics in detail.
Purity, COA and how to read it
A certificate of analysis for semaglutide should show, at minimum, an HPLC chromatogram with a main-peak area percentage, a mass spectrometry result confirming the observed mass against the theoretical 4113.58 Da, the lot number, and the analysis date. Two points are routinely misread. First, HPLC purity is a relative area measure — it tells you what fraction of the UV-absorbing material is the main peak, not how much peptide is in the vial. Net peptide content, which accounts for water and counter-ion, is the figure that governs your true concentration. Second, the lot on the certificate must match the lot on the vial label; an unmatched certificate is a marketing document. Our explainers on reading a COA and HPLC purity walk through both.
Regulatory status
Semaglutide as a pharmaceutical is an approved prescription medicine in the United States and many other jurisdictions, manufactured under pharmaceutical quality systems and dispensed under medical supervision. Research-grade semaglutide is a different thing entirely: a chemical reference material sold for laboratory investigation, labelled research use only, and not approved, formulated or permitted for administration to humans or animals. The two categories are not interchangeable in either direction. See what research use only actually means for the distinction as it stands in 2026.
Related peptides and comparisons
Researchers most often place semaglutide alongside tirzepatide, a dual GIP/GLP-1 agonist, and liraglutide, the shorter-acting palmitoylated predecessor on the same backbone — the head-to-head write-ups are semaglutide vs tirzepatide and liraglutide vs semaglutide. For multi-receptor work see retatrutide.